JP7216119B2 - Water-based primary anticorrosive paint composition and use thereof - Google Patents

Description

One embodiment of the present invention relates to a water-based primary anticorrosive coating composition and its use.

Conventionally, for the purpose of temporarily suppressing rusting when constructing structures such as ships, offshore structures, plants, bridges, land tanks, especially steel structures, primary antirust paints are used to A primary anticorrosive coating is formed on the surface of the base material, which is the material of the structure.

Known examples of the primary antirust paint include organic antirust paints such as wash primers, non-zinc epoxy primers and epoxy zinc-rich primers, and inorganic zinc antirust paints containing a siloxane-based binder and zinc powder.

When constructing a structure using a base material with a primary antirust coating, it may be required to remove the primary antirust coating before welding. In addition, regarding the primary antirust coating that does not conform to the International Maritime Organization (IMO) Performance Standards for Painting (PSPC), 70% or more of the coating is removed from the base material with the primary antirust coating when manufacturing ballast tanks. There is a need. In these cases, it is required that the primary antirust coating can be easily removed.

In addition, the primary antirust paint is desired to improve the working environment, and a low VOC (Volatile Organic Compounds) type paint with reduced volatile organic compounds is particularly desired. Examples of such paints include high-solid solvent-based paints, solvent-free paints, and water-based paints. A water-based paint is desired because it can be applied in a relatively thin film by diluting it with water.

As such a primary anticorrosion coating, US Pat. It is described to have

JP-A-10-060369

As described above, the primary anticorrosion coating film may be required to be easily removable unlike general anticorrosion coating films. The film has room for improvement in terms of the removability of this coating film. Specifically, it takes a lot of time to remove the coating film formed from the conventional primary antirust paint, and the abrasives used to remove the coating film are prone to clogging. As a result, it took a long time to remove the coating film, and the frequency of replacement of the abrasive was increased, making it impossible to remove the coating film economically.

When forming the primary anticorrosive coating film on the base material, line coating is often adopted in which coating is performed while the base material is being transported on a belt conveyor, etc. In the line coating, the primary anticorrosive coating film is formed. Since the base materials are stacked and stored, the primary anticorrosive coating film to be formed must be excellent in stackability (hereinafter simply referred to as "stackability") so that sticking does not occur when stacked in this way. is also required.

One embodiment of the present invention provides a water-based primary antirust coating composition that has sufficient antirust (anticorrosion) properties and is capable of forming a primary antirust coating film that is excellent in removability and stackability.

The present inventors have diligently studied to solve the above problems. As a result, the inventors have found that the above problems can be solved by the following configuration example, and have completed the present invention. A configuration example of the present invention is as follows.

[1] An aqueous primary containing an epoxy resin (A) having a bisphenol skeleton, a flat pigment (B), an antirust pigment (C) (excluding the flat pigment (B)), and water An antirust paint composition,
The content of the flat pigment (B) in the nonvolatile matter of the water-based primary rust preventive coating composition is 40% by mass or more,
A water-based primary antirust paint composition.

[2] The water-based primary rust preventive coating composition according to [1], wherein the flat pigment (B) has a Mohs hardness of 3.5 or less.
[3] The water-based primary antirust paint composition according to [1] or [2], wherein the flat pigment (B) contains at least one selected from talc and mica.

[4] The water-based primary antirust coating composition according to any one of [1] to [3], wherein the epoxy resin (A) is an epoxy resin having a bisphenol A skeleton.
[5] The water-based primary rust preventive coating composition according to any one of [1] to [4], wherein the epoxy resin (A) has a number average molecular weight of 800 or more.

[6] The epoxy resin (A) is at least one selected from epoxy resins modified with an amine compound having a polyoxyalkylene chain, fatty acid-modified epoxy resins, vinyl-modified epoxy resins and (meth)acrylic-modified epoxy resins. The water-based primary antirust coating composition according to any one of [1] to [5].

[7] The water-based primary antirust coating composition according to any one of [1] to [5], further comprising an amine curing agent (D).
[8] The water-based primary antirust coating composition according to [7], wherein the amine curing agent (D) contains a water-soluble amine compound.
[9] A primary antirust coating film formed from the water-based primary antirust coating composition according to any one of [1] to [8].
[10] A base material with a primary rust preventive coating, comprising a base material and the primary rust preventive coating described in [9].

[11] A step of applying the water-based primary anticorrosive coating composition according to any one of [1] to [8] to a substrate, and drying or curing the applied water-based primary anticorrosive coating composition. A method for producing a base material with a primary antirust coating, comprising the step of forming a primary antirust coating.

[12] A step of coating a base material with the water-based primary antirust coating composition according to any one of [1] to [8],
a step of drying or curing the coated water-based primary antirust coating composition to form a primary antirust coating;
A method for producing a substrate with an anticorrosion coating, comprising the steps of removing 70% or more of the primary antirust coating, and applying an anticorrosion coating to the substrate from which 70% or more of the primary antirust coating has been removed. .

According to the water-based primary antirust coating composition according to one embodiment of the present invention, it has sufficient antirust (anticorrosion) properties, especially even with a thin film (eg, 25 μm or less), and has excellent stackability. It is possible to easily form a primary antirust coating film that can be removed in a short time without causing clogging when the coating film is removed with a grinder, sandpaper, or the like.
In addition, the primary anticorrosive coating composition according to one embodiment of the present invention can be a low VOC composition, has excellent quick-drying properties, and can easily form a uniform thin film (eg, 25 μm or less).

FIG. 1 is a photograph showing a specific example of the state of the abrasive cleaning material (disk) according to each evaluation standard after the paint film removal work in the following examples.

≪Water-based primary anticorrosive paint composition≫
A water-based primary anticorrosive coating composition (hereinafter also referred to as "this composition") according to one embodiment of the present invention comprises an epoxy resin (A) having a bisphenol skeleton, a flat pigment (B), and an anticorrosive pigment. (C) (excluding the flat pigment (B)) and water,
It is a composition in which the content of the flat pigment (B) in the non-volatile matter of the composition is 40% by mass or more.
As described above, the present composition contains the above (A) to (C) and water, and in particular contains a specific amount of (B), so that the above-mentioned effects are exhibited.

This composition is a water-based primary antirust coating composition. Here, "aqueous composition" refers to a composition containing water. Water, which is an essential component of the present composition, serves as a dispersion medium when the epoxy resin (A) or the amine curing agent (D), which will be described later, is in the form of an aqueous dispersion, or as a solvent when it is in the form of an aqueous solution. or the epoxy resin (A), the essential component flat pigment (B), the rust preventive pigment (C), and the optional amine curing agent (D) and “other It may be water added in the preparation process of mixing with "components" or water contained in additives of "other components".

The content of water in the composition is not particularly limited, but the solvent and The content of water in 100% by mass of the dispersion medium is preferably 50 to 100% by mass, more preferably 60 to 100% by mass, and particularly preferably 70 to 100% by mass.
In addition, since it is possible to sufficiently disperse the pigment components such as the flat pigment (B) and the antirust pigment (C), and it is possible to easily obtain a composition having excellent paintability, The water content of is preferably 30 to 70% by mass, more preferably 30 to 60% by mass.
Although the present composition may be used after being diluted depending on the coating method and the like, each description in this specification is before dilution, except for the description regarding the VOC content below.

Preferably, the composition is a low VOC type coating composition.
In the present invention, "low VOC" means that the composition does not contain VOC components such as organic solvents at all, or contains almost no VOC components, specifically, the present composition when adjusted to a viscosity suitable for painting. It means that the VOC content in the composition is 200 g/L or less. The VOC content in the present composition is preferably 180 g/L or less, more preferably 150 g/L or less.

The VOC content in this composition can be calculated from the following formula (1) using the following composition specific gravity and heating residue.
VOC content (g/L) = composition specific gravity x 1000 x (100 - heating residue - water content) / 100 (1)

Composition specific gravity (g/ml): Under the temperature condition of 23°C, the composition (if the composition is a two-component composition consisting of a main agent and a curing agent, the main agent and the curing agent are mixed A value calculated by filling a specific gravity cup with an internal volume of 100 ml with the composition immediately after being treated, and weighing the mass of the composition.

Heating residue (% by mass): 1 g of this composition (if the composition is a two-component composition consisting of a main agent and a curing agent, the composition immediately after mixing the main agent and the curing agent) is placed on a flat bottom. Weigh it on a plate, spread it evenly using a wire with a known mass, leave it at 23 ° C for 24 hours, dry it at 105 ° C for 3 hours, and then weigh the residue and the wire. value. It is synonymous with the non-volatile content of the present composition.
Moisture content (% by mass): % by mass of water contained in 100% by mass of the present composition.

The present composition may be a one-component composition or a multi-component composition of two or more components. For example, when the epoxy resin (a1) to be described later is used as the epoxy resin (A), the present composition may be a multi-component composition, but the composition is excellent in ease of storage and coating workability. From this point of view, the composition is preferably a one-component composition. Further, for example, when the epoxy resin (a2) described later is used as the epoxy resin (A), the present composition is preferably a multi-component composition from the viewpoint of excellent storage stability.
In the case of a multi-component composition, these components are usually stored, stored, transported, etc. in separate containers, and mixed just before use.

The present composition is used for the purpose of primary rust prevention of substrates, and is preferably used for steel structures, specifically steel structures such as ships, offshore structures, plants, bridges, and land tanks. .
Moreover, it is preferably a composition used for line coating from the viewpoint that the effect of the present composition is exhibited more.

<Epoxy resin (A) having a bisphenol skeleton>
The epoxy resin (A) having a bisphenol skeleton is not particularly limited, and known bisphenol-type epoxy resins and modified products of the epoxy resins can be used.
The epoxy resin (A) is preferably used in the form of an aqueous dispersion dispersed in a water-containing dispersion medium (hereinafter also referred to as "aqueous medium"), or in the form of an aqueous solution dissolved in an aqueous medium.
The epoxy resin (A) used in this composition may be of one type or two or more types.

The aqueous medium is not particularly limited as long as it contains water, but the content of water in the medium is preferably 25 to 100% by mass, more preferably 50 to 100% by mass, and particularly preferably 60 to 100% by mass. % by mass.

The aqueous medium may contain a medium other than water, and examples of such a medium include acetone, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, and isobutyl alcohol. , 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, diacetone alcohol, dioxane, ethylene glycol, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether , ethylene glycol diethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether. These may be used individually by 1 type, and may use 2 or more types.

The epoxy resin (A) is preferably used in the form of an aqueous dispersion dispersed in an aqueous medium, and more preferably in the form of an emulsion. In the present invention, an emulsion means an emulsion in which oil droplets containing a resin are dispersed in an aqueous medium.

Examples of the method for preparing the emulsion include a method of forcibly emulsifying the epoxy resin (A) in an aqueous medium by a mechanical emulsification method, a phase inversion temperature emulsification method, or the like. In this case, it is preferable to use an emulsifier, and examples of the emulsifier include alkyl-type and alkylphenol-type nonionic surfactants, phosphate ester-type, alkylbenzenesulfonate-type, and sulfosuccinate-type anions. system surfactants. In addition, these emulsifiers may be used individually by 1 type, and may use 2 or more types.

Although the content of the epoxy resin (A) in the emulsion is not particularly limited, it is usually 20 to 90% by mass, preferably 30 to 80% by mass.

Examples of the bisphenol-type epoxy resin include bisphenol-A-type epoxy resin, bisphenol-F-type epoxy resin, and bisphenol-AD-type epoxy resin. From these points, bisphenol A type epoxy resin is preferable.
The bisphenol type epoxy resin may be used singly or in combination of two or more.

As the epoxy resin (A), a modified epoxy resin (a1) capable of forming a coating film exhibiting antirust properties without using a curing agent, or a modified epoxy resin (a1) exhibiting antirust properties when used in combination with a curing agent. It is preferably an epoxy resin (a2) capable of forming a coating film.
Although the epoxy resin (A) may contain the modified epoxy resin (a1) and the epoxy resin (a2), it is usually preferable to contain only one of them.

The number average molecular weight (Mn) of the epoxy resin (A) is such that a composition with excellent quick-drying properties can be easily obtained, and a coating film with excellent rust resistance, stackability, etc. can be easily obtained. , 800 or more.

The number average molecular weight in this specification is measured using GPC (gel permeation chromatography). The GPC conditions are as follows.
(GPC conditions)
・ Apparatus: "HLC-8120GPC" (manufactured by Tosoh Corporation)
Column: "SuperH2000" and "SuperH4000" (both manufactured by Tosoh Corporation, 6 mm (inner diameter), 15 cm (length))
- Eluent: tetrahydrofuran (THF)
・Flow rate: 0.500 ml/min
・Detector: RI
・Column bath temperature: 40°C
・Standard material: polystyrene

<Modified epoxy resin (a1)>
The modified epoxy resin (a1) forms a coating film exhibiting anticorrosive properties without using a curing agent, because it is possible to easily obtain a composition having excellent storage stability and coating workability. Further, resins modified for the purpose of reducing the use of emulsifiers in consideration of the water resistance of the coating film to be formed may be used. The modified epoxy resin can be obtained, for example, by modifying the epoxy group of the bisphenol type epoxy resin with at least one compound selected from amine compounds, fatty acids, glycidyl group-containing vinyl monomers and (meth)acrylic compounds. .

The modified epoxy resin (a1) preferably has a small number of epoxy groups remaining unmodified from the viewpoint of the water resistance and weather resistance of the coating film formed from the present composition. Specifically, the epoxy equivalent of the modified epoxy resin (a1) is preferably 2,200 or more, more preferably 3,000 or more.
The epoxy equivalent is calculated based on JIS K 7236:2001.

In general, even if a resin does not have an epoxy group, if a compound having an epoxy group is used as a raw material, a common name including "epoxy" is used. In the present invention, even a resin having no epoxy group in which all the epoxy groups of a compound having an epoxy group (e.g., a bisphenol type epoxy resin) as a raw material are modified is referred to as a "modified epoxy resin".

The number average molecular weight (Mn) of the modified epoxy resin (a1) may be selected according to the desired coating film properties, but the lower limit of the number average molecular weight is preferably 800 or more, more preferably 1,500 or more. and the upper limit of the number average molecular weight is preferably 100,000 or less, more preferably 70,000 or less, and particularly preferably 30,000 or less.
When Mn is within the above range, a composition having excellent quick-drying property can be easily obtained, and a coating film having excellent rust resistance, stackability, and the like can be easily obtained.
When the modified epoxy resin (a1) having an Mn of less than 800 is used in the form of an aqueous dispersion, it may take a relatively long time to dry and cure the resulting composition, and a coating film may not be formed in line coating or the like. Sticking may easily occur when stacking the base materials.

In the modified epoxy resin (a1), the Mn of the bisphenol-type epoxy resin before modification may be selected according to the desired coating film properties, but the lower limit of Mn is preferably 400 or more, more preferably is 800 or more, and the upper limit of Mn is preferably 6,000 or less, more preferably 5,000 or less, and particularly preferably 3,500 or less.
The bisphenol-type epoxy resin before being modified may be polymerized in advance and the Mn adjusted within the above range.
When Mn is within the above range, a composition having excellent quick-drying property can be easily obtained, and a coating film having excellent rust resistance, stackability, and the like can be easily obtained.
When the modified epoxy resin (a1) obtained by modifying the bisphenol type epoxy resin having an Mn of less than 400 is used in the form of an aqueous dispersion, it may take a relatively long time to dry and cure the resulting composition. In , line coating, etc., sticking may easily occur when stacking substrates on which a coating film is formed.

When the modified epoxy resin (a1) is used as the epoxy resin (A), the non-volatile content of the modified epoxy resin (a1) in the present composition makes it possible to easily obtain a composition having excellent quick-drying properties. It is preferably 5 to 50% by mass, more preferably 10 to 45% by mass, based on 100% by mass of the non-volatile content of the present composition, from the viewpoint that a coating film having excellent rust resistance can be easily obtained.

Specific examples of the modified epoxy resin (a1) include epoxy resins modified with an amine compound having a polyoxyalkylene chain, fatty acid-modified epoxy resins, vinyl-modified epoxy resins, and (meth)acrylic-modified epoxy resins. . Among these, polyoxyalkylene can be easily obtained from the viewpoint that a composition having excellent quick-drying property can be easily obtained, and a coating film having excellent balance of rust resistance, coating film hardness, stackability, etc. can be easily obtained. Epoxy resins modified with chained amine compounds are preferred.
The (meth)acrylic-modified epoxy resin is a resin obtained by modifying an epoxy resin with an acrylic compound and/or a methacrylic compound.

[Epoxy resin modified with amine compound having polyoxyalkylene chain]
The epoxy resin modified with an amine compound having a polyoxyalkylene chain is, for example, a reaction of one or more bisphenol-type epoxy resins with one or more amine compounds having a polyoxyalkylene chain. can be obtained by letting

Examples of the amine compound having a polyoxyalkylene chain include compounds represented by the following structural formula (2).
In Structural Formula (2), R represents a hydrogen atom or a methyl group, X and Y represent the number of repetitions, and are arbitrarily selected so that the molecular weight is a preferable value described later.

The molecular weight of the amine compound having a polyoxyalkylene chain is preferably a weight-average molecular weight (Mw) from the viewpoint that a composition having excellent stability, finish of a coating film, and rust prevention can be easily obtained. is 400-3,000, more preferably 500-1,100. Also, from the same point of view, the number average molecular weight (Mn) is preferably 400 to 4,500, more preferably 500 to 2,500.

As the amine compound having a polyoxyalkylene chain, a commercially available product may be used. Examples of the commercially available product include "Jeffamine M-600" (manufactured by Huntsman, weight average molecular weight: 600), "Jeffamine M-1000" (manufactured by Huntsman, weight average molecular weight: 1,000), "Jeffamine M-2005" (manufactured by Huntsman, weight average molecular weight: 2,000), "Jeffamine M-2070" (manufactured by Huntsman , weight average molecular weight: 2,000). Among these, "Jeffamine M-600" and "Jeffamine M-1000" are particularly preferred.

The amount of the amine compound having a polyoxyalkylene chain can be easily obtained from the point that a resin having excellent dispersibility in an aqueous medium can be easily obtained, and a coating film having excellent water resistance can be easily obtained. It is preferably 1 to 50 parts by mass, more preferably 4 to 30 parts by mass, based on 100 parts by mass of the bisphenol type epoxy resin.

The epoxy resin modified with an amine compound having a polyoxyalkylene chain is, for example, reacted with one or more alkylene glycols and one or more polyvalent isocyanate compounds, followed by isocyanate residues can be obtained by reacting with an amine compound having one or more polyoxyalkylene groups, and further reacting this with one or more epoxy resins.
Further, the resin obtained in this way may be used as an epoxy resin modified with an amine compound having a polyoxyalkylene chain by making the resin water-based by a mechanical emulsification method, a phase inversion temperature emulsification method, or the like. By using an aqueous dispersion containing the resin, a coating film having excellent anticorrosion properties can be easily obtained.
As the epoxy resin modified with an amine compound having a polyoxyalkylene chain, for example, a resin described in Japanese Patent No. 5575295 can be used.

[Fatty acid-modified epoxy resin]
The fatty acid-modified epoxy resin is produced, for example, by reacting one or more bisphenol-type epoxy resins with one or more fatty acids, and if necessary, the fatty acid in the resulting reaction product. It can be obtained by reacting an unsaturated portion with one or more radically polymerizable unsaturated monomers including a radically polymerizable unsaturated monomer containing a carboxyl group.
Further, the resin obtained in this way and a basic compound may be used, and the resin obtained by neutralizing the carboxyl groups in the resin to render it water-based may be used as the fatty acid-modified epoxy resin. A coating film having excellent water resistance can be obtained by using the aqueous dispersion containing the above.

As the fatty acid-modified epoxy resin, for example, a resin described in JP-A-2011-72966 can be used.

[Vinyl-modified epoxy resin]
Examples of the vinyl-modified epoxy resin include one or more bisphenol type epoxy resins, one or more glycidyl group-containing radically polymerizable unsaturated monomers, an amine compound, and a carboxyl group. It can be obtained by reacting with one or more radically polymerizable unsaturated monomers containing the radically polymerizable unsaturated monomer.
Further, the resin obtained in this manner and a basic compound may be used, and the resin obtained by neutralizing the carboxyl groups in the resin to render it water-based may be used as the vinyl-modified epoxy resin. A coating film having excellent water resistance can be obtained by using the aqueous dispersion containing the above.

[(Meth)acrylic modified epoxy resin]
The (meth)acrylic-modified epoxy resin comprises, for example, one or more bisphenol type epoxy resins, one or more carboxyl group-containing radically polymerizable unsaturated monomers or polymers, and further necessary It can be obtained by reacting with one or two or more radically polymerizable unsaturated monomers depending on the conditions.
Further, the resin obtained in this way and a basic compound may be used as the (meth)acrylic-modified epoxy resin to make the resin water-soluble by neutralizing the carboxyl groups in the resin. By using an aqueous dispersion containing the resin, a composition having excellent quick-drying property can be easily obtained, and a coating film having excellent weather resistance can be obtained.

As the vinyl-modified epoxy resin and the (meth)acrylic-modified epoxy resin, for example, resins described in JP-A-2012-1785 can be used.

<Epoxy resin (a2)>
The epoxy resin (a2) is more preferably a bisphenol A type epoxy resin containing two or more epoxy groups in one molecule.

The epoxy equivalent of the epoxy resin (a2) may be appropriately selected depending on the desired coating film properties, but is preferably 400 or more, more preferably 400 to 6,000, and still more preferably 400 to 3,000. .
When the epoxy equivalent is within the above range, a composition having excellent quick-drying property can be easily obtained, and a coating film having excellent rust resistance and the like can be easily obtained.
The epoxy equivalent is calculated based on JIS K 7236:2001.

The number average molecular weight (Mn) of the epoxy resin (a2) may be appropriately selected depending on the desired physical properties of the coating film. , 600.
When the Mn is within the above range, a composition having excellent quick-drying property can be easily obtained, and a coating film having excellent rust resistance and the like can be easily obtained.

When the epoxy equivalent of the epoxy resin (a2) is less than 400 and the Mn is less than 800, it takes a relatively long time to dry and cure the composition, and in line coating, etc., the base on which a coating film is formed. When stacking materials, sticking may easily occur.

A commercially available product may be used as the epoxy resin (a2). Commercially available products of the aqueous dispersion of the epoxy resin (a2) include, for example, "BECKOPOX EP384w/53WAMP" and "BECKOPOX 2307w/45WAMP" (both manufactured by Allnex).

When the epoxy resin (a2) is used as the epoxy resin (A), the non-volatile content of the epoxy resin (a2) in the composition makes it possible to easily obtain a composition having excellent quick-drying properties, and to prevent rust. From the point of view that a coating film having excellent properties such as adhesion and adhesion to a substrate can be easily obtained, it is preferably 1 to 50% by mass, more preferably 5 to 50% by mass, based on 100% by mass of the nonvolatile content of the composition. 50% by weight, particularly preferably 10 to 50% by weight.

<Flate pigment (B)>
Although the flat pigment (B) is not particularly limited, it is usually an inorganic pigment having a plate-like structure.
By using the flat pigment (B), it is possible to obtain a composition capable of forming a coating film excellent in rust prevention, stackability, coating film removability, and the like.
The flat pigment (B) used in the present composition may be of one type or two or more types.

The Mohs hardness of the flat pigment (B) is preferably 3.5 or less, more preferably 1 to 3.5, and particularly preferably 1 to 1 to 2.
Mohs hardness is a relative value obtained by rubbing two minerals together and measuring which mineral is damaged. Examples of the flat pigment (B) having a Mohs hardness within the above range include talc (Mohs hardness: 1) and mica (Mohs hardness: 2 to 3).

The lower limit of the average aspect ratio of the flat pigment (B) is preferably 6 or more. The upper limit is preferably 150 or less, more preferably 120 or less.
When the aspect ratio is within the above range, the flat pigment (B) is likely to be oriented horizontally with respect to the coating film, thereby forming a coating film having excellent coating film removability, salt water resistance, humidity resistance, and the like. can be done.

The aspect ratio of the flat pigment (B) is determined using a scanning electron microscope (SEM), for example, "TM 3030 Plus Miniscope" (manufactured by Hitachi High-Technologies Corporation, desktop SEM), and any 100 flat pigments. It can be calculated by measuring the thickness of (B) and the maximum length on the main surface and calculating the average value of the ratio (maximum length on the main surface/thickness).
The thickness of the flat pigment (B) can be measured by observing from the horizontal direction with respect to the main surface (surface with the largest area) of the flat pigment (B). The maximum length of the main surface of is, for example, the length of the diagonal if the main surface is square, the diameter if the main surface is circular, and the length of the major axis if the main surface is elliptical. means.

The median diameter (d50) of the flat pigment (B) is preferably 1 to 100 μm, more preferably 1 to 60 μm, from the viewpoint that a coating film having excellent coating film removability can be easily formed.
The median diameter can be measured using a laser scattering diffraction particle size distribution analyzer such as "SALD 2200" (manufactured by Shimadzu Corporation).

As the flat pigment (B), talc and mica are preferable because they are inexpensive and readily available, and can form a coating film having excellent rust resistance, stackability, and coating film removability. Talc is most preferred.
Commercial products of the flat pigment (B) include, for example, "TTK Talc" (manufactured by Takehara Chemical Industry Co., Ltd.) and "Talc F-2" (manufactured by Fuji Talc Industry Co., Ltd.). Examples of the mica include "mica powder 100 mesh" and "mica powder 325 mesh" (both manufactured by Fukuoka Talc Kogyosho Co., Ltd.).

The content of the flat pigment (B) in the present composition is 40% by mass or more with respect to 100% by mass of the non-volatile matter of the present composition.
In general paints, one pigment is rarely used in such a high content, but in the present composition, by using the flat pigment (B) in such a high content, sufficient rust prevention is achieved. A coating film having excellent coating film removability and stackability can be easily obtained. When the content of the flat pigment (B) is less than 40% by mass, it becomes difficult to obtain a coating film with excellent coating film removability.
From the point of view of being able to easily obtain an excellent coating film due to the above effect, the content of the flat pigment (B) in the present composition is preferably 40 to 65 mass %, more preferably 45 to 55 mass %.

<Antirust pigment (C)>
The composition contains an antirust pigment (C) in order to obtain a coating film having sufficient primary antirust properties.
The rust preventive pigment (C) is not particularly limited as long as it is a pigment other than the flat pigment (B), and conventionally known rust preventive pigments can be used.
The rust preventive pigment (C) used in the present composition may be of one type or two or more types.

Examples of the antirust pigment (C) include zinc phosphate compounds, calcium phosphate compounds, aluminum phosphate compounds, magnesium phosphate compounds, zinc phosphite compounds, calcium phosphite compounds, aluminum phosphite compounds, compounds, strontium phosphite-based compounds, zinc molybdate-based compounds, aluminum molybdate-based compounds, aluminum tripolyphosphate-based compounds, zinc tripolyphosphate-based compounds, zinc cyanamide-based compounds, borate compounds, nitro compounds, and complex oxides. mentioned. Among these, aluminum phosphate-based compounds are preferable from the viewpoint that a coating film having excellent rust resistance can be easily obtained.

Examples of commercially available antirust pigments (C) include "LF Bosei PW2" (manufactured by Kikuchi Color Co., Ltd.) as a zinc phosphate compound, and "K White #140W" (Taika 140W) as an aluminum tripolyphosphate compound. (manufactured by Kikuchi Color Co., Ltd.), and examples of aluminum phosphate compounds include "LF Bosei PM-303W" (manufactured by Kikuchicolor Co., Ltd.).

The content of the rust preventive pigment (C) in the present composition is, based on 100% by mass of the nonvolatile content of the present composition, from the viewpoint that a coating film having sufficient primary rust preventive power can be easily obtained. It is preferably 1 to 20% by mass, more preferably 3 to 10% by mass.

<Amine curing agent (D)>
When the epoxy resin (a2) is used as the epoxy resin (A), the present composition preferably contains an amine curing agent (D).
The amine curing agent (D) used in the present composition may be of one type or two or more types.

The amine curing agent (D) is not particularly limited as long as it is an amine compound other than a tertiary amine (amine compound having only a tertiary amino group). Preferred are amine compounds, such as polyamine compounds.

Examples of the aliphatic amine compounds include alkylenepolyamines, polyalkylenepolyamines, and alkylaminoalkylamines.

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

As the polyalkylenepolyamine, for example, the formula: "H ₂ N-(C _m H _2m NH) _n H" (m is an integer of 1 to 10, n is an integer of 2 to 10, preferably 2 is an integer of to 6.) Specifically, for example, diethylenetriamine, dipropylenetriamine, triethylenetetramine, tripropylenetetramine, tetraethylenepentamine, tetrapropylenepentamine, pentaethylene Hexamine, nonaethylenedecamine, bis(hexamethylene)triamine, triethylene-bis(trimethylene)hexamine.

Examples of the alkylaminoalkylamine include the formula: "R ² ₂ N--(CH ₂ ) _p --NH ₂ " (R ² is independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, provided that , at least one R ² is an alkyl group having 1 to 8 carbon atoms.), and p is an integer of 1 to 6.) Specifically, for example, dimethylaminoethylamine , diethylaminoethylamine, dibutylaminoethylamine, dimethylaminopropylamine, diethylaminopropylamine, dipropylaminopropylamine, dibutylaminopropylamine, dimethylaminobutylamine.

Aliphatic amine compounds other than these include, for example, tetra(aminomethyl)methane, tetrakis(2-aminoethylaminomethyl)methane, 1,3-bis(2'-aminoethylamino)propane, 2,2' -[ethylenebis(iminotrimethyleneimino)]bis(ethanamine), tris(2-aminoethyl)amine, bis(cyanoethyl)diethylenetriamine, polyoxyalkylenepolyamines (especially diethylene glycol bis(3-aminopropyl) ether) be done.

Specific examples of the alicyclic amine compounds include cyclohexanediamine, diaminodicyclohexylmethane (especially 4,4′-methylenebiscyclohexylamine), 4,4′-isopropylidenebiscyclohexylamine, and norbornanediamine. , bis(aminomethyl)cyclohexane, isophoronediamine, menzenediamine (MDA), 2,4-di(4-aminocyclohexylmethyl)aniline.

Examples of the aromatic amine compounds include bis(aminoalkyl)benzene, bis(aminoalkyl)naphthalene, and aromatic polyamine compounds having two or more primary amino groups bonded to a benzene ring.
More specifically, the aromatic amine compound includes, for example, o-xylylenediamine, m-xylylenediamine (MXDA), p-xylylenediamine, phenylenediamine, naphthalenediamine, diaminodiphenylmethane, 2,2- bis(4-aminophenyl)propane, 4,4'-diaminodiphenyl ether, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenyl sulfone, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, diamino diethylphenylmethane, 2,4'-diaminobiphenyl, 2,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, bis(aminomethyl)naphthalene, bis (Aminoethyl)naphthalene may be mentioned.

Examples of the heterocyclic amine compounds include 1,4-bis(3-aminopropyl)piperazine, 1,4-diazacycloheptane, 1-(2′-aminoethylpiperazine), 1-[2′- (2″-Aminoethylamino)ethyl]piperazine, 1,11-diazacycloeicosane, 1,15-diazacyclooctacosane.

The amine curing agent (D) may further be a modified product of the amine compound described above. Examples of the modified product include fatty acid modified products such as polyamidoamine, amine adducts with epoxy compounds, and Mannich modified products. (eg, phenalkamine, phenalkamide), Michael adducts, ketimine, aldimine. Among these, polyamidoamines, amine adducts with epoxy compounds, and Mannich-modified products are preferred.

A water-soluble amine compound can be used as the amine curing agent (D). The water-soluble amine compound is a compound that becomes transparent in appearance when 30% by mass of water and 70% by mass of an amine compound are mixed at 25° C. and sufficiently stirred.
As such a water-soluble amine compound, the aforementioned amine compound or a compound obtained by hydrophilizing the aforementioned amine compound by a known method can be used. Examples of the hydrophilization method include the introduction of a group that promotes water solubility such as a carboxyl group, a sulfonic acid group, a sulfinic acid group, a phosphonic acid group, and a hydroxyl group; introduction of a sexual group.

Such water-soluble amine compounds may be premixed with water. As the water-soluble amine compound, a commercially available product may be used, and examples of the commercially available product include "Daitoclar I-6020" (manufactured by Daito Sangyo Co., Ltd.), "Anquamine 401", and "Sunmide WH-900". (both manufactured by Evonik Industries AG) and "BECKOPOX EH 613w/80WA" (manufactured by Allnex).

Furthermore, as the amine curing agent (D), an aqueous dispersion in which the amine compound is dispersed in an aqueous medium can be used. The aqueous dispersion is not particularly limited, but includes, for example, an emulsion in which the amine compound is dispersed in the aqueous medium.
As such an emulsion of an amine compound, a commercial product may be used, and examples of the commercial product include "Fujicure FXS-918-FA" (manufactured by T&K TOKA Co., Ltd.), "EPILINK 701" ( manufactured by Evonik Industries AG).

As the amine curing agent (D), a water-soluble amine compound is preferable from the viewpoints of adhesiveness to the substrate and rapid development of water resistance of the coating film.

The active hydrogen equivalent of the amine curing agent (D) is preferably from 50 to 600, more preferably from 100 to 450, from the viewpoint that a coating film having excellent curability and rust resistance can be easily obtained.

In the present composition, the total content of the epoxy resin (A) and an epoxy compound other than the epoxy resin (A) (hereinafter collectively referred to as "epoxy component"), and the amine curing agent (D) The amount is preferably 1.1 to 50% by mass, more preferably 6 to 50% by mass, more preferably 14 to 50% by mass.
Also, the amount of the amine curing agent (D) to be used may be appropriately selected according to the amount of the functional group of the epoxy component to be used.

<Other ingredients>
The present composition contains, as components other than (A) to (D), an epoxy compound other than the epoxy resin (A), pigments (E) other than the pigments (B) and (C), flash last Inhibitor (F), curing catalyst, dispersant, defoamer, anti-settling agent, wetting agent, thickener, film-forming aid, surface control agent, textile material, surfactant, anti-mold agent, preservative, An ultraviolet absorber, a light stabilizer, a pH adjuster, a silane coupling agent, a medium other than water, and the like may be added as necessary.
Each of these may be used alone or in combination of two or more.

The present composition preferably does not contain zinc dust from the viewpoint of cost advantage, conservation of resources, consideration for the environment and health. For example, it is 25% by mass or less with respect to 100% by mass of the non-volatile content of the product.

<Epoxy compounds other than epoxy resin (A)>
The composition may contain an epoxy compound other than the epoxy resin (A). Examples of such epoxy compounds include novolac type epoxy resins, polyglycol type epoxy resins, epoxidized oils, 1,6-hexanediol diglycidyl ether, and neopentyl glycol diglycidyl ether.

<Other pigments (E)>
The present composition may contain the other pigment (E) as long as it does not impair the properties of the present invention. Examples of the pigment (E) include extender pigments and coloring pigments. Any inorganic system may be used.

As the extender pigment, conventionally known pigments can be used, for example, (precipitated) barium sulfate; (potassium) feldspar; alumina white; clay; magnesium carbonate; Clay minerals such as montmorillonite, saponite, and hectorite, or modified products thereof.

When the present composition contains an extender, the content of the extender is preferably 0.01 to 10% by mass with respect to 100% by mass of the non-volatile matter of the present composition.

As the coloring pigment, conventionally known pigments can be used, for example, carbon black, titanium dioxide (titanium white), iron oxide (red iron oxide), yellow iron oxide, inorganic pigments such as ultramarine blue, cyanine blue, cyanine green. and other organic pigments. Among these, titanium white, carbon black, and rouge are preferred.

When the composition contains a coloring pigment, the content of the coloring pigment is preferably 0.01 to 20% by mass, more preferably 0.01 to 15% by mass, based on 100% by mass of the nonvolatile content of the composition. %.

When the present composition contains the flat pigment (B), the antirust pigment (C) and other pigments (E), the pigment volume concentration (PVC) of all these pigments is It is preferably 34 to 70%, more preferably 34 to 65%, particularly preferably 34 to 60%, from the viewpoint that a more excellent coating film can be easily obtained.
If the PVC is less than the above range, the removability of the resulting coating film may be reduced, and if it exceeds the above range, the water resistance and rust resistance of the resulting coating film may be reduced. .

The PVC refers to the total volume concentration of pigments relative to the volume of non-volatile matter in the composition. PVC can specifically be obtained from the following formula (3).
PVC [%] = total volume of all pigments in this composition x 100/volume of non-volatile matter in this composition (3)

<Flash rust preventive agent (F)>
The present composition may contain a flash rust inhibitor (F) from the viewpoint of suppressing flash rust (spotted rust).
The antiflash rust agent (F) is not particularly limited, but examples include nitrites such as sodium nitrite, potassium nitrite, calcium nitrite, strontium nitrite, barium nitrite, and ammonium nitrite; sodium benzoate, potassium benzoate, Benzoates such as calcium benzoate and ammonium benzoate; Phytates such as sodium phytate and potassium phytate; Fatty acid salts such as sebacic acid and dodecanoic acid; Phosphoric acid derivatives such as alkyl phosphoric acid and polyphosphoric acid; Salt; Sulfonic acid metal salt; N-(2-hydroxyethyl)ethylenediaminetriacetic acid (HEDTA), ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), propylenediaminetetraacetic acid (PDTA), iminodiacetic acid, nitrilotriacetic acid Amine-based chelating agents such as acetic acid (NTA), diethylenetriaminepentamethylenephosphonic acid (DTPMP), alkali metal salts thereof; addition reaction products of 4-methyl-γ-oxo-benzenebutanoic acid and N-ethylmorpholine; monoalkylamines Intercalation compounds obtained by intercalating layered phosphates such as aluminum dihydrogen tripolyphosphate with polyamines, quaternary ammonium ions, etc.; hydrazine derivatives such as hydrazide compounds, semicarbazide compounds and hydrazone compounds.

When the present composition contains a flash rust inhibitor (F), the content of the flash rust inhibitor (F) is preferably 0.01 to 0.5 with respect to 100% by mass of the non-volatile matter of the composition. % by mass, more preferably 0.01 to 0.3% by mass.

<<Primary antirust coating film, substrate with primary antirust coating film, method for producing substrate with primary antirust coating film>>
A primary anticorrosive coating film according to an embodiment of the present invention is formed from the present composition, and specifically, the primary anticorrosive coating film is formed by drying and/or curing the present composition. be able to. Such a primary antirust coating film is usually formed on a substrate to form a substrate with a primary antirust coating film.
The primary antirust coating film is preferably formed on the substrate and then removed from the substrate from the viewpoint that the effect of the present composition is more exhibited. , may not be removed from the substrate. In this case, if necessary, another coating may be applied over the primary antirust coating.

The substrate with the primary antirust coating is preferably produced by coating the substrate with the present composition, and drying and/or curing the applied composition. It can be said that this method for producing a base material with a primary rust preventive coating is a primary rust preventive method for a base material.

Examples of the base material include metal base materials such as those made of steel and aluminum, and steel base materials are preferable because the effects of the present invention are more exhibited.
Examples of the steel base material include base materials for steel structures, specifically, steel structures such as ships, offshore structures, plants, bridges, and land tanks.

As for the base material, the surface of the base material may be treated (for example, Blast treatment (ISO8501-1 Sa2 1/2), friction method, treatment to remove oil and dust by degreasing), etc. may also be used.

Although the coating method is not particularly limited, conventionally known methods such as air spray coating, airless spray coating, brush coating, roller coating, and dipping can be employed.
In addition, line coating is preferable because the effect of the present composition is exhibited more effectively.

^The coating amount of the present composition is not particularly limited and may be appropriately selected according to the desired application.
Also, the film thickness of the primary antirust coating film is not particularly limited, and may be appropriately selected according to the desired application. The coating should be applied so that a thick coating film is obtained.
As described above, the present composition is preferably line-coated, and in this case, since quick drying is particularly required, a thin film, preferably 30 μm or less, more preferably 15 to 30 μm, should be formed. is desirable. According to the present composition, even if such a thin coating film is formed, a coating film having sufficient antirust properties can be formed.

The drying and/or curing may be performed at normal temperature or under heating.
Preferred drying and/or curing conditions include conditions for drying and curing for about 3 to 5 minutes at a temperature of about 5 to 80°C. It is preferably preheated to 100°C and then coated with the composition, and then dried and cured at a temperature of about 30 to 100°C for about 5 to 10 minutes.

≪Method for producing base material with anticorrosion coating film≫
A method for producing a substrate with an anticorrosion coating film according to one embodiment of the present invention includes the step of coating the substrate with the present composition,
drying or curing the coated composition to form a primary antirust coating;
The method has a step of removing 70% or more of the primary antirust coating, and a step of applying an anticorrosive coating to the substrate from which 70% or more of the primary antirust coating has been removed.
It can be said that this method for producing a base material with an anticorrosion coating film is a method for preventing the base material from rusting.

Examples of the step of applying the present composition to the base material and the step of forming the primary antirust coating film include the same methods as those described above.
In general, a certain amount of time elapses between the formation of the primary antirust coating and the removal of the coating. As this time, for example, the time from the formation of the primary antirust coating film on the base material to the construction of a structure using the formed base material with the primary antirust coating film, the time required for storage, transportation, etc. mentioned. Usually, the period during which the substrate with the primary anticorrosive coating obtained from the present composition is stored is about 6 months at the longest when the storage is indoors. When the base material with the primary antirust coating film is exposed to the outdoor environment during storage, transportation, or the like, the period is about one week at the longest.

The method for removing the primary anticorrosive coating film is not particularly limited, and conventionally known methods for removing the coating film can be employed. Examples of such a method include a method using a grinder, sandpaper, and the like, and a blasting method such as shot blasting.
The removal is not particularly limited as long as 70% or more of the primary antirust coating film formed on the substrate is removed. In addition, "70% or more is removed" means that 70% or more is removed when the area of the primary rust preventive coating film formed on the substrate is taken as 100% (the primary rust preventive coating film is formed 70% or more of the base material is exposed out of 100% of the exposed portion).

The anticorrosive paint is not particularly limited, and conventionally known anticorrosive paints can be used. Such anticorrosive paints include, for example, epoxy-based anticorrosive paints.
The method of applying the anticorrosion paint, the method of forming the anticorrosion coating film, the film thickness of the anticorrosion coating film, and the like are not particularly limited, and may be appropriately selected according to the desired application.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples.

[Example 1]
15.77 parts by mass of ion-exchanged water, 0.1 parts by mass of sodium nitrite, 0.2 parts by mass of modified bentonite (Note 7), 2 parts by mass of a dispersant (Note 10), and an antifoaming agent (Note 11) ) 0.1 parts by mass, 0.4 parts by mass of wetting agent (Note 12), 6 parts by mass of white titanium oxide (Note 5), 26 parts by mass of talc (Note 1), and antirust pigment (Note 4) 3 parts by mass and 0.03 parts by mass of black pigment (Note 6) are put in a container, and dispersed with a paint shaker until the particle size becomes 50 μm or less (JIS K 5600-2-5: 1999, according to distribution map method evaluation). processed to obtain a pigment paste.

To this pigment paste, 2 parts by mass of a film-forming aid (Note 16), 56 parts by mass of an epoxy resin emulsion (Note 13), 0.2 parts by mass of an antifoaming agent (Note 11), and a surface conditioner (Note 17) 0.2 parts by mass were sequentially added, and the main agent was prepared by stirring for 15 minutes after the completion of the addition.

1.5 parts by mass of a water-soluble epoxyadduct amine (Note 18), 1 part by mass of a film-forming aid (Note 16), and 2.5 parts by mass of ion-exchanged water are put into a container, and a high-speed disperser is used. Then, the curing agent was prepared by mixing under normal temperature and normal pressure.

The resulting main agent and curing agent were mixed at the mixing ratio shown in Table 1 before coating to prepare a water-based primary rust preventive coating composition.

[Examples 2 to 13 and Comparative Examples 1 to 11]
Each coating composition was prepared in the same manner as in Example 1, except that the types and blending amounts of the raw materials were changed as shown in Table 1 or 2 below. Details of the raw materials described in Tables 1 and 2 are as shown in Table 5. Numerical values in the columns of raw materials in Tables 1 and 2 indicate parts by mass.

[Synthesis Example 1]
In a 2-liter glass flask equipped with an inert gas inlet tube, 905 g of bisphenol A type epoxy resin (Epikote 828, manufactured by Mitsubishi Chemical Corporation, number average molecular weight 370), 265 g of bisphenol A (manufactured by Dow Chemical Company) and 0.4 g of triethylbenzylammonium chloride (manufactured by Tokyo Kasei Kogyo Co., Ltd.) was added, and the reaction was allowed to proceed at 160°C over about 2 hours until the viscosity no longer increased, then gradually cooled, and 330 g of butyl cellosolve at 80°C. was added and cooled to room temperature. As described above, a butyl cellosolve solution (A-1) of epoxy resin (number average molecular weight of resin: 819, non-volatile content: 78%) was obtained.

5 g of bisphenol A type epoxy resin (Epikote 828, manufactured by Mitsubishi Chemical Corporation, number average molecular weight of 370) and 3.2 g of butyl cellosolve were added to a separately prepared 2-liter flask equipped with an inert gas inlet tube and heated to 80°C. bottom. Thereafter, while continuing to raise the temperature, 19.1 g of an amine compound having a polyoxyalkylene chain (Jeffamine M-1000, manufactured by Huntsman) was added, and the temperature was raised to 120°C. After stirring at 120°C for 2 hours, 303.9 g of the above solution (A-1) was added, and the mixture was further stirred at 120°C for 2 hours and cooled to 70°C. After that, 18.1 g of monoethanolamine (manufactured by Aldrich) was added and the temperature was raised to 100°C. After stirring at 100° C. for 3 hours, 7.8 g of acrylic acid was added and further stirred for 2 hours. After that, while lowering the temperature to 60°C, 11.9 g of an emulsifier (Newcol N780 (60), polyoxyethylene polycyclic phenyl ether, manufactured by Nippon Nyukazai Co., Ltd.) was added, and 331 g of ion-exchanged water was added at 60°C, followed by thorough stirring. As a result, a modified epoxy resin emulsion (A-1-1) having a heating residue (nonvolatile content) of 42.0% by mass was obtained.

[Example 14]
14.27 parts by mass of ion-exchanged water, 0.1 parts by mass of sodium nitrite, 0.2 parts by mass of modified bentonite (Note 7), 2 parts by mass of a dispersant (Note 10), and an antifoaming agent (Note 11) ) 0.1 parts by mass, wetting agent (Note 12) 0.4 parts by mass, white titanium oxide (Note 5) 6 parts by mass, talc (Note 1) 24.5 parts by mass, antirust pigment (Note 4) 3 parts by mass and 0.03 parts by mass of black pigment (Note 6) are put into a container, and the particle size becomes 50 μm or less (JIS K 5600-2-5: 1999, according to distribution map method evaluation) with a paint shaker. to obtain a pigment paste.

To this pigment paste, 2 parts by mass of a film-forming aid (Note 16), 52 parts by mass of the modified epoxy resin emulsion (A-1-1, Note 15) obtained in Synthesis Example 1, and 0 of an antifoaming agent (Note 11) 2 parts by mass and 0.2 parts by mass of the surface conditioner (Note 17) were added in this order, and stirred for 15 minutes after the completion of the addition to prepare a water-based primary rust preventive coating composition.

[Examples 15-23 and Comparative Examples 12-20]
Each coating composition was prepared in the same manner as in Example 14, except that the types and blending amounts of the raw materials were changed as shown in Table 3 or 4 below. Details of the raw materials described in Tables 3 and 4 are as shown in Table 5. Numerical values in the columns of raw materials in Tables 3 and 4 indicate parts by mass.

(1) Preparation of Test Plate An SS400 sandblasted steel plate (arithmetic mean roughness (Ra): 30 to 75 μm) having dimensions of 150 mm×70 mm×1.6 mm (thickness) was prepared. After preheating this steel plate in an oven to 35° C., each coating composition prepared as described above was applied to the surface of this steel plate using an air spray so that the dry film thickness would be 25 μm. After coating, it was dried in an oven set at 80°C for 7 minutes, then removed from the oven and dried at 23°C for 2 minutes to prepare a coated test panel. Each test plate with a coating film thus obtained was subjected to each test described below. The results are shown in Tables 7-10.

<Moisture resistance test>
Each coated test plate prepared in (1) was held in a constant temperature and humidity tester at a temperature of 50 ± 1 ° C. and a humidity of 95% in accordance with JIS K-5600 7-2: 1999 for 24 hours. was evaluated according to the evaluation criteria shown in Table 6 below with reference to ASTM D610 (rust) and ASTM D714 (blisters).

<Outdoor exposure test>
Each test plate with a coating film prepared in (1) above was held in accordance with JIS K-5600 7-6: 1999 on an exposure stand for 2 weeks. Blisters) was evaluated according to the evaluation criteria shown in Table 6. When the evaluations of rust and blisters are different, the one with the lower evaluation value is listed.

<Stackability test>
Using two test plates with each coating film prepared in (1) above, the two test plates are stacked horizontally so that the coating surfaces are in contact with each other, and a test plate of the same size is placed on these two test plates. After holding for 24 hours in a state in which four sheets of the above were stacked, the degree of sticking between the two test plates with the coating film and the state of the coating film were visually evaluated according to the following criteria.
When the evaluation of this stackability test is ◯, it can be said that the coating film has excellent stackability, and the composition forming the coating film can be said to have excellent quick-drying properties.

(Evaluation criteria)
○: There is no sticking between the two test plates with the coating film. △: There is some sticking between the two test plates with the coating film. stuck with

(2) Preparation of test plate In the preparation of (1) test plate, after removing from the oven, instead of drying at 23 ° C. for 2 minutes, the (1) test plate was cured at 23 ° C. for 48 hours. A test plate with a coating film was prepared in the same manner as in the preparation of .

<Paint film removal workability>
A disc grinder (manufactured by Hitachi Koki Co., Ltd.) was set with Toda sanding disc 4 type 100 × 15.9 CP-40 (manufactured by Toda Abrasive Industry Co., Ltd.), which is an abrasive cleaning material, at a speed of 15 cm / sec. , the coating film was removed from each coated test plate prepared in (2) above. After the coating film was completely removed from the first coated test plate, the same abrasive was used to remove the coating film from the second to fifth test plates in the same manner. The time required to remove the coating film from each of the 1st to 5th coated test plates was measured, and the total time required to remove the coating film from these 5 coated test plates Time was measured as cumulative time. In addition, the ratio of the time required to remove the coating film from the fifth coated test plate to the time required to remove the coating film from the first coated test plate (5th time/first sheet time) was calculated.
Furthermore, after the coating film was removed from the fifth coated test plate, the state of the abrasive cleaning material was visually confirmed, and the state of clogging and the like was evaluated according to the following criteria. A specific example of the following criteria is shown in FIG.

(Evaluation criteria)
5: Clogging is not observed in the abrasive cleaning material, or clogging is in a very small area 4: Clogging is observed in the abrasive cleaning material, but there is no continuous clogging of 5 mm or more 3: Clogging is observed in the abrasive cleaning material Clogging is observed, and there is continuous clogging of more than 5 mm and 8 mm or less 2: Continuous clogging of more than 8 mm and 10 mm or less is scattered on the abrasive 1: More than 10 mm on the abrasive Interspersed with consecutive clogs

Examples 1 to 23 were excellent in moisture resistance test, outdoor exposure test, and stackability, and also in paint film removal workability, clogging of the disk (abrasive cleaning material) was less. On the other hand, Comparative Examples 1 to 20 were inferior in at least one of coating film removal workability and stackability.
For example, in Comparative Example 1, the clogging of the disk was severe, and the ratio of the time required to remove the coating film from the test plate (time for the 5th sheet/time for the 1st sheet) was larger than that of the Examples. result. In such a case, in the actual coating film removal work, it is necessary to frequently replace the disk, and the removal work takes time, which is not preferable.
In addition, the surface of a disc with a clogging evaluation of 3 or less becomes a smooth surface due to the coating film adhering to the disc surface. When this disk is used, slippage occurs during polishing, and the paint film removal operation becomes dangerous. In order to suppress this danger, a force is required to hold down the disk, which reduces the workability of removing the coating film.

Claims (10)

A water-based primary anticorrosive paint composition,
The water-based primary rust preventive coating composition contains an epoxy resin (A) having a bisphenol skeleton, a flat pigment (B), a rust preventive pigment (C) other than the flat pigment (B), and water. death,
The content of the flat pigment (B) in the nonvolatile matter of the water-based primary rust preventive coating composition is 40% by mass or more ,
The epoxy resin (A) is a bisphenol A type epoxy resin containing two or more epoxy groups in one molecule,
The content of zinc dust is 25% by mass or less with respect to 100% by mass of the non-volatile content of the water-based primary rust preventive coating composition.
A water-based primary antirust paint composition. 2. The water-based primary rust preventive coating composition according to claim 1, wherein the flat pigment (B) has a Mohs hardness of 3.5 or less. 3. The water-based primary antirust coating composition according to claim 1, wherein said flat pigment (B) contains at least one selected from talc and mica. The water-based primary antirust coating composition according to any one of claims 1 to 3 , wherein the epoxy resin (A) has a number average molecular weight of 800 or more. The water-based primary antirust coating composition according to any one of claims 1 to 4 , further comprising an amine curing agent (D). 6. The water-based primary antirust coating composition according to claim 5 , wherein said amine curing agent (D) comprises a water-soluble amine compound. A primary antirust coating film formed from the water-based primary antirust coating composition according to any one of claims 1 to 6 . A base material with a primary rust preventive coating, comprising a base material and the primary rust preventive coating according to claim 7 . a step of coating a base material with the water-based primary rust preventive coating composition according to any one of claims 1 to 6 ; and drying or curing the coated water-based primary rust preventive coating composition to perform a primary rust preventive coating. A method for producing a base material with a primary antirust coating, comprising a step of forming a coating. A step of applying the water-based primary rust preventive coating composition according to any one of claims 1 to 6 to a substrate,
a step of drying or curing the coated water-based primary antirust coating composition to form a primary antirust coating;
A method for producing a substrate with an anticorrosion coating, comprising the steps of removing 70% or more of the primary antirust coating, and applying an anticorrosion coating to the substrate from which 70% or more of the primary antirust coating has been removed. .

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