Coating material composition, coating film, coated article, and method for producing coated article

Abstract

This coating material composition contains an epoxy resin (A), an amine curing agent (B), a glycidyl group-containing silane coupling agent (C), and a silicate compound (D) having no glycidyl group, and the content of the glycidyl group-containing silane coupling agent (C) exceeds 50 parts by mass with respect to 100 parts by mass of the silicate compound (D).

Description

Coating composition, coating film, coated article, and method for producing coated article

[0001] The present disclosure relates to coating compositions, coatings, coated articles, and methods for producing coated articles.

[0002] Epoxy resin paints have been conventionally applied to substrates such as ships, marine structures, plants, bridges, and land tanks in order to ensure their long-term use.

[0003] As epoxy resin-based paints, for example, Patent Documents 1 to 3 disclose paints containing epoxy resins and amine curing agents.

[0004] JP 2023-107492 A JP 2017-025158 A JP 2019-531378 A

[0005] From the viewpoint of reducing the viscosity of the paint, it is sometimes desirable to use materials such as reactive diluents and low-molecular-weight resins, but paints using these materials may have poor curing properties.

[0006] An object of the present disclosure is to provide a coating composition that has excellent curability and is capable of forming a coating film having good coating film hardness.

[0007] One embodiment of the coating composition of the present disclosure is a coating composition containing an epoxy resin (A), an amine curing agent (B), a glycidyl group-containing silane coupling agent (C), and a glycidyl group-free silicate compound (D), wherein the content of the glycidyl group-containing silane coupling agent (C) exceeds 50 parts by mass per 100 parts by mass of the silicate compound (D).

[0008] According to the present disclosure, it is possible to obtain a coating composition that has excellent curability and is capable of forming a coating film having good coating film hardness.

[0009] [Paint Composition] The paint composition of the present disclosure (hereinafter also referred to as "the composition") contains an epoxy resin (A), an amine curing agent (B), a glycidyl group-containing silane coupling agent (C), and a silicate compound (D) having no glycidyl group (hereinafter also simply referred to as "silicate compound (D)"), and the content of the glycidyl group-containing silane coupling agent (C) exceeds 50 parts by mass per 100 parts by mass of the silicate compound (D).

[0010] <Epoxy Resin (A)> Examples of the epoxy resin (A) include compounds containing two or more epoxy groups in one molecule. However, the epoxy resin (A) is a compound other than the glycidyl group-containing silane coupling agent (C). The epoxy resin (A) may be used alone or in combination of two or more.

[0011] The epoxy equivalent of the epoxy resin (A) is preferably 500 or less, more preferably 170 to 280, and even more preferably 170 to 210, from the viewpoint of reducing the viscosity and VOC (volatile organic compound) of the coating composition, and of being able to form a coating film that is excellent in oil resistance, solvent resistance, chemical resistance, corrosion resistance, etc. The epoxy equivalent is calculated based on JIS K 7236:2001.

[0012] Examples of the epoxy resin (A) include bisphenol-type epoxy resins, glycidyl ether-type epoxy resins, glycidyl ester-type epoxy resins, glycidyl amine-type epoxy resins, phenol novolac-type epoxy resins, cresol-type epoxy resins, dicyclopentadiene-type epoxy resins, aliphatic epoxy resins, alicyclic epoxy resins, and fatty acid-modified epoxy resins.

[0013] Examples of bisphenol-type epoxy resins include bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, and bisphenol AD-type epoxy resins. Examples of bisphenol A-type epoxy resins include bisphenol A diglycidyl ether, bisphenol A polypropylene oxide diglycidyl ether, and bisphenol A ethylene oxide diglycidyl ether. In addition to the above, examples of bisphenol A-type epoxy resins include hydrogenated bisphenol A-type epoxy resins such as hydrogenated bisphenol A diglycidyl ether and hydrogenated bisphenol A propylene oxide diglycidyl ether. When the present composition contains a hydrogenated bisphenol A-type epoxy resin, it is easy to form a coating film with excellent weather resistance.

[0014] The epoxy resin (A) may be solid or liquid, but from the viewpoint of reducing the viscosity and VOC of the coating composition, an epoxy resin that is liquid at room temperature is preferred, a bisphenol-type epoxy resin that is liquid at room temperature is more preferred, and a bisphenol A-type epoxy resin or a bisphenol F-type epoxy resin that is liquid at room temperature is even more preferred. The present composition preferably contains a bisphenol A-type epoxy resin from the viewpoint of easily obtaining a composition that has excellent curing properties, low viscosity, and is capable of forming a coating film with good coating film properties. In this specification, "room temperature" refers to 25°C.

[0015] The viscosity of the liquid epoxy resin (A) at 25°C measured with an E-type viscometer (FMD type, manufactured by TOKIMEC Corporation, rotation speed: 60 rpm) is preferably 800 mPa s or more, more preferably 3,000 mPa s or more, and is preferably 30,000 mPa s or less, more preferably 25,000 mPa s or less, for example, 800 to 30,000 mPa s.

[0016] The content of the epoxy resin (A) in the composition is preferably 1% by mass or more, more preferably 5% by mass or more, and is preferably 60% by mass or less, more preferably 50% by mass or less, for example 1 to 60% by mass, based on the total content of the epoxy resin (A), the amine curing agent (B), the glycidyl group-containing silane coupling agent (C), and the silicate compound (D), from the viewpoint of being able to easily form a coating film that is excellent in adhesion to the substrate, oil resistance, solvent resistance, chemical resistance, corrosion prevention, etc.

[0017] <Amine Curing Agent (B)> The amine curing agent (B) is preferably a polyamine having two or more primary or secondary amino groups per molecule. Specifically, aliphatic, alicyclic, aromatic, and heterocyclic amine compounds are preferred as the amine curing agent (B). Aliphatic amine curing agents are more preferred because they can easily produce a coating composition with excellent curing properties and a long pot life. 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. One or more types of amine curing agents (B) may be used.

[0018] In the present composition, the amine curing agent (B) is thought to function not only as a curing agent for the epoxy resin (A) but also as a curing catalyst that catalyzes the curing reaction of the silicate compound (D).

[0019] The amine curing agent (B) is preferably liquid at room temperature, from the viewpoint of easily obtaining a high-solids type present composition. The amine curing agent (B) being "liquid at room temperature" means that the viscosity measured with an E-type viscometer at 25°C is 5,000 Pa s or less. By using such an amine curing agent (B), it is possible to reduce the amount of organic solvent used to adjust the viscosity to an appropriate level for coating, and a coating composition that is high-solids type yet has excellent coating workability can be easily obtained.

[0020] Examples of aliphatic amine curing agents include alkylene polyamines, polyalkylene polyamines, alkylamino alkylamines, and polyoxyalkylene polyamines. Of these, polyoxyalkylene polyamines are preferred because they allow for the easy production of a coating composition with a long pot life.

[0021] Examples of alkylene polyamines include those represented by the formula: ２ N-R １ -NH ２ ” (R １ is a divalent hydrocarbon group having 1 to 12 carbon atoms. Specific examples include methylenediamine, ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,5-diaminopentane, 1,6-diaminohexane, and trimethylhexamethylenediamine.

[0022] Examples of polyalkylene polyamines include those represented by the formula: ２ N-(C ｍ H ２ｍ NH) ｎ H" (where m is an integer of 1 to 10, and n is an integer of 2 to 10, preferably an integer of 2 to 6), and specific examples thereof include diethylenetriamine, dipropylenetriamine, triethylenetetramine, tripropylenetetramine, tetraethylenepentamine, tetrapropylenepentamine, pentaethylenehexamine, nonaethylenedecamine, and triethylene-bis(trimethylene)hexamine.

[0023] Examples of alkylaminoalkylamines include those represented by the formula: ２ ２ N-(CH ２ ) ｐ -NH ２ ” (R ２ are independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms (provided that at least one R ２is an alkyl group having 1 to 8 carbon atoms, and p is an integer of 1 to 6. Specific examples thereof include dimethylaminoethylamine, diethylaminoethylamine, dibutylaminoethylamine, dimethylaminopropylamine, diethylaminopropylamine, dipropylaminopropylamine, dibutylaminopropylamine, and dimethylaminobutylamine.

[0024] Polyoxyalkylene polyamines include, for example, polyoxyethylene diamine, polyoxypropylene diamine, polyoxypropylene triamine, polyoxypropylene-polyoxyethylene diamine, trimethylolpropane poly(oxypropylene) triamine, and glyceryl poly(oxypropylene) triamine.

[0025] Examples of alicyclic amine compounds include cyclohexanediamine, diaminodicyclohexylmethane (particularly, 4,4'-methylenebis(cyclohexylamine) [PACM]), 4,4'-isopropylidenebiscyclohexylamine, norbornanediamine (NBDA), and 2,4-di(4-aminocyclohexylmethyl)aniline.

[0026] Examples of the amine curing agent (B) include modified products of the above-mentioned amine curing agents, such as fatty acid modified products of polyamidoamines, amine adducts with epoxy compounds, Mannich modified products (e.g., phenalkamine, phenalkamide), Michael adducts, ketimines, and aldimines.

[0027] The number of functional groups of the amine curing agent (B) is preferably 2 to 6, and more preferably 2 to 3, from the viewpoint of being able to easily form a coating film that has excellent topcoat compatibility (e.g., adhesion to a topcoat film that can be formed on a coating film formed from the present composition).

[0028] The active hydrogen equivalent of the amine curing agent (B) is preferably 20 or more, more preferably 40 or more, and is preferably 1,000 or less, more preferably 500 or less, for example, 20 to 1,000, from the viewpoint that a present composition having excellent curability, coating hardness, and corrosion resistance of the coating can be easily obtained.

[0029] The number average molecular weight (Mn) of the amine curing agent (B) is preferably 100 to 5,000, more preferably 200 to 1,500, and even more preferably 350 to 1,000, from the viewpoint that the present composition having excellent curability, storage stability, coating hardness, and corrosion resistance can be easily obtained.

[0030] The amine curing agent (B) may be obtained by a conventionally known method, or a commercially available product may be used.

[0031] When the composition is a two-part composition having a first part (main part) and a second part (curing agent), the amine curing agent (B) is contained in the second part. The viscosity of this second part at 25°C, as measured with an E-type viscometer, is preferably 100,000 mPa·s or less, more preferably 10,000 mPa·s or less, and preferably 50 mPa·s or more, for example, 50 to 100,000 mPa·s, in order to provide a coating composition with superior handleability and coating workability.

[0032] The content of the amine curing agent (B) in the composition is preferably 1% by mass or more, more preferably 5% by mass or more, and is preferably 40% by mass or less, more preferably 30% by mass or less, for example 1 to 40% by mass, based on the total content of the epoxy resin (A), the amine curing agent (B), the glycidyl group-containing silane coupling agent (C), and the silicate compound (D), from the viewpoint of being able to easily form a coating film that is excellent in oil resistance, solvent resistance, chemical resistance, corrosion resistance, etc.

[0033] From the viewpoint of being able to easily form a coating film that is excellent in corrosion resistance, coating film hardness, drying properties, and topcoat compatibility, it is desirable to use the amine curing agent (B) in an amount such that the reaction ratio calculated by the following formula (1) is preferably 0.3 or more, more preferably 0.7 or more, and preferably 1.2 or less, more preferably 1.1 or less, for example, 0.3 to 1.2.

[0034] Reactivity ratio={(content of amine curing agent (B) / active hydrogen equivalent of amine curing agent (B))+(content of component reactive with epoxy resin (A) / functional group equivalent of component reactive with epoxy resin (A))} / {(content of epoxy resin (A) / epoxy equivalent of epoxy resin (A))+(content of component reactive with amine curing agent (B) / functional group equivalent of component reactive with amine curing agent (B))} (1)

[0035] Here, in the above formula (1), examples of the "component reactive with the amine curing agent (B)" include the components reactive with the amine curing agent (B) among the other components described below, and examples of the "component reactive with the epoxy resin (A)" include the components reactive with the epoxy resin (A) among the other components described below. The "functional group equivalent" of each component above refers to the mass (g) per 1 mol of functional groups obtained by dividing the mass of 1 mol of that component by the number of moles of functional groups contained therein.

[0036] <Glycidyl Group-Containing Silane Coupling Agent (C)> The present composition contains a glycidyl group-containing silane coupling agent (C). One or more types of glycidyl group-containing silane coupling agents (C) may be used. By using the glycidyl group-containing silane coupling agent (C), a low-viscosity coating composition can be easily obtained, and not only can the adhesion of the resulting coating film to the substrate be further improved, but also the corrosion resistance, such as water resistance and saltwater resistance, and heat resistance of the resulting coating film can be improved. In addition, the use of the glycidyl group-containing silane coupling agent (C) tends to improve the compatibility between the epoxy resin (A) and the silicate compound (D).

[0037] The glycidyl group-containing silane coupling agent (C) is not particularly limited, and any conventionally known compound can be used, but it is preferable that the glycidyl group-containing silane coupling agent (C) is a compound that has at least two functional groups in the same molecule and can contribute to improving adhesion to the substrate and reducing the viscosity of the composition.

[0038] The glycidyl group-containing silane coupling agent (C) is preferably a compound represented by the following formula (2).

[0039] In formula (2), Y is a glycidyl group, and R １ is an alkanediyl group having 1 to 8 carbon atoms, such as a methylene group, an ethylene group, or a propylene group, and is preferably an ethylene group or a propylene group; R ２ is a methyl group or an ethyl group, and n is 0 or 1.

[0040] Specific examples of the glycidyl group-containing silane coupling agent (C) include, for example, glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, 2-glycidoxyethyltrimethoxysilane, 2-glycidoxyethyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 8-glycidoxyoctylmethyldimethoxysilane, and 8-glycidoxyoctyltrimethoxysilane.

[0041] The content of the glycidyl group-containing silane coupling agent (C) in this composition is more than 50 parts by mass, preferably more than 100 parts by mass, more preferably 200 parts by mass or more, per 100 parts by mass of the silicate compound (D), and the upper limit is not particularly limited, but is preferably 1500 parts by mass or less, for example, more than 50 parts by mass and 1500 parts by mass or less. When the content of the glycidyl group-containing silane coupling agent (C) is within the above range, a coating composition having excellent curability and low viscosity can be easily obtained, and the adhesion of the resulting coating film to the substrate and the corrosion resistance are improved.

[0042] The content of the glycidyl group-containing silane coupling agent (C) in the composition is preferably 20 parts by mass or more, more preferably 22 parts by mass or more, even more preferably 50 parts by mass or more, and particularly preferably 60 parts by mass or more, per 100 parts by mass of the epoxy resin (A). There is no particular upper limit, but the content is preferably 400 parts by mass or less, for example, 20 to 400 parts by mass. When the content of the glycidyl group-containing silane coupling agent (C) is 20 parts by mass or more per 100 parts by mass of the epoxy resin (A), a coating composition having excellent curability and a long pot life can be easily obtained.

[0043] Furthermore, the content of the glycidyl group-containing silane coupling agent (C) is preferably 1% by mass or more, more preferably 7% by mass or more, even more preferably 15% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 60% by mass or less, for example, 1 to 80% by mass, based on the total content of the epoxy resin (A), the amine curing agent (B), the glycidyl group-containing silane coupling agent (C), and the silicate compound (D). When the content of the glycidyl group-containing silane coupling agent (C) is within the above range, a coating composition having excellent curability and low viscosity can be easily obtained, and the resulting coating film will have improved adhesion to substrates and corrosion resistance.

[0044] <Glycidyl group-free silicate compound (D)> The present composition contains a glycidyl group-free silicate compound (D). By using the silicate compound (D), a coating composition having low viscosity and excellent curability can be easily obtained. One type of silicate compound (D) may be used, or two or more types may be used.

[0045] One embodiment of this composition has excellent curability and a long pot life. The reason for this effect is presumed to be as follows: In this composition, the basic amine curing agent (B) acts as a catalyst, and the silicate compound (D) undergoes a dealcoholization reaction with moisture in the air, forming a polymer. In the container in which the coating composition is stored, the surface area of ​​the coating composition is small, so the effect of moisture is small, and therefore the reaction to form a polymer (curing reaction) does not proceed easily. On the other hand, after application, the surface area of ​​the coating composition is large, so the curing reaction due to moisture in the air is likely to proceed easily. It is presumed that these reasons are why the above effect is produced.

[0046] The silicate compound (D) is not particularly limited as long as it is a silicate compound that does not have a glycidyl group, and examples thereof include silane compounds and low condensates of silane compounds. Examples of the silane compounds include alkoxysilanes such as tetraalkoxysilanes and alkylalkoxysilanes.

[0047] Examples of tetraalkoxysilanes include tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetraisopropoxysilane, tetra-n-butoxysilane, and tetra-sec-butoxysilane. Examples of alkylalkoxysilanes include alkyltrialkoxysilanes. Examples of alkyltrialkoxysilanes include methyltrialkoxysilanes such as methyltrimethoxysilane and methyltriethoxysilane; and ethyltrialkoxysilanes such as ethyltrimethoxysilane and ethyltriethoxysilane. The number of carbon atoms in the alkoxy group contained in the alkoxysilane is preferably 1 to 5, more preferably 1 to 3. The number of carbon atoms in the alkyl group contained in the alkylalkoxysilane is preferably 1 to 5, more preferably 1 to 3.

[0048] The low condensate of alkoxysilane refers to, for example, a condensate of alkoxysilane having a condensation degree of 2 to 20 (number of silicon atoms: 2 to 20), preferably 3 to 10 (number of silicon atoms: 3 to 10).

[0049] Among the silicate compounds (D), low condensation products of alkoxysilanes are preferred from the viewpoint of the balance between low viscosity and curability of the coating composition, and compounds represented by the following formula (3) are more preferred.

[0050]

[0051] In the above formula (3), R １ and R ２ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms (preferably an alkyl group having 1 to 5 carbon atoms), or a phenyl group. １ and X ２ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms (preferably an alkyl group having 1 to 5 carbon atoms), or a phenyl group. n represents the number of repetitions and is an integer of 2 to 20, preferably an integer of 3 to 10. The alkyl group and phenyl group may be substituted or unsubstituted. In addition, the alkyl group may have a linear or branched chain structure.

[0052] From the viewpoint of achieving excellent curability of the present composition, the silicate compound (D) is preferably a compound represented by the formula (3) R １ , R ２ , X １ , and X ２ are all ethyl groups.

[0053] The content of the silicate compound (D) is preferably 35% by mass or less, more preferably 25% by mass or less, based on the total content of the epoxy resin (A), the amine curing agent (B), the glycidyl group-containing silane coupling agent (C), and the silicate compound (D). There is no particular lower limit, but the content is preferably 0.5% by mass or more, more preferably 1% by mass or more, for example, 0.5 to 35% by mass. When the content of the silicate compound (D) is within the above range, a coating composition having excellent curability and low viscosity can be easily obtained, and the resulting coating film will have improved adhesion to substrates and corrosion resistance.

[0054] <Other Components> The present composition may further contain other components. Examples of the other components include an anti-sagging agent (thixotropic agent), a pigment, a (pigment) dispersant, an antifoaming agent, a curing accelerator, a reactive diluent, and a light stabilizer. These other components may each be used alone or in combination of two or more.

[0055] As the other components, conventionally known components can be used, and commercially available products may also be used.

[0056]

[0043] The composition may contain an anti-sagging agent. The anti-sagging agent is not particularly limited, but is preferably a material that can suppress sedimentation of pigments and the like in the composition and improve its storage stability, or a material that can improve the anti-sagging properties of the composition during or after application.

[0057] Examples of anti-sagging agents include organic clay waxes such as stearates, lecithin salts, and alkylsulfonates of Al, Ca, and Zn; organic waxes such as polyethylene wax, amide wax, hydrogenated castor oil wax, a mixture of amide wax and hydrogenated castor oil wax, and oxidized polyethylene wax; and synthetic finely divided silica. Among these, amide wax, oxidized polyethylene wax, synthetic finely divided silica, and organic clay wax are preferred because they can further improve the anti-sagging properties of the composition during and after application.

[0058] When the present composition contains an anti-sagging agent, the content of the solid content of the anti-sagging agent is preferably 0.1 to 10 mass%, more preferably 0.2 to 5 mass%, based on the total content of the epoxy resin (A), the amine curing agent (B), the glycidyl group-containing silane coupling agent (C), and the silicate compound (D). When the content of the anti-sagging agent is within the above range, the present composition having excellent anti-sagging properties can be easily obtained.

[0059] <Pigment> The present composition may contain a pigment, and preferably contains a pigment. Examples of the pigment include an extender pigment, a coloring pigment, and an anti-rust pigment, and the pigment may be either organic or inorganic.

[0060] Examples of extender pigments include talc, mica, (precipitated) barium sulfate, (potassium) feldspar, kaolin, alumina white, bentonite, wollastonite, clay, glass flakes, aluminum flakes, flaky iron oxide, magnesium carbonate, barium carbonate, calcium carbonate, dolomite, and silica, with talc, mica, silica, (precipitated) barium sulfate, and (potassium) feldspar being particularly preferred.

[0061] When the present composition contains a body pigment, the content of the body pigment is preferably 10% by mass or more, more preferably 15% by mass or more, and is preferably 200% by mass or less, more preferably 150% by mass or less, for example, 10 to 200% by mass, based on the total content of the epoxy resin (A), the amine curing agent (B), the glycidyl group-containing silane coupling agent (C), and the silicate compound (D).

[0062] Examples of color pigments include inorganic pigments such as carbon black, titanium dioxide (titanium white), iron oxide (red iron oxide), yellow iron oxide, and ultramarine; and organic pigments such as cyanine blue and cyanine green. Titanium white, carbon black, and red iron oxide are particularly preferred.

[0063] When the present composition contains a color pigment, the content of the color pigment is preferably 1 to 150 mass %, more preferably 1 to 100 mass %, based on the total content of the epoxy resin (A), the amine curing agent (B), the glycidyl group-containing silane coupling agent (C), and the silicate compound (D).

[0064] Examples of anti-rust pigments include zinc powder, zinc alloy powder, zinc phosphate compounds, calcium phosphate compounds, aluminum phosphate compounds, magnesium phosphate compounds, zinc phosphite compounds, calcium phosphite compounds, aluminum phosphite compounds, strontium phosphite compounds, aluminum tripolyphosphate compounds, molybdate compounds, zinc cyanamide compounds, borate compounds, nitro compounds, and composite oxides.

[0065] When the present composition contains a pigment, the pigment volume concentration (PVC) in the present composition is preferably 10 to 70%, more preferably 10 to 50%, from the viewpoints that a composition having excellent coating workability can be easily obtained, and a coating film having excellent adhesion to the substrate due to stress relaxation and excellent water resistance can be easily formed.

[0066] The PVC refers to the total volume concentration of pigments relative to the volume of nonvolatile matter in the composition. Specifically, the PVC can be calculated using the following formula (4): PVC [%] = total volume of all pigments in the composition × 100 / volume of nonvolatile matter in the composition (4).

[0067] The volume of the nonvolatile content in the composition can be calculated from the content and true density of the nonvolatile content of the composition. The content and true density of the nonvolatile content are calculated from the solid content and blending amounts of 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, the volume can be calculated by separating the pigment from other components from the nonvolatile content of the composition and measuring the mass and true density of the separated pigment.

[0068] <Antifoaming Agent> The present composition preferably contains an antifoaming agent, since this can suppress the generation of bubbles during the production or application of the composition, or can break any bubbles that have generated in the present composition, thereby making it possible to easily form a coating film having the desired physical properties.

[0069] When the composition contains an antifoaming agent, the content of the solids of the antifoaming agent is preferably 0.1 to 5 mass%, more preferably 0.1 to 3 mass%, based on the total content of the epoxy resin (A), the amine curing agent (B), the glycidyl group-containing silane coupling agent (C), and the silicate compound (D). When the content of the antifoaming agent is within the above range, foam generation can be sufficiently suppressed, and a coating film with desired physical properties can be easily formed.

[0070] <Reactive Diluent> The present composition may contain a reactive diluent. As the reactive diluent, an epoxy group-containing reactive diluent is preferred.

[0071] The epoxy group-containing reactive diluent is a compound other than the epoxy resin (A) and the glycidyl group-containing silane coupling agent (C). The epoxy group-containing reactive diluent is not particularly limited as long as it is an epoxy compound having a viscosity of 500 mPa·s or less at 25°C as measured with an E-type viscometer (FMD model, manufactured by TOKIMEC Corporation), and may be either a monofunctional or polyfunctional type.

[0072] Examples of the monofunctional epoxy group-containing reactive diluent include alkyl glycidyl ethers (alkyl group having 1 to 13 carbon atoms), phenyl glycidyl ether, o-cresyl glycidyl ether, alkylphenyl glycidyl ethers (alkyl group having 1 to 20, preferably 1 to 5, carbon atoms, e.g., methylphenyl glycidyl ether, ethylphenyl glycidyl ether, propylphenyl glycidyl ether, p-tert-butylphenyl glycidyl ether), phenol glycidyl ether, alkylphenol glycidyl ether, and phenol (EO)n glycidyl ether (repeating number n=3 to 20, EO: -C ２ H ４ O-).

[0073] Examples of polyfunctional epoxy group-containing reactive diluents include 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, resorcinol diglycidyl ether, mono- or polyalkylene glycol diglycidyl ethers (alkylene groups having 1 to 5 carbon atoms, e.g., ethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether), and trimethylolpropane triglycidyl ether.

[0074] When the present composition contains a reactive diluent, the content of the reactive diluent is preferably 20% by mass or less, more preferably 15% by mass or less, and particularly preferably 10% by mass or less, relative to the total content of the epoxy resin (A), the amine curing agent (B), the glycidyl group-containing silane coupling agent (C), and the silicate compound (D), from the viewpoints that a corrosion-protective coating film excellent in oil resistance, solvent resistance, chemical resistance, corrosion prevention properties, etc. can be easily formed, and that the content of the reactive diluent can contribute to a decrease in the viscosity of the present composition and an extension of the pot life, etc., and is preferably 0.1% by mass or more, more preferably 1% or more, and is, for example, 0.1 to 20% by mass.

[0075] <Light Stabilizer> The composition may contain a light stabilizer. The light stabilizer is not particularly limited, and examples thereof include conventionally known light stabilizers such as hindered amine-based light stabilizers. Examples of hindered amine-based light stabilizers include bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, methyl(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, 2,4-bis[N-butyl-N-(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)amino]-6-(2-hydroxyethylamine)-1,3,5-triazine, and decanedioic acid bis(2,2,6,6-tetramethyl-1-(octyloxy)-4-piperidinyl)ester.

[0076] When the present composition contains a light stabilizer, the content of the light stabilizer is preferably 0.1 to 5 mass % based on the total content of the epoxy resin (A), the amine curing agent (B), the glycidyl group-containing silane coupling agent (C), and the silicate compound (D).

[0077] <Composition of the Present> The non-volatile content of the composition of the present invention, calculated from the solid content and blending amounts of each raw material, is preferably 85% by mass or more, more preferably 87% by mass or more, and even more preferably 90% by mass or more. There is no particular upper limit, but it is preferably 100% by mass or less, for example, 85 to 100% by mass. The composition of the present invention, whose non-volatile content falls within the above range, can be said to be a high-solids composition.

[0078] In recent years, paints have been designed to have lower VOC (volatile organic compound) content in line with stricter organic solvent emission regulations aimed at protecting the natural environment and the painting work environment, etc. The content of volatile organic compounds (VOC) in the present composition is preferably 450 g / L or less, more preferably 350 g / L or less, and even more preferably 300 g / L or less, so that the present composition has less impact on the natural environment and the painting work environment.

[0079] The VOC content in the composition can be measured according to ISO 11890-1.

[0080] In this specification, for the raw materials constituting the first or second agent (e.g., epoxy resin (A)), the first agent, and the second agent, the components other than the solvents such as organic solvents and water contained in each of these components are referred to as the "solid content."

[0081] One embodiment of the present composition has excellent curability, a long pot life, and excellent coating workability. In this specification, the viscosity increase rate measured by the method described in the Examples below is used as an index of pot life. The viscosity increase rate of the present composition at 23°C is preferably 105 to 250%, more preferably 105 to 200%, and even more preferably 105 to 170%. The present composition having a viscosity increase rate within the above range can be said to be a coating composition with excellent coating workability and a long pot life.

[0082] The present composition may be a one-component composition containing all of the above components, but is usually a two-component composition containing a first component (main component) containing the epoxy resin (A) and a second component (curing agent) containing the amine curing agent (B). If necessary, the present composition may also be a multi-component composition consisting of three or more components.

[0083] The first and second agents are usually stored, preserved, transported, etc. in separate containers, and are mixed together immediately before use.

[0084] <Method for producing the present composition> The present composition may be produced by mixing the above-mentioned components, but it is preferable to produce it by mixing the first and second agents, which have been prepared separately in advance, at the time of use.

[0085] The first agent can be prepared by blending and stirring the constituent components. In this case, it may be prepared at room temperature or by heating. On the other hand, the second agent may be prepared by uniformly mixing the constituent components with a stirrer or the like, although this depends on the blended components.

[0086] <Uses of the composition> The composition has excellent curability and can form a coating film with excellent hardness. Specifically, one embodiment of the composition can form a coating film with excellent curability, a long pot life, and excellent physical properties such as hardness and corrosion resistance. Corrosion resistance also includes crevice corrosion, galvanic corrosion, stress corrosion, etc.

[0087] In conventional epoxy resin paints, the combination of an epoxy resin and an amine curing agent can sometimes form a coating film with excellent coating film properties, but there is a trade-off between curing speed and pot life, making it difficult to achieve both.One embodiment of the present composition, even though it is a low-VOC paint, has a fast curing speed and a long pot life, providing excellent coating workability, making it possible to achieve both.

[0088] The use of the present composition is not particularly limited, but the present composition can be used, for example, as an undercoat paint, a topcoat paint, a paint that can be used as both an undercoat and a topcoat, a low-VOC zinc-free primer, or a paint for forming an abrasion-resistant coating film.

[0089] Because the present composition is capable of forming a coating film with these excellent performances, it is preferably used on the inner surfaces of cargo tanks (e.g., product carriers and chemical tankers) used to transport chemical substances by land or sea, and on land tanks similarly used to store chemicals, and is preferably used on the inner surfaces of tanks such as WBTs (water ballast tanks), COTs (cargo oil tanks), FWTs (fresh water tanks), and DWTs (drinking water tanks), as well as on the interior and exterior surfaces of ships, etc. In addition to these uses, the composition is also suitable for use in difficult-to-maintain locations such as seawater desalination plants and marine structures, around dams and sluice gates, piping in plants that use seawater, river water, or industrial water as cooling water, water tanks, water storage tanks, spent nuclear fuel storage pools, etc. In particular, the present composition is preferably used as a universal primer for the interior and exterior surfaces of tanks (e.g., product carriers and chemical tankers), WBTs, COTs, pipelines, etc. used to transport or store chemical substances, etc., and for ships, etc.

[0090] The present composition can also be used to repair the surface of a substrate with a corrosion-resistant coating. The present composition can be applied to welds or gaps in non-ferrous metal substrates such as stainless steel, aluminum, zinc-plated metal, and brass, to inhibit localized corrosion of the substrate and also function as an adhesive for adhering a substrate to the coating surface, thereby stably inhibiting localized corrosion for a long period of time. Thus, when repairing a substrate, for example, the present composition can be applied to the surface of a substrate with a weld (weld line) or gap, and another substrate can be adhered to the uncured coating surface, or the present composition can be applied to the other substrate.

[0091] [Coating film, coated article, and method for manufacturing the coated article] The coating film of the present disclosure (hereinafter also referred to as "the present coating film") is formed using the present composition, specifically, can be formed by drying (curing) the present composition, and is usually formed on a substrate. The coated article of the present disclosure includes a substrate and the present coating film.

[0092] The material of the substrate is not particularly limited, and examples thereof include steel (iron, steel, ferroalloy, carbon steel, mild steel, alloy steel, etc.), non-ferrous metals (zinc, aluminum, copper, brass, zinc plating, zinc thermal spraying, etc.), and stainless steel (SUS304, SUS410, etc.). The surface of the substrate may be coated with a shop primer or the like. Furthermore, when mild steel (SS400, etc.) is used as the substrate, it is desirable to perform surface preparation (e.g., adjusting the arithmetic mean roughness (Ra) to about 30 to 75 μm) by polishing the substrate surface by grit blasting or the like, as necessary. The substrate may also be a substrate that has been subjected to pretreatment such as cleaning or blasting to remove rust, dirt, paint (old paint film), etc. adhering to the substrate.

[0093] The substrate is not particularly limited, but substrates that require wear resistance and corrosion resistance are preferred in terms of better demonstrating the effects of using the present composition, and examples thereof include (steel) structures such as ships, marine structures, plants, bridges, tanks, and containers.

[0094] The dry film thickness of the coating is not particularly limited, but is usually 10 to 500 μm, preferably 15 to 400 μm, in order to obtain a coating having sufficient abrasion resistance and corrosion resistance.

[0095] The coating film may be formed to the desired thickness by one coating (one coat), or by two or more coatings (two or more coats). From the viewpoint of film thickness control and taking into consideration residual organic solvents in the coating film, it is preferable to form the coating film to the desired dry film thickness by two or more coatings.

[0096] The coated article may further comprise at least one coating film selected from the group consisting of an undercoat coating film (primer coating film) intended to improve adhesion to the substrate and corrosion resistance, an intermediate coating film intended to improve corrosion resistance, and a topcoat coating film intended to improve weather resistance or aesthetics, etc.

[0097] When the present composition is used as a replacement for a zinc primer, the painted article may include an intermediate coating or a top coating on top of the present coating.

[0098] Examples of the undercoat coating film include coating films formed from various primer compositions such as epoxy resin-based ones. Examples of the intermediate coating film include coating films formed from various intermediate coating paint compositions such as (meth)acrylic resin-based, epoxy resin-based, and urethane resin-based ones. Examples of the topcoat coating film include coating films formed from various topcoat coating paint compositions such as (meth)acrylic resin-based, (meth)acrylic silicone resin-based, urethane resin-based, silicone resin-based, and fluororesin-based ones. The composition of this composition may be changed to form an undercoat coating film, intermediate coating film, and topcoat coating film using this composition.

[0099] Generally, primer coating films formed from epoxy resin-based paint compositions have poor weather resistance, and therefore tend to have poor topcoat compatibility, such as interlayer adhesion with the topcoat coating film and the physical properties of the laminate with the topcoat coating film. In particular, if the period between the primer coating and the topcoat coating of an epoxy resin-based paint composition is long, there is a problem of insufficient interlayer adhesion between the formed primer coating film and the topcoat coating film. One embodiment of the present coating film has superior weather resistance compared to coating films formed from conventional epoxy resin-based paint compositions, and is therefore less likely to have poor topcoat compatibility. Therefore, even when an antifouling coating composition or the like is applied as a topcoat coating composition, a coating film can be formed that has excellent interlayer adhesion with the resulting topcoat coating film and excellent topcoat compatibility.

[0100] The method for producing a coated article of the present disclosure includes: [1] a step of applying the present composition to a substrate; and [2] a step of drying the applied composition to form a coating film.

[0101] <Step [1]> Examples of the coating method in step [1] include airless spray coating, air spray coating, brush coating, and roller coating. When the present composition is applied to a large structure such as a tank, spray coating is preferred because it allows for easy coating of a large surface area of ​​the substrate. Note that, during the coating operation, the present composition may be appropriately diluted with thinner (organic solvent) or the like before use. However, even when diluted in this way, the VOC content in the diluted composition is preferably 450 g / L or less.

[0102] The spray coating conditions may be adjusted as appropriate depending on the dry film thickness of the coating film to be formed, but for example, in the case of airless spraying, the primary (air) pressure is preferably about 0.4 to 0.8 MPa, the secondary (paint) pressure is about 15 to 36 MPa, and the gun movement speed is about 50 to 120 cm / sec. Furthermore, the coating may be applied so that the dry film thickness of the resulting coating film falls within the above range.

[0103] The viscosity of the present composition suitable for spray coating, as measured at 23°C using an E-type viscometer (FMD model, manufactured by TOKIMEC Corporation), is preferably 100 to 5,000 mPa·s, more preferably 500 to 3,000 mPa·s.

[0104] <Step [2]> The drying conditions in step [2] are not particularly limited and may be set appropriately depending on the method for forming the coating film, the type of substrate, the intended use, the coating environment, etc., but examples include conditions of 0 to 35° C. and 12 to 250 hours. If desired, the coating may be forcedly dried and cured by heating or blowing air, but is usually dried and cured under natural conditions.

[0105] When forming a coating film by applying the coating two or more times, particularly two times, steps [1] and [2] are performed, and then the series of steps [1] and [2] are repeated on the resulting coating film to form a coating film. When forming a coating film by applying three times, steps [1] and [2] are further repeated on the coating film that has been applied twice to form a coating film.

[0106] [Example Aspects] The present disclosure relates to, for example, the following [1] to [7]. [1] A coating composition containing an epoxy resin (A), an amine curing agent (B), a glycidyl group-containing silane coupling agent (C), and a glycidyl group-free silicate compound (D), wherein the content of the glycidyl group-containing silane coupling agent (C) is more than 50 parts by mass per 100 parts by mass of the silicate compound (D). [2] The coating composition according to [1], wherein the content of the glycidyl group-containing silane coupling agent (C) is 20 parts by mass or more per 100 parts by mass of the epoxy resin (A). [3] The coating composition according to [1], wherein the content of the glycidyl group-containing silane coupling agent (C) is 22 parts by mass or more per 100 parts by mass of the epoxy resin (A). [4] The coating composition according to any one of [1] to [3], wherein the content of the silicate compound (D) is 35 mass% or less based on the total content of the epoxy resin (A), the amine curing agent (B), the glycidyl group-containing silane coupling agent (C), and the silicate compound (D). [5] A coating film formed from the coating composition according to any one of [1] to [4]. [6] A coated article comprising a substrate and the coating film according to [5]. [7] A method for producing a coated article, comprising the steps of applying the coating composition according to any one of [1] to [4] to a substrate, and drying the coating composition applied to the substrate to form a coating film.

[0107] The coating composition of the present disclosure will be further described below with reference to examples, but the coating composition is not limited to these examples. In the following description, unless otherwise specified, "parts by mass" will be expressed as "parts".

[0108] Example 1: 8.0 parts of epoxy resin 1, 26.0 parts of a glycidyl group-containing silane coupling agent, 10.0 parts of extender pigment 1, 39.07 parts of extender pigment 2, 5.0 parts of extender pigment 3, 5.0 parts of coloring pigment 1, 0.03 parts of coloring pigment 3, and 0.6 parts of an anti-sagging agent were dispersed in a container using a high-speed disperser until the composition reached 60°C, and then 6.0 parts of a silicate compound and 0.3 parts of an antifoaming agent were immediately added and the entire composition was mixed uniformly to prepare a first agent. Next, the first agent prepared as described above and a second agent consisting of amine curing agent 1 were mixed using a high-speed disperser in a ratio of first agent / second agent = 91.0 / 9.0 (mass ratio) until uniform, to prepare a coating composition.

[0109] The description of each component listed in Table 1 is shown in Table 6.

[0110] [Examples 2 to 31 and Comparative Examples 1 to 4] Coating compositions were prepared in the same manner as in Example 1, except that each component shown in Tables 1 to 5 was used in the amount (number, parts by mass) shown in the table and mixed at the mixing ratio shown in Tables 1 to 5. Table 6 shows a description of each component shown in Tables 1 to 5.

[0111] [Non-volatile content] The non-volatile content of the prepared coating composition (amount of non-volatile content in 100% by mass of the composition) was calculated from the solid content and blending amount of each raw material. The results are shown in Tables 1 to 5.

[0112] [PVC] The pigment volume concentration (PVC) in the prepared coating composition was calculated based on the above formula (4). The results are shown in Tables 1 to 5.

[0113] [Drying and curing properties] The drying and curing properties of the prepared coating compositions were evaluated using a drying time recorder (RC-type paint drying time measuring device, manufactured by TP Giken Co., Ltd.) in accordance with the measurement method of ISO 9117-4:2012(E) (Method A of Drying Tests). Specifically, the coating composition was applied to a rectangular piece of glass measuring 300 mm x 25 mm using an applicator with a gap of 0.3 mm, and the drying and curing time (hard-dry time) was measured in accordance with the measurement method described above. Measurements were performed under conditions of 5°C and 50% RH, and 23°C and 50% RH. The results are shown in Tables 1 to 3.

[0114] [Pot life] 300 g of the prepared coating composition (mixture of the first and second parts) was weighed into a container, and the viscosity (initial viscosity, coating temperature 23°C) immediately after mixing the first and second parts was measured. After mixing, the coating composition was stored at 23°C and 50% RH for 6 hours, and the viscosity (viscosity after 6 hours) was measured. The viscosity was measured using a viscometer (TVB-10 VISCOMETER, manufactured by TOKI SANGYO) under conditions of an ambient temperature of 23°C and 50% RH. The viscosity increase rate was calculated from the initial viscosity and the viscosity after 6 hours using the following formula. The results are shown in Tables 1 to 3. In Examples 14 to 16, gelation occurred when the composition was stored at 23°C and 50% RH for 6 hours after mixing. In Table 2, "gelation" indicates that the viscosity after 6 hours could not be measured due to gelation. Viscosity increase rate (%) = viscosity after 6 hours / initial viscosity × 100

[0115] [Pencil Hardness Test] The hardness of the coating film obtained from the prepared coating composition was measured according to the measurement method (hand scratch method) of JIS K5600-5-4:1999. Specifically, the coating composition was applied to a 300 mm x 300 mm tin plate using an applicator with a gap of 0.3 mm, and the hardness of the coating film obtained by curing and drying for 24 hours, 48 ​​hours, and 72 hours under conditions of 23°C and 50% RH was measured. The results are shown in Tables 1 to 3.

[0116] [Neutral Salt Spray Resistance Test] The corrosion resistance of the prepared coating compositions was evaluated according to the test method of JIS K 5600-7-1:1999. Specifically, the coating composition was applied to a steel plate (SS400) of 150 mm length x 70 mm width x 2.3 mm thickness, sandblasted to ISO Sa2.5, using an air spray, to a dry film thickness of 100 μm, and then cured and dried at room temperature for 7 days to prepare a test plate. The prepared test plate was placed in a testing machine, and the condition of the test plate was visually inspected after 120 hours. A rating of ◯ was given when no abnormalities such as rusting were visually observed on the test plate, and an × was given when abnormalities such as rusting were visually observed on the test plate. The results are shown in Table 1.

[0117] [Anti-fouling paint adhesion test] Various anti-fouling paints were applied to the coating film obtained from the prepared coating composition to form an anti-fouling coating film, and the adhesion to the anti-fouling coating film was evaluated. Specifically, the coating composition was applied to a steel plate (SS400) of 150 mm length x 70 mm width x 2.3 mm thickness, which had been sandblasted to ISO Sa2.5, using an air spray, to a dry film thickness of 150 μm, and then cured and dried at room temperature for 1 day to prepare a test plate. Various antifouling paints were applied to the test plates using an applicator (gap: 0.5 mm), dried in a thermostat (40°C / 50% RH) for 48 hours, and then subjected to a 48-hour neutral salt spray test in accordance with JIS K 5600-7-1:1999. A cross-cut adhesion test was then conducted, with three cycles of cooling and heating from -20°C to 60°C (heating from 20°C to 60°C over 1 hour, holding at 60°C for 2 hours, cooling from 60°C to -20°C over 2 hours, holding at -20°C for 2 hours, and heating from -20°C to 20°C over 1 hour). The cross-cut adhesion test was conducted using 25 squares 4 mm wide, and adhesion was evaluated on a 6-point scale from 0 to 5 in accordance with ISO 2409:1992, with 0 indicating the best adhesion. The results are shown in Table 4.

[0118] [Accelerated Weathering Test] The weathering resistance of the coating film obtained from the prepared coating composition was evaluated by an accelerated weathering test. Specifically, the coating composition was applied to an alodine-treated aluminum plate (A1050P) measuring 150 mm long x 70 mm wide x 0.8 mm thick using an applicator (gap: 0.3 mm), and the test plate was then cured and dried at room temperature for 7 days to prepare a test plate. The initial gloss (60°) of the test plate was measured using a gloss meter (Micro Trigloss, manufactured by BYK Japan Co., Ltd.). The initial reflected color of the test plate was also measured using a color difference meter (CM-3700A, manufactured by Konica Minolta Japan Co., Ltd.). The test plate was then placed in a Super Xenon Weather Meter SX75 (manufactured by Suga Test Instruments Co., Ltd.), and the gloss and reflected color were measured again after 1000 hours. The gloss retention was calculated from the initial gloss and the gloss after 1000 hours according to the following formula: Gloss retention (%) = gloss after 1000 hours / initial gloss × 100. The color difference (ΔE) was calculated by comparing the initial reflected color with the reflected color after 1000 hours. Furthermore, the chalkiness of the coating film was evaluated on a 6-point scale from 0 to 5 in accordance with JIS K 5600-8-6:2014, with 0 indicating the best weather resistance. The results are shown in Table 5.

[0119]

[0120] In Table 1, "glycidyl group-containing silane coupling agent / epoxy resin" means the amount of glycidyl group-containing silane coupling agent per 100 parts of epoxy resin. Similarly, "glycidyl group-containing silane coupling agent / silicate compound" means the amount of glycidyl group-containing silane coupling agent per 100 parts of silicate compound.

[0121]

[0122]

[0123]

[0124]

[0125]

Claims

1. A coating composition comprising an epoxy resin (A), an amine curing agent (B), a glycidyl group-containing silane coupling agent (C), and a silicate compound (D) having no glycidyl group, wherein the content of the glycidyl group-containing silane coupling agent (C) exceeds 50 parts by mass per 100 parts by mass of the silicate compound (D).

2. The coating composition according to claim 1, wherein the content of the glycidyl group-containing silane coupling agent (C) is 20 parts by mass or more per 100 parts by mass of the epoxy resin (A).

3. A coating composition according to claim 1, wherein the content of the glycidyl group-containing silane coupling agent (C) is 22 parts by mass or more per 100 parts by mass of the epoxy resin (A).

4. The coating composition according to claim 1, wherein the content of the silicate compound (D) is 35 mass% or less based on the total content of the epoxy resin (A), the amine curing agent (B), the glycidyl group-containing silane coupling agent (C), and the silicate compound (D).

5. A coating film formed from the coating composition according to any one of claims 1 to 4.

6. A coated article comprising a substrate and the coating film according to claim 5.

7. A method for producing a coated product, comprising the steps of applying the coating composition according to any one of claims 1 to 4 to a substrate, and drying the coating composition applied to the substrate to form a coating film.

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