JP7398937B2 - Epoxy resin coating composition, laminated coating film, and coating film repair method - Google Patents

Description

The present invention relates to an epoxy resin coating composition, a laminated coating film, and a coating repair method.

BACKGROUND ART A coating film containing a thermoplastic resin, typified by (meth)acrylic resin, is formed as a top coat on base materials such as ships and bridges. However, paint films containing such thermoplastic resins, particularly (meth)acrylic resin paint films, have a problem in that paint film deterioration (paint film defects) such as blisters and cracks are likely to occur.

Therefore, when a defect occurs in a coating film containing a thermoplastic resin, repair is usually required. During this repair, if the paint film existing on the base material (hereinafter also referred to as "old paint film") can be repainted with a new top coat without removing it, the old paint film can be removed. Such a repair method is desired because it can significantly reduce the process and cost required for repair.

However, when a new top coat is reapplied to an old paint film containing thermoplastic resin, the newly formed paint film is likely to develop paint film defects such as blisters, cracks, lifting (wrinkles), and suppuration. Since the desired function cannot be imparted to the surface of the surface, the conventional repair method has been to remove the deteriorated coating film and reapply a new top coat.
In addition, there are cases where it is necessary to form a coating film on the old coating film using a resin that is different from the resin that made up the old coating film (hereinafter also referred to as "repainting with a different type of coating film"). In this case, coating defects are particularly likely to occur in the dissimilar coating film, so conventionally, the only repair method available was to remove all the old coating film and reapply a new top coat.

To address these problems, Patent Document 1 discloses a new coating that can form a coating film that does not cause cracks, etc., without having to completely peel off the old coating film made of chlorinated rubber paint or vinyl paint. As a method for repairing the film, a method is described in which two layers having an elongation rate within a predetermined range are applied to the surface of the old paint film.

Japanese Patent Application Publication No. 2009-160538

However, when a conventional paint such as the paint described in Patent Document 1 is formed on a coating film containing a thermoplastic resin, particularly on a (meth)acrylic resin coating film, the formed coating film may have blisters, It has been found that coating film defects such as cracks, lifting (wrinkles), and pus are likely to occur, and that the coating film defects cannot be sufficiently suppressed.

The present invention has been made in view of the above-mentioned problems, and provides a coating film containing a thermoplastic resin in which the occurrence of coating film defects such as blisters, cracks, lifting (wrinkles), and pus is suppressed. It is an object of the present invention to provide a formable epoxy resin-based coating composition.

The present inventors have made extensive studies to solve the above problems. As a result, it was discovered that the above-mentioned problems could be solved by the following configuration example, and the present invention was completed. A configuration example of the present invention is as follows.

[1] An epoxy resin coating composition that is coated on a coating film containing a thermoplastic resin, satisfies the following requirement (1), and contains an aliphatic or alicyclic diglycidyl ether (C).
Requirement (1): The storage modulus at 20°C of a coating film with a dry film thickness of 150 μm formed from the epoxy resin coating composition is 1,200 MPa or more and 6,000 MPa or less.

[2] The epoxy resin coating composition according to [1], which contains an amine curing agent (B) and an epoxy compound (A) other than the aliphatic or alicyclic diglycidyl ether (C).

[3] Coated on a coating film containing a thermoplastic resin, containing an aliphatic or alicyclic diglycidyl ether (C), an amine curing agent (B), and the aliphatic or alicyclic diglycidyl ether ( Contains an epoxy compound (A) other than C), and the ratio of the content of the aliphatic or alicyclic diglycidyl ether (C) to the content of the epoxy compound (A) is 0.4 to 1.2 An epoxy resin coating composition.

[4] The epoxy resin coating composition according to any one of [1] to [3], wherein the content of the solvent is 0 to 10% by mass.

[5] The epoxy resin coating composition according to any one of [1] to [4], wherein the thermoplastic resin is a (meth)acrylic resin.

[6] A coating film containing a thermoplastic resin,
A laminated coating film comprising a coating film formed from the epoxy resin coating composition according to any one of [1] to [5].

[7] A method for repairing a paint film, comprising the step of forming a paint film from the epoxy resin coating composition according to any one of [1] to [5] on a paint film containing a thermoplastic resin.

According to the present invention, the occurrence of paint film defects such as blisters, cracks, lifting (wrinkles), and suppuration is suppressed, and in particular, the occurrence of such paint film defects is suppressed even after cooling/heating cycles. The coating film can be formed on a coating film containing a thermoplastic resin, particularly on a (meth)acrylic resin coating film. Further, according to the present invention, it is possible to repaint a coating film formed on a substrate with a coating film of a different type from the resin system forming the coating film.
In other words, according to the present invention, without removing the coating film formed on the base material, the process and cost can be significantly reduced compared to the conventional method, and coating film defects can be suppressed (different types of coating film). ) can be formed. Therefore, according to the present invention, it is possible to repair a coating film formed on a substrate while significantly reducing the steps, costs, etc. compared to the conventional method.

≪Epoxy resin coating composition≫
The epoxy resin coating composition according to the present invention (hereinafter also referred to as "the present composition") is applied onto a coating film containing a thermoplastic resin, and
(I) A composition that satisfies the following requirement (1) and contains an aliphatic or alicyclic diglycidyl ether (C), or
(II) A composition that satisfies the following requirement (2), and preferably satisfies the following requirements (1) and (2).
Requirement (1): The storage modulus at 20° C. of a coating film with a dry film thickness of 150 μm formed from the epoxy resin paint composition is 1,200 MPa or more and 6,000 MPa or less. Requirement (2): The epoxy resin paint composition The composition contains an aliphatic or alicyclic diglycidyl ether (C), an amine curing agent (B), and an epoxy compound (A) other than the aliphatic or alicyclic diglycidyl ether (C). and the ratio of the content of the aliphatic or alicyclic diglycidyl ether (C) to the content of the epoxy compound (A) is 0.4 to 1.2. The present composition that satisfies the above conditions is also referred to as "present composition 1", and the present composition that satisfies the above (II) is also referred to as "present composition 2".

Hereinafter, the "coating film containing a thermoplastic resin" to which the present composition is applied will also be referred to as the "old paint film", and the coating film formed from the present composition will also be referred to as the "main paint film".
In addition, the "old paint film" in the present invention refers to a paint film that is an object to be coated with the present composition and exists on a substrate before the present composition is applied. The old paint film includes not only deteriorated paint films where paint film deterioration (paint film defects) has occurred due to aging or use after the paint film was formed, but also paint films where no paint film deterioration has occurred. . In the latter case, for example, a coating film containing a thermoplastic resin may be formed by mistake, and the present composition may be applied to repair the coating film.

According to this composition, a laminated coating film in which the main coating film is laminated on the old coating film can be obtained. The laminated coating film may include the main coating film as a top coat depending on the substrate on which the multilayer coating film is formed, and one or more layers of other coating films (hereinafter referred to as (Also referred to as "top coat film.") may be formed.
Hereinafter, when the main coating film is used as a top coat, a laminate of the old coating film and the main coating film is used, and when the above-mentioned top coating film is further formed, the old coating film, the main coating film, and the top coating film are used. The laminate is also referred to as the "main laminate coating".

The storage modulus at 20°C of the coating film formed from the present composition 1 is 1,200 to 6,000 MPa, and the storage modulus at 20°C of the coating film formed from the present composition 2 is preferably 7, 000 MPa or less, more preferably 6,000 MPa or less, and preferably 1,200 MPa or more.
The storage modulus at 20° C. of the coating film formed from the present composition is more preferably 5,000 MPa or less, particularly preferably 4,800 MPa or less. The lower limit of the storage modulus is not particularly limited, but is more preferably 1,500 MPa or more, still more preferably 1,800 MPa or more.
When the storage elastic modulus of the main coating film is within the above range, it is possible to easily obtain the main laminated coating film in which the occurrence of coating film defects such as blisters, cracks, lifting (wrinkles), and purulent spots is suppressed. Further, even if the old paint film is a deteriorated paint film with blisters, cracks, etc., it is possible to form the main laminated paint film in which the occurrence of blisters, cracks, etc. is suppressed.
If the storage modulus of the paint film is below the above range, the occurrence of paint film defects such as blisters, cracks, lifting (wrinkles), and suppuration tends to be unable to be suppressed; If it exceeds , the coating film tends to be hard and brittle.
Specifically, the storage modulus can be measured by the method described in the Examples below.
The storage modulus can be controlled, for example, by adjusting the amounts of the epoxy compound (A) and the aliphatic or alicyclic diglycidyl ether (C) in the composition.

The present composition may be a one-component composition, but is preferably a two-component or more composition. In particular, in the case of Composition 2, it is usually a two-component or more composition containing a main component containing an epoxy compound (A) and a curing agent component containing an amine curing agent (B). Moreover, if necessary, it may be a three-component or more composition containing components other than the main component and the curing agent component.
These main component, curing agent component, and other components are usually stored, stored, transported, etc. in separate containers, and mixed immediately before use.

<Coating film containing thermoplastic resin>
The above-mentioned coating film containing a thermoplastic resin (old coating film) refers to a coating film containing a thermoplastic resin, and is similar to the top coating film formed on base materials such as ships and bridges. Say something. The proportion of the thermoplastic resin contained in the coating film containing the thermoplastic resin is not particularly limited, but is preferably 50% by mass or more.
The old paint film may be a laminate of two or more layers.

The thermoplastic resin in this old coating film is not particularly limited, and includes conventionally known thermoplastic resins that have been used for base materials such as ships and bridges. Specific examples of the thermoplastic resin include polyester resins, (meth)acrylic resins, styrene resins, vinyl chloride resins, vinyl acetate resins, chlorinated polyolefins, and synthetic rubbers.
Note that "(meth)acrylic" in the present invention is a concept that includes acrylic, methacryl, or both acrylic and methacryl.

Among these, the old paint film formed from paint containing (meth)acrylic resin (hereinafter also referred to as "old acrylic paint film") can be removed without removing it, such as blisters, cracks, lifting (wrinkles), and internal pus. Conventionally, it has not been easy to form this laminated coating film, especially a dissimilar coating film, in which the occurrence of coating film defects is suppressed. In particular, as the surface old paint film to be coated with the present composition, an acrylic old paint film is preferable.

The (meth)acrylic resin coating composition that forms the old acrylic paint film is not particularly limited, and includes, for example, JP-A No. 2016-180051, JP-A No. 2018-44162, JP-A No. 2019-56064, etc. It may be a coating composition prepared based on the description in , or it may be a commercially available product such as the Acry series manufactured by Chugoku Paint Co., Ltd.

The thickness of the old coating film is not particularly limited. Moreover, when the old paint film is a laminate of two or more layers, the thickness of the old paint film is the sum of the respective layers.

<Epoxy compound (A)>
The epoxy compound (A) is not particularly limited as long as it is a compound having an epoxy group other than the glycidyl ether (C) and the silane coupling agent described below, but for example, a polymer containing two or more epoxy groups in the molecule. Or oligomers, and polymers or oligomers produced by a ring-opening reaction of their epoxy groups.
The epoxy compound (A) may be used alone or in combination of two or more.

Examples of the epoxy compound (A) include bisphenol-type epoxy resins, glycidyl ether-type epoxy resins, glycidyl ester-type epoxy resins, glycidylamine-type epoxy resins, novolac-type epoxy resins, cresol-type epoxy resins, alkylphenol-type epoxy resins, and dimer acids. Examples include modified epoxy resins, aliphatic epoxy resins, alicyclic epoxy resins, and epoxidized oil-based epoxy resins.
Among these, bisphenol-type epoxy resins and alkylphenol-type epoxy resins are preferable because they have excellent adhesion to old paint films and can easily obtain a main paint film with anticorrosion properties, and bisphenol A-type epoxy resins are preferable. , bisphenol F type epoxy resin, and alkylphenol type epoxy resin are more preferable, and bisphenol A type epoxy resin and bisphenol F type epoxy resin are particularly preferable.

Specifically, the epoxy compound (A) includes, for example, epichlorohydrin-bisphenol A epoxy resin (bisphenol A diglycidyl ether type); epichlorohydrin-bisphenol AD epoxy resin; epichlorohydrin-bisphenol F epoxy resin; epoxy novolac resin; Alicyclic epoxy resin obtained from 4-epoxyphenoxy-3',4'-epoxyphenylcarboxymethane, etc.; at least one hydrogen atom bonded to the benzene ring in the epichlorohydrin-bisphenol A epoxy resin is replaced with a bromine atom brominated epoxy resins obtained from epichlorohydrin and aliphatic dihydric alcohol; and polyfunctional epoxy resins obtained from epichlorohydrin and tri(hydroxyphenyl)methane.

Examples of the bisphenol type epoxy resin include bisphenol A type and bisphenol F type epoxy resins, modified bisphenol type epoxy resins such as dimer acid modification and polysulfide modification, and hydrogenated products of these epoxy resins.

Examples of the bisphenol A type epoxy resin include bisphenol A diglycidyl ether, bisphenol A (poly)propylene oxide diglycidyl ether, bisphenol A (poly)ethylene oxide diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, and hydrogenated bisphenol A. Examples include condensation products of bisphenol A type diglycidyl ethers such as (poly)propylene oxide diglycidyl ether and hydrogenated bisphenol A (poly)ethylene oxide diglycidyl ether.

The epoxy compound (A) can be used at room temperature (15 to A liquid or semi-solid product is preferable, and a liquid product is more preferable, and the viscosity measured at 25°C exceeds 1,000 mPa・s based on JIS K 7233. 000 mPa·s or less is particularly preferable.

The epoxy equivalent of the epoxy compound (A) is preferably 150 to 1,000, more preferably 150-800, particularly preferably 150-700.
The epoxy equivalent is calculated based on JIS K 7236:2001.

As the epoxy compound (A), those synthesized by conventionally known methods may be used, or commercially available products may be used.
The commercially available products include "E-028" (manufactured by Ohtake Meishin Kagaku Co., Ltd., bisphenol A type epoxy resin, epoxy equivalent 180-190, solid content 100%), "jER807" (manufactured by Ohtake Meishin Kagaku Co., Ltd., bisphenol A type epoxy resin, epoxy equivalent 180-190, solid content 100%), which is liquid at room temperature. (manufactured by Mitsubishi Chemical Corporation, bisphenol F type epoxy resin, epoxy equivalent 160-175, solid content 100%), "E-028-90X" (manufactured by Ohtake Meishin Chemical Co., Ltd., bisphenol A type epoxy resin xylene solution) (828 type epoxy resin solution, epoxy equivalent 200-210, solid content 90%), "HP-820" (manufactured by DIC Corporation, alkylphenol type epoxy resin, epoxy equivalent 150-200, solid content 100%), etc. "jER834" (manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin, epoxy equivalent 230-270, solid content 100%) and "E-834-85X" (manufactured by Akira Ohtake) are semi-solid at room temperature. Examples include a xylene solution of bisphenol A type epoxy resin (834 type epoxy resin solution, epoxy equivalent 270-320, solid content 85%) manufactured by Shin Kagaku Co., Ltd., and "jER1001" ( (manufactured by Mitsubishi Chemical Co., Ltd., bisphenol A type epoxy resin, epoxy equivalent 450-500, solid content 100%), "E-001-75" (manufactured by Ohtake Meishin Chemical Co., Ltd., bisphenol A type epoxy resin xylene solution) (1001 type epoxy resin solution), epoxy equivalent: 600 to 660, solid content: 75%), etc.

The content of the epoxy compound (A) based on 100% by mass of the solid content (components other than the solvent) of the present composition is such that it has excellent adhesion to the old paint film and can easily obtain a paint film with anticorrosion properties. From these points of view, it is preferably 5 to 40% by mass, more preferably 10 to 30% by mass.
Further, when the present composition is a two-component coating composition consisting of a base component and a curing agent component, the epoxy compound (A) is contained in the base component, and the epoxy compound (A) is contained in the base component, and the epoxy compound (A) is The content of compound (A) is preferably 5 to 80% by weight, more preferably 5 to 50% by weight for the same reason as above.

<Amine curing agent (B)>
The amine curing agent (B) is not particularly limited as long as it is an amine compound excluding tertiary amines (amine compounds having only tertiary amino groups), but includes aliphatic, alicyclic, aromatic, and heterocyclic amines. Amine compounds such as curing agents are preferred. These amine compounds are distinguished by the type of carbon to which the amino group is bonded; for example, an aliphatic amine curing agent refers to a compound having at least one amino group bonded to an aliphatic carbon. .
The amine curing agent (B) may be used alone or in combination of two or more.

Examples of the aliphatic amine curing agent include alkylene polyamines, polyalkylene polyamines, and alkylaminoalkylamines.

Examples of the alkylene polyamine include a compound represented by the formula: "H ₂ NR ¹ --NH ₂ " (R ¹ is a divalent hydrocarbon group having 1 to 12 carbon atoms). , specifically methylenediamine, ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7- Examples include diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, trimethylhexamethylenediamine, and the like.

The polyalkylene polyamine has, for example, the formula: "H ₂ N-(C _m H _2m NH) _n H" (m is an integer of 1 to 10. n is an integer of 2 to 10, preferably 2 ), specifically, diethylenetriamine, dipropylenetriamine, triethylenetetramine, tripropylenetetramine, tetraethylenepentamine, tetrapropylenepentamine, pentaethylenehexamine, Examples include nonaethylenedecamine, bis(hexamethylene)triamine, triethylene-bis(trimethylene)hexamine, and the like.

Other aliphatic amine curing agents include tetra(aminomethyl)methane, tetrakis(2-aminoethylaminomethyl)methane, 1,3-bis(2'-aminoethylamino)propane, tris(2-aminoethylamino)propane, ethyl)amine, bis(cyanoethyl)diethylenetriamine, polyoxyalkylene polyamines (especially diethylene glycol bis(3-aminopropyl)ether), bis(aminomethyl)cyclohexane (1,3-BAC), isophoronediamine, menthenediamine (MDA) ), o-xylylenediamine, m-xylylenediamine (MXDA), p-xylylenediamine, bis(aminomethyl)naphthalene, bis(aminoethyl)naphthalene, 1,4-bis(3-aminopropyl)piperazine, Examples include 1-(2'-aminoethylpiperazine), 1-[2'-(2''-aminoethylamino)ethyl]piperazine, and the like.

Specifically, the alicyclic amine curing agent includes cyclohexane diamine, diaminodicyclohexylmethane (particularly 4,4'-methylenebiscyclohexylamine (PACM)), 4,4'-isopropylidenebiscyclohexylamine, and norbornane. Examples include diamine, 2,4-di(4-aminocyclohexylmethyl)aniline, and the like.

Examples of the aromatic amine curing agent include bis(aminoalkyl)benzene, bis(aminoalkyl)naphthalene, and aromatic polyamine compounds having two or more primary amino groups bonded to a benzene ring.
More specifically, examples of the aromatic amine curing agent include phenylene diamine, naphthalene diamine, diaminodiphenylmethane, 2,2-bis(4-aminophenyl)propane, 4,4'-diaminodiphenyl ether, 4,4'- Diaminobenzophenone, 4,4'-diaminodiphenylsulfone, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, diaminodiethyl phenylmethane, 2,4'-diaminobiphenyl, 2,3'-dimethyl-4,4 '-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, and the like.

Examples of the heterocyclic amine curing agent include 1,4-diazacycloheptane, 1,11-diazacycloeicosane, and 1,15-diazacyclooctacosane.

Examples of the amine curing agent (B) include modified products of the above-mentioned amine curing agents, such as fatty acid modified products such as polyamide amine, amine adducts with epoxy compounds, Mannich modified products (e.g., phenalkamine, phenalkamide), and Michael additions. Examples include mono, ketimine, and aldimine.

The amine curing agent (B) is preferably an aliphatic or alicyclic amine curing agent, an epoxy adduct of an aliphatic or alicyclic amine, and a Mannich modified product of an aliphatic or alicyclic amine. Epoxy adducts of aliphatic or alicyclic amines and Mannich modifications of aliphatic or alicyclic amines are more preferred, and epoxy adducts of aliphatic or alicyclic amines are particularly preferred.
Further, as these aliphatic or alicyclic amines, amines having an alicyclic ring, especially a cyclohexane ring are preferable.
When these amine curing agents are used as the amine curing agent (B), it is easy to form a main coating film that has excellent oil resistance and chemical resistance, has excellent adhesion to old coating films, and has excellent corrosion resistance and water resistance. can be obtained.

The epoxy adduct may be an amine such as an aliphatic or cycloaliphatic amine curing agent, a fatty acid modified product of an aliphatic or cycloaliphatic amine curing agent, or a Mannich modified product of an aliphatic or cycloaliphatic amine curing agent. It is obtained by reacting one or more compounds with one or more epoxy resins such as bisphenol A epoxy resin.
The amount of the epoxy resin used per 100 parts by weight of the amine compound is preferably 5 to 800 parts by weight, more preferably 100 to 800 parts by weight, particularly preferably 300 to 800 parts by weight.

Examples of the epoxy resin include bisphenol A diglycidyl ether; bisphenol F diglycidyl ether; styrene oxide; cyclohexene oxide; (alkyl)phenols such as phenol, cresol, and t-butylphenol; butanol; 2-ethylhexanol; Examples include glycidyl ethers such as alcohols of 8 to 14; alkyl glycidyl ethers (eg, Epodil 759 [manufactured by Evonik]).

The amine curing agent (B) may be synthesized by a conventionally known method, or may be a commercially available product.
Such commercial products include, for example, "PH-836" (manufactured by PTI Japan Co., Ltd.), which is an epoxy adduct of aliphatic amine, and "AD-71" (manufactured by Akira Ohtake), which is a separated epoxy adduct of aliphatic amine. (manufactured by Shin Kagaku Co., Ltd.), "Ancamine 2143" (manufactured by EVONIK), which is an epoxy resin adduct modified product of alicyclic amine, and "PA", which is polyamide amine (dehydrated condensate of aliphatic polyamine and dimer acid). -66S" (manufactured by Ohtake Meishin Chemical Co., Ltd.), and "Cardolite CM-5055" (manufactured by Cardlite), which is phenalkamine (a dehydrated condensate of an aliphatic polyamine, formalin, and cardanol).

The active hydrogen equivalent of the amine curing agent (B) is preferably 50 or more, more preferably 100 or more, and preferably 1,000 or less, from the viewpoint of easily obtaining a main coating film with better corrosion resistance. , more preferably 500 or less.

The amine curing agent (B) preferably has a reaction ratio calculated by the following formula (1) of 0, since it is possible to easily obtain a main coating film with excellent corrosion resistance, coating strength, and drying properties. It is desirable to use the amount in an amount of .3 or more, more preferably 0.4 or more, preferably 1.0 or less, more preferably 0.9 or less.

Reaction ratio = {(Amount of amine curing agent (B)/Active hydrogen equivalent of amine curing agent (B)) + (Amount of component reactive to epoxy compound (A)/Epoxy compound (A) (Functional group equivalent of component that is reactive with)}/{(Blend amount of epoxy compound (A)/Epoxy equivalent of epoxy compound (A))+(Has reactivity with amine curing agent (B) Component blending amount/functional group equivalent of component reactive with amine curing agent (B))} ...(1)

Here, the "component having reactivity with the amine curing agent (B)" in the above formula (1) includes, for example, the aliphatic or alicyclic diglycidyl ether (C) and the silane coupling agent described below. Examples of the "component having reactivity with the epoxy compound (A)" include the silane coupling agent described below. The "functional group equivalent" of each component means the mass (g) per 1 mol of functional groups obtained by dividing the number of mol of functional groups contained therein from the mass of 1 mol of these components.
As the silane coupling agent described below, a silane coupling agent having an amino group or an epoxy group as a reactive group can be used. It is necessary to determine whether the amine curing agent (B) has reactivity with the amine curing agent (B) or the amine curing agent (B), and calculate the reaction ratio.

When the present composition is a two-component composition consisting of a base component and a curing agent component, the amine curing agent (B) is included in the curing agent component. The viscosity of this curing agent component at 25°C as measured by an E-type viscometer is preferably 100,000 mPa·s or less, more preferably is 50 to 10,000 mPa·s.

<Aliphatic or alicyclic diglycidyl ether (C)>
The aliphatic or alicyclic diglycidyl ether (C) is not particularly limited, and conventionally known compounds can be used.
Since the present composition is characterized by using diglycidyl ether, it exhibits the above-mentioned effects. On the other hand, when using only monoglycidyl ether without using diglycidyl ether, the resulting composition tends to dissolve the old paint film, which tends to cause paint film defects such as lifting, and when only triglycidyl ether is used. It has been found that in this case, the viscosity of the resulting composition tends to increase, resulting in a composition that is difficult to coat.
Moreover, since the structure of the diglycidyl ether moiety is important for the diglycidyl ether (C), any aliphatic or alicyclic type can solve the above problem. Note that aromatic compounds tend to result in higher viscosity of the resulting composition and higher hardness of the resulting coating film.
The diglycidyl ether (C) may be used alone or in combination of two or more.

The viscosity of the diglycidyl ether (C) is preferably 1,000 mPa·s or less, more preferably 500 mPa·s or less, and even more preferably is 100 mPa·s or less.
Hereinafter, the viscosity of diglycidyl ether (C) refers to the viscosity measured at 25°C based on JIS K 7233.

Specific examples of the aliphatic diglycidyl ether (C) include 1,4-butanediol diglycidyl ether (viscosity: 13 mPa·s), 1,6-hexanediol diglycidyl ether (Gly-O- (CH ₂ ) ₆ -O-Gly, Gly: glycidyl group) (viscosity: 17 mPa・s), neopentyl glycol diglycidyl ether (Gly-O-CH ₂ -C(CH ₃ ) ₂ -CH ₂ -O-Gly , Gly: Same as above) (viscosity: 14 mPa s), propylene glycol diglycidyl ether (viscosity: 25 mPa s), tripropylene glycol diglycidyl ether (viscosity: 30 mPa s), polypropylene glycol diglycidyl ether (viscosity: 75 mPa s) s), polyglycol diglycidyl ether (viscosity: 35 mPa·s), and glycerin diglycidyl ether (viscosity: 150 mPa·s).

Specific examples of the alicyclic diglycidyl ether (C) include cyclohexanedimethanol diglycidyl ether (viscosity: 60 mPa·s).

The diglycidyl ether (C) suppresses the occurrence of paint film defects such as blisters, cracks, lifting (wrinkles), and suppuration, and particularly suppresses the occurrence of such paint film defects even after cooling/heating cycles. Aliphatic diglycidyl ethers are preferred because they can easily form the laminated coating film with suppressed oxidation.
Further, the epoxy equivalent of the diglycidyl ether (C) is preferably 100 to 300, more preferably 120 to 220.

The content of the diglycidyl ether (C) based on 100% by mass of the solid content of the present composition is such that a coating film having a storage modulus within the above range can be easily obtained, and the occurrence of coating film defects can be suppressed. The content is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, from the standpoint of being able to easily form a laminated coating film.

The ratio (C/A) of the content of the diglycidyl ether (C) to the content of the epoxy compound (A) in the present composition 1 is preferably 0.1 to 1.5, more preferably 0. .2 to 1.5, more preferably 0.4 to 1.2, particularly preferably 0.5 to 1.0. Further, the content ratio (C/A) in the present composition 2 is 0.4 to 1.2, preferably 0.5 to 1.0.
When the content ratio (C/A) is within the above range, a main coating film having a storage modulus within the above range can be easily obtained, and the main laminated coating film in which the occurrence of the coating film defects is suppressed. can be easily formed.

<Additives>
This composition may contain a silane coupling agent, a pigment, an antisagging agent (antisettling agent), an antifoaming agent, a curing accelerator such as a tertiary amine, a plasticizer, a leveling agent, an inorganic dehydrating agent, and ultraviolet rays. Additives such as stabilizers, ultraviolet absorbers, anti-aging agents, dispersants, antifouling agents, and solvents may be contained within the range that does not impair the purpose of the present invention.
These additives include conventionally known additives.
Each of the additives may be used alone or in combination of two or more.

[Silane coupling agent]
By using a silane coupling agent, it is possible not only to further improve the adhesion of the obtained main coating film to the old coating film, but also to improve the anticorrosion properties such as salt water resistance of the obtained main coating film. I can do it.

The silane coupling agent is not particularly limited, and conventionally known compounds can be used; however, it has at least two functional groups in the same molecule to improve adhesion to old paint films and reduce the viscosity of the composition. Preferably, it is a compound that can contribute to the reduction, etc., for example, the formula: "X-SiMe _n Y _3-n " [n is 0 or 1, X is a reactive group capable of reacting with an organic substance (e.g., an amino group , a vinyl group, an epoxy group, a mercapto group, a halogen group, a group in which part of a hydrocarbon group is substituted with one of these groups, or a part of a group in which a part of a hydrocarbon group is substituted with an ether bond, etc. ), Me is a methyl group, and Y is a hydrolyzable group (eg, an alkoxy group such as a methoxy group or an ethoxy group). ] is more preferable.

As the silane coupling agent, a compound having an epoxy group or an amino group as a reactive group is preferable, and specifically, “KBM-403” (γ-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd. ), "SiLaAce S-510" (manufactured by JNC Corporation), and "KBM-603" (3-(2-aminoethylamino)propyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.).

When the present composition contains a silane coupling agent, the silane coupling agent based on 100% by mass of the solid content of the present composition is used because it is possible to easily obtain a final coating film with better adhesion to the old coating film. The content of is preferably 0.2 to 3% by mass, more preferably 0.5 to 2% by mass.

[Pigment]
Preferably, the composition includes a pigment.
The pigment is not particularly limited, and conventionally known pigments can be used, and specific examples thereof include extender pigments, coloring pigments, and antirust pigments.

The extender pigments are not particularly limited, but include, for example, zinc oxide, silica, talc, mica, clay, bentonite, potassium feldspar, wollastonite, glass flakes, calcium carbonate, kaolin, alumina white, white carbon, aluminum hydroxide, Examples include magnesium carbonate and barium sulfate (eg barite powder). Among these, talc, silica, mica, clay, calcium carbonate, kaolin, barium sulfate, and potassium feldspar are preferred.

The colored pigments are not particularly limited, but include, for example, inorganic pigments such as carbon black, titanium dioxide, Bengara, iron oxide, iron hydroxide, ultramarine, and organic pigments such as phthalocyanine blue and phthalocyanine green.

The rust-preventing pigment is not particularly limited, but includes, for example, zinc powder, zinc alloy powder, zinc phosphate compounds, calcium phosphate compounds, aluminum phosphate compounds, magnesium phosphate compounds, zinc phosphite compounds, and zinc phosphate compounds. Calcium phosphate compounds, aluminum phosphite compounds, strontium phosphite compounds, aluminum tripolyphosphate compounds, zinc tripolyphosphate compounds, zinc molybdate compounds, aluminum molybdate compounds, cyanamide zinc compounds, borates Examples include compounds, nitro compounds, and composite oxides.

When the present composition contains a pigment, it is possible to easily obtain a coating film having a storage modulus within the above range, and it is possible to easily form a coating film in which the occurrence of coating defects is suppressed. From the standpoint of performance, the pigment content is preferably 10 to 60% by mass, more preferably 20 to 60% by mass, based on 100% by mass of the solid content of the present composition.
Furthermore, for the same reason, the pigment volume concentration (PVC) in the present composition is preferably 10 to 50%, more preferably 10 to 40%.

The PVC refers to the total volume concentration of all pigments in the present composition, and can be specifically determined from the following formula (2).
PVC [%] = Total volume of all pigments in this composition x 100/Volume of solid content in this composition ... (2)

The volume of the solid content in the present composition can be calculated from the mass and true density of the solid content of the present composition. The mass and true density of the solid content may be measured values or values calculated from the raw materials used.

The volume of the pigment can be calculated from the mass and true density of the pigment used. The mass and true density of the pigment may be measured values or values calculated from the raw materials used. The measured value can be calculated, for example, by separating the pigment from other components from the solid content of the present composition and measuring the mass and true density of the separated pigment.

[Anti-sagging agent (anti-settling agent)]
The present composition may contain an anti-sagging agent (anti-settling agent) from the viewpoint of obtaining the present composition having excellent anti-sagging properties.
Examples of the anti-sagging agent include organic clay waxes such as stearate salts of Al, Ca, and Zn, lecithin salts, and alkyl sulfonate salts, polyethylene waxes, amide waxes, hydrogenated castor oil waxes, and oxidized polyethylene waxes. It will be done.

When the composition contains an anti-sagging agent, the content of the anti-sagging agent is preferably set to 100% by mass of the solid content of the composition, in order to obtain the composition with excellent anti-sagging properties. The amount is 0.1 to 2% by weight, more preferably 0.5 to 1.5% by weight.

[Defoaming agent]
The present composition preferably contains an antifoaming agent from the viewpoint of suppressing the generation of air bubbles and improving the appearance of the resulting laminated coating film.
As the antifoaming agent, for example, various conventionally known antifoaming agents such as polymer-based, acrylic-based, silicone-based, mineral oil-based, and olefin-based defoaming agents can be used. Foaming agents are preferred.

Such antifoaming agents include "BYK-1788", "BYK-1790", and "BYK-1794" manufactured by BYK-Chemie Japan Co., Ltd.; "AFCONA-2290" manufactured by AFCONA ADDITIVE, and manufactured by ExxonMobil Chemical Company. Examples include products such as "SpectraSyn 40", "SpectraSyn Elite150", and "SpectraSyn Elite65".

When the present composition contains an antifoaming agent, the content of the antifoaming agent is preferably 0.01 to 4% by mass, more preferably 0.05 to 2% by mass based on 100% by mass of the solid content of the present composition. It is.

[solvent]
The above-mentioned solvent is not particularly limited, and can be appropriately selected and used depending on the coating method and coating workability of the present composition, but it is preferable that the present composition does not contain a solvent as much as possible.

Examples of the solvent include xylene, toluene, MIBK (methyl isobutyl ketone), 1-methoxy-2-propanol, MEK (methyl ethyl ketone), butyl acetate, n-butanol, IBA (isobutyl alcohol), IPA (isopropyl alcohol), and minerals. Examples include spirit and benzyl alcohol.

The content of the solvent is preferably 0 to 10% by mass, more preferably 0 to 10% by mass based on 100% by mass of the present composition, in order to easily form the present laminated coating film in which the occurrence of coating film defects is suppressed. is 0 to 5% by weight, particularly preferably 0 to 3% by weight.

When the content of the solvent is within the above range, it is possible to suppress the adverse effects of the solvent on the painting environment and painting workers, and also prevent the occurrence of paint film defects such as blisters, cracks, lifting (wrinkles), and pus. It is possible to easily obtain the present laminated coating film in which the In particular, when the old paint film on the surface to which this composition is applied is a old acrylic paint film, since acrylic resin usually has poor solvent resistance, it is difficult to apply a general solvent-based paint on the old acrylic paint film. It was found that the old paint film melted and the resulting laminated paint film was prone to paint film defects such as blisters, cracks, lifting (wrinkles), and purulent spots. On the other hand, when the solvent content is within the above range, the occurrence of paint film defects such as blisters, cracks, lifting (wrinkles), and pus can be further suppressed even when painting on old acrylic paint films. This laminated coating film can be easily obtained.

≪Laminated coating film≫
The laminated coating film according to the present invention has the above-mentioned old coating film and the main coating film, and is usually a laminate in which the base material, the old coating film, and the main coating film are laminated in this order. Accordingly, a top coat film is further provided on the opposite side of the main coat film from the old coat film.
In addition, the laminated coating film may be coated with conventionally known primary anticorrosive paint (shop primer) between the base material and the old paint film, if necessary, from the viewpoint of corrosion resistance, weldability, shearability, etc. of the base material. etc., or other films coated with a primer or the like and dried (cured) may be included.
The old paint film, main paint film, top coat film, and other films that may be included in these laminated paint films may each have one layer, or two or more layers.

The laminated coating film is a method including a step of forming a coating film from the present composition on the old coating film, specifically, a method including a step of painting the present composition on the old coating film and drying (curing) it. Preferably, it is produced by a method. This method of producing a laminated coating film can be said to be a method of repairing a coating film, specifically, a method of repairing an old coating film.
According to the present invention, it is possible to form a real paint film on the old paint film without removing the old paint film, in which the occurrence of paint film defects is suppressed, so that the process and costs can be significantly reduced. From this, the main coating film may be formed without removing the old coating film. Note that if the old paint film is too thick, a part of the old paint film may be removed.

The base material is not particularly limited, but base materials made of steel, nonferrous metals (zinc, aluminum, etc.), stainless steel, etc. are preferable, and structures such as ships, land structures, and bridges made of these materials, especially ships. More preferred.

In addition, the surface of the base material may be treated ( For example, it may be subjected to a blasting process (ISO8501-1 Sa2 1/2), a friction method, or a process to remove oil and dust by degreasing.

There are no particular restrictions on the method of applying this composition onto the old paint film, and conventionally known methods can be used without restriction. Spray painting is preferable because it can be applied easily and the effects of the present invention can be more effectively exerted.

The spray coating conditions may be adjusted as appropriate depending on the thickness of the main coating film to be formed, but during airless spraying, for example, primary (air) pressure: about 0.4 to 0.8 MPa, secondary (paint) pressure: about 0.4 to 0.8 MPa, ) The coating conditions may be set to a pressure of about 10 to 26 MPa and a gun movement speed of about 50 to 120 cm/sec.

The thickness of the main coating film may be appropriately selected depending on the desired use, but is preferably 50 to 1,000 μm, more preferably 100 to 500 μm.

When forming a main coating film with such a film thickness, the main coating film of the desired thickness may be formed in one coat (one coat), or two coats (or more if necessary). A main coating film having a desired thickness may be formed by painting.

The method for drying (curing) the present composition is not particularly limited, and the present composition may be dried (curing) by heating at about 5 to 60 ° C. in order to shorten the drying (curing) time. Usually, the composition is dried (cured) by being left at room temperature in the atmosphere for about 1 to 14 days.

The top coat that forms the top coat is not particularly limited, and can be appropriately selected from conventionally known top coats depending on the base material and the use of the base material, and can be applied by a conventionally known method depending on the paint. It is sufficient to form a coating film.
This coating film not only has excellent adhesion to the old coating film, but also to the top coat film formed on top of it. It is possible to suppress the occurrence of paint film defects such as lifting (wrinkles) and pus.
Therefore, the selectivity of the type of top coat to be formed on the main coat is not limited, and recoating with a different type of coat made of a resin different from that of the resin constituting the old coat can be easily performed.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

[Examples 1 to 5 and Comparative Examples 1 to 3]
A main ingredient was prepared by adding each raw material listed in the main ingredient column of Table 1 to a container in the amount (parts by mass) listed in Table 1, stirring with a high-speed disper, and uniformly dispersing it.
Immediately before coating in the following test, the obtained base component and the raw materials listed in the curing agent column of Table 1 are mixed at the mixing ratio (mass ratio) listed in Table 1 to form an epoxy resin coating composition. was prepared.
In Comparative Example 2, each raw material listed in the hardening agent column of Table 1 was added in advance to a container in the amount (parts by mass) listed in Table 1, and stirred with a high-speed disper to uniformly disperse the mixture. After that, it was mixed with the main ingredient.
Details of each component listed in Table 1 are as shown in Table 2.

<Storage modulus>
The epoxy resin coating compositions obtained in the Examples and Comparative Examples were applied onto release paper so that the resulting coating film had a dry thickness of 150 μm, and was dried for 3 days at room temperature. Thereafter, a rectangular coating film with a long side of 40 mm and a short side of 8 mm was peeled off from the release paper, and this coating film was used to coat the film using DMA Q800 (manufactured by TA Instruments Japan Co., Ltd.). The storage modulus at 20°C was measured. The measurement conditions were a vibration amplitude of 15.0 μm, a static load of 0.1000N, a ForceTrack of 125.0%, and a minimum vibration load of 0.0100N. The results are shown in Table 3.

<Blistering resistance test>
Banno 500 (manufactured by Chugoku Toyo Co., Ltd.), an epoxy resin-based anticorrosive paint, was applied onto a blasted steel plate measuring 150 mm x 70 mm x 1.6 mm (thickness) so that the resulting dry film thickness was 180 μm. A steel plate with an anticorrosive coating was prepared by drying it at room temperature for one day.

An acrylic resin topcoat, Acry 700 Topcoat J (manufactured by Chugoku Toyo Co., Ltd.), was applied onto the anticorrosion coating of the prepared steel plate with an anticorrosion coating so that the resulting coating had a dry film thickness of 160 μm. A steel plate with top coating film 1 was prepared by drying at room temperature for one day.

Acrylic 700 Topcoat J was applied onto the topcoat film 1 of the steel plate with the obtained topcoat film 1 so that the dry film thickness of the resulting paint film was 160 μm, and the topcoat film was dried for one day at room temperature. A steel plate with film 2 is prepared, and then Acry 700 Top Coat J is applied on top coat 2 so that the dry film thickness of the obtained film becomes 160 μm, and the top coat is applied by drying at room temperature for one day. A steel plate with coating film 3 was produced. The obtained steel plate with the top coat film 3 was exposed outdoors for 6 months to cause blisters to occur in the top coat film 3.

The epoxy resin coating compositions obtained in the Examples and Comparative Examples were applied onto the top coating film 3 of the steel plate with the top coating film 3 after the outdoor exposure, so that the dry film thickness of the resulting coating film was 150 μm. A steel plate with an epoxy topcoat film was produced by coating the steel plate with a epoxy top coat and drying it at room temperature for 3 days.
The produced steel plate with an epoxy topcoat film was heated to 60° C. and subjected to the following cooling/heating cycle (12 hours) for 120 cycles (total 60 days), and then kept in a room temperature environment and cooled to room temperature.
Cooling cycle: Hold at 60°C for 2 hours → Cool to 32°C over 1 hour → Cool to 5°C over 1 hour → Cool to -20°C over 1 hour → Hold at -20°C for 2 hours → Over 1 hour Heat to 0°C → Heat to 20°C over 1 hour → Hold at 20°C for 1 hour → Heat to 40°C over 1 hour → Heat to 60°C over 1 hour

The appearance of the obtained steel plate with the epoxy topcoat film after the cooling/heating cycle was visually confirmed, and evaluated as ◯ when there was no blistering on the coated film surface and × when blistering occurred on the coated film surface. The results are shown in Table 3.

<Crack resistance test>
An acrylic resin topcoat, Acry 700 Topcoat ST (manufactured by Chugoku Paint Co., Ltd.) was applied to a steel plate with an anticorrosive coating prepared in the same manner as in the blistering resistance test, until the dry film thickness of the resulting coating was 160 μm. A steel plate with topcoat film 1 was prepared by coating the steel plate so as to have the same color and drying it at room temperature for 3 days.

Next, the following accelerated deterioration test was conducted on the steel plate with the top coat film 1.
After irradiating the top coat 1 with ultraviolet rays for two days using a UV lamp (manufactured by Toshiba Lighting & Technology Co., Ltd., product number: FL40S.BLB) at an ultraviolet intensity of 3.2 mW/cm ² , the JIS Salt water was sprayed for two days in accordance with K5600-7-1. Thereafter, the steel plate with topcoat film 1 was heated to 60° C., subjected to the following cooling/heating cycle (12 hours) for 6 cycles (3 days in total), and then kept in a room temperature environment and cooled to room temperature.
Cooling cycle: Hold at 60°C for 2 hours → Cool to 32°C over 1 hour → Cool to 5°C over 1 hour → Cool to -20°C over 1 hour → Hold at -20°C for 2 hours → Over 1 hour Heat to 0°C → Heat to 20°C over 1 hour → Hold at 20°C for 1 hour → Heat to 40°C over 1 hour → Heat to 60°C over 1 hour

After the accelerated deterioration test, apply Acrylic 700 topcoat ST on topcoat 1 of the steel plate with topcoat 1 so that the dry film thickness of the resulting coating is 160 μm, and dry it at room temperature for 3 days. A steel plate with the top coating film 2 was prepared, and an accelerated deterioration test similar to that described above was conducted. Further, apply Acrylic 700 topcoat ST on the topcoat film 2 of the steel plate with the topcoat film 2 after the accelerated deterioration test so that the dry film thickness of the resulting paint film is 160 μm, and dry it at room temperature for 3 days. A steel plate with the top coating film 3 was prepared, and the same accelerated deterioration test as described above was conducted.

For example, on the outer surface of a ship such as a ferry (deck, upper structure, etc.), an acrylic resin topcoat is formed on a base material on which an epoxy resin anticorrosive coating is formed. Then, usually, an acrylic resin top coat film is further coated on the formed acrylic resin top coat film about once a year.
The steel plate with top coat 1 after the accelerated deterioration test corresponds to a ship one year after being newly built, and the steel plate with top coat 3 after the accelerated deterioration test corresponds to a ship 3 years after new ship. corresponds to

After the accelerated deterioration test, an acrylic resin topcoat, Acry 800 topcoat (manufactured by Chugoku Paint Co., Ltd.) was applied to the topcoat 3 of the steel plate with the topcoat 3, and the dry film thickness of the resulting coating was 40 μm. After drying at room temperature for 3 days, the same accelerated deterioration test as described above was carried out for 3 cycles (21 days in total) to prepare a steel plate with the top coating film 4.

The epoxy resin coating composition obtained in the above Examples and Comparative Examples was applied onto the prepared top coat film of the steel plate with the top coat film 4 so that the dry film thickness of the resulting paint film was 150 μm, A steel plate with an epoxy topcoat film was produced by drying it at room temperature for one day.

Acrylic 800 topcoat was applied to the epoxy topcoat film of the obtained steel plate with epoxy topcoat film so that the dry film thickness of the resulting paint film was 40 μm, and by drying at room temperature for 3 days, the topcoat film was formed. A steel plate with No. 5 was produced.

After carrying out the accelerated deterioration test for 8 cycles (56 days in total) using the prepared steel plate with top coat 5, the appearance of the steel plate with top coat 5 was visually confirmed, and there were no cracks on the coating surface. The case was evaluated as ○, and the case where cracks occurred on the coating surface was evaluated as ×. The results are shown in Table 3.

<Lifting resistance test>
Acrylic 700 topcoat ST was applied onto the anti-corrosion coating of a steel plate with an anti-corrosion coating prepared in the same manner as in the blistering resistance test so that the dry film thickness of the resulting coating was 160 μm, and dried for one day at room temperature. By doing so, a steel plate with top coating film 1 was produced.

On top of the obtained topcoat film 1 of the steel plate with topcoat film 1, an acrylic resin topcoat paint, Acry 700 Topcoat JMS (manufactured by Chugoku Paint Co., Ltd.), is applied so that the dry film thickness of the resulting paint film is 40 μm. A steel plate with the top coating film 2 was prepared by coating it as shown in FIG.

The epoxy resin coating compositions obtained in the Examples and Comparative Examples are applied onto the top coating film 2 of the steel plate with the top coating film 2 so that the resulting coating film has a dry film thickness of 150 μm, A steel plate with an epoxy topcoat film was produced by drying it at room temperature for one day.

Acrylic 700 topcoat ST was applied onto the epoxy topcoat film of the obtained steel plate with epoxy topcoat film so that the dry film thickness of the resulting paint film was 40 μm, and by drying for one day at room temperature, the topcoat was applied. A steel plate with membrane 3 was produced.

The appearance of the obtained steel plate with the top coat film 3 was visually confirmed, and evaluated as ◯ when there was no lifting (wrinkle) on the coated film surface and × when lifting occurred on the coated film surface. The results are shown in Table 3.

<Different types of topcoating test>
The epoxy resin coating compositions obtained in the Examples and Comparative Examples were applied to a steel plate with a top coat 3 prepared in the same manner as in the crack resistance test so that the dry thickness of the resulting coating was 150 μm. A steel plate with an epoxy topcoat film was prepared by coating the epoxy resin and drying it at room temperature for one day.

The prepared steel plate with the epoxy topcoat film was coated with Unimarin (manufactured by Chugoku Paint Co., Ltd.), which is a urethane resin topcoat, so that the dry film thickness of the resulting paint film was 40 μm, and dried for 3 days at room temperature. In this way, a steel plate with the top coating film 4 was produced.

The prepared steel plate with top coat 4 was heated to 60° C., subjected to 120 cycles (total 60 days) of the following cooling/heating cycle (12 hours), and then kept in a room temperature environment and cooled to room temperature.
Cooling cycle: Hold at 60°C for 2 hours → Cool to 32°C over 1 hour → Cool to 5°C over 1 hour → Cool to -20°C over 1 hour → Hold at -20°C for 2 hours → Over 1 hour Heat to 0°C → Heat to 20°C over 1 hour → Hold at 20°C for 1 hour → Heat to 40°C over 1 hour → Heat to 60°C over 1 hour

Visually check the appearance of the steel plate with the top coat 4 after the cooling/heating cycle, and if there is no blistering, cracking or lifting on the coating surface, it is marked as ○, or if there is any blistering, cracking or lifting on the coating surface. Cases where this occurred were evaluated as ×. The results are shown in Table 3.

Claims (5)

Painted on a coating film containing thermoplastic resin,
Meets the following requirements (1), and
an aliphatic or alicyclic diglycidyl ether (C), an amine curing agent (B), and an epoxy compound (A) other than the aliphatic or alicyclic diglycidyl ether (C) ; An epoxy resin coating composition , wherein the ratio of the content of the aliphatic or alicyclic diglycidyl ether (C) to the content of the compound (A) is 0.4 to 1.2 .
Requirement (1): The storage modulus at 20°C of a coating film with a dry film thickness of 150 μm formed from the epoxy resin coating composition is 1,200 MPa or more and 6,000 MPa or less. The epoxy resin coating composition according to claim 1 , wherein the content of the solvent is 0 to 10% by mass. The epoxy resin coating composition according to claim 1 or 2 , wherein the thermoplastic resin is a (meth)acrylic resin. A coating film containing a thermoplastic resin,
A laminated coating film comprising a coating film formed from the epoxy resin coating composition according to any one of claims 1 to 3 . A method for repairing a paint film, comprising the step of forming a paint film from the epoxy resin coating composition according to any one of claims 1 to 3 on a paint film containing a thermoplastic resin.