KR20230156177A - Low-voc coating composition, anticorrosive coating film, base with coating film, and production method for base with coating film - Google Patents

Abstract

The present invention relates to a low VOC coating composition, an anti-corrosive coating film, a coating film-attached substrate, and a method for producing a coating film-attached substrate. The low VOC coating composition includes a bisphenol-type epoxy compound (A) having an epoxy equivalent weight of 200 or less, and an amine-based amine having a cyclic structure. It contains a curing agent (B) and a silane coupling agent (C) having an epoxy group, and the content of the silane coupling agent (C) is 5 to 20% by mass, satisfying (I) or (II) below.
(I) The mass ratio of the epoxy compound (A) and the silane coupling agent (C) is 1.0:0.1 to 0.5.
(II) Contains two or more types of amine-based curing agent (B) having the above-mentioned cyclic structure.

Description

Low-VOC coating composition, anti-corrosion coating, coating film-attached substrate, and coating film-attached substrate manufacturing method

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

Conventionally, the coating composition that forms a coating film with excellent oil resistance, solvent resistance, chemical resistance and corrosion resistance, which is applied to the inner surface of a product carrier tank or a land tank where chemicals are stored, includes solid bisphenol A type epoxy resin, Solid novolak-type epoxy resins and epoxy modified products such as epoxy adducts of diethylenetriamine are used (blended).

These coating compositions contain a relatively high molecular weight resin in order to impart the above effects to the resulting coating film. For this reason, the coating composition contains a large amount of volatile organic compounds (hereinafter referred to as VOC: Volatile Organic Compounds) from the viewpoint of painting workability, etc. Accordingly, paints using semi-solid epoxy resins that can further reduce VOC have been developed, but the amount of VOC reduced is not yet sufficient.

For example, Patent Document 1 discloses a high solid containing a main component containing a bisphenol-type epoxy resin with an epoxy equivalent of 250 to 300, a curing agent component containing an epoxy adduct of xylylenediamine, and an epoxy adduct of polyamide. A type of anticorrosive coating composition is disclosed.

Patent Document 2 discloses a bisphenol-type liquid epoxy resin with an epoxy equivalent weight of less than 250 having two or more epoxy groups per molecule as a coating material layer that covers the surface layer of a steel material, and a modified epoxy resin obtained by modifying xylenediamine or isophoronediamine. Layers containing amines and pigments are disclosed.

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

In Patent Document 4, from the viewpoint of hot water resistance and adhesion, an epoxy resin with an epoxy equivalent weight of 400 to 2,200 is used, and 10 to 40 parts by weight of a silane coupling agent is used based on 100 parts by weight of solid content of the epoxy resin, and the oil absorption is 40 mL/100 g. A hot water-resistant coating composition containing 250 to 500 parts by weight of the following flat talc and 0 to 50 parts by weight of a color pigment is disclosed.

Patent Document 5 includes epoxy functional resins suitable for coating metal or concrete surfaces of chemical devices, amine curing agents for the epoxy functional resins, and organosilicon-containing compounds selected from the group of organosilanes and organosiloxanes. A coating composition is disclosed in which the molar ratio between the silicon atoms and epoxy groups of the organosilicon-containing compound is in the range of 0.20 to 0.75:1.00, preferably in the range of 0.25 to 0.75:1.00.

Additionally, conventionally (large) steel structures such as ships, bridges, tanks, plants, marine buoys, and underwater pipelines are covered with a coating film obtained from an epoxy resin-based anticorrosive coating composition to prevent corrosion. On this coating film, various resin-based topcoat compositions are applied to provide functions such as aesthetics, weather resistance, corrosion resistance, and antifouling properties depending on the use and purpose of the steel structure, thereby forming a topcoat film.

International Publication No. 2007/102587 Japanese Patent Publication No. 3-275773 Japanese Patent No. 5913762 Publication Japanese Patent Publication No. 60-118756 Japanese Patent Publication No. 2017-508598

However, the coating material layer described in Patent Document 2 is poor in oil resistance, solvent resistance, and chemical resistance, and is especially resistant to solvents such as dichloroethane (EDC), methyl ethyl ketone (MEK), and benzene, at room temperature (15 to 25°C, the same below). .), it was found that there was a problem with solvent resistance, such as blisters occurring when contacted.

In addition, it was found that the coating film obtained from the anticorrosive coating composition described in Patent Document 3 had a low crosslinking density and was poor in solvent resistance and chemical resistance.

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

Additionally, what is described in Patent Document 5 is only a composition using a novolak-type epoxy resin as an epoxy resin or a composition containing a large content of a silane coupling agent. In order to adjust a coating composition using such a novolak-type epoxy resin to a coating composition with appropriate painting workability, a large amount of solvent or a reactive diluent containing an epoxy group is required, so it is necessary to use a coating composition with a low VOC content that causes photochemical smog, etc. , it was found that it is difficult to produce a coating composition that is excellent in painting workability and has the above-mentioned various performances.

In addition, compositions with a high content of silane coupling agent generate alcohol through a hydrolysis reaction during storage or during coating film formation, making it impossible to provide them for actual use due to the large load on the environment and painting workers.

When a conventional coating composition as described in Patent Document 1 is used, particularly for painting the inside of a closed structure such as a product carrier tank or a land tank where chemicals are stored, fire due to filling of the tank with VOC The risk is high, and since painting workers are also exposed to high concentrations of VOC, the health damage to painting workers is also significant. In addition, in the case of painting these structures, spray painting, especially airless spray painting, is preferable from the viewpoint of work efficiency, so a paint composition with low paint viscosity and good painting workability is required.

On the other hand, since conventional base coats formed from epoxy resin-based paint compositions have poor weather resistance, their suitability for top coat coating, such as interlayer adhesion with the top coat film and physical properties of the laminate with the top coat film (e.g., blister resistance), is poor. It was found that this was easy to deteriorate. In particular, it was found that when the period from base coating to top coating of the epoxy resin-based coating composition is prolonged, a problem occurs in that the interlayer adhesion between the formed base coating film and the top coating film becomes insufficient.

One embodiment of the present invention is a coating composition capable of forming a coating film excellent in oil resistance, solvent resistance, chemical resistance and corrosion resistance, and a coating composition capable of forming a coating film with excellent balance in topcoat coating compatibility in addition to these performances, Provided is a coating composition that is low VOC (i.e., has a high content of non-volatile components and contains no or almost no volatile organic components) and has excellent drying properties and painting workability.

As a result of repeated studies on methods for solving the above problems, the present inventors have discovered that the above problems can be solved by using a coating composition of a specific composition, and have completed the present invention.

A configuration example of the present invention is as follows.

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

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

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

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

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

<6> Contains a flat pigment (D) and a pigment (E) other than the flat pigment (D),

The coating composition according to any one of <1> to <5>, wherein the volume concentration (PVC) of the flat pigment (D) and pigment (E) in the coating composition is 10 to 70%.

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

<8> An anticorrosion coating film formed from the coating composition according to any one of <1> to <7>.

<9> A base material with a coating film comprising the anti-corrosive coating film and the base material according to <8>.

<10> A method for producing a base material with a coating film, comprising the following steps [1] and [2].

[1] A process of coating the coating composition according to any one of <1> to <7> on a substrate.

[2] Process of forming a coating film by drying the painted paint composition

According to one embodiment of the present invention, a coating composition capable of forming a coating film excellent in oil resistance, solvent resistance, chemical resistance and corrosion resistance, and a coating composition capable of forming a coating film with excellent balance in topcoat coating compatibility in addition to these performances. As a result, a paint composition with low VOC and excellent drying and painting workability, especially spray painting workability, can be obtained.

Furthermore, according to one embodiment of the present invention, a coating film having the above-described various excellent performances can be formed on various substrates (for example, various tanks).

Figure 1 is a schematic diagram of a notched test plate used in the corrosion resistance test of the Example.

≪Low VOC paint composition≫

A low VOC paint composition (hereinafter also referred to as “this composition”), which is an embodiment of the present invention, includes a bisphenol-type epoxy compound (A) having an epoxy equivalent weight of 200 or less, an amine-based curing agent (B) having a cyclic structure, and an epoxy group. Contains a silane coupling agent (C), the content of the silane coupling agent (C) is 5 to 20% by mass, and satisfies (I) or (II) below,

(I) Composition 1, wherein the mass ratio of the bisphenol-type epoxy compound (A) and the silane coupling agent (C) is 1.0:0.1 to 0.5, or

(II) Composition 2 containing two or more types of amine-based curing agent (B) having the above-mentioned cyclic structure

am.

Since the composition 1 contains the above-mentioned (A) to (C), and especially contains a specific amount of (C), and also contains (A) and (C) in a specific amount ratio, the composition 2 also contains the above-mentioned Since it contains (A) to (C), and especially contains two or more specific types of curing agents, and also contains a specific amount of (C), it exhibits the above effect.

Compositions 1 and 2 each exhibit the above effects, wherein Composition 1 is particularly excellent in oil resistance, chemical resistance, and solvent resistance, and Composition 2 is particularly excellent in anti-corrosion (especially electrical anti-corrosion), drying, painting workability, and topcoat properties. The coating suitability is excellent.

Here, excellent oil resistance, solvent resistance, and chemical resistance specifically refers to oils such as heavy oil, gasoline, naphtha, palm oil, methanol, ethanol, xylene, benzene, methyl isobutyl ketone, 1,2-dichloroethane, and ethyl acetate. It has excellent resistance to solvents such as sodium hydroxide and chemicals such as sulfuric acid.

Since these oils, solvents, and chemicals have a significant effect on the coating film, it is believed that a coating film that is resistant to these oils, solvents, and chemicals will also be resistant to general oils, solvents, and chemicals.

In addition, since it is particularly important to prevent corrosion of the base material, a preferred example of this composition is an “anticorrosive coating composition”, but it is not limited to a composition used only to provide corrosion resistance to the base material, and is not limited to a composition used only to provide corrosion resistance to the base material, and provides oil resistance, solvent resistance, A composition used to provide chemical resistance, etc., and an adhesive for bonding a substrate to a substrate or a substrate to a top coat are also included in one aspect of the present composition.

In the present invention, “low VOC” means that the composition does not contain any or almost no VOCs such as solvents, and specifically, the VOC content in the composition when adjusted to a viscosity suitable for painting is 200 g / It means L or less.

Additionally, the VOC content in this composition is preferably 170 g/L or less, and more preferably 155 g/L or less.

The VOC content of this composition can be calculated from equation (1) below, using the values of paint specific gravity and mass NV below.

VOC content (g/L) = Specific gravity of paint × 10000 × (100 - mass NV) / 100 ···(1)

Paint specific gravity (g/cm3): Fill a specific gravity cup with an internal volume of 100 ml with this composition (e.g. composition immediately after mixing the main component and the hardener component) under a temperature condition of 23°C and measure the mass of the composition. calculated value

Mass NV (% by mass): Weigh 1 g of this composition (e.g. composition immediately after mixing the main component and the hardener component) on a plate with a flat bottom, spread it evenly using a wire with a known mass, and incubate at 23°C. After leaving for 24 hours, drying at 110°C for 1 hour, the mass percentage value calculated by weighing the mass of the heated residue (also called “solid content” or “non-volatile content”) and the wire (heated residue in this composition (mass NV) ) content rate)

This composition may be a one-component composition, but is usually a two-component composition consisting of a main component containing an epoxy compound (A) and a curing agent component containing an amine-based curing agent (B). Additionally, if necessary, the present composition may be a three-component composition or more.

These main components and hardener components are usually preserved, stored, and transported in separate containers, and are mixed together immediately before use.

<Bisphenol type epoxy compound (A)>

Examples of the bisphenol-type epoxy compound (A) include polymers or oligomers that have a bisphenol structure in the molecule and contain two or more epoxy groups, and polymers or oligomers produced by a ring-opening reaction of the epoxy groups.

By using this epoxy compound (A) together with specific (B) and (C), a composition with low VOC and excellent painting workability can be obtained, and the composition also has oil resistance, solvent resistance, chemical resistance and corrosion resistance. This excellent coating film can be formed.

One type of epoxy compound (A) may be used, and two or more types may be used.

The epoxy equivalent weight of the epoxy compound (A) is 200 or less, preferably 100 to 200, more preferably 100 to 190, since it can form a coating film excellent in oil resistance, solvent resistance, chemical resistance and corrosion resistance, etc. More preferably, it is 100 to 180, and particularly preferably, it is 100 to 175. Additionally, epoxy equivalent weight is calculated based on JIS K 7236.

Since epoxy compounds with an epoxy equivalent weight exceeding 200 have an excessively large molecular weight, the use of such epoxy compounds often requires a solvent to adjust the viscosity to an appropriate coating viscosity, making it difficult to obtain a low VOC paint composition. It is in

As the epoxy compound (A), an epoxy resin that is liquid at room temperature is preferable, and examples include bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, and bisphenol AD-type epoxy resin.

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

The lower limit of the viscosity (25°C) of the epoxy compound (A) measured with an E-type viscometer (TOKIMEC, FMD type) is preferably 1,500 mPa·s, more preferably 3,000 mPa·s, and the upper limit is preferably is 120,000 mPa·s, more preferably 30,000 mPa·s.

In addition, for example below, a lower limit of preferably 10 means that the preferable range is 10 or more, and an upper limit of preferably 100 means that the preferable range is 100 or less.

The content of the epoxy compound (A) in this composition is based on 100% by mass of the non-volatile content of the composition in order to easily obtain a coating film with excellent adhesion to the substrate, oil resistance, solvent resistance, chemical resistance, and corrosion resistance. The lower limit is preferably 10 mass%, more preferably 15 mass%, and the upper limit is preferably 50 mass%, more preferably 45 mass%.

<Amine-based curing agent (B) with cyclic structure>

The amine-based curing agent (B) having a cyclic structure is not particularly limited as long as it is an amine having a cyclic structure, but is preferably a low VOC type compound and is preferably a polyamine.

As the curing agent (B), for example, polyamines such as alicyclic, aromatic, and heterocyclic, or modified products of these polyamines, and Mannich compounds using aliphatic polyamines and phenolic compounds (e.g., phenalcamine) and aliphatic polyamines. and an adduct of an epoxy compound (eg, bisphenol A type epoxy compound) having an aromatic ring structure.

There may be two or more types of curing agents (B) used in the composition 2, and the number of curing agents (B) used in the composition 1 may be one or two or more types.

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

Examples of the aromatic polyamine include bis(aminoalkyl)benzene, bis(aminoalkyl)naphthalene, and compounds having two or more primary amino groups bonded to a benzene ring.

Specific examples of this aromatic polyamine include 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'-diaminodiphenylsulfone, 3,3'-dimethyl -4,4'-diaminodiphenylmethane, diaminodiethylphenylmethane, 2,4'-diaminobiphenyl, 2,3'-dimethyl-4,4'-diaminobiphenyl, 3,3' -Dimethoxy-4,4'-diaminobiphenyl, bis(aminomethyl)naphthalene, and bis(aminoethyl)naphthalene.

Specific examples of the heterocyclic polyamine include 1,4-bis(3-aminopropyl)piperazine, 1,4-diazacycloheptane, 1-(2'-aminoethylpiperazine), and 1-(2'-aminoethylpiperazine). [2'-(2"-aminoethylamino)ethyl]piperazine, 1,11-diazacycloeicoic acid, and 1,15-diazacyclooctacosane.

Modified products of the above-mentioned alicyclic, aromatic, heterocyclic, etc. polyamines include, for example, Mannich-modified products, epoxy adducts, styrene-modified products, or fatty acid-modified products of the polyamines.

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

Examples of the alkylene polyamine include compounds represented by the formula: “H ₂ N-R ¹ -NH ₂ ” (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-diaminoctane, 1,9-diaminononane, 1,10-diaminodecane, and trimethylhexamethylenediamine.

As the polyalkylene polyamine, for example, the formula: “H ₂ N-(C _m H _2m NH) _n H” (m is an integer of 1 to 10. n is 2 to 10, preferably 2 to 6. (is an integer of). Specific examples include diethylenetriamine, dipropylenetriamine, triethylenetetramine, tripropylenetetramine, tetraethylenepentamine, tetrapropylenepentamine, Pentaethylenehexamine, nonaethylenedecamine, and bis(hexamethylene)triamine can be mentioned.

Examples of aliphatic polyamines other than these include tetra(aminomethyl)methane, tetrakis(2-aminoethylaminomethyl)methane, 1,3-bis(2'-aminoethylamino)propane, and 2,2'-[ Ethylenebis(iminotrimethyleneimino)]bis(ethaneamine), tris(2-aminoethyl)amine, bis(cyanoethyl)diethylenetriamine, polyoxyalkylene polyamine (especially diethylene glycol bis() 3-Aminopropyl) ether) can be mentioned.

Among these polyamines, alicyclic polyamines and their modified products are preferred, polyamines having a cyclohexane ring are more preferred, and 4,4' It is more preferable to include -methylenebiscyclohexylamine, 2,2'-dimethyl-4,4'-methylenebiscyclohexylamine, di(4-aminocyclohexylmethyl)aniline or their modified products, 2 ,2'-dimethyl-4,4'-methylenebiscyclohexylamine, di(4-aminocyclohexylmethyl)aniline or their modified products are more preferably included, and di(4-aminocyclohexylmethyl) It is particularly preferred that it contains aniline or a modified product thereof.

When the present composition contains two or more types of curing agents (B), especially composition 2 is alicyclic polyamine and It is preferable to contain a curing agent (B1) selected from its modified products, and one containing two or more types of curing agents (B1), or a curing agent selected from the curing agent (B1) and m-xylylenediamine and its modified products ( It is more preferable that it contains B2), and that it contains an alicyclic polyamine (B1-1) and a modified product of an alicyclic polyamine (B1-2), or a curing agent (B1) and a curing agent (B2). desirable.

The curing agent (B1) and (B1-1) preferably contains di(4-aminocyclohexylmethyl)aniline.

Examples of the modified products in the curing agents (B1), (B2), and (B1-2) include Mannich modified products, epoxy adducts, styrene modified products, and fatty acid modified products.

There is no particular limitation on the content of the curing agent (B1) and (B2) in the curing agent (B) in this composition, but considering the balance of oil resistance, solvent resistance, chemical resistance, corrosion resistance, and topcoat coating compatibility, the curing agent The content of (B1) is preferably 20% by mass or more, more preferably 30% by mass or more, based on 100% by mass of the curing agent (B). In addition, the content of the curing agent (B1-1) is preferably 30 mass% or more, more preferably 40 mass% or more, and particularly preferably 50 mass% or more, based on 100 mass% of the curing agent (B1).

As the above-mentioned alicyclic polyamine, a commercial product may be used. Examples of the commercial product include “Ancamin 2280,” “Ancamin 2049,” and “Ancamin 2143” (manufactured by Air Products Co., Ltd.), especially D. “Ancamine 2280” containing (4-aminocyclohexylmethyl)aniline as a main component can be suitably used.

<Silane coupling agent (C) having an epoxy group>

As the silane coupling agent (C) having an epoxy group, a compound having an epoxy group and an alkoxy group is preferable because it can easily form a coating film with superior oil resistance, solvent resistance, chemical resistance, and corrosion resistance, etc., 1 An alkoxy group-containing silane coupling agent having one epoxy group in the molecule is more preferable, and a compound represented by the formula below is particularly preferable.

[n is 0 or 1, , Y represents an alkoxy group such as a methoxy group or an ethoxy group.]

The silane coupling agent (C) has the function of chemically bonding the flat pigment (D) or pigment (E), which will be described later, with the coating film forming components such as the epoxy component below and the amine component below, and also acts as a chemical bonding agent for the coating film formed. It has the effect of improving adhesion to the substrate.

Additionally, since the silane coupling agent (C) has an epoxy group, a coating film exhibiting the above effects can be obtained. On the other hand, when only a silane coupling agent without an epoxy group is used, the desired effect is not achieved.

One type of silane coupling agent (C) may be used, and two or more types may be used.

Specifically as the silane coupling agent (C), for example, (3,4-epoxycyclohexyl)ethyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd., "KBM303", etc.), γ-glycidoxypropyl Trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., “KBM403”, etc.) is preferable, and γ-glycidoxypropylmethyldimethoxysilane (manufactured by Toray Dow Corning Co., Ltd., “AY43-026”, etc.) is preferred. ), γ-glycidoxypropylmethyldiethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., “KBE-402”, etc.) may be used.

The content of the silane coupling agent (C) in the composition 1 is preferably a lower limit relative to 100% by mass of the total amount of the composition 1 from the viewpoint of easily obtaining a coating film with superior solvent resistance, chemical resistance, and corrosion resistance. is 5 mass%, more preferably 7 mass%, and the upper limit is preferably 20 mass%, more preferably 15 mass%.

The content of the silane coupling agent (C) in the composition 2 is such that a composition with excellent painting workability can be easily obtained, and a coating film with better solvent resistance, chemical resistance, corrosion resistance, and topcoat coating compatibility can be easily obtained. In light of the above, it is 5 to 20% by mass, preferably 5 to 10% by mass, based on 100% by mass of the total amount of Composition 2.

When the content of the silane coupling agent (C) is less than 5% by mass or exceeds 20% by mass with respect to 100% by mass of the composition, the coating film has good anti-corrosion properties and good adhesion to the substrate, but has excellent solvent resistance and chemical resistance. There is a tendency to not obtain it.

The lower limit of the mass of the silane coupling agent (C) relative to 1.0 parts by mass of the epoxy compound (A) in the composition 1 is preferably 0.1 part by mass, more preferably 0.2 part by mass, and the upper limit is preferably 0.5 part by mass. part, more preferably 0.45 part by mass.

In the composition 1, when the mass of the silane coupling agent (C) is less than 0.1 parts by mass relative to 1.0 parts by mass of the epoxy compound (A), a coating film excellent in solvent resistance and chemical resistance tends not to be obtained, and if the mass of the silane coupling agent (C) exceeds 0.5 parts by mass. In this case, there is a tendency not to obtain a composition with excellent drying properties.

In particular, in the composition 1, when the mass of the silane coupling agent (C) exceeds 0.5 parts by mass relative to 1.0 parts by mass of the epoxy compound (A), and the silane coupling agent (C) is a compound having an alkoxy group, the silane couple Since the alkoxy group in the ring agent (C) undergoes a hydrolysis reaction to produce alcohol, the composition tends to have a large load on the environment and the coating operator during coating film formation.

The mass of the silane coupling agent (C) relative to 1.0 parts by mass of the epoxy compound (A) in the composition 2 is preferably in the same range as that of the composition 1 for the same reason as that of the composition 1.

<Flat-like pigment (D)>

This composition preferably contains a flat pigment (D) because it has superior anti-corrosion properties and can easily obtain a coating film with excellent adhesion to the substrate by relieving internal stress.

One type of flat pigment (D) may be used, and two or more types may be used.

The flat pigment (D) preferably has a median diameter (D50) of 30 to 200 μm, and an average aspect ratio (median diameter/average thickness) is preferable because it can form a coating film that is more excellent in the above effects. Preferably, the pigment content is 10 or more, more preferably 20 or more, preferably 150 or less, and more preferably 100 or less.

D50 can be measured using a laser scattering diffraction type particle size distribution measuring device, for example, “SALD 2200” (manufactured by Shimadzu Corporation).

The average thickness is observed horizontally with respect to the main surface of the flat pigment (D) using a scanning electron microscope (SEM), for example, "XL-30" (manufactured by Philips), and is measured as the thickness of tens to hundreds of pigment particles. It can be calculated as an average value.

Examples of the flat pigment (D) include mica, glass flake, aluminum flake, flaky iron oxide, stainless steel flake, and plastic flake. It is inexpensive, readily available, and can form a coating film with more excellent effects as described above. For reasons such as this, mica is preferable.

Examples of the mica include "Mica Powder 100 Mesh" (manufactured by Fukuoka Talc Industrial Co., Ltd., D50: 41 μm, average aspect ratio: 35).

When the present composition contains a flat pigment (D), the content of the flat pigment (D) in the present composition is 100 mass of the non-volatile content of the present composition, from the point of view that a coating film with more excellent effects as described above can be easily obtained. The lower limit for % is preferably 1 mass%, more preferably 3 mass%, and the upper limit is preferably 40 mass%, more preferably 20 mass%.

＜Pigment (E)＞

The composition may contain a pigment (E) other than the flat pigment (D), and examples of the pigment (E) include extender pigments, colored pigments, and rust-prevention pigments, and may be either organic or inorganic.

One type of pigment (E) may be used, or two or more types may be used.

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

When such an extender is mixed into the present composition, the amount added is preferably 10 to 70% by mass, more preferably 10 to 50% by mass, based on 100% by mass of the non-volatile matter of the composition.

As the coloring pigment, for example, conventionally known inorganic pigments such as carbon black, titanium dioxide (titanium white), iron oxide (bengala), yellow iron oxide, ultramarine, and organic pigments such as cyanine blue and cyanine green can be used. In particular, titanium white, carbon black, and Bengala are preferred.

When such a coloring pigment is blended into the present composition, the mixing amount is preferably 1 to 30 mass%, more preferably 1 to 10 mass%, based on 100 mass% of non-volatile matter of the present composition.

When the present composition contains the above-mentioned flat pigment (D) and/or pigment (E), the volume concentration (PVC) of all these pigments is such that a composition with excellent painting workability can be easily obtained, and the substrate by stress relaxation From the viewpoint of easily obtaining a coating film with excellent adhesion and water resistance, the amount is preferably 10 to 70%, more preferably 10 to 50%, and particularly preferably 10 to 40%.

If the PVC is below the above range, the corrosion resistance of the obtained coating film tends to be lowered and the stress relieving effect becomes insufficient, and if it exceeds the above range, the water resistance of the obtained coating film tends to decrease and painting workability tends to decrease.

The PVC refers to the total volume concentration of pigment relative to the volume of non-volatile matter in this composition. PVC can be specifically calculated from the formula below.

PVC [%] = Total volume of all pigments in this composition × 100 / Volume of non-volatile matter in this composition

The non-volatile content (solid content) of this composition refers to the mass percentage of the coating film (heating residue) after sufficiently reaction curing (heating) of the composition, or the coating film (heating residue) itself. The non-volatile content is measured in accordance with JIS K 5601-1-2 by weighing 1 ± 0.1 g of the present composition (e.g., the composition immediately after mixing the main component and the hardener component) into a plate with a flat bottom and using a wire with a known mass. It can be calculated by spreading it evenly and drying it at 23°C for 24 hours, then measuring the mass of the heated residue and the wire when heated at a heating temperature of 110°C for 1 hour (under normal pressure). In addition, this non-volatile content is equivalent to the total amount of solid content (components other than the solvent) of the raw material components used in this composition.

The volume of the non-volatile matter in the composition can be calculated from the mass and true density of the non-volatile matter in the composition. The mass and true density of the non-volatile matter may be measured values or values calculated from the raw materials used.

The volume of the pigment can be calculated from the mass and true density of the pigment used. The mass and true density of the pigment may be measured values or values calculated from the raw materials used. For example, it can be calculated by separating the pigment and other components from the non-volatile components of the composition and measuring the mass and true density of the separated pigment.

＜Other ingredients＞

Other components in this composition include an epoxy compound other than the epoxy compound (A), an amine-based curing agent other than the curing agent (B), a silane coupling agent other than the silane coupling agent (C), an anti-sagging agent (anti-settling agent), and fiber. Various additives such as substances, surfactants (e.g., surfactants described in Japanese Patent Application Laid-Open No. 2-298563), dispersants, leveling agents, surface conditioners, and organic solvents can be appropriately blended.

One type of each may be used, or two or more types may be used.

The other components mentioned above may be mixed with the main component or may be mixed with the curing agent component.

This composition may contain epoxy compounds other than the epoxy compound (A). Such epoxy compounds include, for example, novolak-type epoxy resin, hydrogenated bisphenol A-type epoxy resin, hydrogenated bisphenol F-type epoxy resin, hydrogenated novolac-type epoxy resin, aliphatic-type epoxy resin, aromatic-type epoxy resin, and epoxy group-containing epoxy resin. A reactive diluent may be mentioned.

Additionally, a bisphenol-type epoxy compound having an epoxy equivalent of more than 200 may be used.

In particular, in terms of being able to easily form a coating film with excellent solvent resistance and chemical resistance, it is preferable to use a novolak-type epoxy resin or a reactive diluent containing a polyfunctional epoxy group, and it is easy to form a coating film with better topcoat coating compatibility. From the viewpoint of easy formation, it is preferable to use a reactive diluent containing a monofunctional epoxy group. In particular, it is preferable to use a polyfunctional epoxy group-containing reactive diluent and a monofunctional epoxy group-containing reactive diluent in combination because it is possible to easily form a better coating film with a balanced chemical resistance and topcoat coating compatibility.

In addition, a reactive diluent containing a monofunctional epoxy group refers to a reactive diluent having one epoxy group, and a reactive diluent containing a polyfunctional epoxy group refers to a reactive diluent having two or more epoxy groups.

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

The epoxy group-containing reactive diluent is not particularly limited as long as it is an epoxy compound with a viscosity of 500 mPa·s or less at 25°C.

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

Examples of the polyfunctional epoxy group-containing reactive diluent include 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and cyclohexanedimethanol diglycidyl. Diyl ether, resorcinol diglycidyl ether, mono or poly alkylene glycol diglycidyl ether (carbon number of alkylene group 1 to 5, examples: ethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether) and trimethylolpropane triglycidyl ether.

Considering the balance of painting workability, low temperature curability, corrosion resistance, oil resistance, etc. among the above reactive diluents containing an epoxy group, neopentyl glycol diglycidyl ether, phenol glycidyl ether, o-cresyl glycidyl ether, p- tert-butylphenylglycidyl ether is preferred.

As the epoxy compound other than the above epoxy compound (A), a commercial product may be used. Examples of the commercial product include "D.E.N.", which is a novolak-type epoxy resin. 425” (manufactured by The Dow Chemical Company, epoxy equivalent weight 169 to 175, non-volatile matter 100%), “D.E.N. 431” (manufactured by The Dow Chemical Company, epoxy equivalent weight 172 to 179, non-volatile matter 100%) and “D.E.N. 438” (manufactured by The Dow Chemical Company, epoxy equivalent 176-181, non-volatile matter 100%), “ERISYS GE-10” (o-cresyl glycidyl ether, manufactured by CVC Thermoset Specialties, epoxy equivalent), a reactive diluent containing an epoxy group 170 to 195, non-volatile matter 100%, viscosity 8 mPa·s/25°C), “ERISYS GE-20” (neopentyl glycol diglycidyl ether, manufactured by CVC Thermoset Specialties, epoxy equivalent weight 125 to 137, non-volatile matter 100) %, viscosity 14 mPa·s/25°C), and “Cardolite 2513HP” (manufactured by Cardolite, epoxy equivalent 413, non-volatile matter 100%, viscosity 30 mPa·s/25°C).

When using the above epoxy compound (A) together with an epoxy compound other than the epoxy compound (A), the content of the epoxy compound other than the epoxy compound (A) is preferably 1 to 85 parts by mass relative to 100 parts by mass of the epoxy compound (A). It is the mass part.

This composition may contain an amine-based curing agent other than the curing agent (B). Examples of such amine-based curing agents include the above-mentioned aliphatic polyamines, and preferably include polyoxyalkylene polyamine, polyalkylene polyamine, or their modified products.

Examples of the modified product include Mannich-modified product, epoxy adduct, or fatty acid-modified product.

As an amine-based curing agent other than the above-mentioned curing agent (B), a commercial product may be used. Examples of the commercial product include "Jeffamine D-230" (manufactured by Huntsman Japan Co., Ltd.), which is polyoxypropylenediamine, and the fatty acid of tetraethylenepentamine. and "Ancamide 506" (manufactured by Air Products Co., Ltd.), which is a modified product.

In this composition, the epoxy compound (A) and epoxy compounds other than the epoxy compound (A) (hereinafter, all of these are also referred to as “epoxy components”), and the curing agent (B) and epoxy compounds other than the curing agent (B). The total content of the amine-based curing agent (hereinafter, all of these are also referred to as “amine components”) is high in crosslinking density, and it is possible to easily obtain a coating film with excellent oil resistance, solvent resistance, chemical resistance, and water resistance, etc. The lower limit is preferably 20% by mass, more preferably 30% by mass, and the upper limit is preferably 70% by mass, more preferably 65% by mass, based on 100% by mass of the non-volatile content of the composition.

The content of the amine component in this composition is calculated by formula (2) below, in order to obtain a composition with excellent drying properties and to easily obtain a coating film with excellent oil resistance, solvent resistance, chemical resistance, water resistance, and adhesion to the substrate. The reaction ratio calculated is preferably 0.5 or more, more preferably 0.6 or more, preferably 1.3 or less, and more preferably 1.0 or less.

Reaction ratio = (Amount of amine component/Active hydrogen equivalent of amine component+Amount of component reactive with epoxy component/Equivalent of functional group of component reactive with epoxy component)/(Amount of epoxy component/Epoxy of epoxy component) Equivalent + Blended amount of component reactive with amine component / Equivalent weight of functional group of component reactive with amine component)... (2)

Here, the “component reactive to the amine component” in the formula (2) includes, for example, the silane coupling agent (C), etc., and also the “component reactive to the epoxy component”. Examples of this include silane coupling agents other than the silane coupling agent (C). In addition, the “functional group equivalent” of each component above means the mass (g) per 1 mol of functional group obtained by subtracting the number of moles of functional groups contained therein from the mass of 1 mol of these components.

The anti-sagging agent (anti-settling agent) includes organic clay-based waxes such as stearate salts of Al, Ca, and Zn, lecithin salts, and alkyl sulfonates, polyethylene wax, amide wax, hydrogenated castor oil wax, hydrogenated castor oil wax, and amides. A mixture of waxes, synthetic fine silica, polyethylene oxide based wax, and other conventionally known waxes can be used. Among them, amide wax, synthetic fine silica, polyethylene oxide based wax, and organic clay based wax are preferred.

As such anti-sagging agents (anti-settling agents), "Disparon 305", "Disparon 4200-20", and "Disparon 6650" manufactured by Kusumoto Chemical Co., Ltd.; "ASAT-" manufactured by Ito Oil Co., Ltd. Products such as “250F”; “Plonon RCM-300” manufactured by Kyoeisha Chemical Co., Ltd.; and “Benton SD-2” manufactured by Elementis Specialties, Inc.

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

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

[Manufacture of low VOC paint composition]

This composition is preferably manufactured by mixing and kneading the main component and the hardener component that have been individually prepared in advance at the time of use.

The main ingredient can be prepared by mixing, stirring and kneading each of the ingredients that make it up. In that case, for example, it is desirable to use an SG mill or high-speed disper to disperse the blended ingredients as uniformly as possible while maintaining the temperature of the mill base at 55 to 60°C for about 30 minutes.

Meanwhile, the hardener component varies depending on the components to be mixed, but each component constituting it can be mixed and uniformly dispersed with a stirrer.

[Use of paint composition]

According to this composition, a coating film (layer) having various properties such as oil resistance, solvent resistance, chemical resistance, water resistance, and corrosion resistance can be formed. The methods also include crevice corrosion, dissimilar metal contact corrosion, and stress corrosion.

This composition can be used for a variety of purposes because it can form a coating film with excellent performance, such as cargo tanks (e.g. product carriers or chemical tankers) for transporting chemicals by land or sea, etc. The inner surface of land tanks for storing chemicals, the inner surface of pipelines in contact with chemicals, WBT (Water Ballast Tank), COT (Crude Oil Tank), FWT (Fresh Water Tank), DWT (Drinking Water Tank), etc. It is preferable to use it on the inner surface of tanks, the inner and outer surfaces of ships, etc. In addition to this use, in areas where maintenance is difficult such as seawater desalination devices and marine structures, around gates of dams and sluices, seawater, river water or industrial water can be used as a coolant. It is suitable for use as piping in plants, etc., and as a pool for storing spent nuclear fuel.

In particular, Composition 1 is preferably used on the inner surface of tanks (e.g., product carriers or chemical tankers) or pipelines used to transport or store chemicals, and Composition 2 is a universal primer for ships, etc. It is preferable to use it as.

Additionally, this composition can also be used to repair and paint the surface of a base material with an anti-corrosion coating film that has caused corrosion. That is, by applying this composition to welds or gaps in a base material such as stainless steel, it prevents local corrosion of the base material, and also acts as an adhesive to adhere the stainless steel plate to the surface of the coating film, thereby stabilizing local corrosion for a long period of time. It can be suppressed.

In this way, when repairing a base material, for example, this composition can be applied to the surface of the base material where there are welds (weld lines) or gaps, and a separate base material can be adhered to the surface of the uncured coating film. In addition, The composition may be applied on a separate substrate.

≪Coating film, coating film-attached substrate, manufacturing method of coating film-attached substrate≫

The coating film of one embodiment of the present invention (hereinafter also referred to as “main coating film”) is formed using the above composition, and the coating film-attached base material of one embodiment of the present composition includes the main coating film and the object to be coated (base material). It is a laminated body.

The material of the base material is not particularly limited and includes steel (iron, steel, alloy steel, carbon steel, mild steel, alloy steel, stainless steel, etc.), non-ferrous metals (zinc, aluminum, etc.), and the surface of the base material is made of shop primer, etc. It may be covered with .

In addition, when using, for example, mild steel (SS400, etc.) as the substrate, adjust the base (e.g., so that the arithmetic mean roughness (Ra) is about 30 to 75 ㎛, such as polishing the surface with grit blasting, etc.) as necessary. It is advisable to adjust it.

The dry film thickness of this coating film is not particularly limited, but from the viewpoint of obtaining a coating film with sufficient anti-corrosion properties, etc., the lower limit is usually 50 ㎛, preferably 200 ㎛, and the upper limit is usually 500 ㎛, preferably. It is 400 ㎛.

As a method of forming this coating film, the desired film thickness may be formed with one coating (one coating), or the coating film with the desired thickness may be formed with two or more coatings (two or more coatings). From the viewpoint of film thickness management and considering the residual organic solvent in the coating film, it is preferable to form the coating film to reach the desired dry film thickness by applying two or more coats.

The method for producing a coated substrate according to an embodiment of the present invention (hereinafter also referred to as “the present method”) includes the following steps [1] and [2].

Process [1]: Process of coating this composition on a substrate

Process [2]: Process of drying the painted paint composition to form a coating film

＜Process [1]＞

The coating method in the above step [1] is not particularly limited, and may be applied to the surface of the substrate according to a normal method such as airless spray coating, air spray coating, brush coating, or roller coating. When painting a structure, spray painting is preferred because it allows easy painting of a large-area base material.

Additionally, during painting work, this composition may be appropriately diluted with a thinner (organic solvent) or the like. However, even when diluted in this way, the VOC content in the composition is preferably 200 g/L or less.

The spray painting conditions can be adjusted appropriately depending on the dry film thickness to be formed. For example, in the case of airless spraying, primary (air) pressure: about 0.4 to 0.8 MPa, secondary (paint) pressure: 15 to 36. It is desirable to have a gun movement speed of about 50 to 120 cm/sec.

Additionally, the coating may be performed so that the dry film thickness of the resulting coating film is within the above range.

The viscosity of this composition suitable for spray painting is preferably 1,500 to 7,000 mPa·s, more preferably 1,500 to 4,000 mPa·s under measurement conditions at 23°C using an E-type viscometer (FMD type, manufactured by TOKIMEC). am.

＜Process [2]＞

Drying conditions in the above step [2] are not particularly limited and can be set appropriately depending on the coating film formation method, type of substrate, use, coating environment, etc., for example, 12 to 250 hours at 5 to 35°C. can be mentioned. Additionally, depending on the purpose, it may be forcibly dried and hardened by heating and blowing, but usually it is dried and hardened under natural conditions.

In addition, when forming a coating film using two or more coatings, especially two coatings, after performing steps [1] and [2], the series of steps [1] and [2] are repeated on the obtained coating film. Forms a film. Additionally, when forming a coating film by applying three coats, the coating film is formed by repeating a series of additional processes for the coating film coated twice.

Example

Below, preferred aspects of the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

[Example 1]

As shown in Table 1 below, in the container, 30 parts by mass of bisphenol F type epoxy resin "jER 807" (Note 1), 9 parts by mass of novolac type epoxy resin "D.E.N.431 Epoxy Novolac Resin" (Note 3), and benzyl 2 parts by mass of alcohol, 26.5 parts by mass of potassium feldspar “Unispar PG-K10” (Note 7), 5 parts by mass of talc “Talc FC-1” (Note 8), and titanium white “TITANE R-5N” (Note 9) ) 5 parts by mass, barium sulfate “Varico #300W” (Note 10) 5 parts by mass, mica “mica powder 100 mesh” (Note 12) 5 parts by mass, silane coupling agent “KBM403” (Note 13) 11 parts by mass and 1.5 parts by mass of anti-sagging agent "DISPARLON 6650" (Note 14) were added, stirred using a high-speed disper at room temperature (23°C) until uniform, and then dispersed at 56 to 60°C for about 30 minutes. . Afterwards, the main ingredient was prepared by cooling to 30°C or lower.

Additionally, 25 parts by mass of alicyclic amine “Ancarmine 2280” (Note 16) was used as a curing agent component.

A coating composition was prepared by mixing these main components and the hardener component before coating.

[Examples 2 to 19 and Comparative Examples 1 to 4]

Each coating composition was prepared in the same manner as in Example 1, except that the types and mixing amounts of the components constituting the main component and the hardener component of Example 1 were changed as shown in Tables 1 to 3 below.

In addition, when two or more types of components were used as the curing agent component, the curing agent component was prepared by mixing these components at room temperature and pressure using a high-speed disper.

In addition, the description of each component listed in Tables 1 to 3 is shown in Table 4. In Tables 1 to 3, the numerical values of each component of the main agent and hardener each represent parts by mass.

＜Dryness test＞

The drying property of the obtained coating composition was tested in accordance with JIS K 5600-3-3 (curing drying property). In addition, the coating composition was prepared by mixing the above-mentioned main component and hardener component immediately before this test. The curing drying time of each paint composition was evaluated based on the following criteria. The results are shown in Tables 5 to 7.

(Evaluation standard)

4: Curing drying time is less than 24 hours at 10℃

3: Curing drying time is more than 24 hours but less than 36 hours at 10℃.

2: Curing drying time is more than 36 hours but less than 48 hours at 10℃.

1: Curing drying time is more than 48 hours at 10℃

[Production of trial version]

A sandblasted steel plate of SS400 (arithmetic average roughness (Ra): 30 to 75 μm) with dimensions of 150 mm × 70 mm × 2.3 mm (thickness) was prepared. Each coating composition prepared as described above was applied to the surface of this steel sheet using an airless sprayer so that the dry film thickness was 300 μm. After that, a steel plate with a coating film (test plate) was produced by drying at 23°C for 10 days. Each of the obtained test plates was used for each test described later. The results are shown in Tables 5 to 7.

In addition, in the obtained test plates, the pencil hardness of the coating film was all "H" or higher. In the present invention, pencil hardness was measured based on JIS K 5600-5-4.

＜Corrosion resistance test＞

The corrosion resistance of the obtained coating film was tested in accordance with JIS K 5600-6-1 (liquid resistance test method).

A cut 2 reaching the steel plate was made from the coating film side at the position shown in FIG. 1 of each obtained test plate. The test plate (1) with the sheath (2) cut was immersed in 3% salt water at 40°C for 90 days with the sheath (2) side facing down (in the direction shown in Fig. 1). After immersion, cuts (3) are made in 11 places in order from the left end of the sheath (2) upward, as if dividing the sheath (2) into equal parts at 5 mm intervals, and 10 measuring parts are made between each cut (3). In (4), the peeling length (length from sheath 2) of the steel plate and the coating film was measured. The average value of 10 measured peeling lengths was evaluated based on the following criteria.

(Evaluation standard)

4: Peeling length is less than 5 mm

3: Peeling length is 5 mm or more and less than 10 mm

2: Peeling length is 10 mm or more and less than 15 mm

1: Peeling length is 15 mm or more

＜Oil resistance test＞

The oil resistance of the obtained coating film was tested in accordance with JIS K 5600-6-1 (liquid resistance test method).

Each obtained test panel was immersed in naphtha at room temperature for 180 days. The test plate after immersion was evaluated based on the following criteria.

(Evaluation standard)

5: No rust occurred on the steel plate, no blisters occurred on the coating film, and the pencil hardness of the coating film was HB or higher.

4: There was no rust in the steel sheet, no blisters in the coating film, and the pencil hardness of the coating film was B to 4B.

3: No rust occurred on the steel plate, no blisters occurred on the coating film, and the pencil hardness of the coating film was 5B or less.

2: Some rust occurred on the steel plate, and blisters were formed on the coating film.

1: Rust occurred on the steel plate, and blisters formed on the coating film.

＜Solvent resistance test＞

The solvent resistance of the obtained coating film was tested in accordance with JIS K 5600-6-1 (liquid resistance test method).

Each obtained test plate was immersed in benzene or ethanol at room temperature for 180 days. The test plate after immersion was evaluated according to the same criteria as the oil resistance test above.

＜Chemical resistance test＞

The chemical resistance of the obtained coating film was tested in accordance with JIS K 5600-6-1 (liquid resistance test method).

Each obtained test plate was immersed in 3% sulfuric acid at room temperature for 90 days. The test plate after immersion was evaluated according to the same criteria as the oil resistance test above.

＜Top coating suitability test＞

The suitability for topcoat coating can be comprehensively evaluated by the interlayer adhesion of the base coat and top coat formed on the substrate from this composition, and the blister resistance of the substrate with a laminated coating film in which the base coat and top coat are laminated on the substrate. .

The interlayer adhesion between the base coat and the top coat tends to depend on the period from the formation of the base coat to the application of the top coat, and the type of resin of the top coat. Specifically, when a cross-linking reaction type top coat is applied over the base coat, the base coat is peeled off from the substrate due to the curing shrinkage stress, which causes rust if the substrate is a metal material. Accordingly, the tolerance for the period from the formation of the base coat film to the application of the top coat material and the tolerance for film defects that may occur due to the type of resin were collectively referred to as top coat coating suitability.

[Manufacturing method of top coat]

As the top coat, a top coat prepared according to the method below was used.

[Epoxy resin-based topcoat]

In a container, 30 parts by weight of epoxy resin "E-001-75X" (manufactured by Otake Meishin Chemical Co., Ltd., xylene solution of bisphenol A type epoxy resin), epoxy resin "E834-85X(T)" (manufactured by Otake Meishin Chemical Co., Ltd.) Manufactured by Note), bisphenol A type epoxy resin (semi-solid state at room temperature), epoxy equivalent weight 290-310 g/eq, non-volatile matter 85%) 10 parts by weight, talc "F-2 Talc" (manufactured by Fuji Talc Co., Ltd.) 20 parts by weight, heavy calcium carbonate “Calcium Carbonate Super SS” (manufactured by Maruo Calcium Co., Ltd.) 10 parts by weight, carbon black “MA-100” (manufactured by Mitsubishi Chemical Co., Ltd.) 3 parts by weight, anti-sagging agent “Dispa” 5 parts by weight of Ron A-630-20X (manufactured by Kusumoto Chemical Co., Ltd., non-volatile matter 20%), 6 parts by weight of propylene glycol monomethyl ether, 7 parts by weight of butyl cellosolve, and 9 parts by weight of methyl isobutyl ketone. The main ingredients constituting the epoxy resin-based topcoat were prepared by adding glass beads and mixing these ingredients with a paint shaker and then removing the glass beads.

Additionally, 80 parts by weight of polyamide adduct-based curing agent "PA-23" (manufactured by Otake Meishin Chemical Co., Ltd., active hydrogen equivalent 375 g/eq, non-volatile matter 60%), tertiary amine "Ancamine K-54" ( 3 parts by weight of 2,4,6-tri(dimethylaminomethyl)phenol (manufactured by Air Products Co., Ltd.), 14 parts by weight of xylene, and 3 parts by weight of n-butanol were mixed using a high-speed disper (at room temperature and pressure). ) By mixing, the curing agent component constituting the epoxy resin-based topcoat was prepared.

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

[Acrylic resin-based topcoat]

The container contains 20 parts by weight of acrylic resin "Pararoid B-66" (manufactured by Rohm & Haas Japan Co., Ltd.), 16 parts by weight of precipitated barium sulfate "Precipitated Barium Sulfate FTB" (manufactured by Fukuoka Talc Kogyo Co., Ltd.), and a titanium bag. 20 parts by weight of “Titanium Bag R-930” (manufactured by Sakai Chemical Industry Co., Ltd.), 3 parts by weight of anti-sagging agent “Disparon A-630-20X”, 27 parts by weight of xylene, 2 parts by weight of butyl cellosolve, aromatic Add 9 parts by weight of hydrocarbon "Ipsol 100" (manufactured by Idemitsu Kosan Co., Ltd.) and 3 parts by weight of n-butanol, add glass beads there, mix these ingredients with a paint shaker, and then remove the glass beads. An acrylic resin-based topcoat was prepared.

[Production of trial version]

The paint compositions of Examples 13 to 19 were applied to a sandblasted steel plate measuring 70 mm , the painted surface was exposed on an outdoor exposure stand (based on JIS K 5600-7-6) installed on the premises of Chugoku Paint Co., Ltd. in Otake City, Hiroshima Prefecture. When applying an epoxy resin-based topcoat as a topcoat composition, after applying the coating composition and exposing it outdoors for 1, 14, or 30 days, apply a film applicator to the painted surface of the coating composition so that the dry film thickness is 50%. An epoxy resin-based topcoat was applied to each surface to a thickness of ㎛. In addition, when applying an acrylic resin-based topcoat, after applying the coating composition and exposing it outdoors for 1, 7, or 14 days, apply a film applicator to the painted surface of the coating composition so that the dry film thickness is 50 ㎛. As much as possible, an acrylic resin-based topcoat was applied to each surface.

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

Each test panel for evaluation of topcoat coating suitability coated with the above epoxy resin-based topcoat or acrylic resin-based topcoat was immersed in salt water (salt concentration 3%) at 40°C for 30 days and then tested for adhesion (in accordance with JIS K 5600-5-6). (based on the specified crosscut method) and blisters of the coating film (based on method A of ASTM D-714-56) were evaluated, respectively. The obtained results are shown in Table 8.

1：Trial version
2: Sheath
3: Cut
4: Measuring part

Claims (10)

It contains a bisphenol-type epoxy compound (A) having an epoxy equivalent of 200 or less, an amine-based curing agent (B) having a cyclic structure, a silane coupling agent (C) having an epoxy group, and an epoxy compound other than the epoxy compound (A),
Contains two or more types of amine-based curing agent (B) having the above cyclic structure,
The content of the silane coupling agent (C) is 5 to 20% by mass,
The epoxy compound other than the epoxy compound (A) is at least one selected from a novolak-type epoxy resin and a reactive diluent containing a polyfunctional epoxy group,
Low VOC paint composition. According to paragraph 1,
A low VOC coating composition wherein the mass ratio of the bisphenol type epoxy compound (A) and the silane coupling agent (C) is 1.0:0.1 to 0.5. According to paragraph 1,
A low VOC paint composition further comprising a flat pigment (D). According to paragraph 1,
A low VOC coating composition wherein the silane coupling agent (C) is a silane coupling agent having one epoxy group per molecule. According to paragraph 1,
A low VOC coating composition, wherein the amine-based curing agent (B) having the cyclic structure includes at least one selected from alicyclic amines and modified products of alicyclic amines. According to paragraph 1,
Contains a flat pigment (D) and a pigment (E) other than the flat pigment (D),
A low VOC coating composition, wherein the volume concentration of the flat pigment (D) and pigment (E) in the low VOC coating composition is 10 to 70%. According to paragraph 1,
A low VOC paint composition wherein the VOC content of the low VOC paint composition is 200 g/L or less. An anti-corrosion coating film formed from the low VOC coating composition according to any one of claims 1 to 7. A coating film-attached substrate comprising the anticorrosive coating film and the substrate according to claim 8. A method for manufacturing a base material with a coating film, comprising the following steps [1] and [2].
[1] Process of painting the low VOC paint composition according to any one of paragraphs 1 to 7 on a substrate.
[2] Process of forming a coating film by drying the painted paint composition