JPH06346024A - Composition for chipping resistant coating and formation of chipping resistant coat - Google Patents

Abstract

PURPOSE:To obtain the subject composition containing a specific poly-isocyanate compound and a hydroxyl group containing resin, which shows excellent flexibility, chipping resistance and appearance of coating, with reduced solvent consumption, useful for a coating of outside plates for the automobile. CONSTITUTION:This composition contains (A) a polyisocyanate compound which is a reactional product of a polycaprolactone diol with an isocyanate compound blocked by an oxime and the like, and (B) a hydroxyl group containing resin which has 2 or more hydroxyl groups in a molecule. In this composition, the component A contains 2 to 5 isocyanate groups in a molecule and its number average molecular weight is 1,000 to 5,000, and the component B, in the case of an acrylic resin containing hydroxyl groups, has a glass transition point of -50 to 0 deg.C, a number average molecular weight of 2,000 to 8,000, and hydroxyl and acid values of 50 to 200 and 1 to 10mgKOH/g, respectively. Further, it is favorable for this composition to contain lactone modified acrylic resins and lactone modified polyester resins besides the components A and B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating composition for providing a chipping-resistant coating film and a method for forming a chipping-resistant coating film. More specifically, it prevents coating film damage due to stepping stones and rusting resulting therefrom. The present invention relates to a chipping-resistant coating composition for coating automobile outer panels, and a method for forming a coating film.

[0002]

BACKGROUND OF THE INVENTION When an automobile runs at high speed, it is unavoidable that pebbles or the like collide with (the painted surface of) the outer skin of the automobile, but this causes cracks in the coating film. In some cases, a phenomenon (so-called chipping) in which the coating film is peeled from the coated member (outer plate or the like) may occur. When chipping occurs in the coating film, water or the like enters from this portion and causes rusting of the substrate to be coated (outer plate).

Especially in foreign countries such as North America, Canada and Northern Europe,
In winter, a large amount of rock salt and sand are sprayed on the road surface due to snow melting.In such areas, chipping resistance is especially important for the coating of automobile outer panels, and the coating is damaged even if pebbles collide. There is a demand for a coating film that does not (peel) and does not rust the substrate (vehicle body outer plate).

Generally, in the coating of outer panels of automobile bodies, an electrodeposition paint (undercoating paint), an intermediate coating paint and a topcoating paint are sequentially coated on a steel sheet which has been subjected to a chemical conversion treatment of iron phosphate / zinc. In order to improve chipping resistance and rust resistance, various proposals have been made so far for each coating such as an electrodeposition coating (undercoating coating), an intermediate coating and a top coating, and a coating method thereof.

For example, JP-A-55-56165 discloses (a) an acidic resin having an acid value within a predetermined range, (b) talc powder, and (c) a metal chromate, a phosphate, or a molybdic acid. Disclosed is a chipping-resistant anticorrosion intermediate coating composition containing at least one of a salt and a tungstate in a predetermined amount.

Further, Japanese Patent Application Laid-Open No. 62-61675 forms a cationic electrodeposition coating film containing a cationic resin having a functional group capable of reacting with an isocyanate group as a main component, and then forming an intermediate coating composition and a top coating composition. Prior to coating, a method of applying an organic solvent-based coating material containing a polyisocyanate compound and forming a coating film having a static glass transition temperature of 0 to −75 ° C. to the electrodeposition coated surface is disclosed. . JP-A-62-61
No. 675, as a preferred polyisocyanate compound, a reaction product of hexamethylene diisocyanate and water,
Addition products of xylylene diisocyanate and trimethylol propane, addition products of tolylene diisocyanate and hexamethylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, etc. are mentioned, and this is a usual blocking agent such as oxime. It is used by blocking. As the cationic resin having a functional group capable of reacting with an isocyanate group, an epoxy resin having a polyphenol and a cationizing agent are mentioned.

Further, JP-B-61-36995 discloses a solvent-type solvent comprising, as a main component, a blocked isocyanate compound having a predetermined isocyanate group content and a polyhydroxy compound having a predetermined hydroxyl group content on an undercoat coating film. Disclosed is a method of applying a one-part composition to form a soft urethane resin film. This Japanese Examined Patent Publication No. 61-36995 discloses (a) polyisocyanates such as hexamethylene diisocyanate (the excess amount) and (b) ethylene glycol as the blocked isocyanate compound in the composition for forming the soft urethane resin film. , Propylene glycol, 1,3 butylene glycol, neopentyl glycol, trimethylol propane, the active isocyanate group of the polyisocyanate obtained by the addition reaction with a low molecular weight polyol, such as,
There is a description that a substance blocked with alcohol or the like can be used. In the specific examples, as the blocked isocyanate compound, hexamethylene diisocyanate is blocked with methanol and 1,6-hexanediol, or hexamethylene diisocyanate / buret type polyisocyanate is simply blocked with n-butanol. I am using what I did.

However, it cannot be said that the above-mentioned coating compositions and coating methods have sufficient chipping resistance. There is also a problem of coating workability in the wet-on-wet method.

Furthermore, JP-A-63-43967 discloses (a)
An organic solvent-soluble urethane polymer having a number average molecular weight of 10,000 to 100,000, which is an adduct of a diisocyanate compound and a polyol having an average of 2 to 3 hydroxyl groups per molecule, and (b) a specific number average molecular weight. Disclosed is a chipping-resistant coating material containing, as a main component, a hydroxyl group-containing resin having (b) and a blocked polyisocyanate compound (c). JP 63
No. 43967 discloses polyester resins and polyethers as preferable examples of the hydroxyl group-containing resin as the component (b).
Further, as the blocked isocyanate compound (c), diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate and tolylene diisocyanate, or those obtained by adding a polyol compound to these diisocyanates are mentioned. Here, examples of the polyol compound include polyether polyol and polyester resin (containing a hydroxyl group). In the specific examples thereof, the blocked isocyanate compound (c)
As the addition reaction product, an addition reaction product of tolylene diisocyanate with polytetramethylene glycol and trimethylol propane or an addition reaction product of tolylene diisocyanate with trimethylol propane is blocked with an oxime.

However, according to the research conducted by the present inventors, the paint disclosed in JP-A-63-43967 contains a resin component having a relatively high molecular weight in the paint (the component (a) is a number average molecular weight). However, when the paint is applied by spraying, a large amount of solvent must be used. The use of a large amount of solvent has drawbacks in terms of environmental problems and economy.

Further, there is a modified polyolefin type chipping primer, but such an existing type chipping primer contains a high molecular weight polymer,
A large amount of solvent must be used to enable spray painting (or to improve painting workability),
After all, there are problems in environmental issues and economics. Further, the existing type of this type of paint is inferior in the cleaning property of the piping in the coating line, the coating machine and the like, and the coating film removability. Furthermore, it is insufficient to prevent compatibility with the intermediate coating film.

Therefore, the object of the present invention is to have good chipping resistance, to reduce the volatile matter (solvent), and to have good cleaning properties for pipes and coating machines in the coating line, and good coating film removability. Another object of the present invention is to provide a chipping-resistant coating composition which gives a coating film which can prevent the compatibility with the intermediate coating film.

Another object of the present invention is to provide a coating method for forming a coating film having good chipping resistance.

[0014]

In view of the above objects, as a result of earnest research on a coating composition containing a hydroxyl group-containing resin and a blocked polyisocyanate compound as a main component, the present inventors have found that (a) polycaprolactone diol A block polyisocyanate compound, which is a reaction product of a blocked isocyanate compound, is combined with (b) a hydroxyl group-containing resin having two or more hydroxyl groups in one molecule, and, if necessary, a lactone-modified acrylic as a component (c). Resin, lactone-modified polyester resin, C2-8 polyol or polycaprolactone polyol at least one resin or compound (provided that component (b) and component (c) are different) is used to prevent chipping. It was discovered that the composition can provide a coating film having excellent properties. Further, these coating compositions can be applied not only to electrodeposition coating-topcoat coating system but also to electrodeposition coating-intermediate coating-topcoat coating system, and in the latter case, as an intermediate coating film in the coating process. It has been found that it is possible to prevent familiarity with and to give a good coating film. The present invention is based on the above findings.

That is, the first chipping resistant coating composition of the present invention comprises (a) a polyisocyanate compound which is a reaction product of a polycaprolactone diol and a blocked isocyanate compound, and (b) 2 in one molecule. A hydroxyl group-containing resin containing one or more hydroxyl groups as a main component.

The second chipping-resistant coating composition of the present invention comprises (a) a polyisocyanate compound which is a reaction product of polycaprolactone diol and a blocked isocyanate compound, and (b) 2 in one molecule. Hydroxyl group-containing resin containing one or more hydroxyl groups, and (c) lactone-modified acrylic resin, lactone-modified polyester resin, carbon number 2-8
At least one resin or compound of the above-mentioned polyol and polycaprolactone polyol (provided that the component (b) and the component (c))
The components are different) and are the main components.

Further, the method of the present invention for forming a chipping-resistant coating film using the above-mentioned coating composition is (1) electrodeposition coating-intermediate coating-top coating system,
(B) interlayer between electrodeposition coating film and intermediate coating film, (b) interlayer between intermediate coating film and top coating film, (c) one-layer top coating film, (d) 2
At least one of a base coating film and / or a clear coating film and (e) an intermediate coating film in a layer type top coating, or (2) an electrodeposition coating-top coating system, Between the coating film and the top coat film, (G) 1-layer type top coat film, (H) 2
It is characterized in that it is applied to at least one of a base coating film and / or a clear coating film in a layer type top coating.

The present invention will be described in detail below. The first chipping-resistant coating composition of the present invention comprises (a) a polyisocyanate compound which is a reaction product of a polycaprolactone diol and a blocked isocyanate compound, and (b) two or more hydroxyl groups in one molecule. The main component is a hydroxyl group-containing resin.

(A) Polyisocyanate Compound The polyisocyanate compound (a) is a reaction product of polycaprolactone diol and an isocyanate compound blocked by a blocking agent described later, and is a compound having an excess of isocyanate groups. Aliphatic or alicyclic polyisocyanates are preferably used, and aliphatic polyisocyanates are more preferably used.

The polycaprolactone diol used in the present invention is obtained by adding ε-caprolactone to a diol and has the general formula:

[Chemical 1] (In the formula, m and n each represent an integer of 0 to 5).

The diol corresponding to R has 2 to 8 carbon atoms, for example, ethylene glycol, propylene glycol, butene glycol, 1,5 pentanediol, 1,6 hexanediol, 2-ethyl-1, Three
-Hexanediol, neopentyl glycol and mixtures thereof can be used. The number average molecular weight is preferably 200 to 4000.

Examples of the aliphatic or alicyclic polyisocyanate include hexamethylene diisocyanate (hereinafter referred to as HDI), lysine diisocyanate, trimethylhexamethylene diisocyanate and isophorone diisocyanate. Moreover, those multimers can be used. Particularly, it is preferable to use HDI and / or a multimer thereof.

The aliphatic polyisocyanate may be of any of adduct type (adduct type) such as polyhydric alcohol, burette type and nurate type, but in particular,
A buret type and a nurate type are preferable. More preferably, a buret type is used. By using the burette type polyisocyanate, a coating film having softness and good chipping resistance can be obtained. In addition,
In the case of the nurate type polyisocyanate, the cyclic structure is present in the skeleton thereof, and therefore the chipping resistance of the coating film is not positive. However, in the present invention, since a polycaprolactone skeleton is introduced into the molecular chain of polyisocyanate as described later, it is possible to provide a sufficiently flexible coating film even with a nurate type polyisocyanate compound.

In the present invention, the above-mentioned aliphatic polyisocyanate is modified with polycaprolactone diol before use. That is, a polycaprolactone skeleton is introduced into the skeleton of the aliphatic polyisocyanate described above to form a soft portion in the molecular chain of the polyisocyanate compound. When the burette type polyisocyanate is used, the component (a) can be used because the polyisocyanate itself has no ring structure and the substance (polycaprolactone part) added thereto has a basically linear structure. It is a compound with high flexibility. Since the hydroxyl group-containing resin component (component (b)) described below is crosslinked and cured using such a compound (polyisocyanate compound), the resulting coating film has good chipping resistance.

In the component (a) (polyisocyanate compound which is a reaction product of a polycaprolactone diol and a blocked isocyanate compound), the ratio of the polyisocyanate-derived portion (eg, HDI portion) to the polycaprolactone portion is a weight ratio. It is preferable that the ratio is 1/1 to 1/4.

Examples of the blocking agent for blocking the active isocyanate group of the polyisocyanate compound include oximes, lactams such as ε-caprolactam, phenols such as phenol and xylenol, and alcohols. Particularly, oximes are used as the blocking agent. Is preferred. As the oxime used as the blocking agent, ME
K oxime, acetoaldoxime, etc. are mentioned.

Isocyanate group (--NC) in component (a)
O: However, this is blocked by the blocking agent described above. The number of) is preferably 2 to 5 in one molecule of the polyisocyanate compound.

The number average molecular weight of the component (a) (polyisocyanate compound which is a reaction product of polycaprolactone diol and blocked isocyanate compound) is 1
It is preferably about 000 to 5000. More preferably, the number average molecular weight is 1000 to 3000.

(B) Hydroxyl group-containing resin In the present invention, as the hydroxyl group-containing resin, one having two or more hydroxyl groups in one molecule is used. Examples of the hydroxyl group-containing resin that can be used include hydroxyl group-containing acrylic resin, hydroxyl group-containing polyester resin, chain hydrocarbon diols having 2 to 8 carbon atoms, and hydroxyl group-containing epoxy resin.

Hydroxyl group-containing acrylic resin As the hydroxyl group-containing acrylic resin, it is preferable to use one having a glass transition temperature (Tg) of -50 to 0 ° C.

The acrylic resin can be polymerized from the following monomers by a conventional method. (1) Hydroxymethyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate,
Ethylenic monomer having hydroxyl group such as N-methylol acrylamide, (2) acrylic acid, methacrylic acid (MAA), crotonic acid, itaconic acid, fumaric acid,
Ethylenic monomers having a carboxyl group such as maleic acid, and (3) methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl acrylate, isopropyl acrylate, isobutyl acrylate, acrylic 2-ethylhexyl acid salt, lauryl (meth) acrylate, n-octyl acrylate, n-dodecyl acrylate, and the like (meth) acrylic acid alkyl ester and the like at least one compound (provided that at least one of the monomers used is (Containing a hydroxyl group) can be obtained by copolymerization by a conventional method.

In addition to the above-mentioned ethylenic monomers, ethylenic monomers such as styrene and (meth) acrylonitrile which are copolymerizable with the above-mentioned monomers (1) to (3) can be used.

In the present invention, it is preferable to select the constituent components and the amount thereof from the above-mentioned monomers so that the glass transition temperature (Tg) of the resulting acrylic resin is 0 to -50 ° C.

Specifically, among acrylic monomers, an acrylic monomer that forms a coating film having a low glass transition temperature Tg (-10 ° C. or less) as a homopolymer (hereinafter, simply referred to as "low Tg acrylic monomer") and a high monomer. Glass transition temperature (Tg)
The acrylic monomer that forms the coating film (hereinafter referred to simply as "high Tg acrylic monomer") is separated, and the blending ratio is adjusted in consideration of this.

Examples of low Tg acrylic monomers include ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, lauryl methacrylate, 4-acrylic acid acrylate.
Examples thereof include hydroxybutyl and 2-hydroxyethyl acrylate. The glass transition temperature (Tg) of a coating film made of a homopolymer of the above monomers is as follows.

Ethyl acrylate (EA) -22 ° C n-butyl acrylate (n-BA) -54 ° C 2-Ethylhexyl acrylate (2-EHA) -85 ° C Lauryl methacrylate (LMA) -65 ° C Acrylic acid 4 -Hydroxybutyl (4-HBA) -43 ° C 2-Hydroxyethyl acrylate (2-HEA) -15 ° C The source of the above glass transition temperature (Tg) is "Introduction to synthetic resins for paints" ) Etc.

It is preferable to synthesize an acrylic resin having a hydroxyl group by using the low Tg acrylic monomer as an essential component and appropriately adding a high Tg acrylic monomer described later. Low Tg
The content of the acrylic monomer is preferably 50 to 95% by weight of the acrylic resin. When the content of the low Tg acrylic monomer is less than 50% by weight, a high elongation is not imparted to the obtained coating film, and when the content exceeds 95% by weight, the required tensile strength cannot be obtained. More preferable content is 60 to 90
% By weight.

On the other hand, as the acrylic monomer having a high Tg, acrylic acid, methacrylic acid, methyl acrylate, isopropyl acrylate, hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, Examples thereof include alkyl esters of (meth) acrylic acid such as n-hexyl methacrylate, 2-hydroxyethyl methacrylate and hydroxypropyl methacrylate, and sterene (st) and acrylonitrile.

The content of the high Tg acrylic monomer is preferably 40% by weight or less of the acrylic resin. If the content exceeds 40% by weight, the elongation of the resulting coating film will be insufficient.
A more preferable content is 5 to 30% by weight.

From the above monomers, Tg is -50 to 0.
It is preferable to synthesize the acrylic resin by appropriately selecting the monomer so that the temperature becomes ℃, and more preferably, the monomer is selected so that the Tg of the obtained coating film becomes -15 to -40 ℃.

The number average molecular weight of the hydroxyl group-containing acrylic resin is preferably 2000 to 8000. Number average molecular weight is
If it is less than 2000, the crosslinks in the coating film are not sufficiently formed,
Does not give a good coating. On the other hand, if the number average molecular weight exceeds 8,000, a coating film with excellent chipping properties cannot be obtained. In addition, it becomes difficult to obtain a high solid paint. More preferable number average molecular weight is 2500 to 6000, and more preferably 30.
00 to 4000.

The hydroxyl value of the acrylic resin is preferably 50 to 200. When the hydroxyl value is less than 50, the chipping property is deteriorated. On the other hand, when it exceeds 200, the flexibility of the coating film becomes insufficient and the chipping property deteriorates. The more preferred hydroxyl value range is 140 to 180.

The acid value of the acrylic resin is preferably 1-10. When the acid value is less than 1, the coating film has poor adhesion. On the other hand, when the acid value exceeds 10, the storage stability of the paint becomes poor. The unit of the hydroxyl value and the acid value in the present invention is mgKOH / g.

The above-mentioned acrylic resin may be modified with lactone before use. As the lactone, ε-
It is preferred to use caprolactone. Further, it is also possible to use those in which an alkyl group, an alkoxy group, a cycloalkyl group, a phenyl group, a benzyl group or the like is further bonded to the ring carbon atom of these lactones. The number average molecular weight of the lactone-modified acrylic resin is preferably 4000 to 15000. The hydroxyl value is preferably 5 to 200.

Hydroxyl group-containing polyester resin The polyester resin used in the present invention has two or more hydroxyl groups in one molecule, and is generally called polyester polyol. The polyester resin is usually obtained by polycondensing a polyhydric alcohol and a polybasic acid or an anhydride thereof (ester reaction).

As the polyhydric alcohol, ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol,
Polypropylene glycol, neopentyl glycol,
1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, hydrogenated bisphenol A,
Hydroxyalkylated bisphenol A, 1,4-cyclohexanedimethanol, 2,2-dimethyl-3-hydroxypropyl, 2,2-dimethyl-3-hydroxypropionate, 2,2,4-trimethyl-1,3- Pentanediol, N, N-bis- (2-hydroxyethyl) dimethylhydantoin, polytetramethylene ether glycol, polycaprolactone polyol, glycerin, sorbitol, anitol, trimethylolethane, trimethylolpropane,
Examples include trimethylol butane, hexanetriol, pentaerythritol, dipentaerythritol, and tris- (hydroxyethyl) isocyanate. Further, two or more of the above polyhydric alcohols can be used in combination.

As the polybasic acid or its anhydride, phthalic acid, phthalic anhydride, tetrahydrophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic acid, hexahydrophthalic anhydride, methyltetrahydrophthalic acid, methyltetrahydrophthalic anhydride, Hymic acid anhydride, trimellitic acid, trimellitic acid anhydride, pyromellitic acid, pyromellitic acid anhydride, isophthalic acid, terephthalic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, adipic acid, azelaic acid, sebacic acid, Examples thereof include succinic acid, succinic anhydride, lactic acid, dodecenyl succinic acid, dodecenyl succinic anhydride, cyclohexane-1,4-dicarboxylic acid and endo acid anhydride. Also, two or more of these may be used in combination.

The polyester resin used in the present invention is obtained by reacting the hydroxyl group of the polyhydric alcohol with the carboxyl group of the polybasic acid or its anhydride in a molar ratio of 1.2 to 1.8. As described above, it has two or more residual hydroxyl groups in one molecule.

The number average molecular weight of the hydroxyl group-containing polyester resin is preferably 500 to 10,000. The hydroxyl value is preferably 40 to 200. Further, the acid value is preferably 2-40.

As the other hydroxyl group-containing polyester resin, those modified with lactone, fat or oil, fatty acid, melamine resin, epoxy resin, urethane resin or the like can be used.

Lactone-modified polyester resin (hydroxyl-containing polyester resin modified with lactone.
Each modified polyester resin shown below also contains a hydroxyl group. ), The number of carbon atoms in the ring is 6 to
Those modified with the lactone of 8 are preferable. Specific examples of the lactone used for modification include ε-caprolactone. Further, it is also possible to use those in which an alkyl group, an alkoxy group, a cycloalkyl group, a phenyl group, a benzyl group or the like is further bonded to the ring carbon atom of these lactones.

The preferred number average molecular weight of the lactone-modified polyester resin is 500 to 15,000, and the preferred hydroxyl value is 40 to 200.

The lactone-modified polyester resin can be produced by adding a desired lactone to the polyester resin and heating. In this reaction, it is preferable to use a tin compound and / or an organic salt of lead or manganese as a catalyst.

The oil-modified polyester resin includes castor oil, dehydrated castor oil, coconut oil, corn oil, cottonseed oil, flaxseed oil, rapeseed oil, poppy oil, safflower oil, soybean oil, tung oil and the like, and these oils and fats. It is obtained by modifying the above polyester resin with a fatty acid extracted from fats and oils.

The preferred number average molecular weight of the oil-modified polyester resin (oil-modified or fatty acid-modified polyester resin) is 500 to 15,000, and the preferred hydroxyl value is 40 to 200.

In the production of the oil-modified polyester resin, 100 parts by weight of the polyester resin is mixed with the above-mentioned fat and oil and / or
Alternatively, it is preferable to add up to about 30 parts by weight of fatty acid in total.

Examples of the melamine resin for modifying the polyester resin include those obtained by adding an aliphatic aldehyde to melamine to form an ether. Particularly preferred is an etherified melamine-formaldehyde addition reaction product.
Examples of the melamine resin obtained by etherifying the addition reaction product of melamine and an aliphatic aldehyde include condensates such as methyl etherified melamine, methyl butyl etherified melamine, and butyl etherified melamine. Further, a resin obtained by etherifying a condensate of benzoquanamine, urea or the like and an aliphatic aldehyde can also be used.

The preferred number average molecular weight of the melamine-modified polyester resin is 500 to 15,000, and the preferred hydroxyl value is 40 to 200. In the production of the melamine-modified polyester resin, it is preferable to add 1 to 10 parts by weight of the melamine resin to 100 parts by weight of the polyester resin.

As the epoxy resin for modifying the polyester resin, those usually used in the paint field can be used. Specifically, Epicote 828, 834,
836, 1001, 1004, 1007, DX-225 (all manufactured by Shell Chemical Co., Ltd.), Araldite GY-260, 6071, 6084 (manufactured by Ciba Geigy), DER-330, 331, 660, 661, 66 (manufactured by Dow Chemical Co.) ), Epicron 800, 830, 850, 860,
Bisphenol type epoxy resins such as 1050 and 4050 (manufactured by Dainippon Ink and Chemicals Co., Ltd.), phenol novolac type epoxy resins such as DEN-431 and 438 (manufactured by Dow Chemical Co.), Araldite CT508 (manufactured by Ciba Geigy), DE
A polyglycol type epoxy resin such as R732 and 736 (manufactured by Dow Chemical Co.), an ester type epoxy resin, a chain type aliphatic epoxy resin, an alicyclic epoxy resin, a polyol type epoxy resin and the like can be used. Moreover, you may use the thing containing halogen in each said epoxy resin.

The preferred number average molecular weight of the epoxy-modified polyester resin is 500 to 15,000, and the preferred hydroxyl value is 50 to 200. In the production of the epoxy-modified polyester resin, it is preferable to add 1 to 50 parts by weight of the epoxy resin to 100 parts by weight of the polyester resin.

The urethane-modified polyester resin is a resin having a polyester portion and a urethane portion, in which a hydroxyl group in the polyester resin is reacted with an isocyanate group of a polyisocyanate compound to introduce a urethane bond into the resin, or a polyol and a polyisocyanate. A dibasic acid is bonded to the hydroxyl group of urethane, which is a reaction product of In each case, one molecule has two or more residual hydroxyl groups.

In the production of the urethane-modified polyester resin, the polyisocyanate compound which has a urethane bond with the hydroxyl group of the polyester resin is a compound having two or more free isocyanate groups in the molecule. , 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, metaxylylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate, isophorone diisocyanate, trimethylhexamethylene diisocyanate, dimer Examples thereof include acid diisocyanate. Also, a urethane compound obtained by reacting a small amount of polyol with a polyisocyanate compound,
When the molecule has two or more isocyanate groups, it is included in the polyisocyanate compound referred to herein.
Examples thereof include an adduct of tolylene diisocyanate (3 mol) and trimethylolpropane (1 mol), an adduct of hexamethylene diisocyanate (3 mol) and trimethylolpropane (1 mol), hexamethylene diisocyanate. And a water, a xylylene diisocyanate (3 mol) and a trimethylolpropane (1 mol) adduct, and the like. One or more compounds are selected from these and used.

Among the above polyisocyanate compounds, a reaction product of hexamethylene diisocyanate and water excellent in weather resistance, an adduct of hexamethylene diisocyanate and trimethylolpropane, and xylylene diisocyanate and trimethylolpropane. Non-yellowing types such as adducts, isophorone diisocyanate, hexamethylene diisocyanate and lysine diisocyanate are preferred.

The urethane modified polyester resin has a preferred number average molecular weight of 500 to 15,000 and a preferred hydroxyl value of 50 to 200.

In the present invention, a hydroxyl group-containing polyester resin modified with a phenol resin may also be used.

Polyols having 2 to 8 carbon atoms and polycaprolactone polyol In the present invention, a chain type C 2 to 8 polyol can be used as the component (b). Specifically, ethylene glycol, propylene glycol, butylene glycol, 1,5 pentanediol, 1,6 hexanediol, 2-
Examples include ethyl 1,3-hexanediol and neopentyl glycol. Furthermore, polycaprolactone polyols such as polycaprolactone diol and polycaprolactone triol can be used.

In the case of polycaprolactone diol, the preferred number average molecular weight is 200 to 5,000.

Hydroxyl Group-Containing Epoxy Resin Examples of the epoxy resin having two or more hydroxyl groups include various bisphenol type epoxy resins.

The number average molecular weight of the hydroxyl group-containing epoxy resin is 300 to 5,000, and the preferable hydroxyl value is 50 to 200.

Further, it is also possible to use a product obtained by modifying such an epoxy resin with a lactone. When modified with a lactone, it is preferable to add 5 to 50 parts by weight of the lactone to 100 parts by weight of the epoxy resin.

Other Resins Further, amines containing a plurality of active hydrogens can be used together with or instead of the above-mentioned (b) hydroxyl group-containing resin. Examples of such amines include polyoxyalkylamines, polyamidoamines, and aliphatic or aromatic amines (polyamines) having two or more amino groups in one molecule. Specific examples of the polyoxyalkylamine include Jeffamine (manufactured by TEXACO CHEMICAL).

The above-mentioned component (a): polyisocyanate compound and component (b): hydroxyl group-containing resin are compounded in a solid content of 20 to 80 parts by weight and (b) of 80 to 20. It is preferable to use parts by weight. less than 20 parts by weight of component (a),
Alternatively, if the amount of the component (a) exceeds 80 parts by weight, the chipping resistance becomes poor. More preferably, (a) is 30 to 70 parts by weight and (b) is 70 to 30 parts by weight.

Further, in the second chipping-resistant coating composition of the present invention, a lactone-modified acrylic resin (the lactone-modified acrylic resin in the above-mentioned (b) component hydroxyl group-containing acrylic resin is used as the component (c). be able to),
Lactone-modified polyester resin (the lactone-modified polyester resin in the above-mentioned hydroxyl group-containing polyester resin in the component (b) can be used), polyol having 2 to 8 carbon atoms (using the polyol in the component (b) above) At least one resin or compound (however, the component (b) and the component (c) are different), and polycaprolactone polyol (the polycaprolactone polyol in the component (b) can be used). By combining and with the component (a) and the component (b), the object of the present invention can be achieved.

The blending amount of these is 2 (a) in terms of solid content.
It is preferable that 0 to 80 parts by weight and (b) + (c) be 80 to 20 parts by weight. If the amount of component (a) is less than 20 parts by weight or the amount of component (a) exceeds 80 parts by weight, chipping resistance will be poor.
More preferably, (a) is 30 to 70 parts by weight, (b) +
(c) is 70 to 30 parts by weight. The ratio between (b) and (c) is 9
0/10 to 20/80 (weight ratio of solid content) is preferable.
The number average molecular weight of the component (c) is preferably 400 to 5,000, more preferably 500 to 3,000.

With the above-mentioned mixing amount, the molar ratio of the isocyanate group (-NCO) in the component (a) to the hydroxyl group (-OH) in the component (b) and, if necessary, the component (c) ( -N
A good cured film can be obtained by adjusting so that (CO / -OH) falls within the range of 2/3 to 3/2.

The chipping-resistant coating composition of the present invention comprises
In addition to the above-mentioned essential components, the following crosslinked polymer fine particles, pigments, various additives and the like can be added.

Addition of the crosslinked polymer fine particles improves the appearance of the coating film and prevents the chipping-resistant coating film and the coating film disposed thereabove from becoming familiar with each other.

Conventionally, crosslinked polymer fine particles (fine resin particles)
Various methods have been proposed for the production method of, but as one of the methods, fine polymerization is performed by suspending or emulsion-polymerizing an ethylenically unsaturated monomer with a crosslinkable copolymerizable monomer in an aqueous medium. There is a method of preparing a resin particle dispersion liquid and removing water by solvent substitution, azeotropic distillation, centrifugal separation drying or the like to obtain fine resin particles. Alternatively, low SP such as aliphatic hydrocarbon
In a non-aqueous organic solvent in which a monomer dissolves but a polymer does not dissolve, such as an organic solvent or a high SP organic solvent such as an ester, a ketone, or an alcohol, a copolymer of an ethylenically unsaturated monomer and a crosslinkable copolymer is used. There is a method of polymerizing and dispersing the obtained fine resin particles (copolymer). This method is N
It is called AD method or precipitation method.

The crosslinked polymer fine particles (fine resin particles) may be produced by any of the above methods. In addition, JP-A-58-12
The method of using a water-soluble resin having a zwitterionic group described in No. 9066 may be adopted.

In the present invention, it is preferable to use crosslinked polymer fine particles (fine resin particles) having an average particle diameter of 0.01 to 10 μm.

Examples of the ethylenically unsaturated monomer for producing the crosslinked polymer fine particles (fine resin particles) include (meth)
Alkyl esters of acrylic acid or methacrylic acid such as methyl acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate, and Other monomers having an ethylenically unsaturated bond capable of being polymerized, for example, styrene, α-methylstyrene, vinyltoluene, t-butylstyrene, ethylene, propylene, vinyl acetate, acrylonitrile, methacrylonitrile, (meth). Examples include dimethylaminoethyl acrylate. You may use these monomers in mixture of 2 or more types.

The crosslinkable copolymerizable monomer is
It includes a monomer having two or more radically polymerizable ethylenically unsaturated bonds in one molecule and / or an ethylenically unsaturated group-containing monomer having a group capable of reacting with each other.

Examples of the monomer having two or more radically polymerizable ethylenically unsaturated bond groups in one molecule include polymerizable unsaturated monocarboxylic acid ester of polyhydric alcohol and polymerizable unsaturated of polybasic acid. Examples include alcohol esters, and aromatic compounds having two or more vinyl groups.

The fine resin particles produced in an aqueous medium or a non-aqueous organic medium can be used as they are, but the fine resin particles can be isolated by a method such as filtration, spray drying or freeze-drying and used as they are or in a mill or the like. It can also be used after being pulverized to a suitable particle size.

Examples of the fine resin particles include AZS797 and AZS597 manufactured by Nippon Paint Co., Ltd. The content of such fine resin particles is preferably 0.1 to 40% by weight, more preferably 0.5 to 30% by weight, based on the resin solid content.

As the pigment, various organic pigments, inorganic pigments such as carbon black, titanium dioxide and iron oxide, extender pigments such as barium sulfate and talc, and scale-like substances such as graphite can be used.

Acrylic and polyoxyethylene surface conditioners (for example, Liponox NC-60: Lion Yushi Co., Ltd.) for the purpose of improving the familiarity with dust.
Manufactured) can be added.

In the present invention, it is desirable to add a catalyst such as an organic tin compound as a curing reaction accelerator to the coating composition. As the tin compound, dimethyltin dilaurate,
Examples include dibutyltin dilaurate, dimethyltin chloride, dibutyltin chloride and di n-octyltin dilaurate. Also, a tertiary amine-based catalyst may be used in combination.

A polyethylene-based anti-settling agent,
A known anti-sedimentation agent such as a polyamide type can be added.

A part of component (a) which is a crosslinking component is
It is also possible to replace it with an amino resin.

The amounts of the various additives described above are such that the total amount of the above-mentioned essential components (a) and (b) and, if necessary, (c) (as solid content) is 100 parts by weight, the pigment is 5-30
It is preferable to use 0.5 parts by weight, 0.5 to 3 parts by weight of the catalyst, and 1 part by weight or less of the anti-settling agent.

When the coating composition of the present invention is used as an organic solvent type coating, as a solvent, an aromatic hydrocarbon such as toluene and xylene, an aliphatic hydrocarbon such as mineral spirit, ethyl acetate, butyl acetate, etc. The solvents of the esters of 1) and ketones such as methyl ethyl ketone can be used alone or in combination (selected appropriately). Further, the coating composition of the present invention can be used not only as an organic solvent type coating material but also as a NAD type coating material or a water dispersion type water-based coating material. In this case, water or various hydrophilic organic solvents can be used as the solvent.

The coating composition of the present invention comprises (1) an electrodeposition coating-intermediate coating-top coating system,
(B) interlayer between electrodeposition coating film and intermediate coating film, (b) interlayer between intermediate coating film and top coating film, (c) one-layer top coating film (d) two-layer top coating film Or at least one of the base coating film and / or the clear coating film (e) intermediate coating film in (3) or (2) electrodeposition coating-top coating system, (f) electrodeposition coating film and top coating film At least one of the base coating film and / or the clear coating film between the layer and the film, (G) one-layer type top coating film, and (H) two-layer type top coating film. As a result, a laminated coating film including the chipping-resistant coating film of the present invention can be obtained.

A coating method using the coating composition of the present invention will be specifically described below. (1) For electrodeposition coating-intermediate coating-top coating

First, the material to be coated is subjected to electrodeposition coating.
As the electrodeposition coating material, any conventional anion type resin type or cation type resin type can be used.

The structure of the resin as the main component of the electrodeposition coating composition is as follows: (1) A liquid rubber system such as a drying oil or polybutadiene, or a resin having an epoxidized resin as a skeleton, such as a maleated oil resin or (2) Those having a fatty acid ester of resinous polyol as the main skeleton, such as maleated polybutadiene resin and amine epoxidized polybutadiene resin, and modified derivatives thereof, for example, epoxy resin, esterified resin, etc. (3) Alkyd resin as the main skeleton And (4) a resin whose main skeleton is an acrylic resin.

When the above-mentioned resin for electrodeposition coating is an acidic resin, it is neutralized with a base such as ammonia, amine, inorganic alkali, and dissolved or dispersed in water. Also, in the case of a basic resin, it is preferable to neutralize with an acid such as acetic acid, lactic acid, boric acid, phosphoric acid and the like to dissolve or disperse in water.

In the electrodeposition paint, melamine resin,
A cross-linking agent such as blocked isocyanate, a commonly used additive such as a pigment and a solvent can be appropriately mixed.

The electrodeposition coating film usually has a film thickness of 10 after baking.
It is preferable that the thickness is set to be about 40 μm. Other conditions in the electrodeposition coating may be the same as those in the conventional electrodeposition coating.

Prior to this electrodeposition coating, it is preferable to carry out an ordinary chemical conversion treatment.

In the above (a), the coating composition of the present invention is applied onto the electrodeposition coating film.

In order to appropriately dissolve the chipping-resistant coating composition of the present invention in a solvent to form a coating composition, it is necessary to satisfactorily disperse and mix the components. For that purpose, a device such as a paint shaker, a dissolver, a ball mill, a sand grind mill, or a kneader which is usually used for producing paint can be used.

The chipping-resistant coating composition of the present invention is diluted with a solvent so as to have an appropriate viscosity, and applied by a method such as spraying or coating. The viscosity of the paint (composition) at the time of painting is
It can be adjusted using the Ford Cup.

As the coating machine, an atomization type coating machine is preferably used, and examples thereof include an air spray coating machine, an airless spray coating machine, and an air atomization type or rotary electrostatic coating machine.

The thickness of the chipping-resistant coating film according to the present invention is preferably 2 to 60 μm as a dry film thickness. If the thickness of the chipping-resistant coating film is less than 2 μm, the chipping resistance is poor. Further, if the thickness exceeds 60 μm, the appearance becomes poor due to the mixing of the upper and lower coating films during wet-on-wet coating. The more preferable thickness of the chipping-resistant coating is 5
Is about 40 μm.

Next, intermediate coating is applied. The intermediate coating can be performed on the coating film of the coating composition of the present invention by using a so-called wet-on-wet method or a preheating method.

As the intermediate coating material, an alkyd resin, polyester resin or acrylic resin based coating material can be used. The coating can be performed by a conventional method, for example, electrostatic coating. Baking can also be performed by a conventional method. The film thickness of the intermediate coating film is preferably 20 to 60 μm as a dry film thickness.

As the intermediate coating material, a "color intermediate coating material" containing a coloring pigment may be used in order to exhibit design characteristics in combination with the top coating material.

As the top-coat paint, paints such as acrylic resin paints, polyester resin paints, and fluororesin paints can be used. In these resins, the resin system may be any of organic solvent type, water type and powder type.

The conditions for the top coating may be the same as the specifications for the conventional top coating of an automobile.

In the case of (b), first, electrodeposition coating /
Bake, then apply an intermediate coat on the electrodeposition coating,
Bake. Then, a coating composition comprising the coating composition of the present invention is applied onto the intermediate coating film, and a wet-on-wet method or a preheating method is used in combination for topcoating. In this case, the thickness of the coating film formed from the coating composition of the present invention is preferably about 2 to 60 μm as a dry film thickness.
The conditions for the electrodeposition coating, the intermediate coating, and the top coating may be the same as those in the above case (a).

Further, in the case of the above (c), the coating composition of the present invention is used as a one-layer type top coating (so-called top coating solid coating). After performing electrodeposition coating / baking and intermediate coating / baking according to the method of (a) above, the coating composition of the present invention is applied onto the intermediate coating film.

When the coating composition of the present invention is used as the top coat solid coating composition, as the component (b), an oil-modified polyester resin or the like can be appropriately used in addition to the above-mentioned acrylic resin.

When the top coating film is composed of a base coating film and a clear coating film (case (d) above), the coating composition of the present invention is applied to whichever coating film (base coating film or clear coating film). It may be used for formation, and further, it may be used for formation of both coating films (base coating film and clear coating film).

When the coating composition of the present invention is used as a top coating, it is preferable to use an acrylic resin as the resin of the component (b). Among them, it is preferable to use a fluorine resin-modified hydroxyl group-containing acrylic resin or a cellulose ester-modified hydroxyl group-containing acrylic resin. As the fluorine resin-modified hydroxyl group-containing acrylic resin, Japanese Patent Application Laid-Open No. 2-24
The fluoroolefin-modified acrylic resin described in No. 5067 can be preferably used.

The cellulose ester-modified hydroxyl group-containing acrylic resin may be any of the above-mentioned hydroxyl group-containing acrylic resin obtained by using cellulose nitrate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose acetate propionate, or the like, or a mixture thereof. Is a modified one. The amount of cellulose ester is preferably about 2 to 50% by weight, and more preferably 5 to 20% by weight, based on the solid content of the hydroxyl group-containing acrylic resin.

When the coating composition of the present invention is used as a base coating for a top coating, it is preferable to select a cellulose ester-modified hydroxyl group-containing acrylic resin as component (b). The film thickness of the base coating film at this time is preferably 15 to 20 μm as a dry film thickness.

When the coating composition of the present invention is used as a clear coating for top coating, it is preferable to select a fluororesin-modified acrylic resin as the component (b). At this time, the thickness of the clear coating film is 30 in terms of dry film thickness.
It is preferably about 50 μm.

Further, the coating composition of the present invention has the above (e)
It can also be used as an intermediate coating as shown in FIG. At this time, as the resin of the component (b) in the coating composition of the present invention, the above-mentioned hydroxyl group-containing polyester resin (including various modified polyester resins of epoxy modified, oil modified, melamine modified, or urethane modified) is selected. Is preferred. The thickness of the intermediate coating film in this case is 30 in terms of dry film thickness.
It is preferably about 50 μm.

(2) Electrodeposition Coating-Topcoat Coating System On the other hand, in the case of (f), after the electrodeposition coating is performed as described above, the coating composition of the present invention is applied to the electrodeposition coating film. Paint on top. In this case, it is preferable to use a polyester resin as the component (b) of the coating composition of the present invention. Particularly preferably, a lactone-modified polyester resin is used. The dry film thickness is preferably 5 to 40 μm.

Then, a top coat is applied on the coating film of the coating composition of the present invention in the same manner as in the case of (a).

In the case of (g), after the electrodeposition coating is performed as described above, the solid top-coating paint of the chipping resistant coating composition of the present invention is applied according to the above (c).

In the case of (h), a base coating film and a clear coating film are formed as a coating material on the electrodeposition coating film in the same manner as in (d) above.

[0124]

The present invention will be described in more detail by the following specific examples. Examples 1 to 3 and Comparative Examples 1 to 4 A 7 cm x 15 cm x 0.8 mm dull steel plate treated with zinc phosphate is dried with a cationic electrodeposition coating [Nippon Paint Co., Ltd., Power Top U-226E]. It was electrodeposited so that the thickness of the coating film was about 20 μm, and baked. Baking conditions are 165 ℃
30 minutes.

Next, (a) a buret type block HDI having polycaprolactone diol bonded thereto ("SBU-0869" manufactured by Sumitomo Bayer Urethane Co., number average molecular weight of about 1500) and (b) acrylic resin (B1). ) (Tg is -34
C., a hydroxyl group-containing acrylic resin having a number average molecular weight of about 5,000, a nonvolatile content of 64%, a hydroxyl value of 160,
The acid value is 2.4. ) And (a): (b) are mixed at a solid content weight ratio of 60:40, and further mixed with other substances so as to have the following composition, and a chipping-resistant coating composition is prepared. The thing was prepared. Here, the molar ratio of the isocyanate group (NCO) in the component (a) and the hydroxyl group (OH) in the component (b) is 1: 1.

Composition of chipping-resistant coating composition (a) component and (b) component: 100 parts by weight in total (as solid content) Titanium dioxide: 5 parts by weight Carbon black: 0.5 parts by weight Liponox NC-60 : 1 part by weight (surface modifier) Dibutyltin dilaurate: 1.5 parts by weight Solvent ⁽¹⁾ : 210 parts by weight Note (1): Internal solvent in the composition, 1/1 (weight of butyl acetate / xylene) Ratio) mixture.

A butyl acetate / toluene 1: 1 (weight ratio) mixture was used as an external solvent for dilution, and the above chipping-resistant coating composition was dissolved in the mixture.
After adjusting the viscosity to 4 seconds and 11 seconds, it was coated by air spray coating so that the dry film thickness was about 10 μm.

After the above coating, set for about 2 minutes,
Next, an intermediate coating (wet-on-wet method) ["Olga P-61-1 Gray" manufactured by Nippon Paint Co., Ltd., polyester / melamine resin coating] is dried to a thickness of about 35 [mu] m. Air spray painting as
It was baked at 0 ° C for 25 minutes.

After that, an acrylic resin-based base coat paint [manufactured by Nippon Paint Co., Ltd., Superlac M-80
Metallic base] was applied so that the dry film thickness was about 15 μm, and the setting was performed for 3 minutes. Next, clear paint [Nippon Paint Co., Ltd., Superlac O-13
0 clear] was applied so that the dry film thickness was about 30 μm, and after setting for about 10 minutes, baking was performed at 140 ° C. for 25 minutes to obtain a test piece (Example 1).

As the component (a) of the chipping-resistant coating composition, instead of using the buret type block HDI bound with polycaprolactone diol, a nurate type block HDI bound with polycaprolactone diol is used.
(Manufactured by Sumitomo Bayer Urethane Co., Ltd.), SBU-0890) (Example 2), or a trimethylolpropane adduct type blocked isocyanate having polycaprolactone diol bonded thereto (NN-5, manufactured by Nippon Polyurethane Co., Ltd.) ( A test piece was prepared in the same manner as in Example 1 except that Example 3) was used. In the chipping-resistant coating compositions used in Examples 2 and 3, the NCO / OH molar ratio was 1/1.

Furthermore, the components of the chipping-resistant coating composition
Example 1 except that a nurate-type block HDI that does not bind polycaprolactone diol was used as (a).
Painted in the same manner as in (Comparative Example 1), the acrylic resin used in Example 1 without using a polyisocyanate compound and the melamine resin used as a curing agent for the acrylic resin (Comparative Example 2). A conventional solvent-type chipping primer was used without using the chipping coating composition, and the thickness of the coating film was 5 μm as a dry film thickness (Comparative Example 3).
Furthermore, without using the chipping-resistant coating composition and the chipping primer according to the present invention, electrodeposition coating-intermediate coating-
A top coat (Comparative Example 4) was prepared.

The obtained test pieces were evaluated for chipping resistance and coating film appearance by the following methods. In addition, the detergency of each coating composition was also evaluated by the method described below. The results are shown in Table 1.

(1) Chipping resistance A test was conducted under the following conditions using a gravure tester (produced by Suga Tester Co., Ltd.). The amount 50g distance 35cm air pressure in size No.7 crushed stone stone stone 4.0 kg / cm ² a 45 ° angle test temperature -20 ° C.

The result of the chipping resistance test was evaluated by visually observing the test piece not using the chipping primer (Comparative Example 4) as "x" in the following five grades. ◎ Excellent (no peeling). ○ Good (slight peeling is observed). △ Normal (Peeling less than 1 mmφ is scattered). ▲ Slightly inferior (peeling is noticeable). × Inferior.

(2) Appearance of coating film The surface of the test piece which had been subjected to the top coating was slightly scratched, blurred, and
The ash fog property was visually evaluated in 5 grades. ◎ Excellent (no tingling, blurring, ash cast). ○ Good (thinness, blurring, and almost no ash cast). △ Normal (a slight amount of blurring, blurring, and ash cast can be seen). ▲ Slightly inferior (there are noticeable thinness, blurring, and ash cast). × Inferior (marked, blurring, and ash cast are noticeable).

(3) Detergency A coating film of the chipping-resistant paint (or conventional chipping primer) alone used in each Example and each Comparative Example was formed on a tin plate, and allowed to stand at 20 ° C. for 5 minutes. / Butyl acetate (8/2) mixed solvent was immersed for 5 minutes, pulled up and rubbed lightly with a brush, and the dissolved state of the coating film was visually examined and evaluated. ○ Almost all the surface is dissolved, and there is no coating film remaining. B. The coating film remains without being dissolved.

Table 1 Example No. Hardener component Resin component Coating film appearance Chipping resistance Detergency Example 1 SBU-0869 ⁽¹⁾ B1 ⁽²⁾ ◎ ○ ○ Example 2 SBU-0890 ⁽³⁾ B1 ⁽²⁾ ○ △ ○ Example 3 NN-5 ⁽⁴⁾ B1 ⁽²⁾ ○ △ ○ Comparative Example 1 BL-3175 ⁽⁵⁾ B1 ⁽²⁾ ○ ▲ ○ Comparative Example 2 U-Van ⁽⁶⁾ B1 ⁽²⁾ ○ ▲ ○ Comparison Example 3 None CP ⁽⁷⁾ ◎ ○ × Comparative Example 4 No chipping primer coating ◎ × −

Table 1 Note (1): Burette type block HDI having polycaprolactone diol bonded thereto (SBU-0869 manufactured by Sumitomo Bayer Urethane Co., number average molecular weight about 150).
0). (2): Acrylic resin (B1), Tg is -34 ° C, hydroxyl value is
At 160, St / LMA / 4HBA / MAA = 13/46
/41/0.3 (weight ratio) is a hydroxyl group-containing acrylic resin with a number average molecular weight of about 5000 and non-volatile content.
64%. Internal solvent is butyl acetate / xylene 20 /
80. (3): Nurate type block HDI with polycaprolactone diol (Sumitomo Bayer Urethane Co., Ltd.)
Made). (4): A trimethylolpropane adduct type blocked isocyanate (manufactured by Nippon Polyurethane Co., Ltd.) to which polycaprolactone diol is bonded. (5): Nurate type block HDI not modified with polycaprolactone diol (Sumitomo Bayer Urethane Co., Ltd., number average molecular weight about 700). (6): Melamine resin "Uban-20N-60", manufactured by Mitsui Toatsu Chemicals, Inc. (7): Solvent type modified polyolefin chipping primer.

Examples 4 to 8 and Comparative Examples 5 and 6 A plurality of the same steel plates as in Example 1 were used, and the above-mentioned SBU-0869 was used as the component (a) and the acrylic resin ( B1) was used, and the compounding ratio (expressed by the molar ratio of —OH / —NCO) of the component (a) and the component (b) was changed as shown in Table 2, and otherwise the same as in Example 1. Painted
Multiple test pieces were obtained.

With respect to each test piece, the appearance of the coating film and the chipping resistance were evaluated in the same manner as in Example 1. The results are shown in Table 2.

Table 2 Example No. -OH / -NCO coating film appearance Chipping resistance Example 4 75/25 △ △ Example 5 60/40 ○ ○ Example 6 50/50 ◎ ○ Example 7 40/60 ◎ ○ Example 8 25/75 ◎ △ Comparative Example 5 100/0 ⁽¹⁾ × ▲ Comparative Example 6 0/100 ⁽²⁾ ◎ ▲ Table 2 Note (1): Component (a) (polyisocyanate compound) was not used It was (2): Component (b) (acrylic resin (B1)) was not used.

Examples 9 to 15 In order to investigate the influence of the change in the molecular weight of component (b) (hydroxyl group-containing acrylic resin) on the coating film appearance and chipping resistance, a plurality of hydroxyl group-containing acrylic resins having different average molecular weights were used. A chipping-resistant coating composition was prepared in this manner, and a test piece was prepared in the same manner as in Example 1. Here, in the chipping-resistant coating composition of each example, -OH / -NC
O (molar ratio) was 1/1.

For these test pieces, the coating film appearance and chipping resistance were evaluated in the same manner as in Example 1. Table 3 shows the number average molecular weight of the hydroxyl group-containing acrylic resin used, its glass transition temperature, and the evaluation results. (The polyisocyanate compound used is Sumitomo Bayer Urethane Co., Ltd.
It is manufactured by "SBU-0869". )

Table 3 Example No. Number average molecular weight Tg (° C.) ⁽¹⁾ Appearance of coating film Chipping resistance Example 9 5000 ⁽²⁾ −34 ◎ ○ Example 10 7000 ⁽³⁾ −34 ◎ △ Example 11 4200 ⁽⁴⁾ -34 ◎ ○ Example 12 3700 ⁽⁵⁾ -34 ○ ◎ Example 13 3500 ⁽⁶⁾ -34 ○ ◎ Example 14 3100 ⁽⁷⁾ -34 ○ ◎ Example 15 2600 ⁽⁸⁾ -34 △ ◎

Table 3 Note (1): The glass transition temperature of the hydroxyl group-containing acrylic resin used. (2): Acrylic resin (B1). (3) to (8): Synthesis conditions of acrylic resin (B1) (temperature,
The amount of catalyst is changed to change the average molecular weight.

Examples 16 to 19 In order to examine the influence of the difference in the glass transition temperature (Tg: ° C.) of the hydroxyl group-containing acrylic resin on the coating film appearance and chipping resistance, a plurality of hydroxyl group-containing acrylic resins having different glass transition temperatures were used. Was used to prepare a chipping-resistant coating composition, and using this, a test piece was prepared in the same manner as in Example 1. Here, in the chipping-resistant coating composition of each example, -OH / -NCO (molar ratio) was 1/1.

For these test pieces, the appearance of the coating film and the chipping resistance were evaluated in the same manner as in Example 1. Table 4 shows the glass transition temperature of the hydroxyl group-containing acrylic resin used and the evaluation results. (The polyisocyanate compound used is "SBU-086" manufactured by Sumitomo Bayer Urethane Co., Ltd.
9 ". )

Table 4 Example No. Tg (° C) ⁽¹⁾ Appearance of coating film Chipping resistance Example 16-5 ⁽³⁾ ◎ △ Example 17-20 ⁽⁴⁾ ◎ ○ Example 18-34 ⁽²⁾ ◎ ○ Example 19 -45 ⁽⁵⁾ ○ △

Table 4 Note (1): The glass transition temperature of the hydroxyl group-containing acrylic resin used. (2): Acrylic resin (B1). (3) to (5): Tg is changed by changing the ratio of St: LMA of the acrylic resin (B1).

Examples 20 to 23 Hydroxyl group-containing acrylic resins shown in Table 5 as the component (b) and the above chipping resistant coating composition containing the above-mentioned SBU-0869 as the component (a) (mole of -OH / -NCO). The dull steel sheet was subjected to electrodeposition coating, chipping resistant coating coating, intermediate coating coating, and top coating coating in the same manner as in Example 1 except that the ratio was 1/1). 20, 21).

Further, the same chipping-resistant coating material as in Example 21 was further added with crosslinked polymer fine particles (AZS793: manufactured by Nippon Paint Co., Ltd.) (based on 100 parts by weight of resin solid content).
Parts by weight, or 10 parts by weight of the coating material added, other than Example 21
A test piece was prepared in the same manner as.

For each of the obtained test pieces, the coating film appearance and chipping resistance were evaluated in the same manner as in Example 1. The results are shown in Table 5.

Table 5 Example No. Acrylic resin resin fine particles ⁽¹⁾ Appearance of coating film Chipping resistance Example 20 B2 ⁽²⁾ 0 ○ to △ ◎ Example 21 B3 ⁽³⁾ 0 ○ ◎ Example 22 B3 ⁽³⁾ 5 parts by weight ◎ to ○ ◎ Example 23 B3 ⁽³⁾ 10 parts by weight ◎ ◎

Table 5 Note (1): Crosslinked polymer fine particles (AZS79
7: manufactured by Nippon Paint Co., Ltd., with a resin solid content of 100
The amount based on parts by weight is shown. (2): B2 is the one in which the internal solvent of the acrylic resin of Example 13 is changed to butyl acetate / xylene (10/90). (3): B3 is the one in which the internal solvent of the acrylic resin of Example 13 is changed to ethyl acetate / toluene (20/80).

Example 24, Comparative Examples 7 to 9 Test pieces were prepared in the same manner as in Example 20 except that the compounds (curing agents) shown in Table 6 were used as the component (a). The coating film appearance and chipping resistance of the obtained test piece were evaluated in the same manner as in Example 20. Table 6 shows the curing agent (polyisocyanate compound or other compound) used, the type of blocked isocyanate (BI), and the evaluation results. For reference, the type of polyisocyanate compound of Example 20 and the evaluation results are also shown in Table 6.

Table 6 Example No. Hardener BI type NCO / OH coating film appearance chipping property Example 20 SBU-0869 ⁽¹⁾ Burette 50/50 ○ to △ ◎ Example 24 SBU-0890 ⁽²⁾ Nurate 50 ／ 50 ○ ○ Comparative Example 7 BL-3175 ⁽³⁾ Nulate 50/50 ◎ ▲ Comparative Example 8 ⁽⁴⁾ U-Van ⁽⁵⁾ − 70/30 ⁽⁶⁾ ◎ ▲ Comparative Example 9 S-HT ⁽⁷⁾ TMP Adducts 50 / 50 ○ ▲

Table 6 Note (1): Burette type block HDI having polycaprolactone diol bonded thereto, manufactured by Sumitomo Bayer Urethane Co., Ltd. (2): Nurate type block HMDI bound with polycaprolactone diol, Sumitomo Bayer Urethane Co., Ltd.
Made. (3): Nurate type block HDI that does not bind polycaprolactone diol, Sumitomo Bayer Urethane Co., Ltd.
Made. (4): The polyisocyanate compound is not contained in the coating material of this example, and the acrylic resin is cured by the melamine resin. (5): Melamine resin "Uban 20N-60", manufactured by Mitsui Toatsu Chemicals, Inc. (6): The ratio 70/30 is the weight ratio of acrylic resin / melamine resin. (7): Sumidule HT (Sumitomo Bayer Urethane Co., Ltd.)
Made).

Examples 25 and 26, Comparative Examples 10 to 15 Test pieces were prepared in the same coating specifications as in Example 1 except that the following two sets of coating materials were used as the top coating material. Note that each set of top-coat paints consists of two paints, a base paint (which forms the lower-layer side coating film) and a clear paint (which forms the upper-layer side coating film).

Topcoat paint: Acrylic / melamine resin type water-based paint (1) "Olga TO-H900 metallic base" (water-based) made by Nippon Paint Co., Ltd. (2) "Olga TO-561 clear" (solvent type) Nippon Paint ( Co., Ltd.

Topcoat paint: Acid rain countermeasure paint (1) "Olga TO-H500 metallic base" (solvent type) made by Nippon Paint Co., Ltd. (2) "Olga TO-H580 clear" (solvent type) Nippon Paint Co., Ltd. ) Made

With respect to the obtained test pieces, the appearance of the coating film and the chipping resistance were evaluated in the same manner as in Example 1. The results are shown in Table 7.

For comparison, a maleinized polyolefin-based chipping primer was used in place of the chipping-resistant coating composition according to the present invention, and the top coating composition was the same as that used in Example 1 (see below). The top-coat paint shown in 1), the above-mentioned top-coat paint, or a top-coat paint was used to prepare test pieces (Comparative Examples 10 to 12). The thickness of the coating film formed with the maleinized polyolefin-based chipping primer was 5 μm as a dry film thickness.

Top coating: Acrylic / melamine resin coating (solvent type) (1) "Superlac M-80 metallic base" manufactured by Nippon Paint Co., Ltd. (2) "Superlac O-130 clear" manufactured by Nippon Paint Co., Ltd.

Further, a test piece which was subjected to electrodeposition coating-intermediate coating-top coating (coating using any one of the top coatings) without using the chipping-resistant coating composition or the existing chipping primer. (Comparative Examples 13 to 15) were produced.

With respect to the obtained test pieces, the appearance of the coating film and the chipping resistance were evaluated in the same manner as in Example 1. The results are shown in Table 7.

[0166] Table 7 Example No. primer top coat ⁽¹⁾ Coating film appearance and chipping resistance Example 25 present inventions ⁽²⁾ ◎ ◎ Example 26 This invention product ⁽²⁾ ◎ ◎ Comparative Example 10 M-PO ^{(3 )} ○ ○ Comparative Example 11 M-PO ⁽³⁾ ◎ ○ Comparative Example 12 M-PO ⁽³⁾ ◎ △ Comparative Example 13 None ◎ ▲ Comparative Example 14 None ◎ ▲ Comparative Example 15 None ◎ ▲

Table 7 Note (1): each is a combination of (base paint / clear paint) described above. (2): Same as the chipping-resistant coating composition of Example 1. (3): A maleinized polyolefin-based chipping primer.

Examples 27 to 29 The same dull steel plate used in Example 1 was electrodeposited and baked in the same manner as in Example 1, and then an intermediate coating was applied on it and baked. . Next, a chipping resistant coating film was formed on the intermediate coating film by the chipping resistant coating composition used in Example 1. The film thickness of the chipping-resistant coating film was set to be 10 μm (as a dry film thickness). After setting for 2 minutes, use the above-mentioned top coat paint ~ (each of which is a combination of base paint / clear paint) to apply a top coat, and apply 2 at 140 ° C.
It was baked for 5 minutes. The obtained test piece was evaluated for the coating film appearance and chipping resistance in the same manner as in Example 1. The results are shown in Table 8.

Table 8 Example No. Topcoat paint coating film appearance Chipping property Example 27 ◎ ◎ Example 28 ◎ ◎ ◎ Example 29 ◎ ◎ ◎

Example 30 The same dull steel plate used in Example 1 was electrodeposited and baked in the same manner as in Example 1 to give Example 1.
A chipping-resistant coating film was formed using the above chipping-resistant coating composition. The film thickness of the chipping-resistant coating film was set to be 10 μm (as a dry film thickness). After setting for 2 minutes, solid polyester resin top coat ("Olga G-75 White" manufactured by Nippon Paint Co., Ltd.)
Was coated to obtain a test piece. About this test piece Example 1
The coating film appearance and chipping resistance were evaluated in the same manner as in.
The appearance of the coating film was ⊚, and the chipping resistance was also ∘.

Examples 31 to 43, Comparative Example 16 The same dull steel plate used in Example 1 was subjected to electrodeposition coating in the same manner as in Example 1.

As component (a), a biuret-type block HDI having polycaprolactone diol bound thereto (“SBU-0869” manufactured by Sumitomo Bayer Urethane Co., number average molecular weight of about 1500) and components of Examples 31 to 39 were used. As (b), in Examples 41 to 43, the component (b) and the resin shown in Table 9 as the component (c) were mixed, and the same as those used in the preparation of the chipping-resistant coating composition of Example 1. Was added to obtain a chipping-resistant coating composition. Where the ingredients
The molar ratio of the isocyanate group (-NCO) in (a) and the hydroxyl group (-OH) in component (b) is 1: 1.

In Example 40, Jeffamine D2000 (polyoxyalkylene amine, manufactured by TEXACO CHEMICAL) was used as the resin of the component (b), and the components (a) and (b) were The mixing ratio is such that the isocyanate group (-NCO) in the component (a) and the active hydrogen (-) in the component (b).
The molar ratio with H) was 1: 1.

The obtained chipping-resistant coating composition was adjusted in viscosity in the same manner as in Example 1 and then coated on the electrodeposition coating film in the same manner as in Example 1. It should be noted that the coating is a dry film thickness of about 5 μm
So that

After the above painting, set for about 2 minutes,
Next, an intermediate coating (wet-on-wet method) ["Olga P-61-1 Gray" manufactured by Nippon Paint Co., Ltd., polyester / melamine resin coating] is dried to a thickness of about 35 [mu] m. Air spray painting as
It was baked at 0 ° C for 25 minutes.

Thereafter, the above-mentioned top coating composition or was applied and baked in accordance with the method of Example 1 to obtain a test piece having a top coating film or the top coating film. The coating order in these examples is electrodeposition coating / CP coating / intermediate coating / top coating, with the chipping-resistant coating composition according to the present invention as CP.

The chipping resistance of the obtained test piece was evaluated in the same manner as in Example 1. The results are shown in Table 9.

Further, a test piece having an overcoat coating film with the overcoat paint was prepared in the same manner as in Example 31 except that the chipping resistant coating composition according to the present invention was not used (Comparative Example 16). The chipping resistance of this test piece was evaluated in the same manner. The results are shown in Table 9.

Table 9 Chipping resistance example No. Component (b) or components (b) and (c) Top coat Top coat Top coat Example 31 Polyester resin ⁽¹⁾ ◎ ◎ ◎ Example 32 Lactone modified polyester resin ⁽²⁾ ◎ ◎ ◎ Example 33 Coconut oil modified polyester resin ⁽³⁾ ◎ ◎ ◎ Example 34 Melamine modified polyester resin ⁽⁴⁾ ◎ ◎ ◎ Example 35 Lactone modified acrylic resin A ⁽⁵⁾ ◎ ◎ ◎ Example 36 Lactone modified acrylic resin B ⁽⁶⁾ ◎ ◎ ◎ Example 37 2 Ethyl 1,3 hexanediol ⁽⁷⁾ ◎ ◎ ◎ Example 38 1,5 Pentanediol ⁽⁸⁾ ◎ ◎ ◎ Example 39 Polycaprolactone diol ⁽⁹⁾ ◎ ◎ ◎ ◎ Example 40 Polyoxyalkylene amine ⁽¹⁰⁾ ◎ ◎ ◎ Example 41 (b) Lactone modified acrylic resin B ⁽⁶⁾ ◎ ◎ ◎ (c) Lactone modified triol ⁽¹¹⁾ ((b) / (c) = 55/45 Solid content weight ratio) Example 42 (b) Urethane-modified polyester resin ⁽¹²⁾ ◎ ◎ (C) Lactone-modified triol ⁽¹³⁾ ((b) / (c) = 60/40 solid content weight ratio) Example 43 (b) Low Tg acrylic resin ⁽¹⁴⁾ ◎ ◎ ◎ (c) Lactone-modified diol ^{( 9)} ((b) / (c) = 70/30 solid content weight ratio) Comparative Example 16 No chipping primer − − ×

Table 9 Note (1): Espel 1690, nonvolatile 64.8
%, Hydroxyl value 120, number average molecular weight 2700, manufactured by Hitachi Chemical Co., Ltd. (2): A lactone-modified polyester resin having a lactone skeleton incorporated in both the main chain and the side chain. CDE-9P, nonvolatile 80
%, Hydroxyl value 90, number average molecular weight 3500, manufactured by Daicel Industries, Ltd. (3): BS57-851-65, nonvolatile content 65%, hydroxyl value 100, number average molecular weight 2109, manufactured by Dainippon Ink and Chemicals, Inc. (4): BL BF-115-65X, nonvolatile content 65%, hydroxyl value 130
, Number average molecular weight 2900, Dainippon Ink and Chemicals, Inc.
Made. (5): EPA-5860, non-volatile content 60%, hydroxyl value 30, number average molecular weight 5000, manufactured by Daicel Industries, Ltd. (6): Praxel DC-2209, nonvolatile content 50%, hydroxyl value 50, number average molecular weight 11000, manufactured by Daicel Industries, Ltd. (7): EHD, nonvolatile content 100%, hydroxyl group equivalent 73, number average molecular weight 146, manufactured by Chisso Petrochemical Co., Ltd. (8): Nonvolatile content 100%, hydroxyl equivalent 52, number average molecular weight
104, manufactured by Wako Pure Chemical Industries, Ltd. (9): Praxel 205H, nonvolatile content 100%, hydroxyl value
212, number average molecular weight 530, manufactured by Daicel Industries, Ltd. (10): Jeffamine D2000, nonvolatile content 100%, hydroxyl group equivalent 520, number average molecular weight 2000, manufactured by TEXACO CHEMICAL. (11): Praxel 320AL, nonvolatile content 100%, hydroxyl value 84, number average molecular weight 2000, manufactured by Daicel Industries, Ltd. (12): XRX2303, nonvolatile content 70%, hydroxyl value 50, number average molecular weight 3600, manufactured by PPG Industries. Inc. (13): Praxel 312AL, nonvolatile content 100%, hydroxyl value 133, number average molecular weight 1250, Daicel Industries, Ltd.
Made. (14): Hitaloid 3635-2, nonvolatile content 55%, hydroxyl value 127, number average molecular weight 8000, Tg-37 ° C., manufactured by Hitachi Chemical Co., Ltd.

Example 44 Examples 31 to 43 except that the chipping resistant coating composition (CP) according to the present invention was applied on the intermediate coating film, not between the electrodeposition coating film and the intermediate coating film. Ten kinds of test pieces were prepared in the same manner as in. Here, the above-mentioned top-coat paint was selected as the top-coat paint.

The order of coating in this example is electrodeposition coating / intermediate coating / CP coating / top coating.

When the obtained test pieces were evaluated for chipping resistance in the same manner as in Example 1, the chipping resistance was ⊚ for all the test pieces.

Example 45 In each of Examples 31 to 43, a buret type block HDI in which polycaprolactone diol was bonded as the component (a) in the chipping resistant coating composition (CP).
Examples 31 to 31 except that a nurate-type block HDI (SBU-0890, manufactured by Sumitomo Bayer Urethane Co., Ltd.) having polycaprolactone diol bonded thereto was used instead of
A test piece was prepared in the same manner as 43. Here, a coating film was formed by the following coating sequence: electrodeposition coating / CP coating / intermediate coating / top coating. The above-mentioned "topcoat paint" was used as the topcoat paint.

The chipping resistance of each test piece was evaluated in the same manner as in Example 1. The results were all good.

Example 46 In the same manner as in Example 1, the dull steel plate was subjected to electrodeposition coating.
(a) As a component, a buret type block HDI having polycaprolactone diol bonded thereto (“SBU-0869” manufactured by Sumitomo Bayer Urethane Co., Ltd., number average molecular weight of about 15).
00) and polyester resin (Esperu) as component (b)
1690, non-volatile content 64.8%, hydroxyl value 120, number average molecular weight
2700, manufactured by Hitachi Chemical Co., Ltd., and other components were further added so as to have the following composition to obtain a chipping-resistant coating composition for intermediate coating (intermediate coating CP). The isocyanate group (--NC) in the component (a) in this intermediate coating CP is
The molar ratio of O) to the hydroxyl group (—OH) in component (b) is 1:
It is 1.

Composition of intermediate coating CP (a) component and (b) component: Total 100 parts by weight (in terms of solid content) Titanium dioxide: 55 parts by weight Carbon black: 2 parts by weight Anti-settling agent: 2 parts by weight Surface modifier : 1 part by weight Dibutyltin dilaurate: 1.5 parts by weight Internal solvent : 65 parts by weight Breakdown of internal solvent: Solvesso 150 (manufactured by Exxon Chemical) / xylene / butyl acetate = 1/2/1 (weight ratio)

Solvesso 150 / Butyl acetate = 1/1 (weight ratio) is used as an external solvent to dilute the above-mentioned intermediate coating composition to adjust its viscosity, and electrodeposition coating is performed so that the dry film thickness becomes 35 μm. Air spray paint on the film, 2 at 140 ℃
Baking was performed for 5 minutes. Then, using the above-mentioned top coating material, a top coating film was formed in the same manner as in Example 1.

The coating order in this example is electrodeposition coating / intermediate coating CP coating / top coating.

The chipping resistance of the obtained test piece was evaluated in the same manner as in Example 1. The result was ◎.

Example 47 As the component (a) in the chipping-resistant intermediate coating composition, instead of the burette type block HDI bound with polycaprolactone diol, a nurate type block HDI bound with polycaprolactone diol was used. (SB
A test piece was prepared in the same manner as in Example 46 except that U-0890 and Sumitomo Bayer Urethane Co., Ltd. were used. The chipping resistance of the obtained test piece was evaluated in the same manner as in Example 1. The result was ◯.

Example 48 Before application of a chipping-resistant intermediate coating (intermediate CP) (ie on top of an electrodeposition coating), (a) a buret type of polycaprolactone diol attached Block HDI (Sumitomo Bayer Urethane Co., Ltd. "SBU-
0869 ", number average molecular weight about 1500), and (b) lactone-modified polyester resin (CDE-9P, nonvolatile content 80%, hydroxyl value 90, number average molecular weight 3500, which incorporates a lactone skeleton in both the main chain and side chains. A test piece was prepared in the same manner as in Example 46 except that a chipping-resistant paint (CP) made from Daicel Industries Ltd. was applied so that the dry film thickness was 5 μm. The molar ratio of -NCO / -OH in CP is 1: 1.

The coating order in this example is electrodeposition coating / CP coating / intermediate coating CP coating / top coating.

The resulting coating film was evaluated for chipping resistance in the same manner as in Example 1. The result was ◎.

Example 49 In Example 48, the coating of a chipping resistant coating (CP) comprising (a) a buret type block HDI having polycaprolactone diol bonded thereto and (b) a lactone modified polyester resin A test piece was prepared in the same manner except that the coating order of the chipping intermediate coating composition (intermediate coating CP) was reversed.

The coating order in this example is electrodeposition coating / intermediate coating CP coating / CP coating / top coating.

The resulting coating film was evaluated for chipping resistance in the same manner as in Example 1. The result was ◎.

Example 50 A chipping-resistant coating composition (C
As the component (a) in P), a nurate type block HDI (SBU-0 having polycaprolactone diol bonded thereto is used.
A test piece was prepared in the same manner as in Example 48 except that 890 and Sumitomo Bayer Urethane Co., Ltd. were used. The chipping resistance of the obtained test piece was evaluated in the same manner as in Example 1. The result was ◯.

Example 51 A dull steel sheet was subjected to electrodeposition coating in the same manner as in Example 1, and the intermediate coating material used in Example 1 was applied thereon to form an intermediate coating film.

(A) A biuret-type block HDI having polycaprolactone diol bonded thereto ("SBU-0869" manufactured by Sumitomo Bayer Urethane Co., Ltd., number average molecular weight: about 15).
00) and (b) a copolymer of cellulose acetate butyrate-modified acrylic resin (styrene / methyl methacrylate / ethyl methacrylate / ethyl acrylate / 2-hexyl ethyl methacrylate / methyl acrylate 100
It is a modified acrylic resin obtained by reacting 100 parts by weight of cellulose acetate butyrate, and
40.5%, hydroxyl value 45, number average molecular weight 11100) and other components were added so as to have the following composition to obtain a chipping-resistant topcoat base coating composition (referred to as topcoat base CP). In addition, in the top coating base CP, the components
The molar ratio of the isocyanate group (-NCO) in (a) and the hydroxyl group (-OH) in component (b) is 1: 1.

Composition of Topcoat Base CP Components (a) and (b): 100 parts by weight in total (as solid content) Titanium dioxide: 60 parts by weight Carbon black: 1 part by weight Anti-settling agent: 2 parts by weight Surface conditioner : 1 part by weight Dibutyltin dilaurate: 1.5 parts by weight Internal solvent : 160 parts by weight Breakdown of internal solvent: xylene / methyl isobutyl ketone /
Ethyl acetate = 7/2/1 (weight ratio)

An ethyl acetate / xylene 1: 1 (weight ratio) mixture was used as an external solvent to dilute the above-mentioned topcoat base CP to obtain a topcoat base paint, and as a topcoat clear paint, Superlac O-130 clear (Nippon Paint Co., Ltd.) was used. (Manufactured by Co., Ltd.) was used and top coating was carried out in accordance with Example 1. The coating amount of the base coating is 1 in dry film thickness.
It was 5 μm. The coating order in this example is electrodeposition coating / intermediate coating / topcoat base CP coating / topcoat clear coating.

The chipping resistance of the obtained test piece was evaluated in the same manner as in Example 1. The result was ◯.

Example 52 Ingredient (a) in topcoat base coating (topcoat base CP)
A test piece was prepared in the same manner as in Example 51, except that a nurate type block HDI (SBU-0890, manufactured by Sumitomo Bayer Urethane Co., Ltd.) having polycaprolactone diol bonded thereto was used. The chipping resistance of the obtained test piece was evaluated in the same manner as in Example 1. The result is ○
Met.

Example 53 Up to the intermediate coating, coating was carried out in the same manner as in Example 51.

(A) A buret type block HDI having polycaprolactone diol bonded thereto ("SBU-0869" manufactured by Sumitomo Bayer Urethane Co., Ltd., number average molecular weight: about 15).
00) and (b) Lumiflon LF9201 (fluorine-containing resin, nonvolatile content 65.5%, hydroxyl value in varnish 52.4, number average molecular weight of about 7,000, manufactured by Asahi Glass Co., Ltd.), and the following composition is obtained. Thus, other components were added to prepare a chipping-resistant topcoat clear coating composition (referred to as topcoat clear CP). In addition, -NCO / -OH in the above-mentioned clear top CP is 1: 1.

Composition of Topcoat Clear CP Components (a) and (b): 100 parts by weight in total (in terms of solid content) Surface modifier: 2 parts by weight UV absorber: 1 part by weight Antioxidant: 1 part by weight dibutyl Tin dilaurate: 1.5 parts by weight Internal solvent : 95 parts by weight Breakdown of internal solvent: Solvesso 150 / xylene = 1/2
(Weight ratio)

Superlac M as a base coating for top coating
Using -80 metallic base (manufactured by Nippon Paint Co., Ltd.) and using the above-mentioned clear topcoat CP as the clear topcoat, topcoating was carried out according to Example 51. The amount of clear CP coated is 35μ in dry film thickness.
m.

The coating sequence in this example is: electrodeposition coating / intermediate coating / topcoat base coating / topcoat clear CP coating.

The chipping resistance of the obtained test piece was evaluated in the same manner as in Example 1. The result was ◯.

Example 54 As the component (a) in the clear top coating, a nurate type block HDI having polycaprolactone diol bonded thereto.
(SBU-0890, Sumitomo Bayer Urethane Co., Ltd.)
A test piece was produced in the same manner as in Example 53 except that was used. The chipping resistance of the obtained test piece was evaluated in the same manner as in Example 1. The result was ◯.

Example 55 The same dull steel plate used in Example 1 was subjected to electrodeposition coating / baking in the same manner as in Example 1.

On the electrodeposition coating film, an intermediate coating composition [“Olga P-61-1, gray” manufactured by Nippon Paint Co., Ltd., polyester / melamine resin coating composition] was dried to a thickness of about 35 μm. Air spray coating as above and baked at 140 ° C for 25 minutes.

(A) A biuret-type block HDI having polycaprolactone diol bonded thereto ("SBU-0869" manufactured by Sumitomo Bayer Urethane Co., Ltd., number average molecular weight: about 15).
00) and (b) coconut oil modified polyester resin (Dainippon Ink and Chemicals, Inc. "BS 57-1086N", nonvolatile content 65).
%, A hydroxyl value of 130 and a number average molecular weight of 3179), and other components were added thereto so as to have the following composition to prepare a chipping-resistant solid top coating composition (referred to as top coating CP). . Here, -NCO /-in the top coat CP
OH is 1: 1.

Composition of Topcoat CP Components (a) and (b): 100 parts by weight in total (as solid content) Titanium dioxide: 50 parts by weight Carbon black: 1 part by weight Anti-settling agent: 2 parts by weight Surface modifier: 1 part by weight Dibutyltin dilaurate: 1.5 parts by weight Internal solvent : 80 parts by weight Breakdown of internal solvent: Solvesso 150 / xylene / methyl isobutyl ketone = 2/5/1 (weight ratio)

On the resulting intermediate coating film, the above-mentioned top coating C
P was painted and baked. The coating amount of the top coat CP was 35 μm as a dry film thickness.

The coating order in this example is electrodeposition coating / intermediate coating / top coating CP coating.

The obtained test piece was evaluated for chipping resistance in the same manner as in Example 1. The result was ◯.

Example 56 A nurate block HDI (SBU-0890, manufactured by Sumitomo Bayer Urethane Co., Ltd.) having polycaprolactone diol bonded thereto was used as the component (a) in the solid top coating composition (top coating CP). A test piece was prepared in the same manner as in Example 55. The chipping resistance of the obtained test piece was evaluated in the same manner as in Example 1. The result was ◯.

Example 57 The same dull steel plate used in Example 1 was subjected to electrodeposition coating / baking in the same manner as in Example 1.

On the electrodeposition coating film, the same chipping resistant coating (CP) used in Example 32 was used, and the dry film thickness was 5
It was coated so that the thickness would be μm.

After the above painting, set for about 2 minutes,
Next, an intermediate coating (wet-on-wet method) ["Olga P-61-1 Gray" manufactured by Nippon Paint Co., Ltd., polyester / melamine resin coating] is dried to a thickness of about 35 [mu] m. Air spray painting as
It was baked at 0 ° C for 25 minutes.

On top of the intermediate coating, the same chipping-resistant solid topcoat paint used in Example 55 (topcoat C
P) was painted. The coating amount of top coat CP is about 35 in dry film thickness.
μm.

The coating sequence in this example is: electrodeposition coating / CP / intermediate coating / top coating CP coating.

The chipping resistance of the obtained test piece was evaluated in the same manner as in Example 1. The result was ◎.

Example 58 A test was conducted in the same manner as in Example 57 except that the coating order of the chipping resistant coating (CP) used in Example 32 and the coating of the intermediate coating was reversed in Example 57. Pieces were made.
The resulting coating film was evaluated for chipping resistance in the same manner as in Example 1. The result was ◎.

Example 59 A nurate block HDI (SBU-0890, manufactured by Sumitomo Bayer Urethane Co., Ltd.) having polycaprolactone diol bonded thereto was used as the component (a) in the solid top coating composition (top coating CP). A test piece was prepared in the same manner as in Example 57. The chipping resistance of the obtained test piece was evaluated in the same manner as in Example 1. The result was ◯.

Comparative Example 17 In Example 57, the chipping-resistant paint was not coated on the electrodeposition coating film, Olga G65 Red (manufactured by Nippon Paint Co., Ltd.) was used as the solid top coating, and the others were used. A test piece was prepared in the same manner as in Example 57. The chipping resistance of the obtained test piece was evaluated in the same manner as in Example 1.
The result was ▲.

[0229]

As described above in detail, since the coating composition of the present invention contains a polycaprolactone diol-modified block polyisocyanate, preferably a polyisocyanate having a buret structure, the coating film obtained has flexibility. It becomes rich and has good chipping resistance. Also,
The coating film has a good appearance and is suitable for coating automobile exterior panels.

Further, the coating composition of the present invention can be made into a low solvent type unlike the existing type chipping primer, and the regulation of VOC can be easily cleared. In addition, the painting work and maintenance of the painting line are easy.

By combining the chipping-resistant coating composition of the present invention with an aqueous coating, it is possible to achieve a reduction in the amount of solvent. In addition, a coating film having good durability can be formed by combining with other acid rain countermeasure type paint.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location // C08G 18/10 NFT 18/80 NFM

Claims (3)

[Claims] 1. A main component comprising (a) a polyisocyanate compound which is a reaction product of a polycaprolactone diol and a blocked isocyanate compound, and (b) a hydroxyl group-containing resin having two or more hydroxyl groups in one molecule. And a chipping-resistant coating composition. 2. A polyisocyanate compound which is a reaction product of a polycaprolactone diol and a blocked isocyanate compound, (b) a hydroxyl group-containing resin having two or more hydroxyl groups in one molecule, and (c) ) Lactone modified acrylic resin, lactone modified polyester resin, carbon number 2
~ 8 at least one resin or compound of polyol and polycaprolactone polyol (provided that (b) component and
(c) The components are different) and a chipping resistant coating composition. 3. The coating composition according to claim 1 or 2, wherein (1) electrodeposition coating-intermediate coating-top coating system,
(B) interlayer between electrodeposition coating film and intermediate coating film, (b) interlayer between intermediate coating film and top coating film, (c) one-layer top coating film, (d) 2
At least one of a base coating film and / or a clear coating film and (e) an intermediate coating film in a layer type top coating, or (2) an electrodeposition coating-top coating system, Between the coating film and the top coat film, (G) 1-layer type top coat film, (H) 2
A method for forming a chipping-resistant coating film, which comprises coating at least one of a base coating film and / or a clear coating film in a layer-type top coating.