JP2000189887A - Method for forming double-layered coating film of car body, and car body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a double-layered coating film have good stain resistance without the necessity of car washing by using a base coating containing a polymer in which a silicate compound expressed by a specified formula is grafted onto a hydroxyl group-containing acrylic resin or a polyester resin and a melamine curing agent as resin components. SOLUTION: The base coating contains a polymer in which a silicate compound is grafted onto a hydroxyl group-containing acrylic resin or a polyester resin and a melamine curing agent resin components. The silicate compound is expressed by formula I, wherein m is an integer of 1-50; R1 is an organic group of 1-20C. An alcohol-modified silicate compound contained in a top coating clear coating is expressed by formula II, wherein n is an integer of 1-50; a part of R2 is a 2-20C alkyl and/or a 7-70C aralkyl, and the residual R2 is methyl.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to weather resistance, acid resistance,
The present invention relates to a method for forming a multi-layer coating film of an automobile body having excellent car wash-free excellent stain resistance and storage stability, and excellent recoat adhesion and water resistance by non-sand recoating (NSR), and an automobile body.

[0002]

2. Description of the Related Art A clear coating for top coating of an automobile constitutes the outermost layer of a coating film for coating an automobile body, so that in addition to storage stability, which is the minimum performance as a coating, cosmetic and weather resistance. It is required to have properties and the like as basic performance. In recent years, from the viewpoint of aesthetics for providing an excellent appearance, it is desired to maintain the aesthetics such that dirt hardly adheres and does not cause discomfort even when repeatedly used.

[0003] Usually, the outermost layer of an automobile paint film is washed by water to remove stains, and if necessary, further waxed to remove stains on the surface. In the case of a luxury car, waxing for luster is very important from the viewpoint of aesthetics.However, in the case of a practical car, for example, a commercial vehicle, it should not cause discomfort even when repeatedly used. Is important from the viewpoint of cosmetics.

Therefore, the function of preventing surface dirt from adhering without particularly removing dirt by washing with water becomes more important. In other words, if a contaminant attached to the surface is washed away by rainwater or the like and a clear coating film having a hydrophilic property necessary for making the car free from the need for removal work is provided, the user does not need to take the trouble of car washing. Therefore, there has been a demand for a clear paint having a hydrophilic property and being excellent in cosmetics for automotive top coating.

[0005] WO 94/06870 pamphlet (1994) discloses a hydroxyl-containing organic base resin containing an organosilicate and / or a condensate thereof, an amino resin crosslinking agent or a (blocked) polyisocyanate compound. A coating composition containing a crosslinking agent as a reaction-curable organic resin is disclosed. Preferred specific examples of the organosilicate include tetrahydroxysilane, tetramethoxysilane, tetraethoxysilane and the like.

[0006] JP-A-7-331165 discloses that acid /
Method for forming a topcoat film formed from a curable coating composition containing a silicon compound having at least one silanol group and / or a hydrolyzable group directly bonded to a silicon atom in one molecule in an epoxy-curable coating material Is disclosed.

[0007] Japanese Patent Application Laid-Open No. 9-220516 discloses, as a base coat paint, an aqueous resin having a tertiary amino group and / or an acid group and a compound having an epoxy group and a hydrolyzable silyl group in one molecule. A method for forming an automotive topcoat multilayer coating film by applying an aqueous coating material containing:

JP-A-10-67844 discloses a silane-treated silicate obtained by treating a polyol resin, a blocked polyisocyanate curing agent or an amino resin, and a partially hydrolyzed condensate of an alkoxysilane compound with a silane coupling agent. A thermosetting resin composition containing a condensate is disclosed. These techniques are intended to solve the above-mentioned problem relating to stain resistance by containing a silicate-based compound having a relatively low molecular weight.

Japanese Patent Application Laid-Open No. Hei 10-140077 discloses an automotive top coat in which an acid / epoxy curable coating is mixed with a low condensate of tetramethyl silicate and / or tetraethyl silicate having a degree of condensation of 2 to 10 (low condensate of silicate). A paint is disclosed. This technique also aims to solve the above-mentioned problem relating to stain resistance.

The low-condensate silicate used in this technique uses a low-condensate of tetramethyl silicate and / or tetraethyl silicate so that the number of carbon atoms of the alkoxyl group is suppressed to maintain the reactivity with water. You are. And the coating film of this coating composition, the methoxy group or ethoxy group of the silicate low-condensate, which is much present near the coating film surface, reacts with water by exposure or treatment with an acid to become a hydroxyl group. The basic principle is to exhibit high hydrophilicity due to hydroxyl groups and to exhibit contamination resistance.

However, when a low-condensate of tetramethylsilicate having only a highly reactive methoxy group is used as the low-condensate silicate, the coating film using the paint at the initial stage of storage shows high hydrophilicity and exhibits high resistance to water. It will be excellent in contamination, but if the storage period is long, in the paint,
The silicate low-condensate reacts with each other, or the silicate low-condensate reacts with the hydroxyl group in the epoxy resin, causing an increase in viscosity, resulting in a marked deterioration in storage stability, and a coating obtained from the coating after storage. The membrane does not show sufficient hydrophilicity,
There remains a problem that the stain resistance cannot be sufficiently exhibited.

When a low condensate of tetraethylsilicate having only an ethoxy group is used as the low silicate condensate, the storage stability of the coating material is relatively improved because the reactivity of the ethoxy group is lower than that of the methoxy group. The resulting coating film does not exhibit sufficient hydrophilicity, and cannot exhibit sufficient stain resistance.

When a low-condensate of tetramethyl silicate and tetraethyl silicate is used as the low silicate condensate, the silicon atom of the low silicate condensate has only a methoxy group or an ethoxy group as a functional group. A problem arises in the storage stability as a coating, and the hydrophilicity of a coating film obtained from a paint used after storage tends to be not sufficiently exhibited.

Further, since the silicate low-condensation product imparts high hydrophilicity to the surface of the coating film, there is a possibility that moisture may be taken into the coating film over time to cause whitening (white blurring), thereby deteriorating the appearance of the coating film.

In the automobile coating line, if the appearance of the coating film becomes abnormal due to the adhesion of dust or the like, the portion is polished with sandpaper or the like to partially repair the coating film, or the base is again applied in blocks of the automobile outer panel. Repainting of paints and clear paints for topcoats has been performed.

In such a case, before the recoating, the coated (first coat) clear coating film is polished, and a new (second coat) base coating material and top clear coating material are applied again. In comparison with the above, when a new (second coat) base paint and a top clear paint are re-applied without polishing the painted (first coat) clear paint film, the first coat clear paint is applied. It is known that the adhesion between the film and the base coat of the second coat is generally inferior when the first clear coat is not polished.

As described above, if the first coat of the clear coating is not polished, the adhesion of the second coat of the base coat is inferior. Thus, the first coat of the clear coat is usually polished. Recoating of the second coat of the base paint and the clear coat for top coating has been performed.

When the second coat base paint and the top coat clear paint are reapplied without polishing the first coat clear coat, if the adhesion of the second coat base coat is not inferior, Since the labor for polishing the first coat of clear coating is eliminated and the cost of repairing or repainting in the automobile coating line is reduced, the base coat and top coat of the second coat without polishing the first coat of clear coat are eliminated. To improve the adhesion (also referred to as “NSR property” in the present specification) of the second coating film when re-applying the clear paint for application (also referred to as “Non-Sandry coat (NSR)” in the present specification) Was desired.

In order for a vehicle body to exhibit stain resistance by repairing or repainting in an automobile coating line, it is necessary to use both the base paint and the clear coating for top coating with the above-mentioned technique.

However, in this case, the base coat of the second coat contains a silicate compound having a relatively low molecular weight, so that the initial adhesion at the time of NSR is sufficient, Because it is inferior in nature,
Water resistance is remarkably poor, and blisters and blisters may be generated in the coating film.

Judging comprehensively from these considerations, if a method for forming a multilayer coating film for an automobile body is obtained, which has excellent adhesion with the first coating film over time and excellent water resistance in NSR properties, A high quality repaired or repainted vehicle body can be obtained.

[0022]

SUMMARY OF THE INVENTION In view of the above situation, the present invention has basic performances such as weather resistance and acid resistance, has excellent car wash-free stain resistance, and has insufficient storage stability. It is an object of the present invention to provide a method for forming a multilayer coating film on an automobile body which does not cause any problem and is excellent in NSR property and water resistance, and to provide an automobile body using the same.

[0023]

According to the present invention, a base paint containing a color pigment and / or a brilliant pigment is applied to a painted automobile outer panel, and a clear top paint is applied wet-on-wet. A method for forming a multilayer coating film for an automobile body, which is followed by heating and curing, wherein the base paint is obtained by grafting a silicate compound (A) to a hydroxyl group-containing acrylic resin or polyester resin, and a melamine-based resin. A curing agent is used as a resin component, and the graft amount of the silicate compound (A) is 0.1 to 50% by weight (in terms of solid content) based on the total amount of the resin component.
The clear coating for top coating is an acid / epoxy-curable clear coating or a melamine-curable clear coating, and the clear coating for top coating contains no alcohol-modified silicate compound (IV) or silicate graft polymer (V), Or the above, wherein the clear coating for overcoating comprises the alcohol-modified silicate compound (IV)
And when the silicate graft polymer (V) is not contained, at least one of the resin components of the acid / epoxy-curable clear paint or the melamine-curable clear paint grafts the silicate compound (A). The silicate graft polymer (V) is obtained by grafting the silicate compound (A) on the hydroxyl group-containing polymer (Va), and comprises the alcohol-modified silicate compound (IV) And / or the graft amount of the silicate compound (A) is 0.1 to 30% by weight (in terms of solid content) based on the total amount of the resin components, and the silicate compound (A) is represented by the general formula ( 1);

[0024]

Embedded image

(Wherein, m represents an integer of 1 to 50. R
¹ may represent a different one, and represents a substituted or unsubstituted organic group having 1 to 20 carbon atoms. )
Wherein the alcohol-modified silicate compound (IV) is represented by the general formula (2):

[0026]

Embedded image

(Wherein, n represents an integer of 1 to 50. R
^Two Some of them have a substituent or have a substituent.
C2-C20 alkyl group and / or substituent not having
Or having 7 to 20 carbon atoms having no substituent
Represents an aralkyl group, and the remaining R ^Two Represents a methyl group
You. ) The formation of multilayer coatings on automobile bodies
Is the way.

The present invention also relates to an automobile body coated with a multilayer coating film, wherein the multilayer coating film is formed by the method for forming a multilayer coating film for an automobile body according to the present invention. But also. Hereinafter, the present invention will be described in detail.

In the method for forming a multilayer coating film of an automobile body according to the present invention, a base coating material containing a color pigment and / or a brilliant pigment is applied on a painted automobile outer plate, and then a clear top coating material is wet-on. It consists of heating and hardening after wet coating.

The above-mentioned coated automobile outer panel is not particularly limited. For example, an undercoating layer (electrodeposition coating layer or, if necessary, an intermediate coating layer) is formed on the automobile outer panel, After coating the base paint containing pigment and / or brilliant pigment, apply a clear coating for top coating wet-on-wet and then heat and cure, or form an undercoat coating layer on the outer panel of the automobile And then apply a solid paint containing a color pigment and heat-cure, or apply a base paint and clear paint wet-on-wet and heat-cure, then apply a clear top paint dry-on-wet And then heat-curing.

The undercoat film layer (electrodeposited film layer or, if necessary, the intermediate coat film layer) on the painted automobile outer panel is formed by a method usually used as a method for forming a multilayer paint film on an automobile body. The base paint and the clear coating for top coating are not particularly limited, and include, for example, those usually used as a method for forming a multilayer coating film of an automobile body, and the like. As the heat curing method, a method usually used as a method for forming a multilayer coating film of an automobile body can be used. Further, as the above-mentioned clear paint for top coating on the painted automobile outer panel, a clear paint for top coating used in the present invention described below can also be used.

The color pigment is not particularly restricted but includes, for example, azochelate pigments, insoluble azo pigments, condensed azo pigments, phthalocyanine pigments, indigo pigments, perinone pigments, perylene pigments, dioxane pigments, quinacridone pigments. Organic pigments such as pigments, isoindolinone pigments and metal complex pigments; inorganic pigments such as yellow salt, yellow iron oxide, red iron oxide, carbon black and titanium dioxide; extender pigments such as calcium carbonate, barium sulfate, clay and talc And the like. These may be used alone or in combination of two or more.

The glitter pigment is not particularly limited.
For example, aluminum powder, copper powder, nickel powder, stainless steel powder, mica powder, interference mica powder, colored mica powder, alumina flake, graphite flake and the like can be mentioned. These may be used alone or in combination of two or more.

The base paint used in the present invention is one obtained by grafting a silicate compound (A) to a hydroxyl group-containing acrylic resin or polyester resin, and one containing a melamine-based curing agent as a resin component.

The hydroxyl group-containing acrylic resin can be obtained by copolymerizing a hydroxyl group-containing acrylic monomer and another ethylenically unsaturated group-containing monomer by a usual method.

The hydroxyl group-containing acrylic monomer is not particularly restricted but includes, for example, 2-hydroxyethyl (meth)
Hydroxyalkyl (meth) acrylates such as acrylate, 2-hydroxypropyl (meth) acrylate and 4-hydroxybutyl methacrylate;
M-1 (trade name, adduct of 2-hydroxyethyl (meth) acrylate and polycaprolactone, manufactured by Daicel Chemical Industries, Ltd.); and polyalkylene glycol mono (meth) acrylates. These may be used alone or in combination of two or more. In this specification, (meth) acrylate means acrylate and / or
Or methacrylate.

The other ethylenically unsaturated group-containing monomer is not particularly restricted but includes, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate,
alkyl (meth) acrylates such as i-butyl (meth) acrylate, t-butyl acrylate, 2-ethylhexyl (meth) acrylate, and lauryl (meth) acrylate; aromatic vinyl monomers such as styrene and vinyltoluene; Epoxy group-containing monomers such as glycidyl (meth) acrylate; amino group-containing monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate; (meth) acrylamide, N-ethyl (meth) Acrylamide monomers such as acrylamide, N, N-butoxymethyl (meth) acrylamide and N-methylacrylamide; acrylonitrile, vinyl acetate, acrylic acid, methacrylic acid and the like. These may be used alone or in combination of two or more.

The polyester resin can be obtained by polycondensing an acid component containing a polyhydric carboxylic acid as a main component and an alcohol component containing a polyhydric alcohol as a main component by a usual method.

The acid component is not particularly restricted but includes, for example, terephthalic acid, isophthalic acid, phthalic acid and their anhydrides; 2,6-naphthalenedicarboxylic acid, 2,7-
Aromatic dicarboxylic acids such as naphthalenedicarboxylic acid and anhydrides thereof; aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and anhydrides thereof; lactones such as γ-butyrolactone and ε-caprolactone; aromatic oxymonocarboxylic acids such as p-oxyethoxybenzoic acid; trivalent or higher polycarboxylic acids such as trimellitic acid, trimezic acid, and pyromellitic acid; Corresponding hydroxycarboxylic acids and the like can be mentioned. These may be used alone or in combination of two or more.

The alcohol component is not particularly restricted but includes, for example, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,5-hexanediol, diethylene glycol and triethylene glycol. Glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, bisphenol A alkylene oxide adduct, bisphenol S alkylene oxide adduct; 1,2-propanediol, neopentyl glycol, 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, 2,3-pentanediol, 1,4-pentanediol, 1,4-hexanediol, 2,5-hexanediol, 3-methyl-1,5-pentane Diol,
Aliphatic glycols having a side chain such as 1,2-dodecanediol and 1,2-octadecanediol; trihydric or higher polyhydric alcohols such as trimethylolpropane, glycerin and pentaerythritol; These may be used alone or in combination of two or more.

The hydroxyl group-containing acrylic resin or the polyester resin has an acid value of 100 mgKOH / g or less, a hydroxyl value of 5 to 200 mgKOH / g, a number average molecular weight (Mn) of 500 to 30,000, and a glass transition. The temperature (Tg) is between -20C and 60C.

When the acid value exceeds 100 mgKOH / g,
The viscosity of the hydroxyl group-containing acrylic resin and the polyester resin is too high to make handling difficult, and it is difficult to obtain a high solid content thermosetting resin paint. Hydroxyl value is 5mgKO
If it is less than H / g, the curability of the coating will be insufficient, and the graft efficiency and amount of the silicate compound (A) will be limited. If it exceeds 200 mgKOH / g, the water resistance of the coating film will decrease. When the number average molecular weight (Mn) is less than 500, the strength of the coating film decreases or the water resistance of the coating film decreases, and when it exceeds 30,000, the viscosities of the hydroxyl group-containing acrylic resin and the polyester resin become too high. Handling becomes difficult, and it is difficult to become a high solid content thermosetting resin paint. When the glass transition temperature (Tg) is less than -20 ° C, the coating film becomes soft, and when it exceeds 60 ° C, the coating film tends to be non-uniform, and the coating film becomes too hard, which tends to cause cracks. .

Preferably, the acid value is 2 to 50 mgKOH /
g, the hydroxyl value is 30 to 200 mgKOH / g, the number average molecular weight (Mn) is 500 to 25,000, and the glass transition temperature (Tg) is 0 ° C to 40 ° C. In this specification, the acid value and the hydroxyl value are values in terms of solid content, and the number average molecular weight (Mn) is the number average molecular weight in terms of polystyrene measured by GPC (gel permeation chromatography).

The melamine-based curing agent is an amino resin and / or a blocked polyisocyanate compound. The amino resin is not particularly limited, for example, melamine resin, benzoguanamine resin, glycoluril resin,
Urea resins and the like can be mentioned. These may be used alone or in combination of two or more. Among these, melamine resins and benzoguanamine resins are common.

The melamine resin can be alkyl-etherified into an alkyl-etherified melamine resin, and among them, a melamine resin substituted with a methoxy group and / or a butoxy group is preferable.

As the melamine resin substituted with the methoxy group and / or butoxy group, those having a methoxy group alone include Cymel 325, Cymel 327,
Cymel 370, mixed types of methoxy and butoxy groups include Cymel 202, Cymel 204, Cymel 232, Cymel 235, Cymel 236, Cymel 238, Cymel 254, Cymel 266, Cymel 2
67 (all trade names, manufactured by Mitsui Cytec Co., Ltd.).
(Trade name, manufactured by Mitsui Cytec), Uban 20N6
0, Uban 20SE (both trade names, manufactured by Mitsui Chemicals, Inc.) and the like. These may be used alone,
More than one species may be used in combination. In addition, the benzoguanamine resin described above can be similarly substituted.

The above blocked polyisocyanate compound is obtained by blocking a polyisocyanate compound with a blocking agent. The polyisocyanate compound is
It is not particularly limited as long as it is a compound having at least two isocyanate groups in the molecule, for example, aliphatic diisocyanates such as hexamethylene diisocyanate (HMDI) and trimethylhexamethylene diisocyanate (TMDI); isophorone diisocyanate (IPDI) Alicyclic diisocyanates; aromatic diisocyanates such as xylylene diisocyanate (XDI); aromatic diisocyanates such as tolylene diisocyanate (TDI) and 4,4-diphenylmethane diisocyanate (MDI); dimer acid diisocyanate (DD)
I), hydrogenated TDI (HTDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12M
Hydrogenated diisocyanates such as DI); dimers and trimers of these diisocyanate compounds; and polyisocyanates having a higher molecular weight; addition to polyhydric alcohols such as trimethylolpropane or water, or low-molecular-weight polyester resins Objects and the like. These may be used alone or in combination of two or more.

The blocking agent is not particularly limited.
For example, oximes such as methyl ethyl ketoxime, acetoxime, cyclohexanone oxime, acetophenone oxime and benzophenone oxime; phenols such as m-cresol and xylenol; methanol, ethanol, butanol, 2-ethylhexanol, cyclohexanol, ethylene glycol monoethyl ether and the like Alcohols; lactams such as ε-caprolactam; diketones such as diethyl malonate and acetoacetate; mercaptans such as thiophenol; ureas such as thiourea; imidazoles; and carbamic acids. These may be used alone or in combination of two or more.

The method for blocking the polyisocyanate compound with the above-mentioned blocking agent is not particularly limited, and examples thereof include a method in which the reaction is carried out by a usual method until the free isocyanate group disappears.

As the above-mentioned block polyisocyanate compound, commercially available products can be used. For example, Desmodur series (trade name, manufactured by Sumitomo Bayer Urethane Co., Ltd.) and Burnock D series (trade name, manufactured by Dainippon Ink and Chemicals, Inc.) , Takenate B series (trade name, manufactured by Takeda Pharmaceutical Company), Coronate 2500 series (trade name,
Manufactured by Nippon Polyurethane Industry Co., Ltd.). Among these, those blocked with an oxime, lactam or diketone are preferred.

The base coating material used in the present invention is preferably blended so as to contain an isocyanate group equivalent to or more than the hydroxyl value of the hydroxyl group-containing acrylic resin or the polyester resin. Specifically, the blending of the melamine-based curing agent is such that the weight ratio of the hydroxyl-containing acrylic resin or the polyester resin to the melamine-based curing agent is 8/2 to 5/5, preferably 7/5.
It is preferably 3 to 6/4. In the case of a polyisocyanate compound, a compounding amount in the range of 0.8 to 1.5 times the equivalent of the hydroxyl value may be used. If the equivalent of the hydroxyl value is less than 0.8 times, the curability of the coating is not sufficient,
Only a soft coating film is obtained, and not only the hardness but also the chemical resistance and stain resistance of the coating film are reduced. If the coating film exceeds 1.5 times, not only the effect of adding the polyisocyanate compound is not obtained. In addition, the strength, hardness, workability, chemical resistance and the like of the coating film are reduced, and yellowing and weather resistance are also apt to be reduced. Preferably,
It is 1.0 to 1.2 times.

The base paint is obtained by grafting the silicate compound (A) to the above-mentioned hydroxyl-containing acrylic resin or the above-mentioned polyester resin, and the above-mentioned melamine-based curing agent as a resin component. It is sufficient that a part of the acrylic resin or the polyester resin is grafted with the silicate compound (A), and it is not necessary that the whole is grafted with the silicate compound (A).

The graft amount of the silicate compound (A) in the base paint is 0.1 to 0.1% based on the total amount of the resin components described above.
50% by weight. When the amount of the silicate compound (A) is less than 0.1% by weight, the hydrophilicity of the coating film is not sufficiently exhibited, and the stain resistance is poor. When the amount exceeds 50% by weight, the appearance of the coating film is excellent. It may not have sufficient water resistance to maintain the water resistance. Preferably it is 3 to 25% by weight, more preferably 5 to 20% by weight. The above weight% is
It is a value in terms of solid content.

The clear top coating used in the present invention is an acid / epoxy-curable clear coating or a melamine-curable clear coating. The acid / epoxy curable clear coating composition preferably contains a half-ester acid group-containing acrylic copolymer (I) and an epoxy group-containing acrylic copolymer (II) as resin components.

The half-ester acid group-containing acrylic copolymer (I) comprises an acid anhydride group-containing radical polymerizable monomer (Ia) and another radical polymerizable monomer (Ib).
And a half-esterification of the acid anhydride group with a low molecular weight alcohol-based compound after obtaining a copolymer.

As the acid anhydride group-containing radical polymerizable monomer (Ia), an acid anhydride group-containing radical polymerizable monomer for obtaining the half ester acid group-containing acrylic copolymer (I) can be used. It is not particularly limited as long as it is a suitable monomer, and examples thereof include itaconic anhydride, maleic anhydride, and citraconic anhydride. These may be used alone,
More than one species may be used in combination.

The other radical polymerizable monomers (I-
b) is not particularly limited, and includes, for example, those similar to the above-mentioned hydroxyl group-containing acrylic monomer and other ethylenically unsaturated group-containing monomers.

The acid anhydride group-containing radical polymerizable monomer (Ia) and the other radical polymerizable monomer (I-
b) in the copolymer composition when obtaining a copolymer by
The above acid anhydride group-containing radical polymerizable monomer (Ia)
Is 10 to 40% by weight, especially 15% by weight, based on the total monomer weight.
~ 30% by weight is preferred.

The copolymerization method is not particularly limited.
For example, it can be performed by solution polymerization such as ordinary radical polymerization. Number average molecular weight (Mn) of the copolymer
Is preferably from 500 to 10,000, particularly preferably from 1,000 to 8,000. If the number average molecular weight (Mn) is less than 500, the curability of the coating is not sufficient, and if it exceeds 10,000, the viscosity of the copolymer becomes high, making it difficult to obtain a high solid content thermosetting coating.

The acid anhydride group in the copolymer is
It contains at least two in one molecule. If the number is less than 2, the curability is insufficient. Preferably 2
There are fifteen.

The above half esterification is performed after obtaining the above copolymer. The half-esterifying agent used for half-esterifying the acid anhydride group is not particularly limited as long as it is a low-molecular-weight alcohol compound. For example, methanol, ethanol, n-propanol, i-
Propanol, n-butanol, i-butanol, t-
Butanol, methyl cellosolve, ethyl cellosolve, dimethylaminoethanol, diethylaminoethanol,
Acetol, allyl alcohol, propargyl alcohol and the like can be mentioned. These may be used alone or in combination of two or more. Among these, particularly preferred compounds are acetol, allyl alcohol, propargyl alcohol and methanol.

The reaction method of the above half esterification is not particularly limited, and for example, the half esterification can be performed at a temperature of from room temperature to 120 ° C. in the presence of a catalyst according to a usual method.
The catalyst is not particularly limited, and includes, for example, tertiary amines such as triethylamine and tributylamine; and quaternary ammonium salts such as benzyltrimethylammonium chloride, benzyltrimethylammonium bromide, benzyltributylammonium chloride, and benzyltributylammonium bromide. Is mentioned. These may be used alone or in combination of two or more.

The epoxy group-containing acrylic copolymer (I)
I) is an epoxy group-containing radical polymerizable monomer (II-
a) 30 to 70 parts by weight, 10 to 50 parts by weight of a hydroxyl group-containing radically polymerizable monomer (II-b), and 20 to 60 parts by weight of another radically polymerizable monomer (II-c) It is a copolymer obtained by the above.

The epoxy group-containing radical polymerizable monomer (II-a) is not particularly restricted but includes, for example, (meth)
Glycidyl acrylate, 3,4-epoxycyclohexanylmethyl methacrylate and the like can be mentioned. These may be used alone or in combination of two or more.

The hydroxyl group-containing radical polymerizable monomer (II)
-B) is not particularly limited, and includes, for example, those similar to the above-mentioned hydroxyl group-containing acrylic monomer. The other radical polymerizable monomer (II-c) is not particularly limited, and includes, for example, those similar to the above-mentioned other ethylenically unsaturated group-containing monomers.

The epoxy group-containing acrylic copolymer (I)
I) is obtained by copolymerization with the above-mentioned radical polymerizable monomer and radical polymerization initiator. The copolymerization method is not particularly limited, and can be carried out by solution polymerization such as ordinary radical polymerization.
The polymerization can be performed at 140 ° C. for a polymerization time of 3 to 8 hours.

The radical polymerization initiator is not particularly restricted but includes, for example, t-butylperoxy-2-ethylhexanoate, dimethyl-2,2'-azobisisobutyrate and the like. These may be used alone,
Two or more kinds may be used in combination. The radical polymerization initiator is preferably used in an amount of 3 to 15% by weight based on the total amount of the above-mentioned monomers. A chain transfer agent or the like may be added as an additive to the copolymerization.

The epoxy group-containing acrylic copolymer (I)
I) has a number average molecular weight (Mn) of 1,000 to 8,000, has 2 to 10 epoxy groups in the molecule, and 2 to 12 hydroxyl groups, and has an epoxy equivalent of 100 to 8,000.
800 and a hydroxyl value of 5 to 200 mgKOH / g. When the epoxy equivalent is less than 100, the cured coating film becomes too hard and the weather resistance is deteriorated. When it exceeds 800, the curability of the coating becomes insufficient. The hydroxyl value is 5
When the amount is less than mgKOH / g, the adhesion is poor and the
If it exceeds gKOH / g, the cured coating film has insufficient water resistance. Preferably, it has 3 to 8 epoxy groups and 4 to 10 hydroxyl groups in the molecule, and has an epoxy equivalent of 200 to 600 and a hydroxyl value of 10 to 150 m.
gKOH / g. In this specification, the epoxy equivalent is a value in terms of solid content.

The acid / epoxy curable clear coating used in the present invention preferably further comprises a carboxyl group-containing polyester resin (III) as a resin component. The above carboxyl group-containing polyester resin (III)
Is obtained by half-esterifying a polyester polyol obtained by adding a lactone compound to a low molecular weight polyhydric alcohol and performing a chain extension reaction with an acid anhydride group-containing compound.

Since the carboxyl group-containing polyester resin (III) has a sharp molecular weight distribution, by using the carboxyl group-containing polyester resin (III) as a resin component, the clear top coating for the present invention can be used. High solid differentiation (high solidification) becomes possible, and a coating film having excellent weather resistance and water resistance can be obtained, and at the same time, a coating film having excellent chipping resistance and skin appearance can be obtained.

The low-molecular-weight polyhydric alcohol is not particularly limited. For example, those having at least three hydroxyl groups in one molecule are preferable, and trimethylolpropane, trimethylolethane, 1,2,4-butanetriol,
Examples include ditrimethylolpropane, pentaerythritol, dipentaerythritol, glycerin and the like. These may be used alone or in combination of two or more.

The lactone compound may be any cyclic compound which has an oxygen atom in the ring, reacts with a nucleophile, opens the ring, and generates a hydroxyl group at the terminal. Since the ring-opening addition reaction easily occurs, the lactone compound has 4 to 7 carbon atoms.
Are preferred.

The lactone compound is not particularly restricted but includes, for example, ε-caprolactone, γ-caprolactone, γ-valerolactone, δ-valerolactone, γ-butyrolactone and the like. These may be used alone or in combination of two or more. Among these, ε
-Caprolactone, γ-valerolactone and γ-butyrolactone are preferred.

The above chain elongation reaction can be carried out under the same conditions as in a usual ring opening addition reaction. For example, the polyester polyol in which the low-molecular-weight polyhydric alcohol is chain-extended can be obtained by reacting in a suitable solvent or without a solvent at a temperature of 80 to 200 ° C. within 5 hours. At this time, a tin-based catalyst or the like may be used.

In the above chain extension reaction, the molar amount of the lactone compound is 0.2 to 10 times the molar amount of the hydroxyl group of the low molecular weight polyhydric alcohol. When the molar amount of the lactone compound is less than 0.2 times the molar amount of the hydroxyl group of the low molecular weight polyhydric alcohol, the coating film becomes hard and the impact resistance of the coating film decreases, and exceeds 10 times the molar amount. In this case, the hardness of the coating film decreases. The amount is preferably 0.25 to 5 times, more preferably 0.3 to 3 times.

The carboxyl group-containing polyester resin (III) has an acid value of 50 to 350 mgKOH / g, a number average molecular weight (Mn) of 400 to 3,500,
Weight average molecular weight (Mw) / number average molecular weight (Mn) is 1.
8 or less. If the acid value is less than 50, the curability of the coating will be insufficient, and if the acid value exceeds 350, the viscosity of the carboxyl group-containing polyester resin (III) will be too high, resulting in a high solid content thermosetting coating. Hateful. Molecular weight 40
When it is less than 0, the curability of the coating material is insufficient or the water resistance of the coating film is reduced, and when the molecular weight exceeds 3500, the viscosity of the carboxyl group-containing polyester resin (III) becomes too high and handling becomes difficult, It is difficult to become a high solid content thermosetting paint. Weight average molecular weight (Mw) / number average molecular weight (M
When n) exceeds 1.8, the water resistance or weather resistance of the coating film decreases.

Preferably, the acid value is 100 to 300 mgK
OH / g and a number average molecular weight (Mn) of 500 to 25
00, and the weight average molecular weight (Mw) / number average molecular weight (Mn) is 1.5 or less. More preferably, the acid value is 150 to 250 mgKOH / g, the number average molecular weight (Mn) is 700 to 2000, and the weight average molecular weight (Mw) / number average molecular weight (Mn) is 1.35 or less.

The method for half-esterification of the polyester polyol with the acid anhydride group-containing compound is not particularly limited. For example, the polyester polyol and the acid anhydride group-containing compound are reacted according to a conventional method. It can be carried out at a temperature from room temperature to 150 ° C. under normal pressure.

The above-mentioned acid anhydride group-containing compound is not particularly restricted but includes, for example, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, trimellitic anhydride, succinic anhydride. And the like. These may be used alone or in combination of two or more.

In general, the molar amount of the acid anhydride group of the acid anhydride group-containing compound is 0.2 to 1.0 times, preferably 0.5 to 1.0 times the molar amount of the hydroxyl group of the polyester polyol.
Preferably, the amount is 0.9 times. If the molar amount of the acid anhydride group of the acid anhydride group-containing compound is less than 0.2 times the molar amount of the hydroxyl group of the polyester polyol, the curability of the coating will be insufficient.

However, it is not necessary to modify all the hydroxyl groups of the polyester polyol to carboxyl groups, and the hydroxyl groups may be left. That is, since the carboxyl group-containing polyester resin (III) having a hydroxyl group simultaneously provides a carboxyl group and a hydroxyl group on the surface of a coating film, for example, when recoated, the carboxyl group-containing polyester resin having no hydroxyl group is used. Compared to (III),
Excellent adhesion can be provided.

When the carboxyl group-containing polyester resin (III) has a hydroxyl group, the carboxyl group-containing polyester resin (III) has a hydroxyl value of 150 mgKOH / g or less. Hydroxyl value is 150m
If it exceeds gKOH / g, the water resistance of the coating film will decrease. Preferably, it is 5 to 100 mgKOH / g, more preferably 10 to 80 mgKOH / g.

The carboxyl group-containing polyester resin (III) having a hydroxyl group and a carboxyl group is
As described later, the epoxy group-containing acrylic copolymer (I
I), alcohol-modified silicate compound (IV), and a polymer obtained by grafting silicate compound (A) can react with and bind to the polymer, so that a stronger coating film can be obtained.
In this case, those having an average of 0.1 or more hydroxyl groups in one molecule are preferable.

The carboxyl group-containing polyester resin (III) is preferably contained in an amount of 5 to 70% by weight based on the total amount of the resin components. If it is less than 5% by weight, it becomes difficult to obtain a high solid content thermosetting paint, and if it exceeds 70% by weight, the weather resistance of the coating film is reduced. Preferably, it is 5 to 50% by weight, more preferably 10 to 40% by weight. In addition, the said weight% is a value of solid content conversion.

In the resin component in the acid / epoxy-curable clear coating composition used in the present invention, [the total number of epoxy groups in the epoxy group-containing acrylic copolymer (II)] / [the half ester acid group-containing acrylic copolymer] (I) and the total number of half-esterified acid anhydride groups and carboxyl groups of the carboxyl group-containing polyester resin (III)] = 0.5 to 1.5, particularly preferably 0.6 to 1.3. Also, [total number of hydroxyl groups in the epoxy group-containing acrylic copolymer (II)] / [total number of half-esterified acid anhydride groups in the half-ester acid group-containing acrylic copolymer (I)] = 0.1 ~ 1.5, especially 0.3 ~ 1.2
It is preferred that

Specifically, the amount of the epoxy group-containing acrylic copolymer (II) giving such a ratio is, for example, the half ester acid group-containing acrylic copolymer (I) and the carboxyl group-containing acrylic copolymer (I). It is preferably 50 to 250 parts by weight, particularly preferably 80 to 150 parts by weight, based on 100 parts by weight of the polyester resin (III) in total. If the amount of the epoxy group-containing acrylic copolymer (II) is less than 50 parts by weight, the coating film is not sufficiently cured, and the water resistance and weather resistance of the cured coating film are reduced. If the amount exceeds the above range, unreacted carboxyl groups remain and the chemical resistance decreases.

The melamine-curable clear coating used in the present invention preferably contains 30 to 85% by weight of a hydroxyl group-containing acrylic resin and 15 to 70% by weight of a melamine-based curing agent as resin components.

Examples of the hydroxyl group-containing acrylic resin and the melamine-based curing agent include the same ones as described above. The hydroxyl group-containing acrylic resin has a number average molecular weight (Mn) of 800 to 8000 and a hydroxyl value of 30 to 200.
It is preferably of mg KOH / g.

The first form of the clear top coating used in the present invention is an alcohol-modified silicate compound (I)
V) and the silicate graft polymer (V). In this case, at least one of the resin components of the acid / epoxy-curable clear coating or the melamine-curable clear coating is obtained by grafting the silicate compound (A).

That is, when the alcohol-modified silicate compound (IV) and the silicate graft polymer (V) are not contained, the acid / epoxy-curable clear coating or the melamine-curable clear coating resin component By at least one of which is obtained by grafting the silicate compound (A), it is intended to impart stain resistance to the clear top coating used in the present invention.

In the first embodiment, when the acid / epoxy curable clear coating is used, (1) the half ester acid group-containing acrylic copolymer (I) is grafted with the silicate compound (A). And
When the epoxy group-containing acrylic copolymer (II) is not a product obtained by grafting the silicate compound (A), (2) the half ester acid group-containing acrylic copolymer (I) is used as the silicate compound (A). Is not grafted, but the epoxy group-containing acrylic copolymer (II) is grafted with the silicate compound (A). (3) The half ester acid group-containing acrylic copolymer There may be mentioned, for example, a case where both the union (I) and the epoxy group-containing acrylic copolymer (II) are obtained by grafting the silicate compound (A).

When the melamine-curable clear coating is used, there may be mentioned a case where the hydroxyl-containing acrylic resin is obtained by grafting the silicate compound (A).

When the acid / epoxy curable clear coating is used, a part of the half-ester acid group-containing acrylic copolymer (I) and / or the epoxy group-containing acrylic copolymer (II) is partially used. It is sufficient that the above silicate compound (A) is grafted. It is not necessary that all of the copolymer is grafted with the above silicate compound (A). It is sufficient that a part of the contained acrylic resin is grafted with the silicate compound (A), and it is not necessary that all of the acrylic resin is grafted with the silicate compound (A).

In these cases, the alcohol-modified silicate compound (IV) and the silicate graft polymer (V) do not need to be contained, which is preferable in that the production process is simplified. When the acid / epoxy-curable clear coating composition is used, when the silicate compound (A) is grafted on the half-ester acid group-containing acrylic copolymer (I), the half-ester acid group-containing acrylic copolymer is used. In the production of coalescence (I),
It is preferable that the above-mentioned hydroxyl group-containing acrylic monomer is copolymerized to contain a hydroxyl group.

In the first embodiment, when the acid / epoxy-curable clear coating is used, the half-ester acid group-containing acrylic copolymer (I) is crosslinked with the grafted silicate compound (A). From the viewpoint that the crosslinking density is improved by the reaction, the epoxy group-containing acrylic copolymer (II) is preferably obtained by grafting the silicate compound (A).

The second form of the clear top coating used in the present invention is a case containing the alcohol-modified silicate compound (IV) or the silicate graft polymer (V). In this case, the silicate graft polymer (V) is obtained by grafting the silicate compound (A) to the hydroxyl group-containing polymer (Va).

In this case, when the acid / epoxy curable clear coating is used, the half ester acid group-containing acrylic copolymer (I) and the epoxy group-containing acrylic copolymer (II) are It may be one obtained by grafting the silicate compound (A) or not one obtained by grafting the silicate compound (A).

That is, in the second embodiment containing the alcohol-modified silicate compound (IV) or the silicate graft polymer (V), when the acid / epoxy curable clear coating material is used, (1) The half ester acid group-containing acrylic copolymer (I) is obtained by grafting the silicate compound (A), and the epoxy group-containing acrylic copolymer (II) is obtained by grafting the silicate compound (A). (2) The half-ester acid group-containing acrylic copolymer (I) is not obtained by grafting the silicate compound (A), but the epoxy group-containing acrylic copolymer (II) is When the silicate compound (A) is grafted, (3) the half ester acid group-containing acrylic copolymer (I) and the epoxy resin In the case where both the acrylic copolymer (II) containing a silicone group is obtained by grafting the above silicate compound (A), (4) the acrylic copolymer (I) containing a half ester acid group and the acrylic copolymer containing an epoxy group There may be mentioned, for example, a case where both the copolymers (II) are not obtained by grafting the silicate compound (A).

When the melamine-curable clear paint is used, the hydroxyl group-containing acrylic resin is as follows:
The case where the above-mentioned silicate compound (A) is grafted, the case where (2) the above-mentioned silicate compound (A) is not grafted, etc. can be mentioned.

When the acid / epoxy curable clear coating is used, the half-ester-acid-group-containing acrylic copolymer (I) and / or the epoxy-group-containing acrylic copolymer (II) are mixed with the silicate compound. When it is obtained by grafting (A), a part of the half-ester acid group-containing acrylic copolymer (I) and / or the epoxy group-containing acrylic copolymer (II) is partially converted to the silicate compound (A). It is not necessary that all of the copolymer is grafted with the silicate compound (A). When the melamine-curable clear coating material is used, the hydroxyl group-containing acrylic resin is converted into the silicate compound. When the compound (A) is grafted, a part of the hydroxyl group-containing acrylic resin is converted to the silicate compound (A). And it is not necessary that all of them are grafted with the silicate compound (A).

When the acid / epoxy curable clear coating composition further contains the carboxyl group-containing polyester resin (III) as a resin component, the carboxyl group-containing polyester resin (III) )
Can be grafted with the above silicate compound (A).

In any of the first and second embodiments constituting the clear top coating used in the present invention, any of the resin components is obtained by grafting the silicate compound (A). And / or contains the above-mentioned alcohol-modified silicate compound (IV) or the above-mentioned silicate graft polymer (V).

The silicate graft polymer (V) used in the present invention is obtained by grafting a silicate compound (A) to a hydroxyl group-containing polymer (Va). The hydroxyl group-containing polymer (Va) is not particularly limited as long as it is a polymer containing a hydroxyl group, and examples thereof include a hydroxyl group-containing acrylic resin, a hydroxyl group-containing polyester resin, and a hydroxyl group-containing alkyd resin. These may be used alone,
Two or more kinds may be used in combination. The hydroxyl group-containing acrylic resin is not particularly limited, and examples thereof include the same ones as described above.

The above-mentioned hydroxyl group-containing polyester resin and hydroxyl group-containing alkyd resin are not particularly limited.
Examples of the polyester resin include those obtained by using a semi-dry oil, a non-dry oil, or the like as necessary in the polycondensation thereof.

The semi-dry oil is not particularly limited, and includes, for example, soybean oil, safflower oil, tall oil and the like. The non-drying oil is not particularly limited, and examples thereof include coconut oil, castor oil and the like. These may be used alone or in combination of two or more. The hydroxyl group-containing polyester resin and the hydroxyl group-containing alkyd resin have an oil length of 40% or less. Preferably, the oil length is 30% or less.

The hydroxyl group-containing polymer (Va) may further have a carboxyl group, an epoxy group or the like as long as it has a hydroxyl group. The hydroxyl group-containing polymer (Va)
Preferably has a hydroxyl value of 20 to 200 mgKOH / g and a number average molecular weight (Mn) of 500 to 10,000.

When the hydroxyl value is less than 20 mgKOH / g, the grafting efficiency and the amount of grafting are limited, and the
If it exceeds gKOH / g, the water resistance of the coating film will decrease. When the number average molecular weight (Mn) is less than 500, the strength of the coating film decreases, and when it exceeds 10,000, the viscosity of the coating material increases, and the appearance deteriorates. Preferably, the hydroxyl value is 40-1.
50, and the number average molecular weight is 800 to 8000.

The amount of the alcohol-modified silicate compound (IV) and / or the amount of grafting of the silicate compound (A) in the clear top coating is determined based on the total amount of the above-mentioned resin components. And / or 0.1 to 30% by weight as the total amount of the silicate compound (A). If the amount of the alcohol-modified silicate compound (IV) and / or the silicate compound (A) is less than 0.1% by weight, the hydrophilicity of the coating film is not sufficiently exhibited, the stain resistance is poor, and the weight is 30%. %
When it exceeds, the coating film may not have sufficient water resistance to maintain excellent appearance. Preferably 3 to 25% by weight
And more preferably 5 to 20% by weight. In addition,
The weight% is a value in terms of solid content, and the total amount of the resin component is an amount including the hydroxyl group-containing polymer (Va) when the silicate graft polymer (V) is included.

The silicate compound (A) used in the present invention has the general formula (1):

[0110]

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This is represented by: The above general formula (1)
In the formula, m represents an integer of 1 to 50. R ¹ may represent a different one, and represents a substituted or unsubstituted organic group having 1 to 20 carbon atoms.

In the general formula (1), when m exceeds 50, the viscosity of the polymer obtained by grafting the silicate compound (A) becomes high, and it becomes difficult to spread the polymer on the surface of the coating film. M is preferably 5 to 30 from the viewpoint of setting the polymer obtained by grafting the silicate compound (A) to an appropriate viscosity. It is more preferably from 7 to 20, and further preferably from 10 to 15.

The above-mentioned organic group having 1 to 20 carbon atoms having a substituent or no substituent is a silicate compound (A)
The polymer obtained by grafting is developed on the coating film surface in a wet coating film at the time of coating to make it more likely to be present in the vicinity of the coating film surface, that is, when the compatibility with other resin components is appropriately reduced. In light of the above, those having 1 to 10 carbon atoms are preferable.

The above-mentioned organic group having 1 to 20 carbon atoms having a substituent or no substituent is not particularly limited.
And an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group and an acyl group. Among them, an alkyl group and an aralkyl group having 1 to 20 carbon atoms which have or do not have a substituent are preferable.

The above-mentioned or unsubstituted alkyl group is not particularly restricted but includes, for example, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group. Examples thereof include linear or branched ones such as a butyl group, an n-amyl group, an isoamyl group, a neoamyl group, a hexyl group, a heptyl group, an octyl group, and a 2-ethylhexyl group. Among them, methyl group, ethyl group, propyl group, isopropyl group, n-
Butyl groups are preferred.

The above-mentioned or unsubstituted cycloalkyl group is not particularly limited.
Examples include a cyclopentyl group and a cyclohexyl group.
The aryl group is not particularly limited, and includes, for example, a phenyl group, a tolyl group, and a xylyl group.

The aralkyl group having a substituent or no substituent is not particularly limited, and examples thereof include a benzyl group, a 2-chlorobenzyl group, a 3-chlorobenzyl group, a 4-chlorobenzyl group, and a 2-bromobenzyl group. Benzyl group, 3
Halogenated benzyl groups such as -bromobenzyl group, 4-bromobenzyl group, 2-iodobenzyl group, 3-iodobenzyl group, 4-iodobenzyl group, dichlorobenzyl group; 2-methylbenzyl group, 3-methylbenzyl group , 4
-Methylbenzyl group, dimethylbenzyl group, 3,4,5
-Trimethylbenzyl group, 4-ethylbenzyl group, 4-
Isopropylbenzyl group, 4-butylbenzyl group, 4-
alkyl-substituted benzyl such as tert-butylbenzyl group; dimethoxybenzyl group, 2-ethoxybenzyl group,
3-ethoxybenzyl group, 4-ethoxybenzyl group, 4
-Butoxybenzyl group, 2-methoxybenzyl group, 3-
Alkoxy-substituted benzyl groups such as methoxybenzyl group and 4-methoxybenzyl group; phenethyl group, benzoin group,
Examples include benzyl groups and phenethyl groups of a phenylpropyl group. Among these, a benzyl group, a chlorobenzyl group, a methylbenzyl group, an ethylbenzyl group, and a methoxybenzyl group are preferred.

The acyl group having a substituent or no substituent is not particularly limited, and examples thereof include acetyl, propynyl, butyryl, ethoxycarbonyl, propoxycarbonyl and the like.

A part or all of the above-mentioned or unsubstituted organic group having 1 to 20 carbon atoms may be a methyl group, an ethyl group, a methyl group, an ethyl group, or the like, from the viewpoint that the coating film exhibits sufficient hydrophilicity. Preferably it is a propyl group. Of these, a methyl group is most preferred.

Further, from the viewpoint that the coating film exhibits sufficient hydrophilicity and has sufficient storage stability, it is more preferable that a part of the organic groups is a methyl group.

Specific examples of the silicate compound (A) include tetramethoxysilane, tetraethoxysilane,
Tetra-n-propoxysilane, tetra-iso-propoxysilane, tetra-n-butoxysilane, tetra-
sec-butoxysilane, tetra-tert-butoxysilane, tetra-n-pentoxysilane, tetra-is
o-pentoxysilane, tetraneopentoxysilane and the like; one or more condensates thereof and the like.

The silicate compound (A) may be a methyl silicate represented by the following formula (3) and / or a condensate thereof, or an ethyl silicate represented by the following formula (4) and / or a condensate thereof: A product obtained by an alcohol exchange reaction using a product as a reaction substrate may also be used.

In this case, the silicate compound (A)
Is an alcohol-modified silicate compound in which methyl silicate and / or a condensate thereof, or ethyl silicate and / or a part of a methyl group or an ethyl group of the condensate are modified by an alcohol exchange reaction.

[0124]

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In the above formula, p is the same as m described above.

[0126]

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In the above formula, q is the same as m described above.

The methyl silicate and / or its condensate are not particularly limited, and include, for example, “MS-51”,
Commercial products such as "MS-56" (all trade names, manufactured by Mitsubishi Chemical Corporation) are exemplified.

The ethyl silicate and / or condensate thereof is not particularly limited, and examples thereof include “ethyl silicate 40”, “ethyl silicate 48”, and “ethyl silicate 28” (all trade names, manufactured by Colcoat). Commercial products can be mentioned.

The alcohol exchange reaction is carried out by reacting the above-mentioned methyl silicate and / or condensate thereof or the above-mentioned ethyl silicate and / or condensate thereof as a reaction substrate with an alcohol compound as a reaction reagent.

Examples of the alcohol compound include a substituted or unsubstituted alkyl alcohol compound having 2 to 20 carbon atoms, and a substituted or unsubstituted aralkyl alcohol compound having 7 to 20 carbon atoms. Is mentioned. These may be used alone or in combination of two or more.

The above-mentioned alkyl alcohol compound having a substituent or no substituent and having 2 to 20 carbon atoms is not particularly limited. Examples thereof include ethyl alcohol, propyl alcohol, isopropyl alcohol, n-butyl alcohol, and sec-butyl. Alcohol, tert-butyl alcohol, n-amyl alcohol, isoamyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, alkyl alcohol compounds such as 2-ethylhexyl alcohol; methyl cellosolve, ethyl cellosolve, butyl cellosolve, hexyl cellosolve, butyl diglycol, etc. Examples include ether alcohol compounds. These may be used alone or in combination of two or more.

The above-mentioned aralkyl alcohol compound having 7 to 20 carbon atoms which has a substituent or no substituent is not particularly limited.
Chlorobenzyl alcohol, 3-chlorobenzyl alcohol, 4-chlorobenzyl alcohol, 2-bromobenzyl alcohol, 3-bromobenzyl alcohol, 4-chlorobenzyl alcohol
Halogenated benzyl alcohols such as bromobenzyl alcohol, 2-iodobenzyl alcohol, 3-iodobenzyl alcohol, 4-iodobenzyl alcohol and dichlorobenzyl alcohol; 2-methylbenzyl alcohol, 3-methylbenzyl alcohol, 4-methylbenzyl alcohol; Dimethylbenzyl alcohol, 3,
Alkyl-substituted benzyl alcohols such as 4,5-trimethylbenzyl alcohol, 4-ethylbenzyl alcohol, 4-isopropylbenzyl alcohol, 4-butylbenzyl alcohol, and 4-tert-butylbenzyl alcohol; dimethoxybenzyl alcohol, 2-ethoxybenzyl alcohol; 3-ethoxybenzyl alcohol, 4-ethoxybenzyl alcohol, 4-butoxybenzyl alcohol, 2-methoxybenzyl alcohol,
Alkoxy-substituted benzyl alcohols such as 3-methoxybenzyl alcohol and 4-methoxybenzyl alcohol;
Examples include benzyl alcohols such as phenethyl alcohol, benzoin, and phenylpropanol, and phenethyl alcohols. These may be used alone or in combination of two or more.

At the time of the alcohol exchange reaction, an alcohol exchange catalyst may be used. The alcohol exchange catalyst is not particularly limited, and includes, for example, an acid or a base. The acid is not particularly limited, and includes, for example, Bronsted acids such as hydrochloric acid, sulfuric acid, phosphoric acid, and sulfonic acid; and Lewis acids such as organic tin compounds. The base is not particularly limited and includes, for example, tertiary amines such as triethylamine, diisopropylethylamine, dimethylbenzylamine, diazabicyclo [2,2,2] octane, and 1,8-diazabicyclo [5,4,0] undecene-7. Amines and the like. These may be used alone or in combination of two or more.

The solvent used in the alcohol exchange reaction may not be particularly used. For example, the solvent may be used in excess of the reaction substrate using an alcohol compound as a reaction reagent as a solvent.

The solvent is not particularly restricted but includes, for example, aromatic hydrocarbons such as toluene, benzene and xylene; halogenated hydrocarbons such as dichloroethane; THF,
Ethers such as dioxane; ketones such as methyl ethyl ketone and methyl isobutyl ketone; esters such as ethyl acetate and butyl acetate; dimethyl carbamate and acetonitrile. These may be used alone,
Two or more kinds may be used in combination.

The amount of the solvent used is not particularly limited, and may be, for example, a total of methyl silicate as a reaction substrate and / or a condensate thereof, or ethyl silicate and / or a condensate thereof and an alcohol compound as a reaction reagent. It is preferably 10 times or less the weight.

The ratio of methyl silicate and / or a condensate thereof, or ethyl silicate and / or a condensate thereof, and an alcohol compound as a reaction reagent in the alcohol exchange reaction is not particularly limited. For example, the amount of the alcohol compound is at least 1 mol% based on the reaction substrate, and the amount required for denaturation may be an amount or more.

The above alcohol exchange reaction may be carried out by azeotropically distilling off the methanol produced by the denaturation.

The reaction temperature of the alcohol exchange reaction is not particularly limited, and is generally 0 ° C. to 200 ° C. The reaction time is not particularly limited, but is preferably, for example, 24 hours or less. The pressure during the reaction is not particularly limited, and is generally normal pressure. However, if necessary, the reaction may be performed under reduced pressure to distill off generated methanol.

The reaction rate in the alcohol exchange reaction can be determined by measuring the amount of produced methanol, NMR spectrum or GC (gas chromatography) analysis. The product obtained as described above is generally a colorless to pale yellow oil.

The silicate compound (A) can be obtained by an alcohol exchange reaction as described above. Other methods for producing the silicate compound include, for example, a polymerizable polysiloxane compound or a silane compound having a chain transfer ability and a monofunctional compound. It can also be obtained by a method of copolymerizing with a hydrophilic monomer. As the silicate compound (A), a condensate of methyl silicate is most preferred from the viewpoint of the mechanism of developing the hydrophilicity of the coating film.

The hydroxyl group-containing acrylic resin used in the present invention is obtained by grafting the silicate compound (A).
A polyester resin grafted with a silicate compound (A), a half ester acid group-containing acrylic copolymer (I) with a silicate compound (A) grafted thereon, an epoxy group-containing acrylic copolymer (II) Grafted with a silicate compound (A), carboxyl group-containing polyester resin (III) with grafted silicate compound (A), and hydroxyl group-containing polymer (Va) with silicate compound (A) The silicate graft polymer (V) obtained by grafting the above silicate) is obtained by grafting the above silicate compound (A) to each of the above polymers by a graft reaction. As the silicate compound (A), one type may be used, or two or more types may be used.

The method of the above graft reaction is not particularly limited, and it can be carried out by a usual method. For example, it may be carried out without a solvent or in an organic solvent.

The organic solvent is not particularly restricted but includes, for example, alcohols such as methanol, ethanol, propanol and butanol; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and dioxane; From the viewpoint that the solvent can be easily removed by the operation, those having a boiling point of 100 ° C. or less are preferable.

The reaction temperature and reaction time in the above grafting reaction vary depending on the type of the raw material, but are usually preferably in the range of room temperature to 150 ° C. and within 24 hours. If the reaction temperature is lower than room temperature, the silicate compound (A) is not sufficiently grafted, and if it exceeds 150 ° C. or exceeds 24 hours, condensation between the silicate compounds (A) occurs. The pressure in the graft reaction is 1 ×
Preferably, it is in the range of 10 ^{-3 to} 7600 Torr.

In the case where the polymer obtained by grafting the silicate compound (A) is an R ¹ O— group, especially a methoxy group,
Since it easily becomes a hydroxyl group with the passage of time, the water contact angle on the surface of the coating film decreases, and the coating film is imparted with hydrophilicity. Therefore, it is considered that a contaminant attached to the surface of the coating film is easily washed away, and the coating film exhibits high stain resistance. Also, due to the presence of the methoxy group and the like, the polymer obtained by grafting the silicate compound (A) has appropriate compatibility with other resin components, and has sufficient stain resistance on the surface of the formed coating film. The character is exhibited.

Further, the polymer obtained by grafting the above silicate compound (A) is tetramethyl silicate and / or
Alternatively, unlike the low-condensation product of tetraethylsilicate, the most reactive alkyl group of the silicate compound (A) reacts with the hydroxyl group of the above-mentioned hydroxyl group-containing polymer, and the most reactive alkyl group of the silicate compound (A) reacts. Since high parts are blocked, it is difficult for condensation reaction and reaction with other resin components to occur during storage of the coating material, and the storage stability of the coating material is excellent, and the coating film obtained from the coating material after storage shows sufficient hydrophilicity. High contamination resistance is stably exhibited even after storage on the membrane surface.

Further, the polymer obtained by grafting the above silicate compound (A) is tetramethyl silicate and / or
Alternatively, unlike the low-condensation product thereof, the above-mentioned silicate compound (A) is grafted to the above-mentioned resin component, so that it has excellent compatibility with other resin components in the coating material, and has a surface layer of a hydrophilic group coating film after coating. Since the localization to the carbon is appropriately suppressed, the water resistance is improved.

The alcohol-modified silicate compound (IV) used in the present invention has the general formula (2):

[0151]

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This is represented by The above general formula (2)
In the formula, n represents an integer of 1 to 50. Part of R ² has a substituted or unsubstituted alkyl group having 2 to 20, preferably 3 to 15 carbon atoms and / or has a substituted or unsubstituted group. It represents an aralkyl group having 7 to 20 carbon atoms, and the remaining R ² represents a methyl group.

In the above general formula (2), when n exceeds 50, the viscosity of the obtained alcohol-modified silicate compound (IV) becomes high, making it difficult for the alcohol-modified silicate compound to migrate to the coating film surface. The resulting alcohol-modified silicate compound (IV) hardly volatilizes from the coating film surface when the coating film is cured by heating,
From the viewpoint of obtaining an appropriate viscosity, n is preferably 5 to 30. More preferably 7 to 20, even more preferably 10 to 1
5

The above-mentioned substituted or unsubstituted alkyl group having 2 to 20 carbon atoms, preferably 3 to 15 carbon atoms, and aralkyl having 7 to 20 carbon atoms having a substituted or unsubstituted group. More preferably, the groups each have 3 to 10 carbon atoms and 7 to 10 carbon atoms.
If the number of carbon atoms is less than the above, the reactivity is too high, and the storage stability is deteriorated. If the number of carbon atoms exceeds the above, the hydrophilic function is not obtained.

The above alcohol-modified silicate compound (I
The method for producing V) is not particularly limited, and includes, for example, a method in which a methyl silicate represented by the above formula (3) and / or a condensate thereof is subjected to an alcohol exchange reaction as a reaction substrate. In this case, the alcohol-modified silicate compound (IV) is obtained by modifying a part of the methyl group of methyl silicate and / or its condensate by an alcohol exchange reaction.

The alcohol exchange reaction is carried out by reacting the methyl silicate and / or condensate thereof as a reaction substrate with an alcohol compound as a reaction reagent, and can be carried out in the same manner as the alcohol exchange reaction described above.

Examples of the alcohol compound include a substituted or unsubstituted alkyl alcohol compound having 2 to 20, preferably 3 to 15 carbon atoms, a substituted or unsubstituted alkyl alcohol compound. Aralkyl alcohol compounds of the formulas 7 to 20 are exemplified. These may be used alone or in combination of two or more.

The alkyl alcohol compound having a substituent or not having a substituent and having 2 to 20 carbon atoms, preferably 3 to 15 carbon atoms, is not particularly limited.
The same compounds as the above-mentioned alkyl alcohol compounds can be used. Among these, propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-
It is preferred to use butyl alcohol, butyl cellosolve, methoxypropanol, ethoxypropanol.

The aralkyl alcohol compound having 7 to 20 carbon atoms having a substituent or not having the substituent is not particularly limited, and examples thereof include the same aralkyl alcohol compounds as described above. Among these, benzyl alcohol, chlorobenzyl alcohol,
It is preferable to use methylbenzyl alcohol, ethylbenzyl alcohol, and methoxybenzyl alcohol.

The above alcohol-modified silicate compound (I
Since the methoxy group of V) tends to become a hydroxyl group with the passage of time, the water contact angle on the surface of the coating film decreases, and the coating film becomes hydrophilic. Therefore, it is considered that a contaminant attached to the surface of the coating film is easily washed away, and the coating film exhibits high stain resistance.

Also, due to the presence of the methoxy group, the alcohol-modified silicate compound (IV) has appropriate compatibility with other resin components, and exhibits sufficient stain resistance on the surface of the formed coating film. Is done.

Further, when the alcohol-modified silicate compound (IV) obtained by the alcohol exchange reaction is, for example, when R ² is a methyl group, the methyl group of the tetramethyl silicate condensate has the highest activity methyl group in order. Since it is substituted with an alkyl group or an aralkyl group having a large number of carbon atoms, and the active portion is blocked, unlike a mere tetramethyl silicate condensate, it hardly causes a condensation reaction or a reaction with other resin components during the storage of the paint, The storage stability of the paint is excellent, and the paint film obtained from the paint after storage also shows sufficient hydrophilicity, and exhibits high stain resistance on the paint film surface even after storage.

The polymer obtained by grafting the silicate compound (A) is tetramethyl silicate and / or
Alternatively, unlike the low-condensation product thereof, the above-mentioned silicate compound (A) is grafted to the above-mentioned hydroxyl group-containing polymer, so that it has excellent compatibility with other resin components in the coating material, and is coated with a hydrophilic group after coating. Since the localization on the film surface layer is appropriately suppressed, the water resistance is improved.

When the clear top coating used in the present invention is the above-mentioned acid / epoxy-curable clear coating, an alcohol compound which is a reaction reagent used for obtaining the above alcohol-modified silicate compound (V) by the above alcohol exchange reaction. Alternatively, an alcohol compound which is a reaction reagent used for obtaining the silicate compound (A) by the alcohol exchange reaction may be added as a solvent.

The addition amount of the alcohol compound is 10 to 2 parts by weight based on 100 parts by weight of the silicate compound (A).
It is preferably 00 parts by weight. By adding the alcohol compound, it is possible to stabilize the polymer obtained by grafting the silicate compound (A) during the storage of the clear coating for overcoating, and to prevent the coating film abnormality in the heat curing step. Can be prevented.

When the base coating material used in the present invention uses the above-mentioned blocked polyisocyanate as the above-mentioned melamine-based curing agent, a curing catalyst can be used. The curing catalyst is not particularly limited, and examples thereof include organic tin compounds such as dibutyltin laurate, dibutyltin octate, and dibutyltin diacetate; aluminum tris (acetylacetonate), titanium tetrakis (acetylacetonate), and titanium bis (acetyl). Acetonate), titanium bis (butoxy) bis (acetylacetonate), titanium bis (isopropoxy) bis (acetylacetonate), zirconium bis (butoxy) bis (acetylacetonate), zirconium bis (isopropoxy) bis (acetyl) Metal chelate compounds such as acetonate). These may be used alone or in combination of two or more. Among these, organotin compounds are common.

In the case where the base paint used in the present invention uses the amino resin as the melamine-based curing agent,
A curing catalyst can be used. The curing catalyst is not particularly limited, and examples thereof include aromatic sulfonic acids such as dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, and p-toluenesulfonic acid; aminotri (methylenephosphonic acid), 1-hydroxyethylidene-1,1 Organic phosphonic acids such as diphosphonic acid; and amine salts thereof. These may be used alone or in combination of two or more.

When the overcoating clear coating used in the present invention is an acid / epoxy-curable clear coating, usually,
A curing catalyst is included. The curing catalyst is not particularly limited, and may be a catalyst usually used for an esterification reaction (reaction between an acid and an epoxy). For example, a quaternary ammonium salt is preferable. Specifically, in addition to the above-mentioned quaternary ammonium salts, benzyltriethylammonium chloride, benzyltriethylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium bromide and the like can be mentioned. These may be used alone or in combination of two or more.

When the clear top coating used in the present invention is a melamine-curable clear coating, the above-mentioned curing catalyst which can be used in the base coating used in the present invention can be used.

The base coating material and the clear coating material for top coating include a melamine / formaldehyde resin for increasing the crosslink density and improving the water resistance, and an ultraviolet absorber and a light stabilizer for improving the weather resistance of the coating film. A microgel or a surface conditioner for rheology control, a diluent for viscosity control or the like may be blended.

The ultraviolet absorber and light stabilizer are not particularly restricted but include, for example, Tinuvin-900 (manufactured by Ciba-Geigy), Sanol LS-292 (manufactured by Sankyo) and the like. The diluent is not particularly restricted but includes, for example, alcohol solvents such as methanol, ethanol, propanol and butanol; and solvents such as hydrocarbons and esters. These may be used alone or in combination of two or more.

The curing catalyst is preferably incorporated in an amount of 0.01 to 3.0% by weight based on the total resin solids. The amount of the diluent is preferably up to 60% by weight, more preferably 20 to 55% by weight, based on the total weight of the paint to which the diluent has been added.

The above clear coating material for top coating usually contains no pigment, but may contain a coloring pigment to the extent that the transparency of the coating film is not impaired. The pigment is not particularly limited and includes, for example, iron oxide, lead oxide, carbon black, coal dust, titanium dioxide, talc, barium sulfate, cadmium yellow, cadmium red, chrome yellow, and metal pigments (for example, aluminum flakes and the like). And organic pigments (for example, phthalocyanine blue, Shinkasia Red and the like), pearl mica and the like. These may be used alone or in combination of two or more.

The solid content of the base paint is 15 to
It is 60% by weight, preferably 20 to 55% by weight. The solid content at the time of application is 10 to 50.
%, Preferably 20 to 45% by weight.

The solid content of the clear coating for top coating is 25 to 70% by weight, preferably 35 to 65% by weight. The solid content at the time of application is 1
It is 5 to 65% by weight, preferably 30 to 60% by weight.

The method for preparing the base coating material and the clear coating material for top coating is not particularly limited, and can be carried out by stirring each of the above-mentioned compounds with a stirrer or the like. It can also be performed by kneading using the method described above.

Further, a polymer obtained by grafting the silicate compound (A) and / or the alcohol-modified silicate compound (IV) may be added to the paint before application and mixed, thereby producing a paint. At this stage, it may be added to the paint in advance and mixed. When it is added and mixed in the paint in advance, it is preferable to store it under conditions that do not allow water to mix so that hydrolysis and condensation reactions do not proceed.

In the case where the base coating film used in the present invention is formed only of a base coating film containing a color pigment and / or a brilliant pigment, the base coating film is applied on the coated automobile outer panel, After applying the clear top coating used in the present invention in a wet-on-wet manner and then heating and curing, a two-coat, one-bake (2C1B) multilayer coating film can be formed.

In the case where the base coating film is formed of a color base coating film and the glitter pigment-containing base coating film, when the color base coating film is independently cured by heating, the glitter pigment-containing base coating film A three-coat, two-bake (3C2B) multi-layer coating film can be formed by applying a paint, further applying the above clear paint for overcoating on a wet-on-wet basis, and then heating and curing. .

When the color base coating film is not cured by heating alone, the bright pigment-containing base coating material is applied thereon by wet-on-wet coating, and the clear coating material for top coating is further applied thereon by wet-on-wet coating. After coating, it can be cured by heating.

That is, the above-mentioned color base coating film, the above-mentioned brilliant pigment-containing base coating film and the above-mentioned clear coating film for overcoating are combined in a wet-on-wet manner, and a composite coating film is formed, followed by heat-curing to form three coats and one bake. (3
A composite coating film of C1B) can be formed, and a composite coating film having more excellent design properties can be formed.

The base coating and the clear coating for top coating can be applied by spray coating, brush coating, dip coating, electrostatic coating, roll coating, flow coating, or the like. The base paint and the clear coating for top coating have a curing temperature of 100 to 180 ° C, preferably 120 to 180 ° C.
A cured coating film having a high degree of crosslinking at 160 ° C. is obtained. The curing time is
Varies depending on the curing temperature, etc.
~ 30 minutes is appropriate.

The dry film thickness of the base paint to be formed is generally preferably about 8 to 40 μm, more preferably about 10 to 30 μm. If the dry film thickness is less than 8 μm, the base cannot be concealed, and if it exceeds 40 μm, problems such as cracks and sagging may occur during coating.

The dry film thickness of the formed clear top coating varies depending on the desired use, but in many cases is preferably 10 to 80 μm, more preferably 1 to 80 μm.
It is about 5 to 60 μm. If the dry film thickness is less than 10 μm, the substrate cannot be concealed, and if it exceeds 60 μm, problems such as cracks and sagging may occur during coating.

As described above, the base coating material and the clear coating material for the top coat used in the present invention are obtained by condensation of the polymer obtained by grafting the alcohol-modified silicate compound (IV) and the silicate compound (A) during the storage of the coating material. It is excellent in storage stability because it hardly causes a reaction or a reaction with other resin components.

The curing reaction of the base coating material used in the present invention is, in addition to the curing reaction between a hydroxyl group-containing acrylic resin or polyester resin and a melamine-based curing agent, and R ¹ in a polymer obtained by grafting a silicate compound (A). It can also be considered that the O-group is hydrolyzed and condensed by the presence of the catalyst, and at the same time reacts with a hydroxyl group-containing acrylic resin, a polyester resin or a melamine-based curing agent to progress the curing.

When the clear coating for top coating is an acid / epoxy curable clear coating, when a polymer containing only an acid anhydride group is used, the reaction with the active hydrogen compound proceeds even at around room temperature. Preservation causes gelation and is not suitable.

When the acid / epoxy-curable clear coating material used in the present invention is used, since the acid anhydride group is modified (half-esterified), no further reaction occurs even when the active hydrogen compound is mixed. One-pack (one-pack)
Is possible.

In the curing reaction with an active hydrogen compound at the time of forming a coating film, the curing rate can be changed by changing the modifier of the acid anhydride group in various ways, and the coating film having an excellent appearance can be obtained. A film can be formed.

When the clear top coating used in the present invention is an acid / epoxy-curable clear coating, the curing reaction is first half-esterified in the half-ester acid group-containing acrylic copolymer (I) to open the ring. The acid anhydride modifying group is closed again at the curing temperature and returns to the acid anhydride group.

Next, the hydroxyl group in the epoxy group-containing acrylic copolymer (II) reacts to form a half ester again. Next, the remaining carboxyl groups in the half-ester acid group-containing acrylic copolymer (I) react with the epoxy groups in the epoxy group-containing acrylic copolymer (II) to form diesters.

Further, in the polymer obtained by grafting the alcohol-modified silicate compound (IV) and / or the silicate compound (A), the R ² O-group and / or the R ¹ O-group may be a half ester acid group-containing acrylic copolymer. The acid-catalyzed action of the polymer (I) causes hydrolysis and condensation, and at the same time, reacts with the hydroxyl group in the epoxy group-containing acrylic copolymer (II) to promote curing.

That is, in the above curing reaction, two groups of the epoxy group and the hydroxyl group in the epoxy group-containing acrylic copolymer (II) were modified with the acid anhydride in the half ester acid group-containing acrylic copolymer (I). The hydroxyl group in the epoxy group-containing acrylic copolymer (II) bonded to the carboxyl group and the ester group, which is a group obtained by grafting the alcohol-modified silicate compound (IV) and / or the silicate compound (A). It is considered that two or three types of components react with each other by bonding to the coalescence and the hydrolyzed condensate thereof, whereby curing proceeds.

When the acid / epoxy-curable clear coating composition further comprises the carboxyl group-containing polyester resin (III) as a resin component, the above resin component and the carboxyl group-containing polyester resin (III)
In both cases, it is considered that curing proceeds by reacting with each other.

When the clear top coating used in the present invention is a melamine-curable clear coating, the curing reaction is considered to proceed in the same manner as the above-described curing reaction of the base coating.

Therefore, the cured coating film formed by the method for forming a multilayer coating film for an automobile body of the present invention has a solid structure,
It will have excellent weather resistance, chemical resistance, scratch resistance, and the like. In addition, the base paint and the clear coating for top coating are coated on the painted outer panel of the automobile by two coats and one bake (2C1 bake).
When the multilayer coating film of B) is formed, the alcohol-modified silicate compound (IV) and / or
Alternatively, it contains a polymer obtained by grafting the silicate compound (A), and the base paint also contains a polymer obtained by grafting the silicate compound (A), so that the alcohol-modified silicate compound (IV) and / or the silicate compound The polymer obtained by grafting (A) spreads on the coating film surface, and a large amount of the polymer obtained by grafting the alcohol-modified silicate compound (IV) and / or the silicate compound (A) was present near the coating film surface. A wet coating is formed,
Then, by heating and curing, a large amount of methoxy groups and the like derived from a polymer obtained by grafting the alcohol-modified silicate compound (IV) and / or the silicate compound (A) are present on the coating film surface. Stain resistance can be exhibited.

The cured coating film formed by the method for forming a multilayer coating film for an automobile body of the present invention is imparted with hydrophilicity by reacting with an acid, but gradually imparts stain resistance with time. Alternatively, stain resistance may be imparted from an early stage by pre-treatment with an acid.

According to the method for forming a multilayer coating film of an automobile body according to the present invention, the base paint and the clear coating material for top coating are coated on the painted automobile outer plate by two coats and one bake (2C).
When the multi-layer coating film of 1B) is formed, the base paint contains a polymer obtained by grafting a silicate compound (A) as a component capable of exhibiting stain resistance. Compared with the case where a low molecular weight silicate compound is contained, NS
Due to excellent R-characteristics, water does not enter between the first coated film and the second coated film with time, and a coating film having excellent NSR properties and water resistance is formed. Can be.

An automobile body formed with a multilayer coating film by using the method for forming a multilayer coating film for an automobile body according to the present invention has a multilayer coating film formed by the method for forming a multilayer coating film for an automobile body according to the invention. It has basic performance such as weather resistance, especially excellent in acid resistance, and can maintain the same effect as maintenance-free car washing because it has high hydrophilicity. In addition, it is capable of stably exhibiting performance even after storage of the paint, and is also excellent in NSR properties and water resistance. Such an automobile body is also one of the present invention.

[0200]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Synthesis Example 1Hydroxyl-containing acrylic resin (a)
-1  Thermometer, stirrer, cooling pipe, nitrogen introduction pipe and dropping funnel
400 parts by weight of toluene and n-butanol
And then heated to 105 ° C. This anti
Using a dropping funnel, 100 parts by weight of styrene,
300 parts by weight of methyl acrylate, ethyl acrylate 44
0 parts by weight, 140 weights of 2-hydroxyethyl methacrylate
Parts, methacrylic acid 20 parts by weight, t-butyl peroxy
20 parts by weight of 2-ethylhexanoate and 3 parts of toluene
A solution consisting of 00 parts by weight was added dropwise over 3 hours. drop
After maintaining at 105 ° C. for 30 minutes after the lower end, t-
Butyl peroxy-2-ethylhexanoate 3 parts by weight
And 200 parts by weight of toluene. End of this addition
Thereafter, the reaction was continued at 105 ° C. for another 2 hours,
Molecular weight (Mn) 18000, acid value 13 mg KOH / g
(In terms of solid content) and hydroxyl value 60 mgKOH / g (solid
(In terms of minutes) containing a hydroxyl group-containing acrylic resin (a) -1
A varnish with a volatile content of 50% was obtained.

Synthesis Example 2Hydroxyl-containing acrylic resin (a)
-2  Thermometer, stirrer, cooling pipe, nitrogen introduction pipe and dropping funnel
Solvesso 100 (trade name, Esso Corporation)
670 parts by weight of aromatic solvent and n-butanol 100
Parts by weight and heated to 125 ° C. In this reactor,
Using a dropping funnel, 300 parts by weight of styrene, methacryl
350 parts by weight of 2-ethylhexyl acid, 2-ethyl acrylate
100 parts by weight of tylhexyl, 2-hydroxy methacrylate
220 parts by weight of siethyl, 30 parts by weight of methacrylic acid, t-
Butyl peroxy-2-ethylhexanoate 40 weight
Parts and a solution consisting of 50 parts by weight of Solvesso 100
It was added dropwise over 3 hours. 1 for 30 minutes after dropping
After holding at 25 ° C., t-butylperoxy-2-ethyl
Luhexanoate 5 parts by weight and Solvesso 100 20
Parts by weight were added. After completion of this addition, 12 hours
The reaction was continued at 5 ° C., and the number average molecular weight (Mn) was 800.
0, acid value 20mgKOH / g (solid content conversion) and hydroxyl group
Hydroxyl group containing 95 mgKOH / g (solid content)
A varnish with a non-volatile content of 55% containing a rill resin (a) -2 was obtained.
Was.

Synthesis Example 3Polyester resin (b)  Thermometer, stirrer, cooling pipe, nitrogen inlet pipe, water separator and
In a reactor equipped with a distillation tower, 415 parts by weight of isophthalic acid,
90 parts by weight of dipic acid, 100 parts of trimethylolpropane
Parts, 200 parts by weight of neopentyl glycol, 2,2-
Dimethyl-3-hydroxypropyl-2,2-dimethyl
195 parts by weight of 3-hydroxypropionate and jib
Charge 2 parts by weight of chill tin oxide and heat to 210 ° C.
To raise the temperature. However, 3 from 160 ° C to 210 ° C
The temperature was raised at a constant rate over a period of time. The shrink to generate
The combined water was distilled out of the system. Keeps warm when it reaches 210 ° C
After 1 hour of heat retention, xylene was used as a reflux solvent in the reaction vessel.
Slowly add 30 parts by weight and switch to condensation in the presence of solvent
And continued the reaction. Thereafter, the acid value was 8.5 mg KOH /
Cool down to 150 ° C when g (solid content conversion) is reached
And add 200 parts by weight of ε-caprolactone,
And then cooled to 100 ° C. In addition,
430 parts by weight of silene was added, and the number average molecular weight (Mn) 3
000, acid value 7mgKOH / g (solid content conversion) and hydroxyl
Polyester with a base value of 93 mg KOH / g (solid content conversion)
A varnish containing resin (b) and having a nonvolatile content of 70% was obtained.

Synthesis Example 4Acrylic containing half ester acid group
Copolymer (c)  Thermometer, stirrer, cooling pipe, nitrogen introduction pipe and dropping funnel
330 parts by weight of xylene and propylene
Renglycol monomethyl ether acetate 110 weight
And heated to 127 ° C. Drops into this reactor
Using a lower funnel, 300 parts by weight of styrene, methacrylic acid
360 parts by weight of 2-ethylhexyl, isobu acrylate
112 parts by weight of chill, 26 parts by weight of acrylic acid, maleic anhydride
Acid 202 parts by weight, propylene glycol monomethyl ester
300 parts by weight of teraacetate and t-butyl peroxy
90 parts by weight of c-2-ethylhexanoate and xylene 1
A solution consisting of 00 parts by weight was added dropwise over 3 hours. drop
After holding at 127 ° C. for 30 minutes after the lower end, t-
Butyl peroxy-2-ethylhexanoate 10 weight
Solution of 50 parts by weight of xylene and 50 parts by weight of xylene in 30 minutes
I dropped it. After the completion of the dropping, the reaction is further performed at 127 ° C. for 1 hour.
The reaction was continued until the number average molecular weight (Mn) was 3000.
Crocodile containing 53% of non-volatile content containing polyanhydride (c) -i
I got it. In 1990 parts by weight of the obtained varnish, methanol
100 parts by weight of the reaction mixture and reacted at 70 ° C. for 23 hours.
Este with a value of 127 mg KOH / g (solid content conversion)
Nonvolatile content 55 containing acrylic acid group-containing acrylic copolymer (c)
% Varnish was obtained. In addition, this half ester acid group containing
Infrared absorption spectrum of acrylic copolymer (c)
The acid anhydride group absorption (1785 cm^-1) Disappears
Was confirmed.

Synthesis Example 5Polyester containing carboxyl group
Resin (d)  Thermometer, stirrer, cooling pipe, nitrogen inlet pipe, water separator and
136 parts by weight of pentol, ε-
456 parts by weight of caprolactone and dibutyltin oxide
0.1 part by weight was charged, the temperature was raised to 170 ° C., and the heating was continued for 3 hours.
At 170 ° C. Then, the heated melted hex
Add 539 parts by weight of sahydrophthalic anhydride and add
After holding for 1 hour, ethyl 3-ethoxypropionate 4
64 parts by weight, number average molecular weight (Mn) 1700, weight
Weight average molecular weight (Mw) / number average molecular weight (Mn) = 1.2
8, acid value 174mgKOH / g (solid content conversion), hydroxyl group
Group having a valency of 25 mgKOH / g (solid content)
Containing polyester resin (d) and having a nonvolatile content of 71%
I got a varnish.

Synthesis Example 6Acrylic copolymer containing epoxy group
Body (e)  Thermometer, stirrer, cooling pipe, nitrogen introduction pipe and dropping funnel
Charge 500 parts by weight of xylene into a 2 L reaction tank equipped
The temperature was raised to 125 ° C. Using a dropping funnel in this reactor,
380 parts by weight of glycidyl methacrylate, 200 styrene
Parts by weight, 292 weight of 2-ethylhexyl methacrylate
Parts, 128 parts by weight of 4-hydroxybutyl acrylate
And t-butylperoxy-2-ethylhexanoate 1
3 parts of a solution consisting of 00 parts by weight and 100 parts by weight of xylene.
It was dropped over time. 12 for 30 minutes after dropping
After maintaining at 5 ° C., t-butylperoxy-2-ethyl
From 10 parts by weight of hexanoate and 10 parts by weight of xylene
Solution was added dropwise over 30 minutes. After this dripping is completed,
The reaction is continued for 1 hour at 125 ° C., and the number average molecular weight is
(Mn) 3700, epoxy equivalent 400 (solid conversion)
Calculation), hydroxyl value of 47 mgKOH / g (solid content conversion)
Non-volatile content 62% including oxy group-containing acrylic resin (e)
Varnish was obtained.

Synthesis Example 7Alcohol-modified silicate compound
Object (f)  MS-56 as methyl silicate (trade name, Mitsubishi Chemical
Exchange reaction with isopropyl alcohol
The alcohol-modified silicate compound
A composition containing (f) and having a nonvolatile content of 100% was obtained. Arco
The reaction conditions were as follows.
21 g of isopropyl alcohol and 0.1 g of triethylamine.
After mixing 2 g and reacting at a temperature of 80 ° C. for 12 hours,
The produced methanol was distilled off under reduced pressure.

Synthesis Example 8Silicate graft polymer
(G) -1  1L equipped with thermometer, stirrer, cooling tube and nitrogen inlet tube
The inside of the reaction vessel was replaced with nitrogen gas, and the alga obtained in Synthesis Example 7 was replaced.
100 parts by weight of coal-modified silicate compound (f), synthesis
Hydroxyl-containing acrylic resin obtained in Example 1 (a) -1 300
Parts by weight and 3 parts by weight of trimethyl orthoacetate
The graft reaction at 90 ° C for 12 hours
Acrylic resin, which is an acrylic resin grafted with a compound
Varnish containing raft polymer (g) -1 and having a nonvolatile content of 63%
I got

Synthesis Example 9Silicate graft polymer
(G) -2  1L equipped with thermometer, stirrer, cooling tube and nitrogen inlet tube
The inside of the reaction vessel was replaced with nitrogen gas, and the alga obtained in Synthesis Example 7 was replaced.
100 parts by weight of coal-modified silicate compound (f), synthesis
150 parts by weight of the polyester resin (b) obtained in Example 3,
And 2 parts by weight of trimethyl orthoacetate.
Perform a grafting reaction for 12 hours to remove the silicate compound.
Silicate graft weight which is a polyester resin
A varnish having a nonvolatile content of 82% containing the coalescence (g) -2 was obtained.

Synthesis Example 10Silicate graft polymer
(G) -3  1L equipped with thermometer, stirrer, cooling tube and nitrogen inlet tube
The inside of the reaction tank is replaced with nitrogen gas, and methyl silicate is replaced.
MS-56 (trade name, manufactured by Mitsubishi Chemical Corporation) 100 weight
Part, and the epoxy group-containing acrylic copolymer obtained in Synthesis Example 6.
Add 270 parts by weight of the coalescence (e), and grind at 90 ° C for 12 hours.
Raft reaction was performed, and the silicate compound was grafted.
A silicate graph which is an acrylic copolymer containing a oxy group
A varnish having a nonvolatile content of 72% containing polymer (g) -3 was obtained.
Was.

Synthesis Example 11Silicate graft polymer
(G) -4  1L equipped with thermometer, stirrer, cooling tube and nitrogen inlet tube
The inside of the reaction vessel was replaced with nitrogen gas, and the alga obtained in Synthesis Example 7 was replaced.
100 parts by weight of coal-modified silicate compound (f), synthesis
Hydroxyl-containing acrylic resin (a) -2 280 obtained in Example 2
Parts by weight and 3 parts by weight of trimethyl orthoacetate
The graft reaction at 90 ° C for 12 hours
Acrylic resin, which is an acrylic resin grafted with a compound
Varnish containing 67% of non-volatile content containing raft polymer (g) -4
I got

Examples 1 to 3 Each of the components shown in Tables 1 and 2 was charged and the mixture was stirred with a disper to obtain a base paint (1) used in the present invention.
And (2), and clear coating for top coating (1) to
(3) was obtained.

Next, the base paints (1) and (2) obtained, and the clear paints for top coating (1) to (3)
Of Ford Cup No. with thinner consisting of butyl acetate / xylene = 1/1. In 4 the coating viscosity was adjusted in 20 seconds.

On a phosphoric acid-treated steel sheet, Nippon Paint Co., Ltd. cationic electrodeposition paint Power Top U-30 and polyester / melamine type gray intermediate paint Olga P-2 (both trade names) were used, each having a dry film thickness of 25 μm. On a test plate coated and heated and cured so as to have a thickness of 40 μm, a silver metallic base paint of Nippon Paint Co., Ltd. super rack M-170 (trade name) is used as an electrostatic coating machine Auto REA.
Atomization pressure of 5 kg (trade name, manufactured by Ransberg Gemma)
/ Cm ² , and after setting for about 7 minutes, wet-on-wet, as shown in Table 3, overcoat clear paints (1) to (3) adjusted to coating viscosity,
Each was applied by spraying, set for about 7 minutes, baked and dried at 140 ° C. for 30 minutes, and prepared a first coating test plate of 2 coats and 1 bake (2C1B) as a coating method, and placed in a desiccator for 30 minutes. Let stand for minutes. In addition, the cured coating film of the base coating material and the clear coating material was applied such that the dry film thickness became 15 μm and 40 μm, respectively.

Then, as shown in Table 3, the obtained 1
The base paint (1) or (2) adjusted to the coating viscosity is applied to each of the coating test plates of the coat by spraying, and the top coating clear coating (1) is adjusted to the coating viscosity on a wet-on-wet basis. ) To (3) are each spray-painted, and after setting for about 7 minutes,
The coating was baked and dried at 30 ° C. for 30 minutes to prepare a coating test plate of a second coat of 2 coats and 1 bake (2C1B) as a coating method. The cured coating film of the base paint and the clear paint has a dry film thickness of 15 μm and 40 μm, respectively.
It was coated to a thickness of μm. The multilayer coating film obtained by the following evaluation method was evaluated. The results are shown in Table 3.

[0216]Evaluation method  (1) NSR property (1-a) Initial recoat adhesion Cutter (NT cutter (trade name) S type, A type or
(Equivalent) to the initial cured coating surface obtained
And hold it at about 30 degrees to reach the substrate.
Is formed, and an adhesive tape (Nichiban Co., Ltd.
Was pressed uniformly with a fingertip so that air bubbles did not remain.
Immediately hold one end of the adhesive tape and sharply
The adhesive tape was peeled off from the test piece by pulling vigorously. this
[Number of squares that did not peel off] / [
The number of squares = 100] is visually measured and the initial recoating adheres.
The sex was evaluated.

(1-b) Adhesion of recoat after hot water resistance test The obtained cured coating film was immersed in warm water at 40 ° C. for 10 days, and then recoated after hot water resistance test in the same manner as in the initial recoat adhesion. The adhesion was evaluated.

(1-c) Warm Water Resistance Test The obtained cured coating film was immersed in warm water at 40 ° C. for 10 days, and the coating film surface was visually evaluated according to the following criteria. ：: No change is observed. Δ: Swelling (blister) is slightly observed. ×: Blisters (blisters) are clearly seen.

(2) Outdoor exposure stain resistance test An outdoor exposure test was performed in accordance with JIS K5400 9.9, and after one and six months, the water contact angle and the lightness difference (ΔL) between the film and the initial coating film were determined. It was measured.

(3) Acid Resistance Test The obtained cured coating film was treated with a 0.1 N H ₂ SO ₄ aqueous solution 0.2
After contacting the resulting solution with 80 ml at 80 ° C. for 30 minutes, the coating film surface was visually evaluated according to the following criteria. ：: No change is observed. Δ: Traces are slightly observed. ×: Traces are clearly seen.

Comparative Examples 1 to 3
As shown in Table 3, instead of the base paint of the coat and the clear paint for the top coat of the second coat, the clear paint for top coat (1) or (2) shown in Table 2 was used as the clear paint for the first coat. ), And the base paint (3) or (4) shown in Table 1 as the second coat base paint, and the clear paint for top coat (1) shown in Table 2 as the clear paint for top coat of the second coat or Except for using (2), in the same manner as in Example, 2 coats and 1 bake (2
C1B) was prepared. The multilayer coating film performance was evaluated in the same manner as in the examples. The results are shown in Table 3.

[0222]

[Table 1]

Note that, in Table 1, Alpaste 7130N
(Trade name, manufactured by Toyo Aluminum Co., Ltd.) is an aluminum flake paste having an aluminum flake content of 64% by weight, and Cymel 254 (trade name, manufactured by Mitsui Cytec) is a melamine resin having a nonvolatile content of 80%. , MS-56
(Trade name, manufactured by Mitsubishi Chemical Corporation) is methyl silicate, and Tinuvin 900 (trade name, manufactured by Ciba Specialty Chemical Co.) is an ultraviolet absorber, and SANOL LS
-770 (trade name, manufactured by Sankyo Co., Ltd.) is a light stabilizer, and the crosslinked resin particles are non-volatile components having a particle diameter of 90 nm.
% Of xylene dispersion (manufactured by Nippon Paint Co., Ltd.), and the surface conditioner is Modaflow (trade name, manufactured by Monsanto Co., Ltd.).

[0224]

[Table 2]

In Table 2, Uban 20N-60 (trade name, manufactured by Mitsui Chemicals, Inc.) is a melamine resin having a nonvolatile content of 60%, and SANOL LS-440 (trade name, manufactured by Sankyo Co., Ltd.) It is a light stabilizer.

[0226]

[Table 3]

In Table 2, the outdoor exposure stain resistance test and the acid resistance test for Comparative Examples 1 to 3 were not carried out because the NSR property was poor.

As is clear from Table 3, the multilayer coating films formed in the examples had excellent acid resistance and low water contact angles after 1 month exposure and after 6 months exposure. The surface shows sufficient hydrophilicity, excellent stain resistance, and furthermore, the initial and after hot water test, recoat adhesion and hot water test were excellent, so the first clear coating film and The NSR with the second base coat was excellent, and the appearance of the coat was not impaired.

On the other hand, the multi-layer coating film formed in the comparative example was inferior in the recoat adhesion and the hot water resistance test after the hot water resistance test, so that the NSR property was poor and the coating film appearance was impaired.

[0230]

The method for forming a multilayer coating film of an automobile body according to the present invention has the above-mentioned constitution, and the cured coating film has a basic property such as weather resistance and acid resistance since it has a high crosslinking density. In addition, it has a high hydrophilicity and is free of car wash, maintains its aesthetics, does not have a defect in storage stability, and has an excellent NSR property and water resistance, which impairs the appearance of the coating film Nothing. The vehicle body of the present invention exhibits excellent appearance and coating film performance, and can be maintenance-free without requiring car washing.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 163/00 C09D 163/00 183/04 183/04 183/10 183/10 F-term (Reference) 4D075 AE06 BB26Z CA32 CA34 CA37 CA38 CA44 DC12 EA43 EB22 EB32 EB33 EB35 EB43 EC37 4J038 CG141 CH171 DA162 DD021 DL021 DL151 DL152 GA03 GA06 GA07 KA03 MA14 NA01 NA03 NA04 NA05 NA26 PB07 PC02

Claims (5)

[Claims] Claims: 1. A colored pigment and
And / or after applying a base paint containing a bright pigment,
I applied the clear paint for application wet-on-wet
After that, it is cured by heating
A method of forming, wherein the base paint comprises a hydroxyl group-containing
Silicate compounds in lull resin or polyester resin
(A) grafted, and melamine-based curing
The silicate compound (A)
The amount of softening is 0.1 to 50 times the total amount of the resin component.
% (In terms of solid content), and the clear paint for top coating
Is acid / epoxy-curable clear paint or melamine-cured
Type clear paint, the clear paint for top coating,
Alcohol-modified silicate compound (IV) or silique
Does not contain or contain the salt graft polymer (V)
Wherein the clear coating for top coating is the alcohol
Modified silicate compound (IV) and silicate graph
When no polymer (V) is contained, the acid / epoxy
Curable clear coating or melamine-curable clear coating
At least one of the resin components of the silicate
The compound (A) is obtained by grafting
The silicate graft polymer (V) is a hydroxyl group-containing polymer.
(Va) is grafted with the silicate compound (A).
The alcohol-modified silicate compound
Of the product (IV) and / or the amount of the silicate compound (A)
The graft amount is 0.1 to 3 with respect to the total amount of the resin components.
0% by weight (in terms of solid content), and the silicate compound
(A) is a compound represented by the general formula (1):(In the formula, m represents an integer of 1 to 50. R¹ Is different
May have a substituent or may have a substituent.
Represents an organic group having 1 to 20 carbon atoms. )
Wherein the alcohol-modified silicate compound (IV)
Is represented by the general formula (2):(In the formula, n represents an integer of 1 to 50. R^Two One of
Part is a carbon with or without a substituent
A compound having 2 to 20 alkyl groups and / or substituents
Or an unsubstituted aralkyl group having 7 to 20 carbon atoms
And the remaining R ^Two Represents a methyl group. )
Forming a multi-layer coating film on an automobile body
Method. 2. An acid / epoxy-curable clear coating composition comprising a half-ester acid group-containing acrylic copolymer (I) and an epoxy group-containing acrylic copolymer (II) as a resin component. The acid group-containing acrylic copolymer (I) comprises an acid anhydride group-containing radical polymerizable monomer (Ia) and another radical polymerizable monomer (Ib).
Is obtained by half-esterifying the acid anhydride group with a low molecular weight alcohol-based compound after obtaining a copolymer by the above method. The epoxy group-containing acrylic copolymer (II) has an epoxy group Containing radical polymerizable monomer (II-a) 30 to 70 parts by weight, hydroxyl group containing radical polymerizable monomer (II-b) 10 to 50 parts by weight, and other radical polymerizable monomer (II-a). c) a copolymer obtained by copolymerizing 20 to 60 parts by weight, having a number average molecular weight (Mn) of 1000 to 8000 and an epoxy equivalent of 100 to
800 (solid content equivalent), hydroxyl value 5 to 200 mg KOH
2 / g (in terms of solid content). 3. The acid / epoxy-curable clear coating composition further comprises a carboxyl group-containing polyester resin (III) as a resin component, wherein the carboxyl group-containing polyester resin (III) is used as a low molecular weight polyhydric alcohol. 3. A multilayer coating film for an automobile body according to claim 2, which is obtained by half-esterifying a polyester polyol obtained by adding a lactone compound and performing a chain extension reaction with an acid anhydride group-containing compound. Method. 4. The melamine-curable clear coating composition comprises 30 to 85% by weight of a hydroxyl group-containing acrylic resin and 15 to 70% by weight of a melamine-based curing agent as resin components. Molecular weight (Mn) 8
00-8000, hydroxyl value 30-200 mgKOH / g
4. The method for forming a multilayer coating film on an automobile body according to claim 1, wherein the coating film is a solid content equivalent. 5. An automobile body coated with a multilayer coating film, wherein said multilayer coating film is formed by the method for forming a multilayer coating film for an automobile body according to claim 1, 2, 3, or 4. An automobile body characterized in that: