JP2002348529A - Coating material composition containing high solid content - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating material composition containing a high solid content, capable of forming a coating film excellent in finished appearance, coating film hardness, acid rain resistance, scratch resistance, etc., and a method for forming a multilayer coating film by using the same composition. SOLUTION: This coating material composition containing the high solid content is characterized by containing (A) a compound of a reaction product of a carboxy group-containing compound with an epoxy group-containing compound and having <=1,000 weight-average molecular weight and 200-800 hydroxy group value, (B) a polyisocyanate compound and (C) a melamine resin, and the method for forming the multilayer coating film is characterized by forming >=1 layers of colored coating film and >=1 layers of transparent coating film, and an uppermost transparent coating film with the above coating material composition containing the high solid content.

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 and a method for forming a multilayer coating film using the composition.

[0002]

2. Description of the Related Art In the field of paints, reducing the amount of organic solvents used has become an important issue from the viewpoints of environmental protection and resource saving against air pollution. As a countermeasure,
In organic solvent-based paints, there is a development of a so-called "high solid content paint composition" in which the amount of an organic solvent contained in the paint is reduced to increase the solid content concentration.

[0003] At present, most of the high solid content coating compositions which have been proposed are those in which a melamine resin is blended as a curing agent with a hydroxyl group-containing resin. However, when the viscosity of the resin is reduced by decreasing the molecular weight of the resin in order to increase the solid content concentration in the coating material, there is a serious defect that the coating film performance is deteriorated. On the other hand, in the state of low molecular weight, when a large number of crosslinkable functional groups such as hydroxyl groups are introduced in order to maintain coating film performance,
The viscosity increases due to the interaction between these functional groups, which is not preferable. Therefore, when a large number of functional groups are introduced, it is difficult to reduce the viscosity. In addition, when a large amount of melamine resin is blended, a large amount of by-products such as alcohol is generated during heat curing, so that the coating film has a defect that "blow" (foaming) is easily generated.

[0004] Further, a top coat containing a melamine resin applied to an outer panel of an automobile used outdoors is liable to cause etching of the coating due to acid rain and stain-like stains, and also to cause scratches due to a car washing machine. It has a defect that it is easy to do. On the other hand, when a polyisocyanate compound is blended as a cross-linking agent, the viscosity of the melamine resin itself is lower than that of the melamine resin, so that high solidification is easily performed, and furthermore, acid rain resistance, car wash abrasion resistance and finish appearance (for example, Gloss, meat feeling, sharpness, etc.), but in the high concentration region where the solid content is 70% by weight or more,
There is a defect that the hardness of the cured coating film is not sufficient.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned deficiencies of the prior art, to reduce the viscosity of the paint and to show no decrease in the performance of the coating, and to further improve the finished appearance, the hardness of the coating, and the like. The present invention relates to a novel high solids coating composition which forms a coating film having excellent resistance to acid rain and scratches, and a method for forming a multilayer coating film using the composition. As a result of earnest research, by using a polyisocyanate compound and a melamine resin in combination with a specific hydroxyl group-containing product obtained by reacting a carboxyl group-containing compound and an epoxy group-containing compound,
The inventors have found that the object can be achieved, and have completed the present invention.

That is, according to the present invention, (A) a reaction product of a carboxyl group-containing compound and an epoxy group-containing compound, having a weight average molecular weight of 1,000 or less and a hydroxyl value of 200 to 800; Compound,
There is provided a high solids coating composition (hereinafter, referred to as "the present composition") containing (B) a polyisocyanate compound and (E) a melamine resin.

[0007] The present invention also relates to a colored coating film having one or more layers.
A multilayer coating film comprising at least one transparent coating film, wherein the uppermost transparent coating film is formed by coating the composition (hereinafter referred to as "the present method") ).

First, the present composition will be described in detail.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The present composition is a high solid content type coating composition having a solid content of, for example, 70% at the time of coating.
% By weight or more, preferably in the range of 75 to 90% by weight.

Component (A): a reaction product of a carboxyl group-containing compound and an epoxy group-containing compound, having a weight average molecular weight of 1,000 or less and a hydroxyl value of 200 to 80.
A hydroxyl group-containing compound which is 0;

The component (A) can be prepared by a ring-opening esterification reaction between the carboxyl group of the carboxyl group-containing compound and the epoxy group of the epoxy group-containing compound. And a hydroxyl group generated by ring opening of the epoxy group.

The carboxyl group-containing compound contains one compound per molecule.
A compound having one or more carboxyl groups, for example, acetic acid, propionic acid, butyric acid, 2-ethylhexanoic acid, octanoic acid, dodecanoic acid, palmitic acid, stearic acid, oleic acid, pivalic acid, versatic acid,
Monocarboxylic acids such as benzoic acid; polycarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecane diacid, tetrahydrophthalic acid, phthalic acid, butanetricarboxylic acid, butanetetracarboxylic acid, trimellitic anhydride; Oxy acids such as glycolic acid, lactic acid, malic acid, citric acid, tartaric acid, hydroxypivalic acid, dimethylolpropionic acid, dimethylolbutanoic acid, and gluconic acid can be mentioned, and anhydrides thereof can also be used. Further, those obtained by reacting these anhydrides and glycols in advance can also be used. Specific examples thereof include a reaction product of trimethylolpropane and hexahydrophthalic anhydride and a reaction product of trimethylolpropane and succinic anhydride. Of these, a large number of hydroxyl groups are introduced into the component (A) by using an oxyacid having both a hydroxyl group and a carboxyl group or a compound having a hydroxyl group and a carboxyl group formed by reacting an anhydride with a glycol. Is preferred.

The epoxy group-containing compound is a compound having one or more epoxy groups in one molecule, and a compound known per se can be used. For example, the following compounds can be suitably used.

A) Glycidol.

B) An epoxy group-containing compound obtained by an etherification reaction between a hydroxyl group-containing compound and epihalohydrin.

C) An epoxy group-containing compound obtained by an esterification reaction between a carboxyl group-containing compound and epihalohydrin.

D) An epoxy group-containing compound obtained by reacting an unsaturated group with a peroxide.

The glycidol of component (a) is 2,3-epoxy-1-propanol, and is obtained, for example, by reacting allyl alcohol with benzoic acid or tungstic acid and hydrogen peroxide.

Examples of the hydroxyl group-containing compound in the component (b) include, for example, aromatic hydroxyl group-containing compounds such as phenol, bisphenol A, bisphenol F, phenol novolak resin, orthocresol novolak resin and bromide thereof; hydrogenated bisphenol A and the like. Alicyclic hydroxyl group-containing compounds; aliphatic monoalcohols having 1 to 20 carbon atoms, such as methanol and ethanol; ethylene glycol, propylene glycol, hexanediol, diethylene glycol, neopentyl glycol, glycerin, trimethylolpropane, pentaerythrene slit,
Examples thereof include aliphatic polyols having 2 to 20 carbon atoms such as dipentaerythritol. Epichlorohydrin can be suitably used as epihalohydrin. The esterification reaction between the hydroxyl group-containing compound and epihalohydrin can be carried out by a known method, and the component b) can be obtained by this reaction.

As commercially available products corresponding to the component (b),
"Denacol EX-313", "Denacol EX-321", "Denacol EX-421", manufactured by Nagase & Co., Ltd.
"Denacol EX-611" (both are trade names).

As the carboxyl group-containing compound in the component (C), for example, the carboxyl group-containing compounds exemplified in the preparation of the component (A) can be suitably used. The esterification reaction between the carboxyl group-containing compound and epihalohydrin such as epichlorohydrin can be performed by a known method, and the reaction can yield the component c). As a commercially available product corresponding to the component (c), “Kajura E1”
0 "(trade name, manufactured by Yuka Shell Epoxy Co., Ltd.)," Gradex N10 "(trade name, manufactured by Exxon)," Araldite PT910 "(trade name, manufactured by Ciba Geigy) and the like.

As the compound in the component (d), commercially available products such as "Celoxide 2021" and "Celoxide 3000" (all trade names) manufactured by Daicel Chemical Industries, Ltd. can be mentioned.

Among these compounds, a carboxy group-containing compound is particularly preferably an oxyacid, and an epoxy group-containing compound is particularly preferably a glycidyl ester having a hydrophobic group.

The ring-opening esterification reaction between the carboxyl group-containing compound and the epoxy group-containing compound for preparing the component (A) proceeds at room temperature.
It is preferable that the heating is carried out at 160 ° C., preferably 115 to 150 ° C., and without a catalyst.

The component (A) has a weight average molecular weight of 1
000 or less, preferably 300 to 700, and a hydroxyl value of 2
It is a compound having two or more hydroxyl groups in one molecule of 00 to 800, preferably 300 to 600. In the component (A), when the weight average molecular weight is more than 1,000, it is difficult to increase the solid content, and the hydroxyl value is 200.
If it is smaller, the curability is inferior. On the other hand, if it is larger than 800, the compatibility with the polyisocyanate compound is undesirably reduced.

Component (B): Polyisocyanate compound The polyisocyanate compound is a compound having two or more free isocyanate groups (non-blocked) in one molecule, and a compound known per se is used. it can. For example, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, dimer acid diisocyanate,
Aliphatic polyisocyanate such as lysine diisocyanate
Alicyclic polyisocyanates such as hydrogenated xylylene diisocyanate, cyclohexylene diisocyanate, methylene bis (cyclohexyl isocyanate) and isophorone diisocyanate; tolylene diisocyanate Aromatic polyisocyanates such as phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, tetramethyl xylylene diisocyanate, and naphthalene diisocyanate : 2-isocyanatoethyl-2,6-diisocyanatocaproate, 3-isocyanatomethyl-1,6-
Trivalent or higher organic polyisocyanate compounds such as hexamethylene diisocyanate and 4-isocyanatomethyl-1,8-octamethylene diisocyanate (commonly called triaminononane triisocyanate); Dimer or trimer of a polyisocyanate compound having two or more isocyanate groups in one molecule; polyisocyanate having two or more isocyanate groups in one molecule
And urethanation reaction of the compound with a polyhydric alcohol, a low molecular weight polyester resin or water under an isocyanate group excess condition, and the like.

In the component (B), a block polyisocyanate compound having an isocyanate group blocked can be used in combination with these non-blocked polyisocyanate compounds.

The block polyisocyanate compound is a compound in which the isocyanate group of the above polyisocyanate compound is blocked with a blocking agent. As a blocking agent,
Examples include phenols, oximes, lactams, alcohols, mercaptans, active methylene compounds such as diethyl malonate, and the like. The ratio of these block polyisocyanate compounds is preferably not more than 50% by weight, particularly preferably not more than 30% by weight, based on the total solid content with the non-blocked polyisocyanate compound.

The number average molecular weight of the component (B) is preferably 2,000 or less, particularly preferably in the range of 200 to 1,000.

Component (C): melamine resin Used as a crosslinking agent together with the above-mentioned component (B), and is obtained by reacting an aldehyde with a part or all of amino groups (—NH ₂ ) in a melamine molecule. Methylolated melamine resins (including those containing imino groups> NH in their molecules). As the aldehyde, formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde and the like can be used. Alkyl etherified melamine resins (including those containing an imino group> NH in the molecule) obtained by etherifying alcohol to part or all of the methylol groups of the methylolated melamine resin are also used as melamine resins. Can be used as

The alcohol used for etherification includes, for example, methyl alcohol, ethyl alcohol, n
-Propyl alcohol, i-propyl alcohol, n-
Butyl alcohol, i-butyl alcohol, 2-ethylbutanol, 2-ethylhexanol, etc.
And monovalent alcohols of 10 to 10. The number average molecular weight of the component (C) is preferably in the range of 150 to 3,000. Of these, the use of a melamine resin containing an imino group is more preferable because the weather resistance of the coating film, particularly the gloss retention, can be improved.

The present composition is a compound (A) which is a reaction product of a carboxyl group-containing compound and an epoxy group-containing compound and has a weight average molecular weight of 1,000 or less and a hydroxyl value of 200 to 800, B) It contains a polyisocyanate compound and a melamine resin (C), and the ratio of these components is not particularly limited and can be arbitrarily selected depending on the purpose. For example, the components (A) to (C) Based on the total solid content, component (A): 10 to 60% by weight, particularly 20 to 45% by weight, component (B): 30 to 70% by weight,
In particular, 35 to 60% by weight, the component (C): 3 to 40% by weight,
The range of 5 to 30% by weight is particularly suitable, and the composition can be prepared by blending these components with an organic solvent and uniformly mixing the components.

In addition, the composition (A) comprises
In addition to the components (B) and (C), it is also possible to further include (D) a curing catalyst and / or (E) a rheology control agent.

Component (D): curing catalyst This is useful for accelerating the crosslinking reaction by the above components (A) to (C). Specifically, tin octylate, dibutyltin di (2-ethylhexanoate), dioctyltin di (2-ethylhexanoate), dioctyltin diacetate, dibutyltin dilaurate, dibutyltin oxide, monobutyltin trioctate, Examples include organotin compounds such as lead 2-ethylhexanoate and zinc octylate. Furthermore, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid,
Acids such as dinonylnaphthalenedisulfonic acid, butyl phosphoric acid and octyl phosphoric acid, and amine neutralized products of these acids are preferred. (D) The amount of the curing catalyst used can be arbitrarily selected depending on the purpose of use, but is 0.005 to 5 parts by weight, particularly 0.01 to 100 parts by weight of the total of the components (A), (B) and (C). A range of ３3 parts by weight is suitable.

Component (E): rheology control agent By blending this component (E), the composition can be imparted with thixotropy, which may cause high shear stress during spray coating or the like. In
When the viscosity is sufficiently reduced, spray coating can be easily performed, while when a low shear stress is applied after coating on the surface to be coated, the apparent viscosity is increased. It becomes possible. As a result, it is possible to prevent the occurrence of coating defects such as sagging and repelling when baking after painting on a vertical surface to be coated or upon baking after coating on the portion, and to form a coating film having a good finished appearance. The effect is obtained. Examples of such a rheology control agent include crosslinked polymer fine particles and polyurea compounds.

The fine particles of the crosslinked polymer are as described in the above (A),
It is an internally crosslinked particulate polymer that is hardly soluble or compatible with the components (B) and (C) and the organic solvent, and can be stably dispersed in the present composition.

As specific examples of the crosslinked polymer fine particles, there can be used an aqueous emulsion or a known intramolecularly crosslinked fine particle polymer 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). , Can be separated in the form of a solid, or when physical or chemical means are applied, the medium of the target crosslinked polymer microparticles is replaced directly from water with another resin or organic solvent, etc. Can also.

As crosslinked polymer fine particles, JP-A-3-66
No. 770, a reactive emulsifier containing at least two radically polymerizable unsaturated groups in the molecule and another radically polymerizable unsaturated monomer in the molecule containing an allyl group. The crosslinked polymer fine particles obtained by emulsion polymerization in the presence of a polymer 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.

As the crosslinked polymer fine particles, poly (1
2-hydroxystearic acid) and a copolymer of a macromonomer (a) having an average of at least about one polymerizable unsaturated double bond per molecule and an ethylenically unsaturated monomer. And the solubility parameter (SP value) is 7.
5 to 9.2, and on average about 1.0 per molecule.
In the presence of a mixture with a macromonomer (b) having from about 1.5 to about 1.5 polymerizable unsaturated double bonds, each having at least two types of complementary functional groups capable of reacting and binding to each other. At least 0.5% by weight of vinyl monomer
The macromonomer (a), macromonomer (b) and the vinyl monomer are dissolved in the contained vinyl monomer mixture in an organic solvent in which the polymer of the vinyl monomer is substantially insoluble. And a dispersion liquid of gel polymer fine particles obtained by copolymerization and cross-linking reaction can be used. The crosslinked polymer fine particles themselves are known, and
This is disclosed in detail in Japanese Patent Publication No. 0110. The macromonomer (a) has a polymerizable unsaturated group-containing reaction product obtained by adding an epoxy group-containing polymerizable unsaturated unsaturated compound to a terminal carboxyl group of poly (12-hydroxystearic acid), and has an epoxy group. About one molecule per molecule obtained by adding a polymerizable unsaturated carboxylic acid to a pendant epoxy group-containing copolymer obtained by graft copolymerization or block copolymerization with a polymerizable unsaturated monomer mixture containing a polymerizable monomer. Macromonomers having from 1 to about 10 polymerizable unsaturated double bonds are preferred. In particular, the macromonomer (a)
Is preferably a macromonomer having one polymerizable unsaturated double bond in one molecule obtained by adding an epoxy group-containing polymerizable unsaturated unsaturated compound to a terminal carboxyl group of poly (12-hydroxystearic acid). It is. The macromonomer (b) preferably has a number average molecular weight of 3,000 to 20,000 and a hydroxyl value of 45 to 150. Examples of the combination of the complementary functional groups include an epoxy group / carboxyl group, an alkoxysilyl group / hydroxyl group, an epoxy group / phosphate group, and an isocyanate group / hydroxyl group.

These crosslinkable 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. Moreover, when added to the present composition containing an organic solvent, the viscosity of the present composition hardly increases,
A solution (dispersion) having a high resin content, that is, a high solid content can be obtained. In the present composition containing the crosslinked polymer fine particles, both the fine particles and the binder resin form a cured coating film. The average particle diameter of the crosslinked polymer fine particles is 0.01
A range of about 2 to about 2 μm, particularly 0.05 to 0.5, is suitable. When the particle size is within this range, the sagging prevention effect of the coating film and the finished appearance of the coating film are excellent.

Further, a rheology control agent (E)
A diisocyanate having 3 to 20 carbon atoms
Also, solid particulate polyurea compounds comprising a reaction product of an isocyanurate trimer obtained from the above compound and an amine compound having one or more primary amino groups can be used (Japanese Patent Publication No. 7-81099). Gazette). The isocyanurate trimer has 3 to 20, preferably 5 to 14,
More preferably they are made from diisocyanates having 8 to 12 carbon atoms, particularly preferably hexamethylene diisocyanate. Examples of suitable diisocyanates include methylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, ω, ω ゜ dipropyl ether diisocyanate, thiodipropyl diisocyanate, cyclohexyl-1,4-diisocyanate, dicyclohexylmethane-4, 4 ゜ -diisocyanate, 1,5-dimethyl-2,4-bis (isocyanatomethyl) -benzene, 1,5-dimethyl-2,4-bis (ω-isocyanatoethyl) -benzene, 1,3,5
Trimethyl-2,4-bis (isocyanatomethyl) benzene, 1,3,5-triethyl-2,4-bis (isocyanatomethyl) benzene, a complex sold under the trademark Desmodur TT of Bayer AG Cyclic diisocyanate, dicyclohexyldimethylmethane-4,4'-diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, diphenylmethane-4,4'-diisocyanate and the like. If desired, heterocyclic trimers of two or three different diisocyanates may be used. Also, a mixture of the above heterocyclic triisocyanates can be used.

The secondary used to make the polyurea compound
Examples of suitable primary amines as components include benzylamine, ethylamine, n-propylamine, sec-
Propylamine, n-butylamine, sec-butylamine, tert-butylamine, n-pentylamine,
α-methylbutylamine, α-ethylpropylamine,
β-ethylbutylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine, aniline, hexamethylenediamine and the like. These primary amines generally contain up to 55 carbon atoms, preferably 1 to 24, more preferably 1 to 12 carbon atoms. Amines having one or more primary amino groups and one or more ether and / or hydroxyl groups can also be used. For example, ethanolamine, 6-aminohexanol, p-methoxybenzylamine, methoxypropylamine, 3,4-
Examples include dimethoxyphenylethylamine, 2,5-dimethoxyaniline, furfurylamine, tetrahydrofurfurylamine, and bis (3-aminopropyl) polytetrahydrofuran (having a molecular weight of about 750). Mixtures of the above amines can also be used.

In the reaction of a heterocyclic triisocyanate with a primary amine to produce a polyurea compound, generally one of the heterocyclic triisocyanate or the primary amine can be used in excess of the stoichiometric amount. For example,
The ratio of the number of amino groups to the number of heterocyclic triisocyanate groups of the primary amine is from 0.7 to 1.5, preferably from 0.9 to 1.
It can be 1.

The reaction between the heterocyclic triisocyanate and the primary amine can generally be carried out in any selected manner by mixing the reactants and, if necessary, increasing the temperature. This reaction is preferably performed at a temperature of 10 ° C to 150 ° C, more preferably at a temperature of 20 ° C to 80 ° C. In general, the reactants can be mixed in any selected manner, but it is desirable to add the heterocyclic triisocyanate to the primary amine, and may be divided into several stages if necessary. Generally, the reaction is carried out in a solvent such as acetone, methyl isobutyl ketone, 1-methoxy-propanol-2,
It is performed in the presence of an aliphatic hydrocarbon such as benzene, toluene, xylene, or petroleum ether.

The amount of component (E) can be arbitrarily selected depending on the purpose of use, but is 1 to 20 parts by weight per 100 parts by weight of the total of components (A), (B) and (C) in terms of solid content. In particular, a range of 2 to 10 parts by weight is suitable.

The present composition comprises the above components (A), (B) and (C) as essential components, and further contains (D) and / or (E) as required. In addition to this, solid color pigments, metallic pigments, light interference pigments, extenders, UV absorbers,
It is also possible to include a light stabilizer, an antisettling agent, a coating surface adjuster, and other paint additives. The composition can be obtained by uniformly mixing these components with an organic solvent.

Examples of solid color pigments include quinacridone-based pigments such as quinacridone red; azo-based pigments such as pigment red; phthalocyanine-based organic pigments such as phthalocyanine blue, phthalocyanine green, and perylene red; and inorganic oxides such as titanium oxide and carbon black. Pigments; examples of metallic pigments include aluminum powder, vapor-deposited aluminum powder, aluminum oxide powder, nickel powder, copper powder, brass powder, and chromium powder; and interference color pigments include pearlescent pearls. Mica powder, pearlescent colored pearl mica powder and the like can be mentioned.

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

In the present composition, the polyisocyanate compound (B) reacts relatively easily with a component having an active hydrogen such as the component (A) at room temperature. Preferably, it is used in the form of a two-pack. In the case of the two-pack type, the components of each group may be mixed immediately before use and then provided for coating. In this case, the components other than the components (A), (B) and (C) may be used in consideration of the reactivity of the component (B).
Or (B) any one of the components,
It is also possible to use three components.

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

The composition may be, for example, at 30 to 80 ° C.
Preferably, the coating can be performed after heating to 40 to 60 ° C. As the heating method, the composition (i) containing the component (A) and the composition (ii) containing the component (B) are each heated and then mixed, and only the composition (i) is heated. And then mixing the composition (ii), heating only the composition (ii) and then mixing the composition (i), mixing the composition (i) and the composition (ii) and then adding There are four ways of warming. This heating may further shorten the pot life of the present composition. Therefore, after heating, a two-liquid mixing apparatus (for example, Precision M, manufactured by GRACO, Inc.)
It is possible to avoid the pot life problem by mixing homogeneously using ix). For example, the composition (i) is charged into the A liquid tank and the composition (ii) is charged into the B liquid tank, and the A liquid tank is heated to 55 ° C. At that time, the liquid B tank is kept at room temperature. When the composition (i) and the composition (ii) are mixed using a two-liquid mixing device, the liquid temperature can be set to 40 ° C. In this case, the heating of the composition (i) and the composition (ii) may be performed in reverse. By heating in this manner, the viscosity of the present composition at the time of coating can be lowered, and as a result, the coatability of the present composition as a high solid content paint can be further improved.

The present composition can be used as a solid paint, a metallic paint or an interference paint by blending various pigments such as a color pigment, a metallic pigment and an interference color pigment. In particular, the composition comprises
Since it is possible to form a cured coating film having excellent acid resistance, abrasion resistance, and finished appearance (for example, gloss, texture, and sharpness), at least one kind of colored paint and at least one
It is suitable to use the present composition as the uppermost clear paint in a method of forming a multilayer coating film by sequentially applying various clear paints.

Next, the present method, that is, a multi-layer coating film composed of one or more colored coating films and one or more transparent coating films, wherein the uppermost transparent coating film is formed by the present composition. The method for forming a multilayer coating film, which is characterized by the following, will be described.

In forming a multilayer coating film by the present method, the following method can be used as a method of using the present composition as the uppermost clear paint.

Method a: A coating method using the present composition 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 using the present composition as the second clear paint in a three-coat system in which a colored paint, a first clear paint, and a second clear paint are sequentially applied.

Method c: A coating method using the present composition as a clear paint in a three-coat system in which a first colored paint, a second colored paint, and a clear paint are sequentially applied.

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

In the above method a, the coloring paint is
Solid color paints, metallic paints and interference color paints are included.

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 alkyl etherified melamine resin, urea resin, guanamine resin for crosslinking and curing the base resin, an optionally blocked polyisocyanate compound, an epoxy compound, and a carboxyl group-containing compound 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 method (a), a metal or plastic object to be coated, such as for an automobile, is applied directly, or an undercoat such as a cationic electrodeposition paint and, if necessary, an intermediate coat are applied;
After curing, the color paint is cured to a thickness of about 10 to 10 by a method such as airless spray, air spray, or rotary atomization (these may be electrostatically applied).
After coating so as to have a thickness of 50 μm, and curing by heating at about 100 to 180 ° C., preferably about 120 to 160 ° C. for about 10 to 40 minutes, or after leaving or preheating at room temperature for several minutes without curing. The clear paint of the present composition is cured to a film thickness of about 10 by the same coating method.
~ 70μm, about 100-180 ℃,
A two-coat, one-bake method (2C1B) or a two-coat, two-bake method (2C2B), which preferably comprises heating at about 120 to 160 ° C. for about 10 to 40 minutes for crosslinking and curing.
Can be performed.

In the method b, the same coloring paint as that described in the method a can be used as the coloring paint. The first clear coating is a coating for forming a transparent coating film, and a coating obtained by removing most or all of a pigment from a colored coating (the present coating composition may be used) can be used. Then, as the second clear paint, a clear paint composed of the present composition is used. Method b is a method a
In the same process as above, after applying and curing the colored paint,
Alternatively, after leaving or preheating at room temperature for several minutes without curing, the first clear paint is similarly applied on the colored coating by a coating method so that the film thickness becomes about 10 to 50 μm in the cured film thickness. 100-180 ° C, preferably about 120-
After heating and curing at 160 ° C for about 10 to 40 minutes,
Alternatively, after leaving or preheating at room temperature for several minutes without curing, a second clear paint comprising the present composition is applied by a similar coating method so that the cured film thickness is about 10 to 50 μm, 100-180 ° C, preferably about 1
3 coats 1 bake method (3C1B) consisting of heating and curing at 20 to 160 ° C. for about 10 to 40 minutes, 3
It can be performed by a coat 2 bake method (3C2B) or a 3 coat 3 bake method (3C3B).

In the method c, as the first colored paint,
The same coloring paints as described in the section of the method a can be used. The second colored paint is applied on the painted surface of the first colored paint, and the color tone (solid color, metallic color, interference color) of the painted surface of the first colored paint can be visually recognized through the second colored paint film. A colored transparent paint having a small degree of hiding power is used. Therefore, the second
The hiding power of the colored coating film is usually smaller than that of the first colored coating film. A clear paint is applied on the second colored paint film. This clear paint is a paint for forming a transparent coating film, and the present composition is used. In method c, in the same process as method a, the first colored paint is applied and cured as a colored paint, or left or left at room temperature for a few minutes without curing before the first colored paint The second colored paint is applied so that the cured film thickness is about 10 to 50 μm, and is applied at about 100 to 180 ° C., preferably about 120 to 160 ° C.
After curing by heating at about 10 to 40 minutes at about 10 ° C., or after leaving or preheating at room temperature for several minutes without curing, the clear coating composed of the present composition is cured by a similar coating method. At about 100 to 180 ° C., preferably about 120 to 16 μm.
A three-coat, one-bake method (3C1B), a three-coat, two-bake method (3C2B) or a three-coat, three-bake method (3C) comprising heating and curing at 0 ° C. for about 10 to 40 minutes.
3B).

[0064]

The present invention relates to a so-called high solid content coating composition in which the amount of an organic solvent is reduced to increase the solid content from the viewpoint of environmental protection and resource saving. Is 1000 or less, and the hydroxyl value is 200 to 8
Reaction product of a carboxyl group-containing compound and an epoxy group-containing compound of No. 00, (B) polyisocyanate compound%
And (C) containing a melamine resin, and in particular, there is no generation of foam (foaming) on the coated surface, and it is possible to prevent etching of the coating film due to acid rain and generation of stain-like stains. In addition, it has an effect that it is particularly effective as a paint for forming an uppermost overcoat film for an automobile, with almost no occurrence of scratches due to a car wash machine or the like.

[0065]

EXAMPLES Examples and comparative examples according to the present invention will be described below. Parts and percentages are all by weight and the thickness of the coating is for the cured coating.

1. Preparation of Sample 1) Component (A) (A-1): 296 parts of dimethylolbutanoic acid was charged into a reactor equipped with a stirrer, a cooler, a temperature controller, a nitrogen inlet tube and a dropping funnel, and placed in a reaction vessel. Was replaced with nitrogen and heated to 120 ° C. There, "Kajura E1
490 parts was added dropwise over 2 hours, and the reaction was terminated at 120 ° C. when the acid value became 9 or less. The component (A-1) obtained had a solid content of about 98%, Gardner viscosity (20 ° C.) Z6Z7, and a hydroxyl value of 428 mgK.
OH / g, number average molecular weight 600, weight average molecular weight 610
Met.

(A-2): A reactor equipped with a stirrer, a cooler, a temperature controller, a nitrogen inlet tube and a dropping funnel was charged with 268 parts of dimethylolpropionic acid, and nitrogen in the reaction vessel was replaced. Heated to 150 ° C. There,
After dropping 490 parts of "Cardura E10" over 1 hour, the temperature was lowered to 120 ° C, and the reaction was terminated when the acid value became 9 or less at the same temperature. The component (A-2) obtained had a solid content of about 97% and a Gardner viscosity (20%).
C) Z6, hydroxyl value 444 mg KOH / g, number average molecular weight 590, weight average molecular weight 600.

(A-3): A reactor equipped with a stirrer, a cooler, a temperature controller, a nitrogen inlet tube and a dropping funnel was charged with 292 parts of adipic acid, and the inside of the reaction vessel was purged with nitrogen. Heated. There, "Kajura E1
490 parts was added dropwise over 2 hours, and the reaction was terminated at 120 ° C. when the acid value became 9 or less. The obtained component (A-3) has a solid content of about 98%, Gardner viscosity (20 ° C.) Z6, and a hydroxyl value of 176 mg KOH.
/ G, number average molecular weight 800 and weight average molecular weight 910. (For comparison) (A-4): "TONE301" (manufactured by Union Carbide Co., Ltd., trade name, ring-opening esterification reaction product of polyhydric alcohol and lactone, hydroxyl value about 561 mgKOH / g,
(Weight average molecular weight: about 700) (for comparison) 2) (E) component (E-1): A resin acid value of 30 obtained by dehydration-condensation of 12-hydroxystearic acid with methanesulfonic acid as a catalyst under reflux of toluene. Glycidyl methacrylate was added to the terminal carboxyl group of the self-condensed polyester resin having an average molecular weight of about 1800 using dimethylaminoethanol as a catalyst to introduce a polymerizable double bond to obtain a macromonomer (a). It had a solids content of 70% and had about one polymerizable double bond based on the number average molecular weight per molecule.

On the other hand, 174 parts of butyl acetate was placed in a flask and heated to reflux, and 70% of the macromonomer (a) was added thereto.
297 parts of a solution, 195.9 parts of methyl methacrylate, 18.5 parts of glycidyl methacrylate, 163.
A mixture consisting of 0 parts and 9.6 parts of 2,2-azobisisobutyronitrile was added dropwise at a uniform rate over 3 hours, followed by aging for 2 hours. Then, a mixture of 0.05 parts of pt-butylcatechol, 3.8 parts of methacrylic acid, and 0.5 part of dimethylaminoethanol was added to the flask, and the mixture was heated at 140 ° C. until the resin acid value reached 0.5. The reaction was carried out for 5 hours to obtain a macromonomer (b) having a solid content of 50%. The obtained macromonomer (b) is a graft polymer having a first segment made of poly 12-hydroxystearic acid and a second segment made of a copolymer of methyl methacrylate and glycidyl methacrylate. It had an average of four polymerizable unsaturated double bonds.

On the other hand, 153 parts of xylene was placed in a flask and heated to 125 ° C., and then 50 parts of 2-ethylhexyl acrylate, 23 parts of n-butyl acrylate, 25 parts of 2-hydroxyethyl acrylate, 2 parts of acrylic acid, t
A mixture of 4.5 parts of butyl peroctoate in 4 parts
The mixture was dropped over a period of time, and then aged for 2 hours. The obtained acrylic resin varnish had a solid content of 65% and a number average molecular weight of 7,000. This acrylic resin varnish 1
To 00 parts, 2 parts of glycidyl methacrylate, 0.01 part of 4-t-butylpyrocatechol, and 0.15 part of tetrabutylammonium bromide were added, and the mixture was stirred at 115 ° C. for 7 hours to introduce a copolymerized double bond into the molecule. As a result, a macromonomer (c) was obtained. The number of introduced double bonds in the macromonomer (c) is about 1.0 based on the number average molecular weight per molecule, the SP value is 8.70, and the hydroxyl value is 121 mgKOH /
g.

A flask was charged with heptane 190, 20 parts of a 50% macromonomer (b) solution, and 23 parts of a 65% macromonomer (c) solution. At reflux temperature, 20 parts of a 50% macromonomer (b) solution, 65% 23 parts of macromonomer (c) solution, 50 parts of methyl methacrylate, 2-
50 parts of hydroxyethyl acrylate, 1.5 parts of glycidyl methacrylate, 0.8 part of methacrylic acid, 2,2
A mixture consisting of 2 parts of '-azobisisobutyronitrile was added dropwise over 5 hours, followed by aging for 2 hours. Then
0.1 part of dimethylaminoethanol was added, and the mixture was aged for 4 hours to obtain a non-aqueous dispersion of polymer fine particles. The obtained dispersion was a white dispersion having a solid content of 40%, and the particle diameter was about 160 nm (peak particle diameter). The particle diameter was measured using a "COULTER N4 submicron particle analyzer" manufactured by Coal Tar. The particles were insoluble in organic solvents such as acetone, ethyl acetate and xylene.

2. Examples and Comparative Examples The above components were used and mixed at the weight ratios shown in Table 1 to obtain an organic solvent-based high solids type paint (clear paint).
The amounts of the components (A) to (E) are all solids ratios.

The performance tests (finishness, hardness, abrasion resistance and acid resistance) of the coating film were carried out by coating a cold-rolled dull steel plate subjected to a chemical conversion treatment with an epoxy resin-based cationic electrodeposition paint (film thickness 25%).
μm) and cured by heating at 170 ° C. for 30 minutes, and then an intermediate coating (“Lugabake AM” manufactured by Kansai Paint Co., Ltd., trade name,
A polyester resin / melamine resin paint (gray color) is applied to a film thickness of 30 μm and cured by heating at 140 ° C. for 30 minutes. Then, a metallic paint (“TWX-4”) is applied to the coated surface.
02 "(Kansai Paint Co., Ltd., trade name, acrylic resin / melamine resin-based paint) applied to a film thickness of 18 μm and left at room temperature for 3 minutes. High solids type paint (clear paint) (viscosity 50 seconds /
(Ford cup # 4 / adjusted to 20 ° C.) was applied to a film thickness of 35 μm, and heated at 140 ° C. for 30 minutes to simultaneously cure both coating films. Table 1 also shows the results of these performance tests.

The “solid content concentration at the time of coating” in Table 1 is a viscosity of 50.
Seconds / Ford Cup # 4 / viscosity of high solids type paint (clear paint) immediately before coating adjusted to 20 ° C.

[0075]

[Table 1]

(Note 1): "Death module N3300"
An isocyanurate type of hexamethylene diisocyanate, manufactured by Sumitomo Bayer Urethane Co., Ltd.

(Note 2) “LT1” manufactured by Kyowa Hakko Co., Ltd., trade name, 2-isocyanatoethyl-2,6-diisocyanatocaproate. Weight average molecular weight about 267.

(Note 3): “Cymel 325” manufactured by Mitsui Cyanamid Co., Ltd., a melamine resin containing an imino group.

(Note 4): "CYMER 303" A product of Mitsui Cyanamid Co., Ltd., a completely methylol type (not containing imino group) alkyl ether melamine resin.

(Note 5): N5543 “A product of King Industries, USA, trade name, amine neutralized solution of dodecylbenzenesulfonic acid.

(Note 6): “Scat 24” manufactured by Sankyoki Gosei Co., Ltd., trade name, tin catalyst.

(Note 7) “Setalux C-7176VB-60” manufactured by Akzo Nobel, trade name, rheology modifier. Polyurea compound.

(Note 8): The appearance of the multi-layer coating surface of the test coated plate was visually judged. ○ is good in smoothness, gloss and sharpness and no abnormality is recognized, △ is slightly inferior in smoothness, gloss and sharpness, × is one in smoothness, gloss and sharpness Significantly worse.

(Note 9): The two-cone hardness (20 ° C.) of the multilayer coating film of the test coated plate was measured.

(Note 10): Polishing sand (Dalmac Cleanser) was kneaded with water and placed on the multi-layer coating surface of the test coated plate, and the surface was pressed with a testing machine terminal and a load of 0.5 kg was applied. 25
After reciprocating, evaluation was made visually. ○ indicates that no change was observed in the gloss of the coated surface, △ indicates that some shine was observed, and x indicates that shine was significantly observed.

(Note 11): 0.4 cc of a 30% aqueous sulfuric acid solution was dropped in a spot form on the surface of the multilayer coating film of the test plate, heated at 60 ° C. for 15 minutes with a hot air dryer, washed with water, and coated. The surface was evaluated visually. ○ indicates that no change in the coating surface was observed, △ indicates that some spot marks were observed, and x indicates that spots, whitening or blisters were markedly observed in the spot marks.

(Note 12): The gloss retention (60 ° mirror reflectance) of the coated surface after a 480 hour test was measured using a sunshine weatherometer.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Naoshi Isaka 4-171-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa F-term in Kansai Paint Co., Ltd. 4D075 CA02 CA32 DB02 DC12 EA08 EA43 EB32 EB38 EB52 4J038 DA031 DA162 DG081 DG271 DG281 DG291 DG301 GA03 KA04 KA07 MA14 NA27 PB07

Claims (3)

[Claims] (A) a hydroxyl-containing compound which is a reaction product of a carboxyl group-containing compound and an epoxy group-containing compound and has a weight average molecular weight of 1,000 or less and a hydroxyl value of 200 to 800; A high solids coating composition comprising an isocyanate compound and (C) a melamine resin. 2. The method according to claim 1, further comprising: (D) a curing catalyst and / or (E).
2. The method according to claim 1, further comprising a rheology control agent.
A high solids coating composition as described in the above. 3. A high solids coating composition according to claim 1 or 2, which is a multilayer coating comprising at least one colored coating and at least one transparent coating, wherein the uppermost transparent coating is a multilayer coating. A method for forming a multilayer coating film, comprising: