JPH11189744A - Coating material composition having high solid content - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject coating material composition capable of forming a coating film excellent in acid resistance and scratch resistance by including a vinylic polymer having a specific functional group, a low molecular weight polyol, a polyisocyanate compound and an acid catalyst. SOLUTION: This coating material composition comprises (A) a vinylic polymer having a hydroxyl group containing >=20 mol.% silylated hydroxyl group of the formula [R<1> and R<2> are each a 1-18C alkyl, a 1-6C alkoxy, etc.; R<3> is a 1-18C alkyl, phenyl, etc.], and an alkoxysilyl group in the same molecule and having 2,000-10,000 number-average molecular weight, (B) a polyol compound having <1,000 molecular weight and 120-1,000 mgKOH/g hydroxyl value, (C) a polyisocyanate compound having <=2,000 number-average molecular weight and (D) a silanol group-producing catalyst and has >=70 wt.% solid content. The composition can further contain crosslinked polymer fine particles and a urethane-forming catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel high solids coating composition, a method of forming a coating film using the composition, and an article having a coating film formed by the method.

[0002]

2. Description of the Related Art In the field of paints, there is an urgent need to reduce the amount of organic solvents used from the viewpoint of environmental protection against air pollution and resource saving.

[0003] As one of the measures, there is a development of a so-called high solid content paint in which the amount of the organic solvent in the paint is reduced to a high solid content concentration.

At present, most of high-solids paints being developed are those obtained by mixing a melamine resin as a curing agent with a hydroxyl group-containing resin, but such paints have the following drawbacks. First, in order to increase the solid content concentration, it is necessary to lower the viscosity of the hydroxyl-containing resin and the melamine resin,
If these resins are reduced in molecular weight in order to lower the viscosity, the coating film performance will be reduced.

[0005] In order to reduce the molecular weight of the resin and obtain sufficient coating film performance, it is necessary to increase the content of a crosslinkable functional group such as a hydroxyl group or a methylol group in the resin. However, since the crosslinkable functional group generally increases the viscosity due to the interaction between the functional groups, it becomes difficult to reduce the viscosity when the number of the functional groups is large.

Secondly, in the case of a paint containing the above-mentioned melamine resin as a curing agent as a high solid content paint, a large amount of by-products such as alcohol is generated at the time of heat curing. ) Is liable to occur.

[0007] Further, in the case of an overcoat film used for an automobile outer panel or the like used outdoors, etching of the coating film due to acid rain and stain stains have become a problem worldwide. Further, with the spread of car wash machines, abrasion caused by the car wash machines has also become a problem.
Therefore, there is a demand for a topcoat paint, particularly a clear topcoat, capable of forming a coating film having both sufficient acid resistance and abrasion resistance to acid rain and the like. A coating film obtained from a resin-based coating of a combination of the hydroxyl group-containing acrylic resin and the melamine resin has a problem that the acid resistance and the scratch resistance are poor.

A urethane-based paint which is crosslinked and cured by a urethanization reaction between a hydroxyl group and an isocyanate group is excellent in acid resistance, abrasion resistance, finished appearance (for example, gloss and meat holding feeling, sharpness). It can form cured coatings and is widely used. However, since it is difficult for the urethane-based coating material to have a solid content content of 70% by weight or more at the time of coating without deteriorating the performance, it is necessary to prevent air pollution and save resources. In recent years, which have been regarded as important, the above-mentioned characteristics cannot be fully utilized, and applications thereof are limited.

It is an object of the present invention to provide a novel high solid content coating composition which can solve the above-mentioned disadvantages of the prior art and can form a coating film having excellent acid resistance and abrasion resistance. It is to provide a coating film forming method.

[0010]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a vinyl polymer having both a silylated hydroxyl group and an alkoxysilyl group, a low-molecular-weight polyol, a polyisocyanate compound and an acid catalyst are prepared. The present inventors have found that the contained paint can achieve the above object, and have completed the present invention.

That is, the present invention relates to (A) a vinyl polymer having both a hydroxyl group and an alkoxysilyl group in the same molecule and having a number average molecular weight in the range of 2,000 to 10,000, At least 20 mol% of the hydroxyl groups are represented by the following general formula (1)

[0012]

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(Wherein R ¹ and R ² are the same or different and are each an alkyl group having 1 to 18 carbon atoms, an alkoxyl group having 1 to 6 carbon atoms, a phenyl group, an aryl group, a trimethylsiloxy group, A hydrogen atom, a chlorine atom or a fluorine atom, and R ³ represents an alkyl group having 1 to 18 carbon atoms, a phenyl group, an aryl group or a trimethylsiloxy group.) A (B) polyol compound having a molecular weight of less than 1000 and a hydroxyl value of 120 to 1000 mgKOH / g, wherein the hydroxyl group may be a silylated hydroxyl group represented by the above general formula (1) Compound,
(C) an organic solvent type high solid containing a polyisocyanate compound having a number average molecular weight of 2,000 or less and (D) a silanol group-forming catalyst, and having a solid content of 70% by weight or more. The present invention provides a coating composition.

Further, the present invention provides a method for forming a coating film by sequentially applying at least one kind of colored paint and at least one kind of clear paint, wherein the above-mentioned paint composition is used as an uppermost clear paint. To provide a coating film forming method.

Further, the present invention provides an article having a coated film formed by the above method for forming a top coated film.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Each component of the coating composition of the present invention will be described below.

Vinyl polymer (A) The vinyl polymer (A) used in the present invention is a vinyl polymer having both a hydroxyl group and an alkoxysilyl group in the same molecule, and 20 mol% or more of the hydroxyl group. Is a polymer having a silylated hydroxyl group. By silylating the hydroxyl group, thickening based on the hydroxyl group can be suppressed, and high solid differentiation of the coating composition can be achieved.

The vinyl polymer (A) comprises a vinyl monomer having a silylated hydroxyl group, a vinyl monomer having a hydrolyzable alkoxysilyl group, a vinyl monomer having a hydroxyl group, if necessary, and other vinyl monomers. It can be easily obtained by copolymerization.

The above-mentioned vinyl monomer having a silylated hydroxyl group is a vinyl monomer having a hydroxyl group in which the hydroxyl group is silylated, and the silylated hydroxyl group is a group represented by the following general formula. .

[0020]

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(Wherein R ¹ and R ² are the same or different and are each an alkyl group having 1 to 18 carbon atoms, an alkoxyl group having 1 to 6 carbon atoms, a phenyl group, an aryl group, a trimethylsiloxy group, A hydrogen atom, a chlorine atom or a fluorine atom, and R ³ represents an alkyl group having 1 to 18 carbon atoms, a phenyl group, an aryl group or a trimethylsiloxy group.) In the general formula (1), R ¹ and R 2 Examples of the alkyl group having 1 to 18 carbon atoms in ² and R ³ include methyl,
Ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, hexyl, 2-ethylhexyl, n-octyl, dodecyl, octadecyl group, etc., and the aryl group include benzyl, phenethyl, tolyl, etc. Can be mentioned. R ¹ and R
^As the alkoxyl group having 1 to 6 carbon atoms in ² , a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a t-
Butoxy and hexoxy groups.

The silylated hydroxyl group is selected from R ¹ , R ² and R ³ among the groups represented by the general formula (1).
Is preferably a group represented by a methyl group or an ethyl group, from the viewpoint of reactivity and a small volatilization amount of a blocking agent volatilized during curing, and in particular, any of R ¹ , R ² and R ³ Trimethylsiloxy groups, which are all methyl groups, are preferred.

Examples of a method for silylating the hydroxyl group of the vinyl monomer having a hydroxyl group include the following (a):
The method (b) and the like can be mentioned.

(A) A method in which a vinyl monomer having a hydroxyl group is reacted with an iminodisilane compound as shown in the following reaction formula (2).

[0025]

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(B) A method of reacting a vinyl monomer having a hydroxyl group with a chlorosilane compound as shown in the following reaction formula (3).

[0027]

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In the above reaction formulas (2) and (3), Y
-OH represents a vinyl monomer having a hydroxyl group, Y represents a residue other than the hydroxyl group in the vinyl monomer having a hydroxyl group, and R ¹ , R ² and R ³ have the same meanings as described above. In the reaction formula (2), two R ¹ ,
R ² and R ³ may be the same or different.

The vinyl monomer having a hydrolyzable alkoxysilyl group is a monomer which generates a silanol group by hydrolysis, and is a compound having at least one alkoxysilyl group and at least one polymerizable unsaturated group in one molecule. Yes, for example, vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, vinyltris (2
-Methoxyethoxy) silane, γ- (meth) acryloyloxypropyltrimethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane, γ-
(Meth) acryloyloxypropyltripropoxysilane, γ- (meth) acryloyloxypropylmethyldimethoxysilane, γ- (meth) acryloyloxypropylmethyldiethoxysilane, γ- (meth) acryloyloxypropylmethyldipropoxysilane, vinyltri Acetoxysilane, β- (meth) acryloyloxyethyltrimethoxysilane, γ- (meth) acryloyloxybutylphenyldimethoxysilane, γ- (meth) acryloyloxybutylphenyldiethoxysilane, γ- (meth) acryloyloxybutylphenyldiphenyl Propoxysilane, γ- (meth) acryloyloxypropyldimethylmethoxysilane, γ- (meth) acryloyloxypropyldimethylethoxysilane, γ- (meth) acryloyloxy Pills phenylmethyl silane, .gamma. (meth) acryloyloxy propyl phenylmethyl silane can be cited,
Among these, from the viewpoint of low-temperature curability and storage stability,
Those in which the hydrolyzable alkoxysilyl group is a methoxysilyl group or an ethoxysilyl group are preferred.

Examples of the vinyl monomer having a hydroxyl group used as needed to obtain the vinyl polymer (A) include 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate. C2-C8 hydroxyalkyl esters of acrylic acid or methacrylic acid such as 3-hydroxypropyl (meth) acrylate and hydroxybutyl (meth) acrylate; and polyether polyols such as polyethylene glycol, polypropylene glycol and polybutylene glycol; Monoesters with unsaturated carboxylic acids such as (meth) acrylic acid; polyether polyols such as polyethylene glycol, polypropylene glycol and polybutylene glycol and hydroxyl groups such as 2-hydroxyethyl (meth) acrylate Monoether of unsaturated monomers;
Monoester or diester of an acid anhydride group-containing unsaturated compound such as maleic anhydride or itaconic anhydride with glycols such as ethylene glycol, 1,6-hexanediol and neopentyl glycol; such as hydroxyethyl vinyl ether Hydroxyalkyl vinyl ethers; allyl alcohols and the like; adducts of α, β-unsaturated carboxylic acids with monoepoxy compounds such as Cardura E10 (trade name, manufactured by Shell Chemical Co., Ltd.) and α-olefin epoxides; ) Adducts of acrylates with acetic acid, propionic acid, p-tert-butylbenzoic acid, monobasic acids such as fatty acids; these hydroxyl-containing monomers and lactones (eg, ε-caprolactone,
and γ-valerolactone).

Examples of other vinyl monomers used as needed to obtain the vinyl polymer (A) include, for example, (meth) acrylates.

Examples of the above (meth) acrylates include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, butyl acrylate (n-, i-, t-), acrylic acid Hexyl,
2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate, lauryl acrylate, stearyl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, butyl methacrylate ( n-, i-, t-), hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, decyl methacrylate, lauryl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, etc. To 22 alkyl esters or cycloalkyl esters: methoxybutyl acrylate, methoxybutyl methacrylate, methoxyethyl acrylate, methoxyethyl methacrylate, ethoxybutyl acrylate, Alkoxyalkyl esters having 2 to 18 carbon atoms methacrylic acid acrylic acid or methacrylic acid ethoxy butyl, and the like.

Other vinyl monomers other than (meth) acrylates include, for example, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N-tert-butylamino Aminoalkyl acrylate monomers such as ethyl (meth) acrylate and N, N-dimethylaminopropyl (meth) acrylate; acrylamide, methacrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N- Acrylamide monomers such as butyl (meth) acrylamide and N, N-dimethyl (meth) acrylamide; unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid, maleic acid, itaconic acid, fumaric acid, mesaconic acid and the like Acid anhydrides and half-esterified compounds Carboxyl group-containing monomers such as unsaturated dicarboxylic acids or modified products thereof; glycidyl group-containing monomers such as glycidyl acrylate and glycidyl methacrylate; vinyl aromatic compounds such as styrene, α-methylstyrene and vinyl toluene; acrylonitrile, acetic acid Vinyl and vinyl chloride.

The vinyl polymer (A) contains the above-mentioned vinyl monomer having a silylated hydroxyl group and the vinyl monomer having a hydrolyzable alkoxysilyl group as essential components, and optionally contains a vinyl monomer having a hydroxyl group and other monomers. These can be obtained by copolymerizing these by a conventional method using the vinyl monomer. For example,
The polymer (A) can be obtained by subjecting the above monomer component to solution polymerization in the presence of a radical polymerization initiator. As the radical polymerization initiator, a peroxide or an azo compound known per se can be used.
It can be performed under the condition of heating at 0 ° C. for about 1 to 15 hours.

The proportion of the above-mentioned monomers may be appropriately selected according to the purpose of use of the coating composition of the present invention, etc., but in general, the following proportions among all the monomers are appropriate. . That is, the total amount of a vinyl monomer having a silylated hydroxyl group or a vinyl monomer having a non-silylated hydroxyl group is curability, storage stability,
From the viewpoints of acid resistance, scratch resistance, water resistance, and adhesion of the coating film, it is appropriate that the content is 3 to 50% by weight, preferably 15 to 35% by weight. Further, the amount of the vinyl monomer having a hydrolyzable alkoxysilyl group is 3 to 40% by weight, preferably 5 to 20% by weight from the viewpoints of curability, acid resistance of coating film, scratch resistance, cost and the like. Is good. The other vinyl monomer is suitably used in an amount of 10 to 80% by weight, preferably 20 to 50% by weight. The amount of styrene used among the other vinyl monomers is suitably up to about 20% by weight from the viewpoint of the weather resistance of the cured coating film.

The polymer (A) obtained by polymerization in the above-mentioned copolymerization amount usually has a hydroxyl value based on both silylated hydroxyl groups and non-silylated hydroxyl groups of 10 to 200 mgKOH /. g, especially 70-14
The content is within the range of 0 mgKOH / g, and the content of the hydrolyzable alkoxysilyl group is within the range of 0.3 to 5.0 mmol / g, preferably 1.0 to 3.0 mmol / g.

The polymer (A) has a number average molecular weight of 2,000.
It has from 10,000 to 10,000, preferably from 3,000 to 7,000. When the number average molecular weight of the polymer (A) is less than 2,000, the curability and the weather resistance of the cured coating film tend to decrease, and when it exceeds 10,000, the viscosity tends to increase. Not preferred.

The polymer (A) can be obtained by copolymerization using a vinyl monomer having a silylated hydroxyl group as described above, but can also be obtained by the following method.

For example, when the polymer (A) is obtained by copolymerization, copolymerization is carried out by using a vinyl monomer having a non-silylated hydroxyl group instead of a vinyl monomer having a silylated hydroxyl group. The polymer (A) having a silylated hydroxyl group can also be obtained by silylating the hydroxyl group in the copolymer. The silylation of the hydroxyl group in the copolymer is carried out according to the reaction formula (2) or (3).
In the above, the reaction can be carried out by using the above-mentioned unsilylated copolymer having a hydroxyl group instead of the vinyl monomer having a hydroxyl group.

In the polymer (A), it is necessary that at least 20%, preferably at least 50% of the hydroxyl groups are silylated. If the degree of silylation is less than 20%, the effect of lowering the viscosity by the silylation of the hydroxyl group cannot be sufficiently exhibited.

The silylated vinyl polymer (A) is
It can be obtained by copolymerization using a vinyl monomer having a silylated hydroxyl group as described above, but can also be obtained by the following method.

For example, when the above vinyl polymer (A) is obtained by copolymerization, a vinyl monomer having a hydroxyl group is used instead of a vinyl monomer having a silylated hydroxyl group, and the copolymer is then copolymerized. The vinyl polymer (A) having a silylated hydroxyl group can also be obtained by silylating the hydroxyl group of (A). The silylation of the hydroxyl group in the copolymer can be carried out according to the reaction of the above formula (2) or (3) using the above-mentioned copolymer having a hydroxyl group instead of the vinyl monomer having a hydroxyl group.

In the vinyl polymer (A), it is necessary that at least 20%, preferably at least 50% of the hydroxyl groups are silylated. If the degree of silylation is less than 20%, the effect of lowering the viscosity by the silylation of the hydroxyl group cannot be sufficiently exhibited.

Polyol Compound (B) The polyol compound (B) has two or more, preferably three or more hydroxyl groups in one molecule, a molecular weight of less than 1,000, preferably 200 to 900, and a hydroxyl value of 120 to 10
00mgKOH / g, preferably 150-800mgK
It is a compound having OH / g.

In the polyol compound (B), when the number of hydroxyl groups in one molecule is less than 2, the curability of the composition becomes insufficient, and when the molecular weight is 1,000 or more, the viscosity of the composition increases, so that the solidification of the paint is high. Becomes insufficient. The compound (B) has a hydroxyl value of 120 mgKOH
/ G, the curability of the composition decreases, while the
If it exceeds 00 mgKOH / g, the viscosity tends to increase due to hydrogen bonding between hydroxyl groups, and the water resistance of the obtained coating film decreases.

The polyol compound (B) reacts with a hydrolyzable alkoxysilyl group in the polymer (A) at the time of heat curing and contributes to curing, and also has a low molecular weight, which contributes to lowering the viscosity of a coating material. can do.

The polyol compound (B) can be used without particular limitation as long as it satisfies the above conditions. As preferred polyol compounds (B), for example, the following general formula

[0048]

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Wherein R ⁴ is a (m + n) -valent hydrocarbon group having 2 to 10 carbon atoms, k is an integer of 1 to 3,
Represents an integer of 0 to 2, n represents an integer of 1 to 3, and (m + n)
Represents an integer of 2 to 4. And acryl oligomers.

The number of carbon atoms represented by R ⁴ is 2 to 10
Examples of the (m + n) -valent hydrocarbon group having

[0051]

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The above polyol compound (B) is preferably used after the hydroxyl group is silylated from the viewpoint of lowering the viscosity of the paint. The silylation ratio is preferably at least 20 mol% of the hydroxyl groups, more preferably at least 50 mol%. The silylated hydroxyl group in the polyol compound (B) is a group represented by the general formula (1),
The silylation of the hydroxyl group can be performed according to the method of silylating the hydroxyl group in the polymer (A).

Polyisocyanate Compound (C) The polyisocyanate compound (C) is a compound having two or more isocyanate groups in the molecule, and the polymer (A)
And a compound which crosslinks by reacting with a hydroxyl group in the polyol compound (B).

Examples of the polyisocyanate compound (C) include aliphatic diisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, dimer acid diisocyanate, and lysine diisocyanate; hydrogenated xylylene diisocyanate, cyclohexylene diisocyanate, and methylene bis (cyclohexyl isocyanate). ), Cycloaliphatic diisocyanates such as isophorone diisocyanate; tolylene diisocyanate, phenylene diisocyanate,
Organic diisocyanates such as aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate xylylene diisocyanate, tetramethyl xylylene diisocyanate, and naphthalene diisocyanate; 2-isocyanatoethyl-2,6-diisocyanatocaproate, 3-isocyanate Methyl-1,6-hexamethylene diisocyanate, 4-isocyanatomethyl-1,8-
Trivalent or higher organic polyisocyanate compounds such as octamethylene diisocyanate (commonly called triaminononane triisocyanate); dimers or trimers of these divalent or trivalent or higher organic polyisocyanates; divalent or trivalent thereof Adducts obtained by reacting an organic polyisocyanate having a valency or higher with a polyhydric alcohol, a low molecular weight polyester resin, water, or the like under an isocyanate group excess condition, and the like. Furthermore, the polyisocyanate compound (C) also includes a blocked polyisocyanate in which the free isocyanate group of the above-mentioned isocyanate compound having a free isocyanate group is blocked with a blocking agent such as phenols, oximes, lactams, alcohols, and mercaptans. Included.

The polyisocyanate compound (C) needs to have a number average molecular weight of 2,000 or less, preferably 1,000 or less. If the number average molecular weight exceeds 2,000, the viscosity of the composition increases. High solid differentiation of paint becomes insufficient.

Silanol Group Generating Catalyst (D) The silanol group generating catalyst (D) incorporated in the coating composition of the present invention hydrolyzes the alkoxysilyl groups in the polymer (A) to promote the generation of silanol groups. A catalyst,
Eventually, it has a function of promoting a crosslinking reaction between a hydroxyl group in the polymer (A) or the polyol compound (B) and an alkoxysilyl group in the polymer (A).

Examples of the silanol group-forming catalyst (D) include organic sulfonic acid compounds such as dodecylbenzenesulfonic acid, paratoluenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalenedisulfonic acid, and trifluorosulfonic acid; Amine neutralized organic sulfonic acid compound; monobutyl phosphate, dibutyl phosphate, monoisopropyl phosphate, diisopropyl phosphate, monooctyl phosphate, dioctyl phosphate, monodecyl phosphate,
Didecyl phosphate, metaphosphoric acid, orthophosphoric acid, pyrophosphoric acid, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate, tris / chloroethyl phosphate, triphenyl phosphate, tricresyl phosphate, etc. And the like.

The mixing ratios of the vinyl polymer (A), the polyol compound (B), the polyisocyanate compound (C) and the silanol group-forming catalyst (D), which are essential components in the composition of the present invention, are as follows. . It is generally appropriate that the compounding ratio of the polymer (A) and the compound (B) is in the following range based on 100 parts by weight of the total solid content of both.

Polymer (A): 20 to 60 parts by weight, preferably 30 to 50 parts by weight, Compound (B): 40 to 80 parts by weight, preferably 50 to 7 parts by weight
0 parts by weight.

The compounding ratio of the compound (C) is determined by the equivalent ratio of the total of the hydroxyl groups (including the silylated hydroxyl groups) in the polymer (A) and the compound (B) to the isocyanate group of the compound (C). In the former: the latter is 1: 0.5-
It is suitable that the ratio is in the range of 0.5: 1, preferably 1: 0.6 to 0.6: 1.

The mixing ratio of the catalyst (D) is based on 100 parts by weight of the total solid content of the polymer (A) and the compound (B).
Suitably, it is in the range of 0.01 to 5 parts by weight, preferably 0.05 to 1 part by weight.

The composition of the present invention may further comprise, if necessary,
It may contain a crosslinked polymer fine particle (E) and a urethanization catalyst (F).

The crosslinked polymer fine particles (E) are not dissolved in the components of the polymer (A), the compound (B), the compound (C) and the catalyst (D) or in the solvent, and are stable in the composition of the present invention. Is an internally crosslinked particulate polymer that can be dispersed in water. By mixing the crosslinked polymer fine particles (E), thixotropic properties can be imparted to the coating composition.

When the coating composition is applied to a vertical surface of a substrate, or during baking after the application, coating defects such as sagging and repelling may appear. When the crosslinked polymer fine particles (E) are blended into the coating composition, the apparent viscosity at the time of standing is increased, but when a high shear stress is applied such as during spray coating, the viscosity is sufficiently small. Spray coating work can be easily performed, and after coating on the base material, a thixotropic property is developed within a short time, and a good coating film without coating defects such as sagging and cissing The effect of preventing coating film defects, that is, the formation of a film, works sufficiently.

As specific examples of the crosslinked polymer fine particles (E), there can be used aqueous emulsions or known intramolecularly crosslinked fine particle polymers obtained by an aqueous suspension polymerization method or a non-aqueous dispersion polymerization method. Among them, the aqueous emulsion or the finely divided polymer having an intramolecular crosslinked structure obtained by the aqueous suspension polymerization method is obtained by physical or chemical means such as evaporation or azeotropic distillation of water or precipitation or aggregation of the polymer (particles). ,
It can be separated in solid form, or
In applying physical or chemical means, the medium of the desired crosslinked polymer fine particles can be directly replaced with water from another resin or an organic solvent.

In the present invention, as the crosslinked polymer fine particles (E), polymerizable monomers having at least two radically polymerizable unsaturated groups in a molecule as disclosed in JP-A-3-66770 are used. Crosslinked polymer fine particles obtained by subjecting another radical polymerizable unsaturated monomer to emulsion polymerization in the presence of a reactive emulsifier having an allyl group in the molecule can be suitably used. In this case, the polymer fine particles are internally cross-linked by a polymerizable monomer having at least two unsaturated groups capable of radical polymerization in the molecule.

Further, as a crosslinked polymer fine particle (E), a polymer containing an alkoxysilyl group-containing vinyl monomer as an essential monomer component as disclosed in JP-A-1-95116 is used as a dispersion stabilizer resin. And a non-aqueous dispersion of a fine particle polymer insoluble in the organic liquid obtained by polymerizing a radical polymerizable unsaturated monomer in an organic liquid in the presence of the dispersion stabilizer resin. In this case, the alkoxysilyl groups based on the alkoxysilyl group-containing vinyl monomer in the dispersion stabilizer resin and the alkoxysilyl groups react with the functional groups such as hydroxyl groups in the polymer fine particles to form a crosslink. Further, as a radical polymerizable unsaturated monomer forming the fine particle polymer,
Using polymerizable monomers having at least two unsaturated groups capable of radical polymerization in a molecule, vinyl monomers containing an alkoxysilyl group, or two types of monomers that are a combination of complementary functional groups, the polymer fine particles are further embedded therein. Crosslinking may be performed, and internal crosslinking is preferred.

Examples of the combination of the complementary functional groups include a combination of an isocyanate group and a hydroxyl group, and a combination of a carboxyl group and an epoxy group. Examples of the vinyl monomer having an isocyanate group, which is a monomer used in this case, include isocyanatoethyl (meth) acrylate and m-isopropenyl-α, α-dimethylbenzyl isocyanate. Examples of the hydroxyl group-containing vinyl monomer include those described above, and among them, 2-hydroxyethyl (meth) acrylate can be suitably used. Examples of the carboxyl group-containing vinyl monomer include (meth) acrylic acid and the like. Examples of the epoxy group-containing vinyl monomer include glycidyl (meth) acrylate and methyl glycidyl (meth) acrylate.

The crosslinked polymer fine particles have a high crosslink density and are substantially non-swellable and non-fusible even in an organic solvent having a high polymer dissolving power such as toluene or ethyl acetate. When added to a binder resin solution or dispersion containing an organic solvent, the solution (dispersion) does not significantly increase the viscosity of the solution (dispersion), and has a high resin content, that is, a solution having a high solid content ( Dispersion). Further, in the composition containing the crosslinked polymer fine particles, after drying, the fine particles and the binder resin together form a cured coating film.

The crosslinked polymer fine particles (E) have an average particle diameter of about 0.01 to 2 μm, preferably 0.05 to 2 μm.
It is appropriate that the thickness is about 0.5 μm. When the average particle size is in this range, it is easy to achieve both a sagging prevention effect and a good finished appearance of the coating film.

In the composition of the present invention, the crosslinked polymer fine particles (E)
Is blended, the amount is preferably from 1 to 20 parts by weight, particularly preferably from 2 to 10 parts by weight, based on 100 parts by weight of the total of the polymer (A), the compound (B) and the compound (C).

The urethanization catalyst (F), which is optionally added to the composition of the present invention, contains a silanol group derived from a hydroxyl group or a hydrolyzable alkoxysilyl group in the polymer (A) and the compound (B). And a isocyanate group in the compound (C); for example, tin catalysts such as dibutyltin diacetate, dibutyltin dioctate, dibutyltin dilaurate, and dioctyltin diacetate; titanium catalysts such as tetrabutyl titanate System catalysts; amines such as triethylamine and tributylamine; When the urethanization catalyst (F) is blended in the composition of the present invention, it is usually 0.01 to 100 parts by weight based on the total of the polymer (A), the compound (B) and the compound (C).
5 parts by weight, particularly in the range of 0.05 to 1.0 part by weight, is suitable.

In the coating composition of the present invention, if necessary, a so-called dehydrating agent such as trimethyl orthoacetate can be used in order to suppress the deterioration of the coating due to the solvent contained and moisture present in the air.

The coating composition of the present invention may contain, if necessary, known pigments such as coloring pigments, metallic pigments, interference color pigments, extender pigments and rust preventive pigments.

Examples of the coloring pigment include quinacridone-based pigments such as quinacridone red, azo-based pigments such as pigment red, phthalocyanine blue, phthalocyanine green, and the like.
Organic pigments such as phthalocyanine-based such as perylene red; inorganic pigments such as titanium oxide and carbon black;
Examples of the metallic pigment include aluminum powder, nickel powder, copper powder, brass powder, and chromium powder, and examples of the interference color pigment include pearlescent pearl mica powder and pearlescent colored pearl mica powder. Can be mentioned.

The coating composition of the present invention may further contain, if necessary, various resins such as polyester resins, alkyd resins, silicone resins, fluororesins, etc .; ultraviolet absorbers, antioxidants, surface conditioners, defoamers, etc. Can be blended.

The coating composition of the present invention is used as an organic solvent type high solid content coating composition. Examples of the solvent include organic solvents for various coatings, for example, aromatic or aliphatic hydrocarbon solvents, alcohol solvents, and the like. Ester solvents, ketone solvents, ether solvents and the like can be used. The solid content concentration of the coating composition of the present invention is a high solid content of 70% by weight or more, and preferably 75 to 90% by weight.

The coating composition of the present invention is, for example,
It can be prepared by dissolving or dispersing the polymer (A), compound (B), compound (C) and other components in an organic solvent.

The coating composition of the present invention may be of a one-pack type or a two-pack type. In particular, most of the hydroxyl groups of the polymer (A) and the compound (B) are silylated, and When the number of unconverted hydroxyl groups is small, the storage stability is good even in a one-pack type, and the one-pack type is practical. On the other hand, when the polymer (A) and the compound (B) have many non-silylated hydroxyl groups, it is necessary to avoid deterioration of storage stability due to the reaction between these hydroxyl groups and isocyanate groups in the compound (C). It is preferable to use a two-pack type separated into a group of the polymer (A) and the compound (B) and a group of the compound (C). In the case of two-pack type,
Each group may be mixed and used immediately before use.

Since the coating composition of the present invention has a low viscosity that can be applied even when the solid content concentration is 70% by weight or more at the time of application, it can be easily applied by an airless spray, an air spray, a rotary atomization type coating method or the like. Can be painted. These coatings may be performed by applying static electricity. The coating composition of the present invention is excellent in atomization by these coating methods, and can form a coating film excellent in smoothness, sharpness, and feeling of holding.

The coating composition of the present invention can be used as a clear coating
In addition, various pigments such as color pigments, metallic pigments, and interference color pigments can be blended and used as solid color paints, metallic paints, and interference color paints. Since the coating composition of the present invention can form a cured coating film having excellent acid resistance, scratch resistance, and finished appearance (for example, luster, texture, and sharpness), the coating composition of the present invention is preferably used. It is suitable for use as the uppermost clear paint in a method of forming a multilayer coating film by sequentially applying at least one coloring paint and at least one clear paint.

In forming a multi-layer coating film, the following method may be used as a method for using the coating composition of the present invention as the uppermost clear coating.

Method a: A coating method using the coating composition of the present invention as a clear paint in a two-coat system in which a colored paint and a clear paint are sequentially applied.

Method b: A coating method in which the coating composition of the present invention is used as the second clear coating in a three-coat system in which a colored coating, a first clear coating, and a second clear coating are sequentially applied.

Method c: A coating method in which the coating composition of the present invention is used as a clear coating in a three-coat system in which a first coloring coating, a second coloring coating, and a clear coating are sequentially applied.

The methods a, b and c will be described in more detail.

In the above method a, the coloring paint may be
Solid color paints, metallic paints and interference color paints are included, and thermosetting paints known per se containing a resin component, a coloring pigment and a solvent can be used.

In the above colored paint, the resin component is, for example, an acrylic resin having a crosslinkable functional group (for example, a hydroxyl group, an epoxy group, a carboxyl group, an alkoxysilyl group, etc.), a vinyl resin, a polyester resin, an alkyd resin,
At least one kind of base resin such as urethane resin, and an alkyletherified melamine resin, urea resin, guanamine resin, cross-linked polyisocyanate compound, epoxy compound, carboxyl group-containing compound for crosslinking and curing the base resin And the like, and 50 to 90% of the base resin and 50 to 10% of the crosslinker component based on the total weight of both components.
It is preferable to use them together in a ratio of%. Pigments such as coloring pigments, metallic pigments, and interference color pigments, which are listed as known pigments that can be blended with the coating composition of the present invention, are blended with the coloring paint. These pigments can be used alone or in combination of two or more. Further, the coloring paint may be of an organic solvent type or an aqueous type.

In the above method (a), a metal or plastic object such as an automobile is coated directly, or an undercoat such as a cationic electrodeposition paint and, if necessary, an intermediate paint are applied and cured. The above colored paint is applied by a method such as airless spray, air spray, or rotary atomization coating (these may be electrostatically applied) so that the film thickness becomes about 10 to 50 μm in cured film thickness. 100-180
C., preferably from about 120 to 160 ° C. for about 10 to 40 minutes, and then cured, or left uncured for several minutes at room temperature or preheated. Is applied so that the cured film thickness is about 10 to 70 μm,
0-180 ° C, preferably about 120-160 ° C for about 10
It can be carried out by a two-coat one-bake method (2C1B) or a two-coat two-bake method (2C2B), which comprises heating and crosslinking for 40 minutes.

In the above method b, the coloring paint is
The same coloring paints as those described in the section of the method a can be used. The first clear paint is a paint for forming a transparent coating film, and a paint (including the paint composition of the present invention) obtained by removing most or all of the pigment from the colored paint can be used. Then, as the second clear coating, a clear coating composed of the coating composition of the present invention is used. In method b, in the same step as method a, after applying and curing the colored paint, or leaving or preheating at room temperature for several minutes without curing, the first clear paint is applied on the colored coating film. Similarly, a coating method is applied so that the cured film thickness is about 10 to 50 μm, and about 100 to 18 μm.
After curing by heating at 0 ° C., preferably at about 120 to 160 ° C. for about 10 to 40 minutes, or leaving or preheating at room temperature for several minutes without curing, the second clear comprising the coating composition of the present invention. Apply the paint by the same coating method so that the film thickness becomes about 10 to 50 μm in the cured film thickness,
Curing by heating at about 100-180 ° C, preferably about 120-160 ° C for about 10-40 minutes.
Coat 1 bake method (3C1B), 3 coat 2 bake method (3C2B) or 3 coat 3 bake method (3C3B)
Can be performed.

In the above-mentioned method c, as the first coloring paint, the same one as the coloring paint explained in the section of the above-mentioned method a can be used. The second colored paint is applied to the painted surface of the first colored paint, and the color tone (solid color,
A colored transparent paint having a small concealing property such that metallic colors and interference colors can be visually recognized is used. Therefore, the concealing property of the second colored paint film is usually smaller than that of the first colored paint film. A clear paint is applied on the second colored paint film. The clear paint is a paint for forming a transparent coating film, and the paint composition of the present invention is used. Method c
In the same process as in method a, after coating and curing the first colored paint as a colored paint, or leaving or preheating at room temperature for several minutes without curing, the first colored paint is applied on the first colored coating film. (2) The thickness of the colored coating is about 10 to 50 μm in the cured thickness.
And then cured by heating at about 100 to 180 ° C, preferably about 120 to 160 ° C for about 10 to 40 minutes, or leaving or preheating at room temperature for several minutes without curing, A clear coating comprising the coating composition of the present invention is cured by a similar coating method to a film thickness of about 10
~ 50μm, about 100-180 ℃,
Preferably, the coating is performed by heating at about 120 to 160 ° C. for about 10 to 40 minutes for curing, by a three-coat one-bake method (3C1B), a three-coat two-bake method (3C2B), or a three-coat three-bake method (3C3B). be able to.

[0092]

The present invention will be described more specifically with reference to examples and comparative examples. Note that “parts” and “%” are based on weight.

Production example 1 of vinyl polymer Cyclohexyl methacrylate 15 parts n-butyl methacrylate 6 parts 2-ethylhexyl methacrylate 13.5 parts 2-hydroxyethyl methacrylate 13.9 parts Silylated hydroxyl group-containing monomer (Note 1) 21.6 parts γ-methacryloxypropyltrimethoxysilane 30 parts A resin solution (A-1) having a solid content of 75% was obtained by subjecting the above monomer composition to solution polymerization in a conventional manner. The obtained resin had a hydroxyl value of 60 mgKOH / g, a methoxysilyl group content of 14%, and a number average molecular weight of 4000.

(Note 1) Monomer having a silylated hydroxyl group: The hydroxyl group of 2-hydroxyethyl methacrylate is silylated to obtain R ¹ , R 2
^{2. A} compound in which each of R and R ³ is a siloxy group which is a methyl group.

Production Example 2 Cyclohexyl methacrylate 15 parts n-butyl methacrylate 7.5 parts 2-ethylhexyl methacrylate 19.7 parts 2-hydroxyethyl methacrylate 27.8 parts γ-methacryloxypropyltrimethoxysilane (Note 1) 30 parts The above A resin solution (A-2) having a solid content of 75% was obtained by subjecting the monomer composition to solution polymerization in a conventional manner. The obtained resin had a hydroxyl value of 120 mgKOH / g, a methoxysilyl group content of 14%, and a number average molecular weight of 3,500.

Examples 1 to 4 and Comparative Examples 1 and 2 The vinyl polymer resin solution (A-
Using 1) or (A-2), the mixture was mixed at the ratio shown in Table 1 below to obtain a high solid content paint.

The components (B), (C), (D) and (E) and (Note 1) shown in Table 1 are as follows.

(B) Component (B-1): "TONE301" (trade name, manufactured by Union Carbide Co.), which is obtained by reacting 3 mol of ε-caprolactam per 1 mol of trimethylolpropane.
Number average molecular weight about 300, hydroxyl value about 561 mg KOH /
g.

(B-2): 1 of the above “TONE301”
Of the three hydroxyl groups per molecule, an average of two hydroxyl groups is trimethylsilyl etherified, and has a number average molecular weight of about 4
00, having a hydroxyl value of 140 mg KOH / g.

(C) Component (C-1): "LTI" (trade name, manufactured by Kyowa Hakko Co., Ltd.), 2
-Isocyanatoethyl-2,6-diisocyanatocaproate, molecular weight about 267.

(C-2): "Desmodur N-350
0 "(trade name, manufactured by Sumitomo Bayer Urethane Co., Ltd.), a trimer of hexamethylene diisocyanate.

(D) Component (D-1): "Nacure5543" (trade name, manufactured by King Industries, USA), a solution of an amine neutralized dodecylbenzenesulfonic acid.

(E) Component (E-1) γ-methacryloxypropyltrimethoxysilane 5 parts Styrene 10 parts n-butyl methacrylate 35 parts 2-ethylhexyl methacrylate 25 parts Lauryl methacrylate 25 parts Number average molecular weight 8000 comprising the above monomer composition Is a crosslinked polymer fine particle (E-1) obtained by copolymerizing the following monomer composition in a heptane / xylol mixed solvent using 100 parts of the dispersion stabilizer described above.

Γ-methacryloxypropyltrimethoxysilane 20 parts Styrene 15 parts Acrylonitrile 15 parts Methyl methacrylate 50 parts (Note 1) Modaflow: trade name, manufactured by Monsanto Co., USA, a surface conditioner.

In Table 1, the compounding amount of the component (D) is represented by the amount of the active ingredient, and the compounding amounts of the other components are represented by the solid content.
NCO / OH is represented by the equivalent ratio of the isocyanate group content of the component (D) to the total hydroxyl group content of the components (A) and (B).

Preparation of Test Coated Plate An epoxy resin-based cationic electrodeposition paint was applied to a chemically treated cold-rolled dull steel plate (film thickness: 25 μm), and cured by heating at 170 ° C. for 30 minutes.
M "(manufactured by Kansai Paint Co., Ltd., trade name, polyester resin / melamine resin paint, gray color) with a cured coating film of 30
It was coated to a thickness of μm and was cured by heating at 140 ° C. for 30 minutes. Then, the coated surface was water-sharpened with # 240 sandpaper, dried, and wiped with petroleum benzene to obtain an object to be coated.

A water-based metallic paint (“TW
X-402 "manufactured by Kansai Paint Co., Ltd., trade name, acrylic / melamine resin-based aluminum powder-containing metallic paint) as a cured coating film of about 18 μm,
Left at room temperature for 3 minutes. Then, on this uncured coating film,
The viscosity of each of the clear coating compositions of Examples and Comparative Examples shown in Table 1 was adjusted so that the coating viscosity was 50 seconds (Ford Cup # 4, 20 ° C.), and the cured film thickness was about 37 μm by air spray coating. Then, the coating was left at room temperature for 3 minutes, and then heated at 140 ° C. for 30 minutes to simultaneously cure the two coating films, thereby obtaining a coated film for forming a multilayer coating film. A performance test was performed on the obtained test coated plate, and the results are shown in Table 1.

In Table 1, the “solid content at the time of painting” is 50
It means the solid content of the clear paint immediately before coating, the viscosity of which has been adjusted to seconds (Ford Cup # 4, 20 ° C.).

Test Method Compatibility: The clear paints of the respective Examples and Comparative Examples were applied to a glass plate so as to have a cured film thickness of 50 μm.
The transparency of the coating film cured by heating for 0 minutes was visually determined. The evaluation criteria are as follows.

：: good transparency ：: coating film is slightly clouded ×: coating film is significantly clouded

The following test was conducted on the test coated plate obtained by the above-mentioned "Preparation of test coated plate".

Finishability: The appearance of the coated surface of the test coated plate was visually determined. The evaluation criteria are as follows.

：: Smoothness, gloss and sharpness are good and no abnormality is observed. Δ: Slightly poor in smoothness, gloss and sharpness ×: Any of smoothness, gloss and sharpness Is significantly inferior.

Hardness: means the two-cone hardness of the multilayer coating film of the test coated plate.

Scratch resistance: The coated surface of the multilayer coating film of the test coated plate
Polishing powder (Dalma Cleanser) is stiffened with water and placed on it.
After 25 reciprocations, the evaluation was made visually. The evaluation criteria are as follows.

：: No change in the gloss of the coated surface is observed. Δ: A little gloss is observed. X: A gloss is noticeably observed.

Acid resistance: 30 on the coated surface of the multilayer coating film of the test coated plate
0.4 cc of a sulfuric acid aqueous solution was dropped in a spot form, heated at 60 ° C. for 15 minutes with a hot air drier, washed with water, and the coated surface was visually evaluated. The evaluation criteria are as follows.

：: No change is observed on the coated surface. 少 し: Slight trace of spot is observed. X: Spot, whitening or blistering is remarkably recognized on the spot trace.

[0119]

[Table 1]

[0120]

The coating composition of the present invention has the following effects.

(1) The coating composition of the present invention reduces the excellent properties of conventional urethane coatings such as acid resistance, abrasion resistance, and finished appearance (for example, gloss, sharpness, solid feeling). No, the solid content at the time of painting is 70% by weight
It is possible to achieve the above high solid content concentration.

(2) The coating composition of the present invention comprises a polymer (A)
The high solid differentiation can be achieved by silylating the hydroxyl groups of the above and further blending the low molecular weight polyol compound (B).

(3) In the coating composition of the present invention, when the hydroxyl group of the polymer (A) and the hydroxyl group of the low-molecular-weight polyol compound (B) are highly silylated, storage which is a drawback of the conventional urethane coating is considered. Stability can be improved and one-packing can be achieved.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C09D 183/04 C09D 183/04 (72) Inventor Seiji Wada 4-171-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Prefecture Kansai Paint Co., Ltd. (72) Inventor Kosuke Noura 4-171-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Pref. Kansai Paint Co., Ltd. (72) Inventor Yasumasa Okumura 4-171-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Pref.

Claims (10)

[Claims] (A) a compound having both a hydroxyl group and an alkoxysilyl group in the same molecule and having a number average molecular weight of 2,000 to
A vinyl polymer in the range of 10,000,
At least 20 mol% of the hydroxyl groups are represented by the following general formula (1): (Wherein R ¹ and R ² are the same or different,
Alkyl group having 1 to 18 carbon atoms, an alkoxyl group having 1 to 6 carbon atoms, a phenyl group, an aryl group, a trimethylsiloxy group, a hydrogen atom, a chlorine atom or a fluorine atom, R ³ is 1 to carbon atoms 18 represents an alkyl group, a phenyl group, an aryl group or a trimethylsiloxy group. )
(B) a vinyl polymer having a molecular weight of less than 1,000 and a hydroxyl value of 120 to
It contains 1000 mg KOH / g of a polyol compound, (C) a polyisocyanate compound having a number average molecular weight of 2,000 or less, and (D) a silanol group-forming catalyst, and has a solid content of 70% by weight or more. Organic solvent type high solid content paint composition. 2. The polymer (A) has a hydroxyl value of 10 to 200.
mgKOH / g, alkoxysilyl group content 0.3 to
The coating composition according to claim 1, which is a polymer having 5.0 mmol. 3. The polyol compound (B) wherein at least 20 mol% of the hydroxyl group is a silylated hydroxyl group represented by the general formula (1).
The coating composition according to any one of the preceding claims. 4. The coating composition according to claim 1, further comprising crosslinked polymer fine particles (E). 5. The coating composition according to claim 1, further comprising a urethanization catalyst (F). 6. The compounding ratio of the total amount of the polymer (A) and the polyol compound (B) to the polyisocyanate compound (C) is 1: 0.5 in equivalent ratio of the former hydroxyl group and the latter isocyanate group. The coating composition according to any one of claims 1 to 5, wherein the ratio is in a range of 0.5 to 0.5: 1. 7. The coating according to claim 1, wherein at least one coloring coating and at least one clear coating are sequentially coated to form a coating film. A method for forming a coating film, comprising using a composition. 8. A two-coat coating comprising applying a paint for forming a colored base coat, applying a paint for forming a clear top coat on an uncured colored base coat, and then heating and curing both coating films. The method for forming a coating film according to claim 7, wherein the coating film is formed by a one-bake method. 9. The method according to claim 7, wherein the object to be coated is an automobile body. 10. An article on which a coating film is formed by the coating film forming method according to claim 7.