JPWO2019022218A1 - Low VOC coating composition, anticorrosion coating, coated substrate and method for producing coated substrate - Google Patents

Abstract

[Summary] The present invention relates to a low VOC coating composition, an anticorrosive coating, a coated substrate and a method for producing a coated substrate, wherein the low VOC coating composition has an epoxy equivalent of 200 or less. The compound (A), the amine-based curing agent (B) having a cyclic structure, and the silane coupling agent (C) having an epoxy group are contained, and the content of the silane coupling agent (C) is 5 to 20 mass. %, which satisfies the following (I) or (II). (I) The mass ratio of the epoxy compound (A) to the silane coupling agent (C) is 1.0:0.1 to 0.5 (II) The amine-based curing agent having the cyclic structure (B) 2) or more

Description

  The present invention relates to a low VOC coating composition, an anticorrosive coating film, a coated substrate and a method for producing a coated substrate.

  Conventionally, for a coating composition that forms a coating film excellent in oil resistance, solvent resistance, chemical resistance and corrosion resistance, which is applied to the inner surface of a product carrier tank or a land tank where chemicals are stored, , A solid bisphenol A type epoxy resin, a solid novolac type epoxy resin, and an epoxy modified product such as an epoxy adduct of diethylenetriamine are used (blended).

  Such a coating composition contains a resin having a relatively high molecular weight in order to impart the above effect to the obtained coating film. Therefore, the coating composition contains a large amount of volatile organic components (hereinafter, referred to as VOC: Volatile Organic Compounds) from the viewpoint of coating workability and the like. Therefore, paints using a semi-solid epoxy resin capable of further reducing VOC have been developed, but the amount of VOC reduction is not yet sufficient.

  For example, Patent Document 1 contains a main component containing a bisphenol type epoxy resin having an epoxy equivalent of 250 to 300, a hardener component containing an epoxy adduct of xylylenediamine, and an epoxy adduct of polyamide. Solid type anticorrosion coating compositions are disclosed.

  In Patent Document 2, a bisphenol type liquid epoxy resin having an epoxy equivalent of less than 250 having two or more epoxy groups in one molecule, xylenediamine or isophoronediamine is used as an epoxy resin as a coating material layer for coating a surface layer of a steel material. A layer containing a modified amine modified with and a pigment is disclosed.

  Patent Document 3 discloses an anticorrosive coating composition comprising a first agent containing a bisphenol A type epoxy resin, a second amine containing a specific amine curing agent, and a monoepoxide compound.

  In Patent Document 4, from the viewpoint of hot water resistance and adhesion, an epoxy resin having an epoxy equivalent of 400 to 2200 is used, and 10 to 40 parts by weight of a silane coupling agent is used with respect to 100 parts by weight of the solid content of the epoxy resin. A hot water resistant coating composition containing 250 to 500 parts by weight of flat talc having an oil absorption of 40 ml/100 g or less and 0 to 50 parts by weight of a color pigment is disclosed.

  US Pat. No. 6,037,056 discloses an epoxy-functional resin suitable for coating metal or concrete surfaces of chemical equipment, an amine curing agent for said epoxy-functional resin, and an organic selected from the group of organosilanes and organosiloxanes. A coating composition containing a silicon-containing compound, wherein the organosilicon-containing compound in the coating composition has a molar ratio of silicon atoms to epoxy groups of 0.20 to 0.75:1.00, preferably 0. Coating compositions ranging from 25 to 0.75:1.00 are disclosed.

  Further, conventionally, (large) steel structures such as ships, bridges, tanks, plants, offshore buoys and undersea pipelines are covered with a coating film obtained from an epoxy resin anticorrosion coating composition for corrosion prevention. . On such a coating film, various resin-based top coating compositions are provided to impart functions such as aesthetic appearance, weather resistance, anticorrosion property and antifouling property according to the use and purpose of the steel structure. The object is painted and the top coat film is formed.

International Publication No. 2007/102587 JP, A, 3-275773 Japanese Patent No. 5913762 JP 60-118756 A Special table 2017-508598 gazette

However, the coating material layer described in Patent Document 2 is inferior in oil resistance, solvent resistance and chemical resistance, and is particularly dichloroethane (EDC), methyl ethyl ketone (MEK), a solvent such as benzene, and room temperature (15 to 25° C.). , The same shall apply hereinafter), there is a problem in solvent resistance such as blistering.
Further, it was found that the coating film obtained from the anticorrosion coating composition described in Patent Document 3 had a low crosslink density and was inferior in solvent resistance and chemical resistance.

  As described in Patent Document 1, a coating composition capable of forming a coating film excellent in oil resistance, solvent resistance, chemical resistance and corrosion resistance is known, but these coating compositions are known. A solid or semi-solid epoxy resin is used for. Similarly, a solid epoxy resin is used in the hot water resistant coating composition described in Patent Document 4.

Further, Patent Document 5 describes only a composition using a novolac type epoxy resin as an epoxy resin or a composition containing a large amount of a silane coupling agent. In order to adjust a coating composition using such a novolac type epoxy resin to a coating composition having an appropriate coating workability, a large amount of solvent or an epoxy group-containing reactive diluent is required, so photochemical It has been found that it is difficult to obtain a coating composition having a small VOC content that causes smog and the like, excellent coating workability, and excellent in the above-mentioned various performances.
Furthermore, a composition containing a large amount of a silane coupling agent cannot be put into practical use because it produces an alcohol by a hydrolysis reaction during storage or during film formation, which imposes a heavy burden on the environment and a coating operator. .

  When the conventional coating composition as described in Patent Document 1 is used for coating the inner surface of a closed structure such as a product carrier tank or a land tank in which chemicals are similarly stored, There is a high risk of fire due to the VOC filling the tank, and since the coating worker is also exposed to the high concentration of VOC, the coating worker's health damage is large. Further, in the coating of these structures, spray coating, particularly coating by airless spray is desirable from the viewpoint of work efficiency, and therefore it is required that the coating composition has low coating viscosity and good coating workability. ing.

  On the other hand, a conventional undercoating film formed from an epoxy resin-based coating composition has poor weather resistance, and thus physical properties (eg, anti-blurring property) exhibited by interlayer adhesion with the topcoating film and the laminate with the topcoating film. It was found that the suitability for topcoating such as) easily deteriorates. In particular, it has been found that when the period from the undercoating to the topcoating of the epoxy resin-based coating composition becomes long, there arises a problem that interlayer adhesion between the formed undercoating film and the topcoating film becomes insufficient.

  One embodiment of the present invention is a coating composition capable of forming a coating film excellent in oil resistance, solvent resistance, chemical resistance and corrosion resistance, and in addition to these performances, a coating film excellent in well-balanced top coating compatibility. Which has a low VOC (that is, a high content of non-volatile components and no or almost no volatile organic components) and is excellent in drying properties and coating workability. I will provide a.

As a result of the inventors' earnest studies on a method for solving the above problems, they have found that a coating composition having a specific composition can solve the above problems, and have completed the present invention.
The configuration example of the present invention is as follows.

  <1> A bisphenol-type epoxy compound (A) having an epoxy equivalent of 200 or less, an amine-based curing agent (B) having a cyclic structure, and a silane coupling agent (C) having an epoxy group, and the silane coupling The content of the agent (C) is 5 to 20% by mass, and the mass ratio of the bisphenol type epoxy compound (A) and the silane coupling agent (C) is 1.0:0.1 to 0.5. A low VOC coating composition.

  <2> A bisphenol type epoxy compound (A) having an epoxy equivalent of 200 or less, an amine-based curing agent (B) having a cyclic structure, and a silane coupling agent (C) having an epoxy group are contained, and the cyclic structure is formed. A low VOC coating composition containing two or more kinds of the amine-based curing agent (B), and the content of the silane coupling agent (C) is 5 to 20% by mass.

  <3> The coating composition according to <1> or <2>, further containing a flat pigment (D).

  <4> The coating composition according to any one of <1> to <3>, wherein the silane coupling agent (C) is a silane coupling agent having one epoxy group in one molecule.

  <5> In any one of <1> to <4>, the amine-based curing agent (B) having a cyclic structure contains at least one selected from alicyclic amine and modified products of alicyclic amine. The coating composition described.

<6> A flat pigment (D) and a pigment (E) other than the flat pigment (D) are contained,
The coating composition according to any one of <1> to <5>, wherein the flat pigment (D) and the pigment (E) in the coating composition have a volume concentration (PVC) of 10 to 70%.

  <7> The coating composition according to any one of <1> to <6>, wherein the VOC content of the coating composition is 200 g/L or less.

<8> An anticorrosive coating film formed from the coating composition according to any one of <1> to <7>.
<9> A substrate with a coating film, which comprises the anticorrosion coating film according to <8> and a substrate.
<10> A method for producing a coated substrate, which comprises the following steps [1] and [2].
[1] A step of coating the coating composition according to any one of <1> to <7> on a substrate [2] A step of drying the coated coating composition to form a coating film

According to one embodiment of the present invention, a coating composition capable of forming a coating film excellent in oil resistance, solvent resistance, chemical resistance and corrosion resistance, and, in addition to these performances, excellent in topcoat coating compatibility in a well-balanced manner. A coating composition capable of forming a coating film, which has a low VOC and is excellent in drying property and coating workability, particularly spray painting workability, can be obtained.
Furthermore, according to one embodiment of the present invention, it is possible to form a coating film having the above various excellent performances on various base materials (for example, various tanks).

FIG. 1 is a schematic view of a notched test plate used in the anticorrosion test of Examples.

<<Low VOC coating composition>>
The low VOC coating composition (hereinafter also referred to as “the composition”), which is an embodiment of the present invention, comprises a bisphenol epoxy compound (A) having an epoxy equivalent of 200 or less, an amine-based curing agent (B) having a cyclic structure. ), and a silane coupling agent (C) having an epoxy group, the content of the silane coupling agent (C) is 5 to 20 mass%, and satisfies the following (I) or (II),
(I) A composition 1 in which the mass ratio of the bisphenol type epoxy compound (A) and the silane coupling agent (C) is 1.0:0.1 to 0.5, or
(II) Composition 2 containing two or more amine-based curing agents (B) having the above cyclic structure
Is.

The composition 1 contains the above-mentioned (A) to (C), in particular, contains a specific amount of (C) and contains (A) and (C) in a specific amount ratio. 2 contains the above-mentioned (A) to (C), and in particular, contains two or more specific curing agents and contains a specific amount of (C), so that the above-mentioned effect is exhibited.
The compositions 1 and 2 have the above-mentioned effects, respectively, but the composition 1 is particularly excellent in oil resistance, chemical resistance and solvent resistance, and the composition 2 is particularly anticorrosive (especially electrocorrosive). Excellent in drying property, coating workability and topcoating compatibility.

Here, oil resistance, solvent resistance, and excellent chemical resistance, specifically, heavy oil, gasoline, naphtha, oils such as palm oil, methanol, ethanol, xylene, benzene, methyl isobutyl ketone, 1, It has excellent resistance to solvents such as 2-dichloroethane and ethyl acetate, and chemicals such as sodium hydroxide and sulfuric acid.
Since these oils, solvents and chemicals have a large effect on the coating film, the coating film resistant to these oils, solvents and chemicals is also resistant to general oils, solvents and chemicals. It is thought that.

  Incidentally, since it is particularly important to prevent corrosion of the substrate, a suitable example of the present composition is a "corrosion preventive coating composition", but a composition used only for imparting corrosion resistance to the substrate The composition used for imparting oil resistance, solvent resistance, chemical resistance, etc. to the base material, and the base material and the base material, or the base material and the top coating film. An adhesive that adheres to and is also included in one embodiment of the present composition.

In the present invention, “low VOC” means that the composition does not contain VOC such as a solvent at all or contains almost no VOC. Specifically, the composition has a viscosity suitable for coating. This means that the VOC content in the composition is 200 g/L or less.
The VOC content in the composition is preferably 170 g/L or less, more preferably 155 g/L or less.

The VOC content of this composition can be calculated from the following formula (1) using the values of the paint specific gravity and mass NV shown below.
VOC content (g/L)=paint specific gravity×1000×(100−mass NV)/100 (1)

Specific gravity of paint (g/cm ³ ): Under a temperature condition of 23° C., a specific gravity cup having an internal volume of 100 ml was filled with the present composition (eg, a composition immediately after mixing a main component and a curing agent component), Value calculated by measuring the mass of the composition

  Mass NV (mass %): 1 g of the present composition (eg, composition immediately after mixing the main component and the curing agent component) is weighed in a flat-bottom dish, spread evenly using a wire of known mass, and at 23° C. After standing for 24 hours, it is dried at 110° C. for 1 hour, and the value of the mass percentage calculated by measuring the mass of the heating residue (also referred to as “solid content” or “nonvolatile content”) and the wire (this composition Content of heating residue (mass NV) in

Although the composition may be a one-component composition, it is usually a two-component composition consisting of a main component containing an epoxy compound (A) and a curing agent component containing an amine-based curing agent (B). Mold composition. Further, if necessary, the present composition may be a three-component or more composition.
The main ingredient component and the curing agent component are usually stored, stored, transported, etc. in separate containers and mixed together just before use.

<Bisphenol type epoxy compound (A)>
Examples of the bisphenol type epoxy compound (A) include a polymer or oligomer having a bisphenol structure in the molecule and containing two or more epoxy groups, and a polymer produced by a ring-opening reaction of the epoxy groups. An oligomer is mentioned.
By using such an epoxy compound (A) together with the specific (B) and (C), a composition having a low VOC and excellent coating workability can be obtained. Further, according to the composition, oil resistance A coating film having excellent solvent resistance, chemical resistance and corrosion resistance can be formed.
As the epoxy compound (A), one type may be used, or two or more types may be used.

The epoxy equivalent of the epoxy compound (A) is 200 or less, preferably 100 to 200, more preferably 100 to 190, since it is possible to form a coating film excellent in oil resistance, solvent resistance, chemical resistance and corrosion resistance. It is more preferably 100 to 180, and particularly preferably 100 to 175. The epoxy equivalent is calculated based on JIS K7236.
Since an epoxy compound having an epoxy equivalent of more than 200 has an excessively large molecular weight, when such an epoxy compound is used, a solvent for adjusting an appropriate viscosity for coating is often required, and a low VOC coating composition can be easily prepared. There is a tendency that cannot be obtained.

  The epoxy compound (A) is preferably an epoxy resin which is liquid at room temperature, and examples thereof include a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, and a bisphenol AD type epoxy resin.

  As the epoxy compound (A), a commercially available product may be used, and as the commercially available product, for example, "E-028" which is a bisphenol A type epoxy resin (manufactured by Otake Meishin Chemical Co., Ltd., epoxy equivalent 180 to 190). , Non-volatile content 100%), and bisphenol F type epoxy resin "jER 807" (Mitsubishi Chemical Corporation, epoxy equivalent 160-175, non-volatile content 100%).

The viscosity (25° C.) of the epoxy compound (A) measured with an E-type viscometer (manufactured by TOKIMEC, FMD type) has a lower limit of preferably 1500 mPa·s, more preferably 3000 mPa·s, and an upper limit thereof. Is 120,000 mPa·s, more preferably 30,000 mPa·s.
In the following, for example, the lower limit is preferably 10 means that the preferable range is 10 or more, and the upper limit is preferably 100 means that the preferable range is 100 or less.

  The content of the epoxy compound (A) in the composition is such that a coating film having excellent adhesion to a substrate, oil resistance, solvent resistance, chemical resistance, corrosion resistance, etc. can be easily obtained. Therefore, the lower limit is preferably 10% by mass, more preferably 15% by mass, and the upper limit is preferably 50% by mass, more preferably 45% by mass, relative to 100% by mass of the nonvolatile content of the composition. .

<Amine-based curing agent (B) having a cyclic structure>
The amine-based curing agent (B) having a cyclic structure is not particularly limited as long as it is an amine having a cyclic structure, but is preferably a low VOC type compound, and is preferably a polyamine.
Examples of the curing agent (B) include alicyclic, aromatic, and heterocyclic polyamines, modified products of these polyamines, and Mannich compounds using an aliphatic polyamine and a phenolic compound (eg, phenalkamine). ) Or an aliphatic polyamine and an epoxy compound having an aromatic ring structure (eg, bisphenol A type epoxy compound).
The curing agent (B) used in the composition 2 is 2 or more types, and the curing agent (B) used in the composition 1 may be 1 type or 2 or more types.

  Specific examples of the alicyclic polyamine include 1,4-cyclohexanediamine, diaminodicyclohexylmethane (particularly 4,4′-methylenebiscyclohexylamine), 2,2′-dimethyl-4,4′. -Methylenebiscyclohexylamine, 4,4'-isopropylidenebiscyclohexylamine, norbornanediamine, bis(aminomethyl)cyclohexane, isophoronediamine, mensendiamine (MDA), 2,5-di(4-aminocyclohexylmethyl)cyclohexyl Amine, 4-(p-aminobenzyl)cyclohexylamine, 2,4′-bis(4″-aminocyclohexyl)-2′,4-methylenedianiline, 4-[(4-aminocyclohexyl)methyl]-N Examples include -[4-[(4-aminocyclohexyl)methyl]cyclohexyl]-cyclohexylamine, 2,4-di(4-aminocyclohexylmethyl)aniline and 2,5-di(4-aminocyclohexylmethyl)aniline.

Examples of the aromatic polyamine include bis(aminoalkyl)benzene, bis(aminoalkyl)naphthalene, and compounds having two or more primary amino groups bonded to a benzene ring.
Specific examples of the aromatic polyamine include o-xylylenediamine, m-xylylenediamine (MXDA), p-xylylenediamine, phenylenediamine, naphthalenediamine, diaminodiphenylmethane, and 2,2-bis( 4-aminophenyl)propane, 4,4'-diaminodiphenyl ether, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenyl sulfone, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, diaminodiethylphenyl Methane, 2,4'-diaminobiphenyl, 2,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, bis(aminomethyl)naphthalene, bis(amino Ethyl)naphthalene.

  Specific examples of the heterocyclic polyamine include 1,4-bis(3-aminopropyl)piperazine, 1,4-diazacycloheptane, 1-(2′-aminoethylpiperazine), 1- [2′-(2″-aminoethylamino)ethyl]piperazine, 1,11-diazacycloeicosane, 1,15-diazacyclooctacosane.

  Examples of the modified product of an alicyclic, aromatic, or heterocyclic polyamine include Mannich modified products, epoxy adducts, styrene modified products, or fatty acid modified products of the polyamines.

  Examples of the aliphatic polyamine include alkylene polyamine, polyalkylene polyamine, and alkylaminoalkylamine.

Examples of the alkylene polyamines, for example, the formula: "H ₂ N-R ¹ -NH _2" (. R ¹ is a divalent hydrocarbon group having 1 to 12 carbon atoms) is a compound represented by the like, Specifically, for example, methylenediamine, ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7. -Diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane and trimethylhexamethylenediamine.

Examples of the polyalkylene polyamines, for example, the formula: is _{"H 2 N- (C m H 2m} NH) n H " (m is an integer of 1 to 10 .n is 2-10, preferably 2-6 Is an integer of), and specifically, for example, diethylenetriamine, dipropylenetriamine, triethylenetetramine, tripropylenetetramine, tetraethylenepentamine, tetrapropylenepentamine, pentaethylenehexamine, Examples thereof include nonaethylenedecamine and bis(hexamethylene)triamine.

  Examples of the aliphatic polyamine other than these include, for example, tetra(aminomethyl)methane, tetrakis(2-aminoethylaminomethyl)methane, 1,3-bis(2′-aminoethylamino)propane, 2,2′-[ Examples thereof include ethylenebis(iminotrimethyleneimino)]bis(ethaneamine), tris(2-aminoethyl)amine, bis(cyanoethyl)diethylenetriamine, and polyoxyalkylenepolyamine (particularly diethyleneglycolbis(3-aminopropyl)ether).

  Among these polyamines, from the viewpoint of easily obtaining a coating film excellent in solvent resistance, chemical resistance and the like, alicyclic polyamines and modified products thereof are preferable, and polyamines having a cyclohexane ring are more preferable, It is even more preferable that 4,4′-methylenebiscyclohexylamine, 2,2′-dimethyl-4,4′-methylenebiscyclohexylamine, di(4-aminocyclohexylmethyl)aniline or modified products thereof be included. , 2'-dimethyl-4,4'-methylenebiscyclohexylamine, di(4-aminocyclohexylmethyl)aniline or modified products thereof are more preferred, and di(4-aminocyclohexylmethyl)aniline or modified products thereof. It is particularly preferable to include the thing.

When the present composition contains two or more curing agents (B), the composition 2 is particularly advantageous in that it is easy to obtain a composition excellent in anticorrosion property (particularly electrocorrosion property) and drying property. Preferably containing a curing agent (B1) selected from alicyclic polyamines and modified products thereof, containing two or more curing agents (B1), or containing a curing agent (B1) and m-xylylenediamine and It is more preferable to include a curing agent (B2) selected from the modified products thereof, and to include an alicyclic polyamine (B1-1) and a modified product of the alicyclic polyamine (B1-2), or a curing agent. It is more preferable to include (B1) and a curing agent (B2).
The curing agents (B1) and (B1-1) preferably include di(4-aminocyclohexylmethyl)aniline.
Examples of the modified products in the curing agents (B1), (B2) and (B1-2) include Mannich modified products, epoxy adducts, styrene modified products or fatty acid modified products.

  The content of the curing agents (B1) and (B2) in the curing agent (B) in the composition is not particularly limited, but may be oil resistance, solvent resistance, chemical resistance, corrosion resistance, and topcoat compatibility. Considering the balance, the content of the curing agent (B1) is preferably 20% by mass or more, and more preferably 30% by mass or more with respect to 100% by mass of the curing agent (B). Further, the content of the curing agent (B1-1) is preferably 30% by mass or more, more preferably 40% by mass or more, and particularly preferably 50% by mass or more, with respect to 100% by mass of the curing agent (B1). .

  As the alicyclic polyamine, a commercially available product may be used, and examples of the commercially available product include "Ancamine 2280", "Ancamine 2049" and "Ancamine 2143" (all manufactured by Air Products Co., Ltd.). In particular, “Ancamine 2280” containing di(4-aminocyclohexylmethyl)aniline as a main component can be preferably used.

<Silane coupling agent (C) having an epoxy group>
The epoxy group-containing silane coupling agent (C) has an epoxy group and an alkoxy group from the viewpoint of easily forming a coating film excellent in oil resistance, solvent resistance, chemical resistance, corrosion resistance and the like. A compound is preferable, an alkoxy group-containing silane coupling agent having one epoxy group in one molecule is more preferable, and a compound represented by the following formula is particularly preferable.
X-SiMe _n Y _3-n
[N is 0 or 1, X is an epoxy group, a group in which a part of the hydrocarbon group is substituted with an epoxy group, or a part of a group in which a part of the hydrocarbon group is substituted with an ether bond, etc. A group substituted with an epoxy group is shown, Me is a methyl group, and Y is an alkoxy group such as a methoxy group and an ethoxy group. ]

The silane coupling agent (C) has a function of chemically bonding a flat pigment (D) or a pigment (E) described later with a coating film forming component such as the following epoxy component or the following amine component, and It has the effect of improving the adhesion of the coating film formed to the substrate.
Since the silane coupling agent (C) has an epoxy group, it is possible to obtain a coating film that exhibits the above effects. On the other hand, when only the silane coupling agent having no epoxy group is used, the desired effect is not exhibited.
As the silane coupling agent (C), one type may be used, or two or more types may be used.

  Specific examples of the silane coupling agent (C) include (3,4-epoxycyclohexyl)ethyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., “KBM303”, etc.), γ-glycidoxypropyl. Trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., “KBM403”, etc.) is preferable, and γ-glycidoxypropylmethyldimethoxysilane (manufactured by Toray Dow Corning Co., Ltd., “AY43-026”, etc.), γ-glycidoxypropylmethyldiethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., “KBE-402” or the like) may be used.

The content of the silane coupling agent (C) in the composition 1 is the total amount of the composition 1 from the viewpoint that a coating film excellent in solvent resistance, chemical resistance and corrosion resistance can be easily obtained. With respect to 100% by mass, the lower limit is preferably 5% by mass, more preferably 7% by mass, and the upper limit is preferably 20% by mass, more preferably 15% by mass.
The content of the silane coupling agent (C) in the composition 2 is such that a composition having excellent coating workability can be easily obtained, and solvent resistance, chemical resistance, corrosion resistance, and topcoat compatibility From the viewpoint that a coating film having better properties can be easily obtained, it is 5 to 20% by mass, preferably 5 to 10% by mass, relative to 100% by mass of the total amount of the composition 2.
When the content of the silane coupling agent (C) is less than 5% by mass or more than 20% by mass with respect to 100% by mass of the present composition, the anticorrosive property and the adhesion to the substrate are good. However, a coating film having excellent solvent resistance and chemical resistance tends not to be obtained.

The lower limit of the mass of the silane coupling agent (C) with respect to 1.0 part by mass of the epoxy compound (A) in the composition 1 is preferably 0.1 part by mass, more preferably 0.2 part by mass. And the upper limit is preferably 0.5 parts by mass, more preferably 0.45 parts by mass.
In the composition 1, when the mass of the silane coupling agent (C) with respect to 1.0 part by mass of the epoxy compound (A) is less than 0.1 parts by mass, a coating film excellent in solvent resistance and chemical resistance is obtained. If it exceeds 0.5 parts by mass, a composition having excellent dryness tends not to be obtained.
Particularly, in the above composition 1, when the mass of the silane coupling agent (C) is more than 0.5 parts by mass relative to 1.0 part by mass of the epoxy compound (A), the silane coupling agent (C) is an alkoxy In the case of a compound having a group, since the alkoxy group in the silane coupling agent (C) undergoes a hydrolysis reaction to generate alcohol, the composition has a large load on the environment during coating film formation and a coating worker. It tends to become a thing.
The mass of the silane coupling agent (C) with respect to 1.0 part by mass of the epoxy compound (A) in the composition 2 is the same as that of the composition 1 for the same reason as in the case of the composition 1. It is preferably in the range.

<Flat pigment (D)>
The present composition preferably contains the flat pigment (D) from the viewpoint that a coating film having excellent anticorrosive properties and excellent adhesion to a substrate due to relaxation of internal stress can be easily obtained.
As the flat pigment (D), one type may be used, or two or more types may be used.

As the flat pigment (D), a median diameter (D50) is preferably 30 to 200 μm, and an average aspect ratio (median diameter/average thickness) from the viewpoint that a coating film more excellent in the above effects can be formed. It is desirable that the pigment has a size of 10 or more, more preferably 20 or more, preferably 150 or less, and more preferably 100 or less.
D50 can be measured using a laser scattering diffraction type particle size distribution measuring device, for example, "SALD 2200" (manufactured by Shimadzu Corporation).
The average thickness is measured by a scanning electron microscope (SEM), for example, "XL-30" (manufactured by Philips), and observed from the horizontal direction with respect to the main surface of the flat pigment (D). It can be calculated as an average value of the thickness of individual pigment particles.

Examples of the flat pigment (D) include mica, glass flakes, aluminum flakes, scaly iron oxide, stainless flakes, and plastic flakes, which form a coating film that is inexpensive, easily available, and more excellent in the above effects. Mica is preferable because it can be treated.
Examples of the mica include "mica powder 100 mesh" (Fukuoka Talc Industry Co., Ltd., D50: 41 µm, average aspect ratio: 35).

  When the present composition contains the flat pigment (D), the content of the flat pigment (D) in the present composition is such that the excellent coating film can be easily obtained due to the above effects. The lower limit is preferably 1% by mass, more preferably 3% by mass, and the upper limit is preferably 40% by mass, more preferably 20% by mass, relative to 100% by mass of the nonvolatile content of the product.

<Pigment (E)>
The composition may contain a pigment (E) other than the flat pigment (D), and examples of the pigment (E) include extender pigments, coloring pigments, rust preventive pigments, and the like. Any of the systems may be used.
As the pigment (E), one type may be used, or two or more types may be used.

  As the extender pigment, for example, conventionally known talc, (precipitating) barium sulfate, (potassium) feldspar, kaolin, alumina white, clay, magnesium carbonate, barium carbonate, calcium carbonate, dolomite, and silica can be used. . Particularly, talc, silica, (precipitating) barium sulfate, and (potassium) feldspar are preferable.

  When such an extender pigment is added to the present composition, the amount thereof is preferably 10 to 70% by mass, more preferably 10 to 50% by mass, relative to 100% by mass of the nonvolatile content of the present composition. .

  As the color pigment, for example, conventionally known inorganic pigments such as carbon black, titanium dioxide (titanium white), iron oxide (bengal), yellow iron oxide, ultramarine blue, cyanine blue, cyanine green, etc. are used. be able to. In particular, titanium white, carbon black, and rouge are preferable.

  When such a color pigment is compounded in the composition, the compounding amount is preferably 1 to 30% by mass, more preferably 1 to 10% by mass, relative to 100% by mass of the nonvolatile content of the composition. ..

When the present composition contains the flat pigment (D) and/or the pigment (E), the volume concentration (PVC) of all of these pigments makes it possible to easily obtain a composition having excellent coating workability. From the standpoint of easily obtaining a coating film having excellent adhesion to a base material by stress relaxation and water resistance, etc., preferably 10 to 70%, more preferably 10 to 50%, particularly preferably 10 to 40%. %.
If the PVC is less than the above range, the resulting coating film tends to have a reduced anticorrosion effect and a stress relaxation effect, and if it exceeds the above range, the water resistance of the obtained coating film is reduced and the coating work is also performed. Sex tends to decrease.
The PVC refers to the total volume concentration of the pigment with respect to the volume of non-volatile components in the composition. The PVC can be specifically calculated from the following formula.
PVC [%]=total volume of all pigments in the composition×100/volume of non-volatile content in the composition

  The non-volatile content (solid content) of the composition means the mass percentage of the coating film (heating residue) after the composition is sufficiently reaction-cured (heating), or the coating film (heating residue) itself. To do. According to JIS K 5601-1-2, the non-volatile content is obtained by weighing 1±0.1 g of the composition (for example, the composition immediately after mixing the main component and the curing agent component) in a flat bottom dish, and wire having a known mass. It can be calculated by measuring the heating residue and the mass of the wire when it is heated at 110°C for 1 hour (under normal pressure) after being uniformly spread using it can. In addition, this non-volatile component is a value equivalent to the total amount of solid components (components other than the solvent) of the raw material components used in the present composition.

The volume of the non-volatile matter in the present composition can be calculated from the mass and the true density of the non-volatile matter of the present composition. The mass and true density of the nonvolatile matter 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. For example, it can be calculated by separating the pigment and other components from the nonvolatile content of the composition and measuring the mass and true density of the separated pigment.

<Other ingredients>
In the composition, as other components, an epoxy compound other than the epoxy compound (A), an amine curing agent other than the curing agent (B), a silane coupling agent other than the silane coupling agent (C), Various additives such as anti-sagging agents (anti-settling agents), fiber substances, surfactants (eg, the surfactants described in JP-A-2-298563), dispersants, leveling agents, surface conditioners, organic solvents, etc. The agent can be appropriately mixed.
Each of these may be used alone or in combination of two or more.
The other components may be added to the main component or the curing agent component.

The composition may contain an epoxy compound other than the epoxy compound (A). Examples of such epoxy compound include novolac type epoxy resin, hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, hydrogenated novolac type epoxy resin, aliphatic type epoxy resin, aromatic type epoxy resin, An epoxy group-containing reactive diluent may be mentioned.
Moreover, you may use the bisphenol type epoxy compound whose epoxy equivalent exceeds 200.

In particular, in terms of easily forming a coating film having excellent solvent resistance and chemical resistance, it is preferable to use a novolac type epoxy resin or a polyfunctional epoxy group-containing reactive diluent, which is superior in overcoating compatibility. A monofunctional epoxy group-containing reactive diluent is preferably used from the viewpoint that a coating film can be easily formed. In particular, a polyfunctional epoxy group-containing reactive diluent and a monofunctional epoxy group-containing reactive diluent are used in order to easily form a better coating film with a good balance of chemical resistance and topcoat compatibility. It is preferable to use them together.
The monofunctional epoxy group-containing reactive diluent means a reactive diluent having one epoxy group, and the polyfunctional epoxy group-containing reactive diluent has two or more epoxy groups. Refers to a reactive diluent.

  When a reactive diluent is used in combination, the lower limit of the mass of the monofunctional epoxy group-containing reactive diluent to 1 part by mass of the polyfunctional epoxy group-containing reactive diluent in the present composition is preferably 0.1. Parts by mass, more preferably 0.2 parts by mass, particularly preferably 0.3 parts by mass, and the upper limit is preferably 3 parts by mass, more preferably 2 parts by mass, particularly preferably 1.5 parts by mass.

The epoxy group-containing reactive diluent is not particularly limited as long as it is an epoxy compound having a viscosity at 25° C. of 500 mPa·s or less.
Examples of the monofunctional epoxy group-containing reactive diluent include alkyl glycidyl ether (alkyl group having 1 to 13 carbon atoms), phenyl glycidyl ether, o-cresyl glycidyl ether, alkyl phenyl glycidyl ether (alkyl group having carbon number). 1 to 20, preferably 1 to 5, for example: methylphenyl glycidyl ether, ethylphenyl glycidyl ether, propylphenyl glycidyl ether, p-tert-butylphenyl glycidyl ether), phenol glycidyl ether, alkylphenol glycidyl ether, phenol (EO) _n glycidyl ether (number of repetitions _{n = 3~20, EO: -C 2} H 4 O-) and the like.
Examples of the polyfunctional epoxy group-containing reactive diluent include 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, and resorcinol. Diglycidyl ether, mono- or polyalkylene glycol diglycidyl ether (alkylene group having 1 to 5 carbon atoms, eg, ethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether), trimethylolpropane triglycidyl ether Is mentioned.
Among the epoxy group-containing reactive diluents, considering the balance of coating workability, low temperature curing property, anticorrosion property, oil resistance, etc., neopentyl glycol diglycidyl ether, phenol glycidyl ether, o-cresyl glycidyl ether, p -Tert-Butylphenyl glycidyl ether is preferred.

  As the epoxy compound other than the epoxy compound (A), a commercially available product may be used, and as the commercially available product, for example, a novolac type epoxy resin “DEN 425” (manufactured by The Dow Chemical Company) is used. , Epoxy equivalent 169-175, non-volatile content 100%), "DEN 431" (manufactured by The Dow Chemical Company, epoxy equivalent 172-179, non-volatile content 100%) and "DEN 438". (The Dow Chemical Company, epoxy equivalent 176-181, nonvolatile content 100%), epoxy group-containing reactive diluent "ERISYS GE-10" (o-cresyl glycidyl ether, CVC Thermoset Specialties, epoxy equivalent). 170 to 195, nonvolatile content 100%, viscosity 8 mPa·s/25° C.), “ERISYS GE-20” (neopentyl glycol diglycidyl ether, CVC Thermoset Specialties, epoxy equivalent 125 to 137, nonvolatile content 100%, viscosity 14 mPa·s/25° C.), “Cardolite 2513 HP” (manufactured by Cardolite, epoxy equivalent 413, nonvolatile content 100%, viscosity 30 mPa·s/25° C.).

  When the epoxy compound (A) is used in combination with an epoxy compound other than the epoxy compound (A), the content of the epoxy compound other than the epoxy compound (A) is preferably 100 parts by mass of the epoxy compound (A). Is 1 to 85 parts by mass.

The composition may contain an amine-based curing agent other than the curing agent (B). Examples of such an amine-based curing agent include the above-mentioned aliphatic polyamines, preferably polyoxyalkylene polyamines, polyalkylene polyamines or modified products thereof.
Examples of the modified product include a Mannich modified product, an epoxy adduct or a fatty acid modified product.
As the amine-based curing agent other than the curing agent (B), a commercially available product may be used, and as the commercially available product, for example, polyoxypropylenediamine "Jeffamine D-230" (Huntsman Japan KK). Manufactured by Air Products Co., Ltd.) and “Ancamide 506”, which is a fatty acid modified product of tetraethylenepentamine.

  In the present composition, the epoxy compound (A) and an epoxy compound other than the epoxy compound (A) (hereinafter, these are also collectively referred to as “epoxy component”), the curing agent (B) and the curing agent. The total content of amine-based curing agents other than (B) (hereinafter collectively referred to as "amine component") has a high crosslink density and is excellent in oil resistance, solvent resistance, chemical resistance and water resistance. From the viewpoint that an excellent coating film can be easily obtained, etc., the lower limit is preferably 20% by mass, more preferably 30% by mass, and the upper limit is preferably 100% by mass of the nonvolatile content of the composition. 70% by mass, more preferably 65% by mass.

The content of the amine component in the composition is such that a composition having excellent dryness can be obtained, and a coating film having excellent oil resistance, solvent resistance, chemical resistance, water resistance and adhesion to a substrate can be easily obtained. From the viewpoint that it can be achieved, the reaction ratio calculated by the following formula (2) is preferably 0.5 or more, more preferably 0.6 or more, preferably 1.3 or less, more preferably Is an amount of 1.0 or less.
Reaction ratio=(amount of amine component/amount of active hydrogen equivalent of amine component+amount of component reactive with epoxy component/equivalent amount of functional group of component reactive with epoxy component)/(epoxy component (Amount of compound/epoxy equivalent of epoxy component+amount of component reactive with amine component/functional group equivalent of component reactive with amine component) (2)

  Here, examples of the “component reactive with the amine component” in the above formula (2) include the silane coupling agent (C) and the like, and also “reactivity with an epoxy component. Examples of the “components” include silane coupling agents other than the silane coupling agent (C). Further, the “functional group equivalent” of each component means the mass (g) per 1 mol functional group obtained by dividing the mass of 1 mol of these components by the mol number of the functional groups contained therein. .

  As the anti-sagging agent (anti-settling agent), organic clay wax such as stearate salt of Al, Ca and Zn, lecithin salt, alkyl sulfonate, polyethylene wax, amide wax, hydrogenated castor oil wax, hydrogenated Conventionally known materials such as a mixture of castor oil wax and amide wax, synthetic fine powder silica, polyethylene oxide wax can be used. Among them, amide wax, synthetic fine silica, polyethylene oxide wax and organic clay wax are preferable.

  As such an anti-sagging agent (anti-settling agent), "Disparon 305", "Disparon 4200-20", "Disparon 6650" manufactured by Kusumoto Kasei Co., Ltd.; "ASAT-250F" manufactured by Ito Oil Co., Ltd. "Flowon RCM-300" manufactured by Kyoeisha Chemical Co., Ltd.; products such as "Benton SD-2" manufactured by Elementis Specialties, Inc.;

  When an anti-sagging agent (anti-settling agent) is added to the composition, it may be added to the main component in an amount of, for example, 0.1 to 10% by mass.

  The organic solvent is not particularly limited, for example, aromatic hydrocarbon solvents such as toluene and xylene, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as butyl acetate, isopropanol, benzyl alcohol and the like. Examples thereof include alcohol solvents, mineral spirits, n-hexane, n-octane, 2,2,2-trimethylpentane, isooctane, n-nonane, cyclohexane, methylcyclohexane, and other aliphatic hydrocarbon solvents.

[Manufacture of low VOC coating composition]
The present composition is preferably produced by mixing and kneading the main agent component and the curing agent component, which are individually prepared in advance, at the time of use.

The main ingredient can be prepared by blending the constituents of the main ingredient and stirring and kneading. In that case, for example, it is preferable to use an SG mill or a high speed disperser, and maintain the temperature of the mill base at 55 to 60° C. for about 30 minutes while dispersing the blended components as uniformly as possible.
On the other hand, the hardener component may be mixed with each other and mixed uniformly with a stirrer, depending on the components to be mixed.

[Uses of coating composition]
According to the present composition, a coating film (layer) having various properties such as oil resistance, solvent resistance, chemical resistance, water resistance and corrosion resistance can be formed. The anticorrosion includes crevice corrosion, dissimilar metal contact corrosion, stress corrosion and the like.
The composition can be used for various purposes because it can form a coating film with these excellent performances. However, it is a cargo tank for transporting chemical substances by land transportation or sea transportation (eg, product carrier or chemical Tanker), the inner surface of a land tank for storing chemicals similarly, the inner surface of a pipeline in contact with chemical substances, WBT (Water Ballast Tank), COT (Crude Oil Tank), FWT (Fresh Water Tank), DWT. (Drinking Water Tank) and the like are preferably used for the inner surface of tanks, the inner and outer surfaces of ships and the like. In addition to this application, seawater desalination equipment, marine structures, etc. where maintenance is difficult, dams and sluices, etc. It is suitable for use around gates, piping for plants that use seawater/river water or industrial water as cooling water, and pools for storing spent nuclear fuel.
In particular, the composition 1 is preferably used for the inner surface of a tank (eg, product carrier or chemical tanker) used for transporting or storing chemical substances or the like, or a pipeline, and the composition 2 is It is preferably used as a universal primer for ships and the like.

Further, the present composition can also be used for repair-coating the surface of a base material with an anticorrosion coating having corrosion. That is, the present composition is applied to a welded portion or a gap of a base material such as stainless steel to prevent local corrosion of the base material, and as an adhesive for further adhering a stainless steel plate to the surface of the coating film. By also acting, local corrosion can be stably suppressed for a long period of time.
Thus, when repairing a base material, for example, the present composition is applied to the surface of a base material having a welded portion (welding line) or a gap, and another base material is adhered to the surface of the uncured coating film. And the like, and the composition may be applied onto the other substrate.

≪Coating film, substrate with coating film, manufacturing method of substrate with coating film≫
A coating film according to an embodiment of the present invention (hereinafter, also referred to as “present coating film”) is formed using the present composition, and a substrate with a coating film according to an embodiment of the present composition is It is a laminated body including the main coating film and an article to be coated (base material).
The material of the base material is not particularly limited, and examples thereof include iron and steel (iron, steel, alloy iron, carbon steel, mild steel, alloy steel, stainless steel, etc.), non-ferrous metals (zinc, aluminum, etc.), and the like. The surface may be covered with a shop primer or the like.
When mild steel (SS400, etc.) is used as the base material, if necessary, the surface is polished by grit blasting or the like to adjust the substrate (eg, the arithmetic average roughness (Ra) is about 30 to 75 μm). It is desirable to adjust so that

The dry film thickness of the present coating film is not particularly limited, but from the viewpoint of obtaining a coating film having sufficient anticorrosion property, etc., the lower limit is usually 50 μm, preferably 200 μm, and the upper limit is usually 500 μm. It is preferably 400 μm.
As a method for forming the present coating film, a desired film thickness may be formed by one coating (coating once) or a coating having a desired film thickness by coating two or more times (coating two or more times). May be formed. From the viewpoint of controlling the film thickness and considering the residual organic solvent in the coating film, it is preferable to form the coating film so as to obtain a desired dry film thickness by coating twice or more.

A method of manufacturing a coated substrate according to an embodiment of the present invention (hereinafter also referred to as “the present method”) includes the following steps [1] and [2].
Step [1]: Step of coating the present composition on a substrate Step [2]: Step of drying the coated coating composition to form a coating film

<Step [1]>
The coating method in the step [1] is not particularly limited, and may be coated on the surface of the base material according to a conventional method such as airless spray coating, air spray coating, brush coating, roller coating, or the like. When coating on a large structure, spray coating is preferable from the viewpoint that a large area base material can be easily coated.
In addition, at the time of coating work, the composition may be appropriately diluted with a thinner (organic solvent) or the like. However, even when diluted in this way, the VOC content in the present composition is preferably 200 g/L or less.

The conditions of the spray coating may be appropriately adjusted according to the dry film thickness to be formed. For example, in the case of airless spraying, primary (air) pressure: about 0.4 to 0.8 MPa, secondary (paint) The pressure is preferably about 15 to 36 MPa and the gun moving speed is about 50 to 120 cm/sec.
Further, the coating film to be obtained may be coated so that the dry film thickness falls within the above range.

  The viscosity of the present composition suitable for spray coating is preferably 1500 to 7000 mPa·s, more preferably 1500 to 7000 mPa·s, using an E-type viscometer (manufactured by TOKIMEC, FMD type) under measurement conditions at 23°C. It is 1500 to 4000 mPa·s.

<Step [2]>
The drying conditions in the step [2] are not particularly limited and may be appropriately set depending on the method of forming a coating film, the type of base material, the application, the coating environment, etc., for example, at 5 to 35°C. , 12 to 250 hours. Further, if desired, it may be dried by force by heating and blowing to be cured, but it is usually dried and cured under natural conditions.

  When the coating film is formed by coating twice or more, particularly twice, after performing steps [1] and [2], the obtained coating film is subjected to steps [1] and [2]. A coating film is formed by repeating a series of steps. When the coating film is formed by applying three times, the coating film formed by repeating the series of steps for the coating film applied twice.

  Hereinafter, preferred embodiments of the present invention will be described more specifically based on examples, but the present invention is not limited to these examples.

[Example 1]
In a container, as shown in Table 1 below, 30 parts by mass of bisphenol F type epoxy resin "jER 807" (Note 1) and novolac type epoxy resin "DEN 431 Epoxy Novolac Resin" (Note 3) 9 2 parts by weight of benzyl alcohol, 26.5 parts by weight of potassium feldspar "Unispar PG-K10" (Note 7), 5 parts by weight of talc "Talc FC-1" (Note 8), and titanium white "TITANE". R-5N" (Note 9) 5 parts by mass, barium sulfate "Varico #300W" (Note 10) 5 parts by mass, mica "Mica powder 100 mesh" (Note 12) 5 parts by mass, and silane coupling agent " 11 parts by mass of KBM403” (Note 13) and 1.5 parts by mass of anti-sagging agent “DISPARLON 6650” (Note 14) were added, and the mixture was stirred using a high speed disperser at room temperature (23° C.) until uniform. Then, the mixture was dispersed at 56 to 60° C. for about 30 minutes. Then, the main ingredient was prepared by cooling to 30°C or lower.
Further, 25 parts by mass of an alicyclic amine “Ancamine 2280” (Note 16) was used as a curing agent component.
A coating composition was prepared by mixing the main component and the curing agent component before coating.

[Examples 2 to 19 and Comparative Examples 1 to 4]
Each coating composition was prepared in the same manner as in Example 1 except that the types and amounts of the components constituting the main agent component and the curing agent component of Example 1 were changed as shown in Tables 1 to 3 below.
When two or more kinds of components are used as the curing agent component, a high speed disper was used and the curing agent component was prepared by mixing these components under normal temperature and pressure.
Table 4 shows a description of each component described in Tables 1 to 3. Numerical values of each component of the main agent and the curing agent in Tables 1 to 3 indicate parts by mass.

<Drying test>
The drying property of the obtained coating composition was tested according to JIS K 5600-3-3 (curing drying property). The coating composition is a mixture of the main component and the curing agent component immediately before this test. The curing and drying time of each coating composition was evaluated according to the following criteria. The results are shown in Tables 5-7.
(Evaluation criteria)
4: Curing and drying time at 10°C for less than 24 hours 3: Curing and drying time at 10°C for 24 hours or more but less than 36 hours 2: Curing and drying time at 10°C for 36 hours or more but less than 48 hours 1: Curing and drying time at 10°C Over 48 hours

[Creation of test plate]
An SS400 sandblasted steel plate (arithmetic mean roughness (Ra): 30 to 75 μm) having dimensions of 150 mm×70 mm×2.3 mm (thickness) was prepared. Each coating composition prepared as described above was coated on the surface of this steel sheet by using airless spray so that the dry film thickness was 300 μm. Then, the coated steel sheet (test plate) was created by drying at 23° C. for 10 days. Each of the obtained test plates was subjected to each test described below. The results are shown in Tables 5-7.
The pencil hardness of the coating film on each of the obtained test plates was "H" or higher. In the present invention, the pencil hardness was measured based on JIS K 5600-5-4.

<Corrosion resistance test>
The corrosion resistance of the obtained coating film was tested according to JIS K 5600-6-1 (testing method for liquid resistance).
A notch 2 reaching the steel plate from the coating film side was made at the position shown in FIG. 1 of each obtained test plate. The test plate 1 with the notches 2 was immersed in 3% salt water at 40° C. for 90 days so that the notches 2 side faced down (in the direction shown in FIG. 1). After the dipping, 11 cuts 3 are made in order from the left end of the cuts 2 so that the cuts 2 are equally divided at intervals of 5 mm, and a steel plate and a coating film are provided at 10 measurement portions 4 between the cuts 3. The peeling length (length from the cut 2) was measured. The average of the measured peel lengths at 10 points was evaluated according to the following criteria.
(Evaluation criteria)
4: Peeling length is less than 5 mm 3: Peeling length is 5 mm or more and less than 10 mm 2: Peeling length is 10 mm or more and less than 15 mm 1: Peeling length is 15 mm or more

<Oil resistance test>
The oil resistance of the obtained coating film was tested according to JIS K 5600-6-1 (liquid resistance test method).
Each of the obtained test plates was immersed in naphtha at room temperature for 180 days. The test plate after immersion was evaluated according to the following criteria.
(Evaluation criteria)
5: No rust was generated on the steel sheet, no blister was generated on the coating film, and the pencil hardness of the coating film was HB or higher.
4: No rust was generated on the steel sheet, no blistering was generated on the coating film, and the pencil hardness of the coating film was B to 4B.
3: No rust was generated on the steel plate, no blistering was generated on the coating film, and the pencil hardness of the coating film was 5B or less.
2: Slight rust was generated on the steel plate, and blisters were generated on the coating film.
1: Rust was generated on the steel plate, and blisters were generated on the coating film.

<Solvent resistance test>
The solvent resistance of the obtained coating film was tested according to JIS K 5600-6-1 (liquid resistance test method).
Each of the obtained test plates was immersed in benzene or ethanol at room temperature for 180 days. The test plate after immersion was evaluated according to the same criteria as in the oil resistance test.

<Chemical resistance test>
The chemical resistance of the obtained coating film was tested according to JIS K 5600-6-1 (liquid resistance test method).
Each of the obtained test plates was immersed in 3% sulfuric acid at room temperature for 90 days. The test plate after immersion was evaluated according to the same criteria as in the oil resistance test.

<Topcoat compatibility test>
The above-mentioned topcoat compatibility is the interlaminar adhesion between the undercoat coating film and the topcoat coating film formed on the substrate from the present composition, and the laminated anticorrosion coating obtained by laminating the undercoat coating film and the topcoat coating film on the substrate. It can be comprehensively evaluated by the anti-blurring property of the film-coated substrate.

  The interlayer adhesion between the undercoating film and the topcoating film tends to be affected by the period from the formation of the undercoating film to the coating of the topcoating paint, and the resin type of the topcoating paint. Specifically, when the cross-linking reaction type top coat paint is repeatedly applied to the undercoat coat, the undercoat coat peels off from the base material due to the curing shrinkage stress, and if the base material is a metal material, it causes rusting. Become. Therefore, the acceptability for the period from the formation of the undercoat coating film to the application of the topcoat paint and the allowance for coating film defects that may occur due to the type of resin were collectively defined as the topcoat coating compatibility.

[Manufacturing method of top coat]
As the topcoat paint, a topcoat paint prepared according to the following method was used.

[Epoxy resin top coating]
Epoxy resin “E-001-75X” (manufactured by Ohtake Meishin Chemical Co., Ltd., xylene solution of bisphenol A type epoxy resin) 30 parts by weight, epoxy resin “E834-85X(T)” (Otake Meishin Chemical Co., Ltd.) Bisphenol A type epoxy resin (semisolid at room temperature), epoxy equivalent 290 to 310 g/eq, non-volatile content 85%) 10 parts by weight, talc "F-2 talc" (manufactured by Fuji Talc Co., Ltd.) 20 parts by weight, heavy calcium carbonate "calcium carbonate super-SS" (manufactured by Maruo Calcium Co., Ltd.) 10 parts by weight, carbon black "MA-100" (manufactured by Mitsubishi Chemical Corporation) 3 parts by weight, anti-sagging agent " Disparlon A-630-20X" (Kusumoto Kasei Co., Ltd., nonvolatile content 20%) 5 parts by weight, propylene glycol monomethyl ether 6 parts by weight, butyl cellosolve 7 parts by weight, and methyl isobutyl ketone 9 parts by weight are put therein. After adding glass beads and mixing these compounding ingredients with a paint shaker, the glass beads were removed to prepare a main component constituting the epoxy resin-based top coating composition.

  Further, polyamide adduct-based curing agent "PA-23" (manufactured by Ohtake Meishin Chemical Co., Ltd., active hydrogen equivalent 375 g/eq, nonvolatile content 60%) 80 parts by weight, tertiary amine "Ancamine K-54" (2, 3 parts by weight of 4,6-tri(dimethylaminomethyl)phenol, manufactured by Air Products Co., Ltd., 14 parts by weight of xylene, and 3 parts by weight of n-butanol were mixed with a high speed disperser (at room temperature under normal pressure). ) By mixing, a curing agent component constituting the epoxy resin-based top coating composition was prepared.

  An epoxy resin-based topcoat paint was prepared by mixing the obtained main agent component and curing agent component in a predetermined mixing ratio (main agent component:curing agent component=9:1) before coating.

[Acrylic resin topcoat paint]
In a container, 20 parts by weight of acrylic resin "Paraloid B-66" (manufactured by Rohm and Haas Japan Co., Ltd.), precipitated barium sulfate "precipitated sulfate barium FTB" (manufactured by Fukuoka Talc Industrial Co., Ltd.) 16 Parts by weight, titanium white "Titanium white R-930" (manufactured by Sakai Chemical Industry Co., Ltd.) 20 parts by weight, anti-sagging agent "Disparlon A-630-20X" 3 parts by weight, xylene 27 parts by weight, butyl cellosolve 2 parts by weight, After 9 parts by weight of the aromatic hydrocarbon "Ipsol 100" (manufactured by Idemitsu Kosan Co., Ltd.) and 3 parts by weight of n-butanol were added, glass beads were added thereto, and these compounding ingredients were mixed with a paint shaker. An acrylic resin-based topcoat paint was prepared by removing the glass beads.

[Creation of test plate]
The coating composition of Examples 13 to 19 was applied to a sandblasted steel plate having a size of 70 mm×150 mm×1.6 mm (thickness) using an air spray so that the dry film thickness was 200 μm, and then dried at room temperature all day and night. , An outdoor exposure table (according to JIS K 5600-7-6) installed on the premises of China Paint Co., Ltd. in Otake City, Hiroshima Prefecture so that the painted surface is exposed. When an epoxy resin-based top coating composition is applied as the top coating composition, it is exposed to the outdoors for 1, 14, or 30 days after the coating composition is applied, and then a film applicator is applied to the coated surface of the coating composition. Was used to apply an epoxy resin-based topcoat paint to a dry film thickness of 50 μm. In addition, when applying an acrylic resin-based top coating composition, after applying the coating composition for 1 day, 7 days, or 14 days of outdoor exposure, the coating surface of the coating composition is dried using a film applicator. Acrylic resin-based topcoat paints were applied so that the film thickness was 50 μm.

  After coating the top coating composition, it was dried in an atmosphere of 23° C. and 50% RH for 7 days in accordance with JIS K 5600-1-6 to prepare each test plate for evaluation of top coating compatibility.

  After dipping each test plate for evaluating the compatibility of the top coat coated with the epoxy resin-based top coat paint or the acrylic resin-based top coat paint in salt water (salt concentration 3%) at 40° C. for 30 days, the adhesion (JIS K 5600-5-6), and blistering of the coating film (based on A method of ASTM D-714-56) were evaluated. The results obtained are shown in Table 8.

1: Test plate 2: Notch 3: Cut 4: Measuring part

Claims (10)

A bisphenol type epoxy compound (A) having an epoxy equivalent of 200 or less, an amine curing agent (B) having a cyclic structure, and a silane coupling agent (C) having an epoxy group,
The content of the silane coupling agent (C) is 5 to 20% by mass,
The mass ratio of the bisphenol type epoxy compound (A) and the silane coupling agent (C) is 1.0:0.1 to 0.5,
Low VOC coating composition. A bisphenol type epoxy compound (A) having an epoxy equivalent of 200 or less, an amine curing agent (B) having a cyclic structure, and a silane coupling agent (C) having an epoxy group,
Containing two or more kinds of the amine-based curing agent (B) having the cyclic structure,
The content of the silane coupling agent (C) is 5 to 20% by mass,
Low VOC coating composition.   The low VOC coating composition according to claim 1 or 2, further comprising a flat pigment (D).   The low VOC coating composition according to any one of claims 1 to 3, wherein the silane coupling agent (C) is a silane coupling agent having one epoxy group in one molecule.   The amine-based curing agent (B) having a cyclic structure comprises at least one selected from alicyclic amines and modified products of alicyclic amines. VOC coating composition. Containing a flat pigment (D) and a pigment (E) other than the flat pigment (D),
The low VOC coating composition according to any one of claims 1 to 5, wherein a volume concentration of the flat pigment (D) and the pigment (E) in the low VOC coating composition is 10 to 70%.   The low VOC coating composition according to any one of claims 1 to 6, wherein the VOC content of the low VOC coating composition is 200 g/L or less.   An anticorrosion coating film formed from the low VOC coating composition according to claim 1.   A coated substrate comprising the anticorrosive coating according to claim 8 and a substrate. A method for producing a substrate with a coating film, which comprises the following steps [1] and [2].
[1] A step of coating the low VOC coating composition according to any one of claims 1 to 7 on a substrate [2] A step of drying the coated coating composition to form a coating film

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