阅读说明：本技术 防蚀涂料组合物 (Anticorrosive coating composition ) 是由 田渕秀典 于 2020-02-24 设计创作，主要内容包括：本发明的课题在于提供一种能够形成防腐蚀性优异的涂膜、干燥性和固化性优异的防蚀涂料组合物。本发明涉及防蚀涂料组合物、涂膜、带涂膜的基材及其制造方法,该防蚀涂料组合物含有：第一剂,其含有在1分子中具有1个以上的羧基且不挥发成分的酸值为1～20mgKOH/g的水性环氧树脂(A)；和含有锌粉(B)的第二剂,相对于上述防蚀涂料组合物的不挥发成分100质量％,该防蚀涂料组合物含有43～85质量％的上述锌粉(B)。(The invention provides an anticorrosive coating composition which can form a coating film with excellent anticorrosive performance and has excellent drying performance and curing performance. The present invention relates to an anticorrosive coating composition, a coating film, a substrate with a coating film, and a method for producing the same, the anticorrosive coating composition comprising: a first agent containing an aqueous epoxy resin (A) having 1 or more carboxyl groups in 1 molecule and having an acid value of a nonvolatile content of 1 to 20 mgKOH/g; and a second agent containing a zinc powder (B), wherein the zinc powder (B) is contained in an amount of 43 to 85 mass% based on 100 mass% of a nonvolatile component of the anticorrosive coating composition.)

1. An anticorrosive coating composition characterized by comprising:

a first agent containing an aqueous epoxy resin (A) having 1 or more carboxyl groups in 1 molecule and having an acid value of a nonvolatile content of 1 to 20 mgKOH/g; and

a second agent containing zinc powder (B),

the anticorrosive coating composition contains 43-85 mass% of the zinc powder (B) relative to 100 mass% of nonvolatile components of the anticorrosive coating composition.

2. The corrosion resistant coating composition of claim 1, wherein:

the waterborne epoxy resin (A) is a waterborne amine modified epoxy resin (A1).

3. The anticorrosive coating composition according to claim 1 or 2, wherein:

the nonvolatile content of the water-based epoxy resin (A) has an amine value of 1 to 150 mgKOH/g.

4. The corrosion resistant coating composition of claim 1, wherein:

the second agent contains a glycol ether solvent or an alcohol solvent having 1 to 3 carbon atoms.

5. The anticorrosive coating composition according to claim 1,2 or 4, wherein:

the second agent contains a binder other than the aqueous epoxy resin (A).

6. The anticorrosive coating composition according to claim 1,2 or 4, wherein:

the content of the volatile organic compound in 100 mass% of the anticorrosive coating composition is 10 mass% or less.

7. A coating film characterized by:

formed from the anticorrosive coating composition of any one of claims 1 to 6.

8. A substrate with a coating film, characterized in that:

comprising a substrate and the coating film according to claim 7.

9. A method for producing a substrate with a coating film, comprising:

comprising the following steps [1] and [2 ]:

[1] a step of applying the anticorrosive coating composition according to any one of claims 1 to 6 on a substrate; and

[2] and a step of drying the composition applied to the substrate to form a coating film.

Technical Field

The present invention relates to an anticorrosive coating composition, a coating film, a substrate with a coating film, and a method for producing the same.

Background

Conventionally, an anticorrosive coating film is provided on a base material of a land or marine structure such as a bridge, a storage tank, a factory facility, a (transport) container, or the like, for the purpose of preventing corrosion or the like. As an example of a coating material for forming the anticorrosive coating film, a zinc-rich coating material containing a zinc powder at a high content is used. As such a zinc-rich coating material, a solvent-based coating material using an organic solvent as a solvent is used in terms of corrosion resistance, coating workability, and the like.

In recent years, from the viewpoint of environmental protection, safety of working environment, and the like, the content of Volatile Organic Compounds (VOC) has been strictly regulated, and there is a demand for a replacement of the above-mentioned coating materials from solvent-based ones to aqueous ones.

As such a water-based zinc-rich paint, patent document 1 describes a 2-liquid 1-powder type water-based zinc-rich paint composed of a main agent containing an epoxy resin emulsion, a pigment component (powder component) containing a zinc powder, and an amine-based curing agent.

Patent document 2 describes a zinc-rich coating material containing an aqueous urethane resin.

Disclosure of Invention

Technical problem to be solved by the invention

The conventional aqueous zinc-rich coating materials described in patent documents 1 and 2 and the like have insufficient drying properties and/or curability, and the obtained coating film has room for improvement in terms of corrosion resistance.

Further, as described in patent document 1, the conventional aqueous zinc-rich paint using a known amine-based curing agent conventionally used as a curing agent for epoxy resins has insufficient drying property, curability, and/or pot life (pot life), and there is room for improvement in this respect.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an anticorrosive coating composition which can form a coating film having excellent anticorrosive properties and has excellent drying properties and curability.

Technical solution for solving technical problem

As a result of extensive and intensive studies on a method for solving the above-mentioned problems, it was found that the above-mentioned problems can be solved by a specific coating composition, and the present invention was completed.

The constitution of the present invention is as follows.

< 1 > an anticorrosive coating composition comprising:

a first agent containing an aqueous epoxy resin (A) having 1 or more carboxyl groups in 1 molecule and having an acid value of a nonvolatile content of 1 to 20 mgKOH/g; and

a second agent containing zinc powder (B),

the anticorrosive coating composition contains 43-85 mass% of the zinc powder (B) relative to 100 mass% of nonvolatile components of the anticorrosive coating composition.

< 2 > the anticorrosive coating composition according to < 1 >, wherein the aqueous epoxy resin (A) is an aqueous amine-modified epoxy resin (A1).

The anticorrosive coating composition is < 3 > such as < 1 > or < 2 >, wherein the nonvolatile component of the water-based epoxy resin (A) has an amine value of 1-150 mgKOH/g.

The anticorrosive coating composition of any one of < 4 > to < 1 > to < 3 >, wherein the second agent contains a glycol ether solvent or an alcohol solvent having 1 to 3 carbon atoms.

The anticorrosive coating composition of any one of < 5 > to < 4 >, wherein the second agent contains a binder other than the aqueous epoxy resin (A).

The anticorrosive coating composition according to any one of < 6 > to < 1 > -5 >, wherein the content of Volatile Organic Compounds (VOC) in 100% by mass of the anticorrosive coating composition is 10% by mass or less.

< 7 > a coating film formed from the anticorrosive coating composition of any one of < 1 > to < 6 >.

< 8 > a substrate with a coating film, comprising a substrate and < 7 > said coating film.

< 9 > a method for producing a substrate with a coating film, comprising the following steps [1] and [2 ]:

[1] a step of applying the anticorrosive coating composition described in any one of (1) to (6) to a substrate; and

[2] and a step of drying the composition applied to the substrate to form a coating film.

ADVANTAGEOUS EFFECTS OF INVENTION

The present invention provides an aqueous anticorrosive coating composition having excellent drying properties and curability, zinc powder dispersibility, storage stability, and water dilutability, and having a long pot life. Further, according to the present invention, a water-based anticorrosive coating composition having excellent drying properties and curability can be provided without using a known amine-based curing agent which has been conventionally used as a curing agent for epoxy resins.

Further, according to the present invention, a coating film excellent in corrosion resistance and adhesion to a substrate can be formed.

Detailed Description

Anticorrosive paint composition

The anticorrosive coating composition according to the present invention (hereinafter, may be simply referred to as "the present composition") contains:

a first agent containing an aqueous epoxy resin (A) having 1 or more carboxyl groups in 1 molecule and having an acid value of a nonvolatile content of 1 to 20 mgKOH/g; and

a second agent containing zinc powder (B),

the composition contains 43-85 mass% of the zinc powder (B) relative to 100 mass% of nonvolatile components of the composition.

The present composition is not particularly limited as long as it is a multi-component composition containing the first agent and the second agent, and depending on the components used, it may be a 3-component or more composition containing a third agent other than the first agent and the second agent, but the present composition can be a 2-component composition having excellent drying properties and curability, zinc powder dispersibility, and water dilutability and a long pot life without making such a 3-component or more.

Therefore, the present composition is a multi-component composition containing the first agent and the second agent, but from the viewpoint of space saving during storage, ease of production, and excellent coating workability, the present composition is preferably a 2-component composition composed of (only) the first agent and the second agent.

The present composition may be a 1-liquid-1-powder composition in which the first agent is liquid and the second agent is powder, or a 2-liquid composition in which the first agent and the second agent are liquid (including paste), but the 2-liquid composition is preferable in terms of excellent handling at the application site (miscibility of zinc powder) and storage easiness of the second agent.

The first to third agents and the like (hereinafter, these agents may be collectively referred to as "the n-th agent") are usually stored, transported, and the like in separate containers, and are mixed at the time of application (for example, immediately before application) to prepare the present composition. In other words, these nth agents can be said to be components of a kit (kit) for preparing the present composition, and in other words, the present composition can be said to be a kit for an anticorrosive coating composition containing the first agent and the second agent.

In the present invention, the agent n is an agent which can be stored after the preparation of these agents and before the preparation of the present composition, and for example, a mill base (mill base) described in the following examples and the like are usually used by being mixed with other components immediately after the preparation of the mill base, and therefore, they do not belong to the agent n of the present invention.

The present composition is prepared by mixing the above-mentioned nth agent, but may be used after or at the time of the preparation by diluting it according to a coating method or the like.

The respective descriptions in the present specification relate to the description before dilution, except for the contents relating to the above-described dilution.

The present composition is usually a water-based paint composition because it contains the water-based epoxy resin (a). The aqueous coating composition is a composition obtained by dispersing and/or dissolving components such as the resin (a) and the zinc powder (B) in water or a medium (aqueous medium) mainly composed of water.

The content of water in the aqueous coating composition is preferably 50% by mass or more, preferably 60 to 100% by mass, and more preferably 65 to 100% by mass, based on 100% by mass of the total amount of the dispersion medium and the solvent in the composition.

In an environment where a coating material is applied to a substrate such as a container, drying equipment may be insufficient. Under such circumstances, when a conventional water-based zinc-rich coating material is applied, importance is placed on drying properties, and an organic solvent is added to the coating material.

However, according to the present invention, since a coating composition excellent in drying property and curability can be obtained, a desired coating film can be easily formed in a place where a drying facility is insufficient even if an organic solvent is not blended as such.

Therefore, from the viewpoint of environmental protection, safety of working environment, and the like, the content of Volatile Organic Compounds (VOC) in 100% by mass of the present composition is preferably 10% by mass or less, more preferably 8% by mass or less, and the VOC content in the present composition is preferably 200g/L or less, more preferably 180g/L or less.

The VOC content in the present composition can be calculated from the following formulae (1) and (2) by using the specific gravity of the composition, the heating residual component fraction (mass ratio of nonvolatile components), and the value of the moisture fraction. The specific gravity of the composition, the fraction of remaining heat component and the water content may be measured as described below or calculated from the raw materials used.

VOC content (mass%) (100-heating residual composition fraction-moisture percentage)/100. cndot. (1)

VOC content (g/L) × 1000 × (100-residual heating component ratio-water content)/100 · (2)

Composition specific gravity (g/ml): the composition (composition immediately after the n-th agent was mixed) was filled in a specific gravity cup having an internal volume of 100ml at a temperature of 23 ℃ and the mass of the composition was calculated.

Heating residual component percentage (mass%): the composition (composition immediately after the n-th agent was mixed) and/or 1. + -. 0.1g of each component were weighed out on a flat pan, spread uniformly using a wire of known mass, and the value of mass percentage was calculated by measuring the remaining components (non-volatile components) after heating at a heating temperature of 125 ℃ for 1 hour (under normal pressure) and the mass of the wire.

Water content (mass%): the value of the mass percentage of water contained in the present composition at 100 mass% was measured by the Karl Fischer's method.

The composition is suitably used for a base material of steel (iron, steel, alloy iron, carbon steel, mild steel, alloy steel, etc.), nonferrous metal (zinc, aluminum, copper, brass, zinc plating, zinc spraying, etc.), stainless steel (SUS304, SUS410, etc.), etc., and particularly suitable for a base material of steel.

The composition is suitably used for (large) steel structures such as ships, marine structures, plant facilities, bridges, tanks, and containers.

< first dose >

The first component of the present composition is not particularly limited as long as it contains the above aqueous epoxy resin (a), and is usually a liquid agent containing water because it contains the resin (a).

The content of water in the first agent is preferably 50% by mass or more, more preferably 70 to 100% by mass, and particularly preferably 80 to 100% by mass, based on 100% by mass of the total amount of the dispersion medium and the solvent in the first agent, from the viewpoint of easily obtaining a desired aqueous coating composition.

In the first formulation, other components, for example, conventionally known components such as a binder other than the resin (a), water, a pigment (for example, a bulk pigment or a colored pigment), a rust inhibitor, a flash rust inhibitor, a dispersant, an antifoaming agent, a thixotropic agent (anti-sagging/anti-settling agent), a leveling agent, a wetting agent, a thickener, a film-forming aid, a drying agent, a fibrous material, a surfactant, an organic solvent, a fungicide, an antiseptic, an ultraviolet absorber, a light stabilizer, a pH adjuster, and the like may be appropriately blended as necessary within a range not to impair the effects of the present invention.

These may be used alone in 1 kind, or in 2 or more kinds.

[ Water-based epoxy resin (A) ]

The resin (A) is not particularly limited as long as it is a water-based epoxy resin having 1 or more carboxyl groups in 1 molecule and having a nonvolatile content and an acid value of 1 to 20 mgKOH/g.

As the resin (a), 1 kind or 2 or more kinds may be used.

By using such a resin (a), even if the VOC content is in the above range, and even in a 2-component type composition, a composition excellent in drying property, curability, storage stability and pot life can be obtained, and a coating film having a better balance of corrosion resistance, water resistance, adhesion to a substrate and impact resistance and excellent in the balance can be easily formed.

By using such a resin (a), a coating film can be formed without using a conventional amine-based curing agent that has been used as a curing agent for an epoxy resin. Therefore, it is preferable that the amine-based curing agent is not used in the present composition, from the viewpoint that a composition having more excellent drying property, curability, and pot life can be obtained.

In addition, when the first agent contains a pigment, the resin (a) having a carboxyl group tends to have affinity for the pigment, and thus, it is expected that the dispersibility of the pigment is improved. Therefore, improvement in production efficiency due to improvement in dispersibility of the pigment can be expected.

In the present invention, the "aqueous resin" refers to water, a resin mainly containing water as a solvent or a dispersion medium, or a resin capable of being mixed with water (capable of being diluted with water), and more specifically, a water-dispersible resin, a water-soluble resin, a self-emulsifiable resin, and the like are exemplified. Such an aqueous resin can be synthesized by a conventionally known method, for example, solution polymerization, suspension polymerization, emulsion polymerization, seed polymerization, miniemulsion polymerization, microemulsion polymerization, emulsifier-free (soap-free) emulsion polymerization, or the like. In addition to these, the aqueous resin can be obtained by emulsifying the resin by a known method, for example, phase inversion emulsification, phase D emulsification, forced emulsification, gel emulsification, reverse emulsification, high pressure emulsification, or the like.

In addition, since a generic term including "epoxy" can be used for the resin having no epoxy group as long as it is a resin using a compound having an epoxy group as a raw material, the "epoxy resin" in the present invention also includes a resin having no epoxy group.

The nonvolatile component of the resin (a) has an epoxy equivalent of preferably 1500 or more, more preferably 2000 or more, and particularly preferably the resin (a) has no epoxy group, from the viewpoint that a composition having more excellent drying property and/or curability can be easily obtained.

The above epoxy equivalent may be measured according to JIS K7236: 2001.

The acid value of the nonvolatile portion of the resin (A) is 20mgKOH/g or less, preferably 15mgKOH/g or less, more preferably 10mgKOH/g or less, still more preferably 9mgKOH/g or less, particularly preferably 8mgKOH/g or less, still more preferably 7mgKOH/g or less, and 1mgKOH/g or more, preferably 1.5mgKOH/g or more, and particularly preferably 2mgKOH/g or more.

By using the resin (a) having an acid value within the above range, a composition having further excellent drying properties and/or curability can be easily obtained, and a coating film having excellent corrosion resistance can be easily formed.

The acid value can be measured according to JIS K0070: 1992.

The amine value of the nonvolatile content of the resin (A) is preferably not more than 150mgKOH/g, more preferably not more than 100mgKOH/g, particularly preferably not more than 75mgKOH/g, preferably not less than 1mgKOH/g, more preferably not less than 25mgKOH/g, and particularly preferably not less than 50 mgKOH/g.

By using the resin (a) having an amine value within the above range, a composition having further excellent drying properties and/or curability can be easily obtained, and a coating film having excellent corrosion resistance can be easily formed.

The amine value can be measured according to JIS K7273: 1995.

As the resin (a) satisfying the epoxy equivalent (having no epoxy group), the acid value and/or the amine value as described above, a reaction product of an epoxy resin (a1) and a conventionally known compound (a2) having reactivity with an epoxy group (wherein the reaction product has 1 or more carboxyl groups in the molecule) can be cited.

The compound (a2) having reactivity with an epoxy group is preferably an amine in view of easiness of reaction with an epoxy group.

The above-mentioned compound (a2) may be used alone or in combination of 2 or more.

The amine is not particularly limited, and examples thereof include monoamines and polyamines such as aliphatic amines, alicyclic amines, aromatic aliphatic amines, and heterocyclic amines. The amine may be used alone in 1 kind, or may be used in 2 or more kinds.

The amine is not particularly limited, and examples thereof include: primary alkyl amines such as butylamine, octylamine, oleylamine, and 2-ethylhexylamine; primary aliphatic alcohol amines such as monoethanolamine, 2-ethoxyethanolamine, and 2-hydroxypropanolamine; aliphatic polyamines such as diethylenetriamine, triethylenetetramine, and tetraethylenepentamine; alicyclic polyamines such as 1, 3-diaminocyclohexane and isophoronediamine; aromatic polyamines such as diaminodiphenylmethane; aromatic aliphatic amines such as o-xylylenediamine, m-xylylenediamine, and p-xylylenediamine; mannich bases formed from polycondensates of polyamines, aldehyde compounds and monohydric or polyhydric phenols; polyamidopolyamines obtained by reacting polyamines with polycarboxylic acids or dimer acids; polyoxyalkylene amines such as polyoxyethylene amine and polyoxypropylene amine. From the viewpoint of excellent dispersibility in an aqueous medium and storage stability thereof, preferred are primary alkyl amines, primary aliphatic alcohol amines, and polyoxyalkylene amines, and more preferred are primary aliphatic alcohol amines and polyoxyalkylene polyamines.

Examples of the polyoxyalkylene amines include compounds represented by the following structural formula (a 2-1).

(in the formula, R¹Is hydrogen atom, methyl, ethyl, propyl or tert-butyl, R²Independently is ethylene, 1, 2-propylene, 2, 3-propylene, 1, 3-propylene, R³Is methylene, ethylene, 1, 2-propylene, 2, 3-propylene, 1, 3-propylene, n is the average value of the repeating units and is 2 to 100. )

The molecular weight of the polyoxyalkylene amine is preferably 300 to 5,000, more preferably 400 to 1,500 in terms of easily obtaining a composition having excellent storage stability and corrosion resistance.

As the polyoxyalkylene amines, commercially available products can be used, and examples thereof include "JEFFAMINE M-600" (weight average molecular weight: 600), "JEFFAMINE M-1000" (weight average molecular weight: 1,000), "JEFFAMINE M-2005" (weight average molecular weight: 2,000) and "JEFFAMINE M-2070" (weight average molecular weight: 2,000) (both of which are manufactured by Huntsman Corporation). Among these, "JEFFAMINE M-600" and "JEFFAMINE M-1000" are preferable.

The resin (a) obtained using the amine is a water-based amine-modified epoxy resin (a 1). By using the resin (a1), a composition having more excellent drying properties and curability can be easily obtained, and a coating film having more excellent corrosion resistance and adhesion to a substrate can be easily formed.

The modified epoxy resin in the present invention is a resin in which the monomer component constituting the epoxy resin exceeds 50 mass% with respect to 100 mass% of the total monomer components constituting the resin.

The epoxy resin (a1) is preferably a bisphenol epoxy resin, preferably a bisphenol a epoxy resin, a bisphenol F epoxy resin, or a bisphenol AD epoxy resin, and more preferably a bisphenol a epoxy resin, from the viewpoints of toughness of the obtained coating film, adhesion to a substrate, and the like.

The epoxy resins (a1) may be used alone or in combination of 2 or more.

In order to convert the reaction product into a resin having 1 or more carboxyl groups in the molecule, a compound having a carboxyl group may be used as the epoxy resin (a1), a compound having a carboxyl group may be used as the compound (a2), a carboxyl group may be generated during the reaction, a resin finally obtained after the reaction may be modified to have a carboxyl group, and the like, and it is preferable to use an unsaturated carboxylic acid (a3) other than the epoxy resin (a1) and the compound (a2) during the reaction.

Examples of the unsaturated carboxylic acid (a3) include (meth) acrylic acid. These may be used alone or in combination of 2 or more.

The order of reacting the epoxy resin (a1), the compound (a2), and the unsaturated carboxylic acid (a3) is not particularly limited, and it is preferable to react the epoxy resin (a1) with the compound (a2) (hereinafter, sometimes referred to as "reaction 1"), and then react the compound obtained from the reaction 1 with the unsaturated carboxylic acid (a3) (hereinafter, sometimes referred to as "reaction 2"), in view of easily obtaining a resin or the like satisfying the acid value and the amine value as described above.

These reactions 1 and 2 can be carried out by a conventionally known method.

The mixing ratio of the epoxy resin (a1) and the compound (a2) in the above reaction 1 is preferably such that the epoxy group is not left as much as possible in the obtained resin (a), for example, the amino group is preferably in an amount of about 1.1 to 1.5 moles, more preferably about 1.1 to 1.3 moles, based on 1 mole of the epoxy group, because the storage stability of the composition may be lowered if the epoxy group is left in the obtained resin (a).

The mixing ratio of the compound obtained in the above reaction 1 and the unsaturated carboxylic acid (a3) in the above reaction 2 is preferably such that the carboxyl group is about 1.1 to 1.5 moles, more preferably about 1.1 to 1.3 moles, based on 1 mole of the amino group, because the corrosion resistance of the obtained coating film may be lowered if the amino group remains in the obtained resin (a).

As the resin (A), a commercially available product can be used, and for example, EPICLON C-250 EP (manufactured by DIC Co., Ltd., epoxy group-free, acid value: 5.7 mgKOH/g, amine value: 60mgKOH/g) which is a water-based amine-modified epoxy resin having a bisphenol A structure and 1 or more carboxyl groups in the molecule can be mentioned.

The content of the nonvolatile component of the resin (a) is preferably 5 to 30% by mass, more preferably 6 to 20% by mass, based on 100% by mass of the nonvolatile component of the present composition, from the viewpoints that a composition having excellent drying properties and curability can be easily obtained, and a coating film having a better balance between corrosion resistance and adhesion to a substrate and excellent adhesion can be easily formed.

The content of the nonvolatile component (resin) in 100% by mass of the resin (a) is preferably 30 to 75% by mass, more preferably 35 to 60% by mass, from the viewpoint of obtaining a composition having further excellent preparation easiness, storage stability and the like.

The remaining components of the resin (a) may contain water, or may contain conventionally known components such as a surfactant, if necessary.

[ Water ]

Although the resin (a) may contain water, it is preferable to further add water to the first formulation from the viewpoint of facilitating the preparation of the present composition and obtaining a composition excellent in coating workability.

The water is not particularly limited, and tap water or the like can be used, and ion exchange water or the like is preferably used.

The content of water in the first agent (including water that may be contained in the resin (a) and the like) is not particularly limited, and is preferably 20 to 70% by mass.

[ thixotropic agent (sag-prevention agent) ]

The composition preferably contains a thixotropic agent for improving the thick coating property, the sagging resistance, and the prevention of the precipitation of insoluble components such as the zinc powder (B) and the pigment in water and organic solvents during coating. In particular, the composition is excellent in drying property, and therefore, cracks are likely to occur when a thick (for example, 80 μm or more) coating film is formed, but the occurrence of cracks can be suppressed by using a thixotropic agent.

The thixotropic agent may be used in 1 kind or 2 or more kinds.

Examples of the thixotropic agent include organic clay salts such as stearates, lecithin salts and alkylsulfonates of Al, Ca and Zn, oxidized polyethylene waxes, ethylene-vinyl acetate waxes, polyamide waxes, hydrogenated castor oil waxes, and synthetic fine powder silica. Among these, organic thixotropic agents such as oxidized polyethylene wax, ethylene-vinyl acetate wax, and polyamide wax are preferable because a coating film having excellent crack resistance can be easily formed.

The content of the non-volatile component of the thixotropic agent is preferably 0.01 to 3.5% by mass, more preferably 0.05 to 3% by mass, based on 100% by mass of the non-volatile component of the present composition, from the viewpoint of easily forming a coating film having excellent crack resistance.

[ dispersing agent ]

The present composition preferably contains a dispersant in order to improve dispersibility of the zinc powder (B) and the pigment in the composition, to easily form a cured film having good appearance, to easily form a coating film having excellent crack resistance, and the like.

The dispersant may be used in 1 kind, or 2 or more kinds.

The dispersant is not particularly limited, and examples thereof include: and various dispersants such as copolymers having a pigment-adsorbing group such as a carboxyl group, a phosphoric acid group, an amino group, a salt group thereof, and an ammonium salt group, and having a compatible chain such as a fatty acid, a polyamino group, a polyether, a polyester, a polyurethane, and a polyacrylate.

The content of the nonvolatile component of the dispersant is preferably 0.1 to 3% by mass, more preferably 0.1 to 2.5% by mass, based on 100% by mass of the nonvolatile component of the present composition, from the viewpoint of easily forming a coating film having excellent crack resistance.

[ flash rust preventive ]

When the water-based paint is applied to the surface of an active steel material, rust and flash rust appearing on the surface of a coating film due to iron ions or the like eluted from the surface of the steel material may occur in the course of drying from immediately after the application. Particularly under high-temperature and high-humidity conditions, the occurrence of flash rusting sometimes becomes remarkable.

For the purpose of suppressing such flash rust, a flash rust inhibitor is preferably used in the present composition.

The flash rust inhibitor may be used in 1 kind or 2 or more kinds.

Examples of flash rust inhibitors include: nitrites such as sodium nitrite, potassium nitrite, calcium nitrite, strontium nitrite, barium nitrite, and ammonium nitrite; benzoates such as sodium benzoate, potassium benzoate, calcium benzoate, and ammonium benzoate; phytates such as sodium phytate and potassium phytate; fatty acid salts of sebacic acid, dodecanoic acid, and the like; phosphoric acid derivatives such as alkyl phosphoric acid and polyphosphoric acid; a tannin salt; amine-based chelating agents such as N- (2-hydroxyethyl) ethylenediaminotriacetic acid (HEDTA), ethylenediaminotetraacetic acid (EDTA), diethylenetriamine pentaacetic acid (DTPA), propylenediaminetetraacetic acid (PDTA), iminodiacetic acid, nitrilotriacetic acid (NTA), diethylenetriamine pentamethylenephosphonic acid (DTPMP), and alkali metal salts thereof; an addition reactant of 4-methyl- γ -oxo-phenylbutyric acid to N-ethylmorpholine; an interlayer compound obtained by intercalating monoalkylamine or polyamine, quaternary ammonium ion, or the like into a layered phosphate such as aluminum dihydrogen tripolyphosphate; hydrazine derivatives such as hydrazide compounds, Semicarbazide (Semicarbazide) compounds, and hydrazone compounds.

Among these, from the viewpoint of excellent flash rust resistance, low cost, and the like, nitrites (for example, metal salts and ammonium salts of sodium, potassium, calcium, and the like) and benzoates (for example, metal salts and ammonium salts of sodium, potassium, calcium, and the like) are preferable, and from the viewpoint of easily obtaining a composition exhibiting high flash rust resistance even with a small amount of use, nitrites are more preferable, and sodium nitrite is particularly preferable.

The content of the flash rust inhibitor is preferably 0.01 to 2% by mass, more preferably 0.05 to 1.0% by mass, based on 100% by mass of the nonvolatile matter of the composition, from the viewpoint of easily forming a composition having excellent flash rust resistance.

[ organic solvent ]

In the case where the first agent contains water, an organic solvent which can be mixed with water in an arbitrary amount can be used in order to suppress freezing in winter and to obtain a composition having more excellent coating workability.

The organic solvent may be used in 1 kind, or 2 or more kinds.

Examples of such organic solvents include alcohol solvents having 1 to 3 carbon atoms such as isopropyl alcohol and ethylene glycol, and glycol ether solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, and propylene glycol monoethyl ether.

< second agent >

The second agent of the present composition is not particularly limited as long as it contains the zinc powder (B), and may be substantially composed of only the zinc powder (B), or may contain components other than the zinc powder (B) within a range not impairing the effects of the present invention.

These other components may be used alone in 1 kind, or in 2 or more kinds.

[ Zinc powder (B) ]

The zinc powder (B) includes a powder of metallic zinc or a powder of an alloy mainly containing zinc (the zinc content is 90 mass% or more of the total amount), for example, an alloy of zinc and at least 1 kind selected from aluminum, magnesium and tin, preferably a zinc-aluminum alloy or a zinc-tin alloy.

As the zinc powder (B), 1 kind or 2 or more kinds may be used.

The shape of the zinc powder (B) is not particularly limited, and is preferably a particulate zinc powder having a median diameter (D50) of preferably 2 to 15 μm, more preferably 2 to 7 μm, from the viewpoint of easily obtaining a coating film having a further excellent corrosion resistance.

This D50 can be measured using a laser scattering diffraction particle size distribution measuring apparatus, for example, "SALD 2200" (manufactured by Shimadzu corporation).

The content of the zinc powder (B) is 43 to 85% by mass based on 100% by mass of the nonvolatile content of the present composition, and is preferably 45 to 85% by mass, more preferably 50 to 85% by mass, and particularly preferably 65 to 82% by mass, from the viewpoint of easily obtaining a coating film having more excellent corrosion resistance.

When the content of the zinc powder (B) is less than 43% by mass, the sacrificial anode action of zinc becomes insufficient, and the corrosion resistance is liable to be lowered, and when it exceeds 85% by mass, the pigment component in the dried coating film becomes excessive, and the water permeability resistance is liable to be lowered.

The components other than the zinc powder (B) may be the same as the other components described in the first part.

As described above, the second agent is preferably in a liquid state (paste state), and in this case, the second agent preferably contains an organic solvent in view of excellent dispersibility of the zinc powder (B), excellent miscibility with the first agent, and the present composition in which the zinc powder (B) is uniformly dispersed can be easily obtained.

As a specific example of such an organic solvent, the same organic solvents as those listed in the section of the first agent are preferable.

In addition, the second agent is preferably free of water, because the zinc powder (B) reacts with water, and thus the corrosion resistance is reduced by oxidation of the zinc powder (B), and the risk of fire due to the generation of hydrogen is increased.

The content of the organic solvent in the second agent is preferably an amount such that the VOC amount in the present composition falls within the above range, but from the viewpoint of excellent dispersibility of the zinc powder (B), the content of the organic solvent in the second agent is preferably 1 to 10% by mass, more preferably 3 to 8% by mass, based on 100% by mass of the second agent.

In addition, the second agent preferably contains a thixotropic agent for the same reasons as described above, the transportability and storage stability of the second agent, and the thixotropic agent may be the same as those listed for the first agent.

[ Binders other than the resin (A) ]

The second agent preferably contains a binder other than the resin (a), and more preferably a compound reactive with the resin (a). Examples of such compounds include epoxy resins, isocyanate-based curing agents, carbodiimide-based curing agents, and epoxy group-containing silane coupling agents, and epoxy resins are particularly preferable because a coating film having more excellent corrosion resistance can be easily obtained.

The epoxy resin preferably has 2 or more epoxy groups in 1 molecule, and resin physical properties such as molecular weight and epoxy equivalent of the resin are not particularly limited, and the epoxy resin is preferably in a liquid state at room temperature (23 ℃) from the viewpoint of suppressing an increase in VOC content of the present composition.

In the case of using the epoxy resin, it is preferable to use the epoxy resin together with the organic solvent in view of the miscibility with the zinc powder (B) and the like.

The epoxy resin may be used in 1 kind, or 2 or more kinds.

Examples of the epoxy resin include bisphenol a type epoxy resins, bisphenol F type epoxy resins, phenol novolac type epoxy resins (for example, phenol novolac type epoxy resins, cresol novolac type epoxy resins), alicyclic epoxy resins, and fatty acid-modified epoxy resins. Among these, bisphenol a type epoxy resins and bisphenol F type epoxy resins are preferred in terms of ease of obtaining a coating film having more excellent corrosion resistance, low viscosity, and excellent workability in producing the second agent.

As the above-mentioned epoxy resin, a commercially available product can be used, and examples of the commercially available product include jER828 (manufactured by Mitsubishi chemical corporation, bisphenol A type epoxy resin, acid value: < 1mgKOH/g), jER807 (manufactured by Mitsubishi chemical corporation, bisphenol F type epoxy resin, acid value: < 1mgKOH/g) which is an epoxy resin having no carboxyl group.

When such an epoxy resin is contained, the content of the resin is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass, based on 100% by mass of the nonvolatile content of the present composition, from the viewpoint of easily obtaining a coating film having more excellent corrosion resistance.

< preparation of anticorrosive coating composition >

The first agent and the second agent may be prepared by mixing (kneading) the respective components to be blended with these agents, and when the mixing (kneading) is performed, the respective components may be added and mixed at once, or may be added and mixed in plural portions.

The present composition can be prepared by mixing (kneading) these first agent, second agent and other agents (for example, third agent) used as needed.

For the mixing (kneading), conventionally known devices such as a mixer, a disperser, a stirrer and the like can be used, and examples of the device include a disperser, a mixing-dispersing mill, a mortar stirrer, a roll, a paint shaker and a homogenizer. In the case of the above-mentioned mixing (kneading), the mixing (kneading) may be carried out while heating, cooling, etc. are carried out depending on the season, environment, etc.

When the present composition is prepared by mixing the above-mentioned respective agents, the zinc powder (B) content in the obtained composition may be adjusted so as to fall within the above-mentioned range and then mixed.

Coating film, substrate with coating film

The coating film according to the present invention (hereinafter, also referred to as "the present coating film") is formed using the present composition, and the substrate with a coating film according to the present invention (hereinafter, also referred to as "the substrate with a coating film according to the present invention") is a laminate having the coating film according to the present invention and the substrate.

The material of the base material is not particularly limited, and examples thereof include steel (iron, steel, alloy iron, carbon steel, mild steel, alloy steel, etc.), nonferrous metals (zinc, aluminum, copper, brass, zinc plating, zinc spray, etc.), and stainless steel (SUS304, SUS410, etc.).

When mild steel (SS400, etc.) is used as the base material, it is preferable to perform a base adjustment (for example, adjustment such that the arithmetic average roughness (Ra) is about 30 to 75 μm) by, for example, polishing the surface of the base material with a grit blast or the like as necessary.

The substrate may be one that has been subjected to a pretreatment such as a cleaning treatment for removing rust, dirt, paint (old coating film) and the like adhering to the substrate, a blasting treatment and the like.

The substrate is not particularly limited, and any substrate requiring corrosion resistance can be used without limitation, and from the viewpoint of further exhibiting the effects of using the present composition, a (steel) structure such as a ship, a marine structure, a plant, a bridge, a storage tank, and a container is preferable.

The dry film thickness of the coating film of the present invention is not particularly limited, but is usually 10 to 100. mu.m, preferably 15 to 80 μm, and more preferably 20 to 60 μm, from the viewpoint of obtaining a coating film having sufficient corrosion resistance.

The substrate with a coating film of the present invention is a laminate comprising the coating film of the present invention and a substrate, and an intermediate layer coating film for the purpose of improving corrosion resistance and a surface layer coating film excellent in weather resistance, appearance and the like can be further formed on the coating film of the present invention. Examples of the intermediate layer coating film include coating films formed from various intermediate coating composition such as acrylic resin-based, epoxy resin-based, and urethane resin-based coating films. Examples of the top coating film include coating films formed from various top coating compositions such as acrylic resin-based, acrylic silicone resin-based, urethane resin-based, silicone resin-based, and fluorine resin-based coating compositions.

Method for producing substrate with coating film

The method for producing a substrate with a coating film according to the present invention (hereinafter, also referred to as "the present method") includes the following steps [1] and [2 ]:

step [1 ]: a step of applying the present composition to a substrate;

step [2 ]: and drying the present composition applied to the substrate to form a coating film.

< Process [1] >

The coating method in the step [1] is not particularly limited, and examples thereof include conventionally known methods such as spray coating such as airless spray coating and air spray coating, brush coating, and roll coating. Among these, spray coating is preferable because it can be easily applied to a large-area substrate such as the above-described structure.

When such coating is performed, it is preferable to perform the coating so that the dry film thickness of the obtained coating film falls within the above range.

The conditions of the spray coating can be appropriately adjusted depending on the thickness of the dry film to be formed, and for example, in the case of airless spray coating, it is preferable to perform the spray coating at 1 (air) pressure: about 0.3-0.6 MPa, 2 times (coating) pressure: about 10 to 15MPa, and a moving speed of the spray gun is about 50 to 120 cm/sec.

When the present composition is applied, the viscosity of the coating composition can be adjusted as desired. As a diluent for such viscosity adjustment, water is preferably used.

In this case, the diluent is preferably used so as to have a coating viscosity suitable for each coating method, and for example, in the case of airless spray coating, the amount of the diluent used is preferably 1 to 30 parts by mass, and more preferably 1 to 20 parts by mass, per 100 parts by mass of the present composition.

The viscosity of the present composition (diluted composition if necessary) suitable for the spray coating is preferably 3,000 to 15,000mPa · s, more preferably 5,000 to 12,000mPa · s, as measured by a B-type viscometer (RION co., ltd., model VT-06) as a measuring device under a measuring condition of 23 ℃.

< Process [2] >

The drying conditions in the step [2] are not particularly limited, and may be appropriately set depending on the method of forming the coating film, the type and use of the substrate, the coating environment, and the like, and the drying temperature is usually 5 to 35 ℃ and more preferably 10 to 30 ℃ in the case of drying at normal temperature, and is usually 30 to 90 ℃ and more preferably 40 to 80 ℃ in the case of forced drying by a hot air dryer or the like. According to the present composition, the composition can be cured even by such drying at room temperature.

The drying time varies depending on the method of drying the coating film, and when drying at room temperature, it may be about 1 to 7 days as in the case of the conventional coating material, but the drying time is preferably 3 to 12 hours, more preferably 5 to 10 hours, by using the present composition. In the case of forced drying, it may be about 5 minutes to 60 minutes as in the case of the conventional coating material, but it is preferably dried for 5 minutes to 30 minutes, more preferably 10 minutes to 20 minutes by using the present composition.