JP2023135579A - Modified (meth)acrylic resin coating composition, laminated coating film, substrate with coating film, and method for producing the same - Google Patents

Abstract

To provide a modified (meth)acrylic resin coating composition, capable of forming a coating film with an optimal balance of resistance to bubble bulging, yellowing, water whitening, and weathering.SOLUTION: A modified (meth)acrylic resin coating composition contains a modified (meth)acrylic resin (a) having an iodine value of less than 4 and a manganese-containing drying accelerator (b).SELECTED DRAWING: None

Description

The present invention relates to a modified (meth)acrylic resin coating composition, a laminated coating film, a substrate with a coating film, and a method for producing the same.

Traditionally, (large) steel structures such as ships, bridges, tanks, plants, offshore buoys, and underwater pipelines have been coated with laminated coatings of various specifications for the purpose of imparting various functions such as corrosion resistance. ing. For example, after applying an epoxy resin-based anticorrosive paint composition as an undercoat, a topcoat paint composition is applied onto the formed anticorrosive paint film for the purpose of improving design, weather resistance, and the like.

As the top coating composition, a two-component reaction curing type top coating composition (eg, an acrylic urethane resin coating composition, a fluorine urethane resin coating composition) is used. However, such two-component reaction-curing top coat compositions are expensive, and require mixing of the main component and curing agent component, making them difficult to handle. There are also problems with workability, such as limitations due to usage time, and there are cases where it is not suitable for painting large areas such as the large steel structures mentioned above.

In addition, the above-mentioned top coating composition is a one-component composition that is inexpensive, has excellent workability, and is free from the labor involved in mixing the main component and curing agent component, and is not limited by pot life after mixing. Top coating compositions for molds, specifically (meth)acrylic resin coating compositions, are also known.

In the (meth)acrylic resin coating composition, air bubbles generated during coating remain in the formed coating film, and when the coating film is exposed to a high temperature environment such as in the summer, it may expand or It is known that there is a problem of fusion and expansion and blisters appearing on the surface of the coating film. In order to solve this problem, Patent Document 1 describes the use of an acrylic resin with a high iodine value and a drying accelerator. A (meth)acrylic resin coating composition is disclosed.

JP 2018-44162 Publication

For example, a (meth)acrylic resin coating composition as described in Patent Document 1 includes a drying accelerator (dryer) as an essential component for drying the composition. Metal salts such as cobalt, zirconium, calcium, and barium are commonly used as drying accelerators. Among these, cobalt dryers have been used as the main drying accelerator due to their excellent drying performance. has been used.

As mentioned above, a drying accelerator is essential for a (meth)acrylic resin coating composition as described in Patent Document 1, but the present inventors have discovered that the use of such a drying accelerator can provide benefits. It was found that the resulting paint film yellowed, and the water whitening resistance and weather resistance of the resulting paint film decreased.

The present invention has been made in view of the above-mentioned problems, and provides a modified (meth)acrylic resin coating composition that can form a coating film that is excellent in a well-balanced manner in bubble resistance, yellowing resistance, water whitening resistance, and weather resistance. The purpose is to provide

As a result of intensive studies to solve the above-mentioned problems, the present inventor found that the above-mentioned problems could be solved according to the following configuration example, and completed the present invention.
A configuration example of the present invention is as follows.

[1] A modified (meth)acrylic resin coating composition containing a modified (meth)acrylic resin (a) having an iodine value of less than 4 and a drying accelerator (b) containing manganese.

[2] The modified (meth)acrylic resin coating composition according to [1], wherein the drying accelerator (b) is a fatty acid manganese salt.

[3] Further contains a pigment,
The pigment volume concentration (PVC) in the modified (meth)acrylic resin coating composition is 15 to 45%,
The modified (meth)acrylic resin coating composition according to [1] or [2].

[4] A laminated coating film comprising an epoxy resin undercoat anticorrosive coating film and a topcoat coating film formed from the modified (meth)acrylic resin coating composition according to any one of [1] to [3].

[5] A base material with a coating film, comprising the laminated coating film according to [4] and a base material.
[6] The coated base material according to [5], wherein the base material is a steel structure.

[7] A method for producing a coated base material, including the following steps 1 and 2.
Step 1: Step of coating the base material with an epoxy resin-based anticorrosive coating composition to form an undercoat anticorrosion coating (A) Step 2: Applying [1] to [3] on the undercoat anticorrosion coating (A). A step of applying any of the modified (meth)acrylic resin coating compositions to form a topcoat film (B).

According to the present invention, it is possible to provide a modified (meth)acrylic resin coating composition that can form a coating film that is excellent in a well-balanced manner in bubble blistering resistance, yellowing resistance, water whitening resistance, and weather resistance.
Further, according to the present invention, even if the thickness of the coating film to be formed is increased, a coating film that is less likely to cause blisters can be easily formed.
Further, according to the present invention, it is possible to provide a modified (meth)acrylic resin coating composition that is highly safe, and which does not form a skin even without using an anti-skinning agent. can provide things.

<<Modified (meth)acrylic resin coating composition>>
The modified (meth)acrylic resin coating composition (hereinafter also referred to as "this composition") according to the present invention is a modified (meth)acrylic resin (a) having an iodine value of less than 4 (hereinafter simply "modified (meth) acrylic resin (a)") and a drying accelerator (b) containing manganese (hereinafter also simply referred to as "drying accelerator (b)").

In this specification, "(meth)acrylic" means acrylic and/or methacryl, and expressions such as "(meth)acrylate" below also mean the same thing.

The present composition is preferably a composition that is coated on an epoxy resin-based anticorrosive coating film in order to better exhibit the effects of the present invention, and is preferably a composition for use in steel structures, especially ships. It is preferable that there be.

The present composition may be a one-component type composition or a two- or more-component type composition, but according to the present composition, it can be a one-component type composition. It is preferable that it is a thing. The one-component type composition is preferably a one-component type composition, and such a composition does not require mixing of the main component and the curing agent component, is easy to handle, and is flexible. It is desirable because it has excellent workability, such as no restrictions on usage time, and is suitable for painting large areas such as large steel structures.

<Modified (meth)acrylic resin (a)>
The modified (meth)acrylic resin (a) is not particularly limited as long as it is a resin obtained using a (meth)acrylic compound so that the iodine value falls within the above range.
The modified (meth)acrylic resin (a) may be used alone or in combination of two or more.

The modified (meth)acrylic resin (a) is preferably an oxidatively polymerizable modified (meth)acrylic resin having an oxidatively polymerizable group that can undergo oxidative polymerization.
By using an oxidative polymerization type modified (meth)acrylic resin, it is possible to form a crosslinked structure through oxidative polymerization, which makes the coating film stronger than that obtained from a composition containing a conventional acrylic resin that does not undergo oxidative polymerization. As a result, it is considered to have excellent bubble and blistering resistance.
Suitable examples of the oxidation-polymerized modified (meth)acrylic resin include alkyd resin-modified (meth)acrylic resin and fatty acid-modified (meth)acrylic resin, with alkyd resin-modified (meth)acrylic resin being particularly preferred. preferable.

The modified (meth)acrylic resin (a) is preferably a resin that does not have a structural unit represented by the following formula [I].

（式中、Ｒ１は、水素原子または－Ｏ－Ｒ３（Ｒ３は、水素原子または炭素数１～４のアルキル基を表す。）を表し、Ｒ２は、水素原子または炭素数１～４のアルキル基を表す。）

(In the formula, R1 represents a hydrogen atom or -O-R3 (R3 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms), and R2 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. )

Iodine value refers to the number of grams (grams) of iodine absorbed when 100 g of modified (meth)acrylic resin (a) is treated with iodine. Indicates degree.
The iodine value of the modified (meth)acrylic resin (a) is less than 4, since it is possible to obtain a coating film that is excellent in a well-balanced manner in bubble blistering resistance, yellowing resistance, water whitening resistance, and weather resistance. Preferably it is 0.1 or more and less than 4, more preferably 1 or more and less than 4.
When the iodine value is 4 or more, the weather resistance of the resulting coating film tends to decrease, and the resulting composition tends to become skin-like, making it necessary to use a skin-preventing agent. It is in.

The weight average molecular weight (Mw) of the modified (meth)acrylic resin (a) measured by the gel permeation chromatography (GPC) method in terms of standard polystyrene makes it possible to easily obtain a coating film with excellent blistering resistance. From these points of view, it is preferably 20,000 to 250,000, more preferably 25,000 to 200,000.

The acid value of the modified (meth)acrylic resin (a) varies depending on the number of carboxy groups contained in the resin, so it is important to know how many carboxy groups (COOH groups) are present in the modified (meth)acrylic resin (a). It serves as an indicator of whether
Here, the COOH group of the modified (meth)acrylic resin (a) forms a hydrogen bond with the OH group on the surface of the base material and the OH group derived from the epoxy resin in the undercoat anticorrosion coating, thereby preventing adhesion to the coated object. It is thought that it affects sex. However, if the modified (meth)acrylic resin (a) contains an excess of carboxyl groups, the water resistance of the resulting coating film may be reduced. From these viewpoints, the acid value of the modified (meth)acrylic resin (a) is preferably 0.5 to 10 mgKOH/g.

In order to obtain the present composition with excellent coating properties, the modified (meth)acrylic resin (a) preferably has a viscosity (25° C., mPa·s) in a 50% xylene or toluene solution of the resin. 300 to 15,000, more preferably 500 to 12,000.

In the modified (meth)acrylic resin (a), the glass transition temperature (Tg, theoretical value) of the structural unit derived from the following unsaturated monomer is excellent in hardness, stain resistance, crack resistance, and interval adhesion in a well-balanced manner. The temperature is preferably 20 to 70°C, more preferably 25 to 50°C, from the viewpoint of easily obtaining a coating film.

The Tg is Fox T. G. , Bull. Am. Physics Soc. 1, 3, p. 123 (1956), it can be approximately calculated using the following Fox formula.

［式中、Ｘ_nは、変性（メタ）アクリル樹脂（ａ）の合成に用いる下記不飽和モノマーの合計１００質量％に対する不飽和モノマーｎの質量分率（質量％／１００）であり、Ｔｇ_nは、該モノマーｎのホモポリマーのガラス転移温度（ケルビン）である。］

[In the formula, X _n is the mass fraction (mass%/100) of the unsaturated monomer n with respect to the total 100 mass% of the following unsaturated monomers used for the synthesis of the modified (meth)acrylic resin (a), and Tg _n is the glass transition temperature (in Kelvin) of the homopolymer of monomer n. ]

Tg _n is, for example, as described in Polymer Handbook 2nd Edition, J. The values described in Wiley & Sons, New York (1975) can be referred to. According to this handbook, for example, the Tg of polystyrene is 373K, the Tg of poly(methyl methacrylate) is 378K, the Tg of poly(butyl methacrylate) is 297K, and the Tg of poly2-hydroxylethyl methacrylate is 328K, and the Tg of polymethacrylic acid is 458K.

The content of the modified (meth)acrylic resin (a) is determined from the viewpoint that it is possible to easily obtain a coating film that is excellent in bubble resistance, yellowing resistance, water whitening resistance, and weather resistance in a well-balanced manner. It is preferably 20 to 60% by mass, more preferably 30 to 50% by mass based on 100% by mass of solid content.

In addition, the "solid content of this composition" in this specification refers to the heating residue of this composition measured according to the standard of JIS K 5601-1-2 (heating temperature: 125 ° C., heating time: 60 minutes). It usually consists of main coating film-forming components such as a modified (meth)acrylic resin (a) and a drying accelerator (b), as well as solid components among the other components listed below.

- Alkyd resin-modified (meth)acrylic resin The alkyd resin-modified (meth)acrylic resin can be synthesized using, for example, a (meth)acrylic compound and an alkyd resin.
Specifically, it is synthesized by adding a solvent to an alkyd resin, adding a predetermined amount of an unsaturated monomer containing a (meth)acrylic compound and a polymerization initiator, and reacting at 80 to 150°C for about 3 to 10 hours. be able to.

The alkyd resin can be obtained by a conventionally known method, but it is a resin obtained by polycondensing a (semi-)drying oil or a (semi-)drying oil fatty acid, an acid component, and a polyhydric alcohol component. is preferred.

Examples of the (semi-)drying oil include fish oil, dehydrated castor oil, safflower oil, linseed oil, soybean oil, sesame oil, poppy oil, eno oil, hempseed oil, grape kernel oil, corn oil, tall oil, and sunflower oil. , cottonseed oil, walnut oil, rubber seed oil; (semi-)drying oil fatty acids include, for example, fish oil fatty acids, dehydrated castor oil fatty acids, safflower oil fatty acids, linseed oil fatty acids, soybean oil fatty acids, sesame oil fatty acids, poppy oil fatty acids. Fatty acids include eno oil fatty acids, hempseed oil fatty acids, grape kernel oil fatty acids, corn oil fatty acids, tall oil fatty acids, sunflower oil fatty acids, cottonseed oil fatty acids, walnut oil fatty acids, and rubber seed oil fatty acids. These can be used alone or in combination of two or more.

The amounts of the (semi-)drying oil and (semi-)drying oil fatty acid to be used are such that when the resulting modified (meth)acrylic resin (a) is used, it has the following properties: blistering resistance, yellowing resistance, water whitening resistance, and weather resistance. From the viewpoint that it is possible to easily obtain a coating film that is excellent in a well-balanced manner, it is preferably 20 to 70% by mass, more preferably 30 to 60% by mass, based on 100% by mass of the monomer component when synthesizing the alkyd resin. be.

Examples of the acid component include phthalic anhydride, isophthalic acid, terephthalic acid, maleic anhydride, trimellitic anhydride, adipic acid, benzoic acid, rosin, and succinic acid. These can be used alone or in combination of two or more.

The amount of the acid component to be used is not particularly limited as it does not significantly affect the performance of the present composition, but it is preferably 10 to 50% by mass, more preferably 10 to 50% by mass, based on 100% by mass of the monomer component when synthesizing the alkyd resin. is 20 to 40% by mass.

Examples of the polyhydric alcohol component include ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 3-methylpentanediol, 1,4-hexanediol, and 1,6-hexanediol. Examples include dihydric alcohols, trihydric or higher alcohols such as glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol. These can be used alone or in combination of two or more.

The amount of the polyhydric alcohol component to be used is not particularly limited since it does not significantly affect the performance of the present composition, but it is preferably 10 to 50% by mass, based on 100% by mass of the monomer component when synthesizing the alkyd resin. More preferably 20 to 40% by mass.

The amount of alkyd resin used when synthesizing the modified (meth)acrylic resin (a) is determined by the amount of blistering resistance, yellowing resistance, and water whitening resistance when using the obtained modified (meth)acrylic resin (a). The structure derived from (semi-)drying oil and (semi-)drying oil fatty acid in 100% by mass of modified (meth)acrylic resin (a), because it is possible to easily obtain a coating film with good balance and excellent weather resistance. The content of the units is preferably 0.1 to 25% by mass, more preferably 0.5 to 10% by mass.

The unsaturated monomer is not particularly limited as long as a (meth)acrylic compound is used, and other unsaturated monomers other than the (meth)acrylic compound may be used together with the (meth)acrylic compound.

Examples of the (meth)acrylic compound include methyl (meth)acrylate, ethyl (meth)acrylate, n- or iso-propyl (meth)acrylate, n-, iso- or tert-butyl (meth)acrylate, hexyl ( meth)acrylate, 2-ethylhexyl(meth)acrylate, n-octyl(meth)acrylate, n-nonyl(meth)acrylate, isononyl(meth)acrylate, tridecyl(meth)acrylate, lauryl(meth)acrylate, stearyl(meth)acrylate (meth)acrylic acid alkyl esters such as acrylate, cyclohexyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, glycidyl (meth)acrylate, dicyclopentanyl (meth)acrylate, Alicyclic, aromatic, heterocyclic or vinyl group-containing (meth)acrylic acid esters such as tetrahydrofurfuryl (meth)acrylate, allyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate Acrylate, hydroxyl group-containing (meth)acrylic acid ester such as 2-hydroxybutyl (meth)acrylate, adduct of 2-hydroxyethyl (meth)acrylate with ethylene oxide, propylene oxide, γ-butyrolactone or ε-caprolactone, etc. (meth)acrylic acid ester containing multiple hydroxyl groups such as glycerol (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, m- or Alkoxy group-containing (such as p-methoxyphenyl (meth)acrylate, o-, m- or p-methoxyphenylethyl (meth)acrylate, phenoxyethyl (meth)acrylate, 2-dicyclopentenoxyethyl (meth)acrylate, etc. meth)acrylic acid ester, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, dimethylaminobutyl (meth)acrylate, dibutylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate ) Tertiary amino group- and (meth)acryloyl group-containing monomers such as acrylamide and dimethylaminopropyl (meth)acrylamide; primary or secondary amino groups such as (meth)acrylamide and butylaminoethyl (meth)acrylate; Examples include (meth)acryloyl group-containing monomers, acrylonitrile, methacrylonitrile, and (meth)acrylic acid. These can be used alone or in combination of two or more.

Examples of the other unsaturated monomers include heterocyclic basic monomers such as vinylpyrrolidone and vinylpyridine, vinyl monomers such as styrene, vinyltoluene, α-methylstyrene, vinyl acetate, and vinyl propionate, and crotonic acid. , monoesters of monobasic or dibasic acid monomers such as maleic acid, fumaric acid, and itaconic acid, and dibasic acid monomers such as monomethyl maleate, monoethyl maleate, monomethyl itaconate, and monoethyl itaconate. These can be used alone or in combination of two or more.

The amount of the (meth)acrylic compound to be used is determined from the viewpoint that when the obtained modified (meth)acrylic resin (a) is used, a coating film with excellent bubble blistering resistance can be easily obtained. The amount is preferably 10 to 100% by weight, more preferably 20 to 90% by weight, and even more preferably 30 to 80% by weight, based on 100% by weight of the saturated monomer.

When the obtained modified (meth)acrylic resin (a) is used as the unsaturated monomer, the present composition has excellent pigment dispersibility, and also has good adhesion to the object to be coated, especially the undercoat anticorrosion coating. It is preferable to include 2-hydroxyethyl methacrylate or methacrylic acid, and especially to use these in combination, since an excellent coating film tends to be obtained.

When 2-hydroxyethyl methacrylate is used as the unsaturated monomer, the content of the structural unit derived from 2-hydroxyethyl methacrylate with respect to 100% by mass of the modified (meth)acrylic resin (a) is such that the content of structural units derived from 2-hydroxyethyl methacrylate has a corrosion resistance (e.g. The content is preferably 2% by mass or more, and preferably 20% by mass or less, from the viewpoint of easily obtaining a coating film having excellent water resistance).
In addition, when methacrylic acid is used as the unsaturated monomer, the content of structural units derived from methacrylic acid with respect to 100% by mass of the modified (meth)acrylic resin (a) is determined by From the viewpoint of being able to easily obtain an excellent coating film, the content is preferably 0.5% by mass or more, and preferably 10% by mass or less.

The unsaturated monomer preferably contains styrene because when the resulting modified (meth)acrylic resin (a) is used, a coating film with excellent hardness tends to be easily obtained. In this case, the content of the structural unit derived from styrene is preferably 10 to 60% by mass, more preferably 15 to 50% by mass, based on 100% by mass of the modified (meth)acrylic resin (a).

-Fatty acid-modified (meth)acrylic resin The fatty acid-modified (meth)acrylic resin can be synthesized by a conventionally known method using, for example, the unsaturated monomer and a fatty acid-modified polymerizable unsaturated monomer.

Examples of the fatty acid-modified polymerizable unsaturated monomer include monomers obtained by reacting a polymerizable unsaturated monomer having an epoxy group or a hydroxyl group with a (semi-)drying oil fatty acid.
Conditions for the reaction include, for example, conditions such as allowing the reaction to occur at 140 to 170° C. for approximately 6 to 15 hours in the presence of a polymerization inhibitor.

Examples of the polymerizable unsaturated monomer having an epoxy group include glycidyl (meth)acrylate, β-methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, and 3,4-epoxycyclohexylethyl ( Examples include meth)acrylate, 3,4-epoxycyclohexylpropyl(meth)acrylate, and allyl glycidyl ether. These can be used alone or in combination of two or more.

Examples of the polymerizable unsaturated monomer having a hydroxyl group include the same compounds as the (plural) hydroxyl group-containing (meth)acrylic esters. These can be used alone or in combination of two or more.

The amount of the fatty acid-modified polymerizable unsaturated monomer to be used is such that when the obtained modified (meth)acrylic resin (a) is used, a coating film that is well-balanced and excellent in bubble blistering resistance, yellowing resistance, water whitening resistance, and weather resistance is determined. The content of structural units derived from (semi-)drying oil fatty acids in 100% by mass of the modified (meth)acrylic resin (a) is preferably 2 to 25% by mass, more preferably from the viewpoint of being easily obtainable. is an amount of 3 to 10% by mass.

Furthermore, the modified (meth)acrylic resin (a) may be a resin obtained by obtaining a (meth)acrylic resin using the unsaturated monomer and then introducing an oxidatively polymerizable group into the resin.
Examples of the oxidatively polymerizable group include a group derived from a (semi-)drying oil fatty acid, a dicyclopentadieneoxyalkyl group, and an allyl group.

For example, in order to introduce a group derived from a (semi)drying oil fatty acid into a (meth)acrylic resin, an unsaturated monomer having an epoxy group or a hydroxyl group is used as the unsaturated monomer, and in the resulting (meth)acrylic resin, A (semi-)drying oil fatty acid may be added to the epoxy group or hydroxyl group of.

The amount of the oxidation-polymerizable group introduced is such that when the obtained modified (meth)acrylic resin (a) is used, a coating film that is excellent in a well-balanced manner in bubble resistance, yellowing resistance, water whitening resistance, and weather resistance can be easily formed. The content of oxidatively polymerizable groups in 100% by mass of the modified (meth)acrylic resin (a) is preferably 0.1 to 25% by mass, more preferably 1 to 10% by mass. This is the amount.

<Drying accelerator (b)>
"Drying accelerator" is a component commonly called "dryer", and metal salts such as cobalt, zirconium, calcium, barium, etc. are commonly used. Among these, cobalt dryer has the highest drying performance. Because of its excellent drying properties, it has been used as a major drying accelerator.
However, cobalt dryers are suspected of being carcinogenic to humans and may be subject to use regulations, and the inventor has conducted extensive research and found that cobalt dryers are not used as drying accelerators other than drying accelerator (b). It was found that when using such agents, it was not possible to obtain a coating film that was well-balanced and excellent in bubble resistance, yellowing resistance, water whitening resistance, and weather resistance.
On the other hand, since the present composition contains a manganese-containing drying accelerator (b) together with the specific modified (meth)acrylic resin (a), it is a composition with excellent safety, and has excellent bubble resistance and yellowing resistance. It is possible to obtain a coating film that is excellent in a well-balanced manner in modification, water whitening resistance, and weather resistance.

The drying accelerator (b) is not particularly limited as long as it contains manganese, but it is preferably a substance that has the effect of promoting crosslinking reaction by oxidative polymerization, and specifically, fatty acid manganese salt, Examples include manganese oxide and simple manganese.
The drying accelerator (b) may be used alone or in combination of two or more.

Examples of the fatty acids include octylic acid, naphthenic acid, neodecanoic acid, isononanoic acid, butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, aragic acid, behenic acid, and lignoceric acid. , cerotic acid, montanic acid, melisic acid, tuccinic acid, lindelic acid, tuzunic acid, macconic acid, myristoleic acid, zomarinic acid, petroselic acid, oleic acid, vaccenic acid, gadoleic acid, whale oil acid, erucic acid, shark Oil acid, tung oil acid, linseed oil acid, linoleic acid, hirago acid, eleostearic acid, punic acid, tricosanoic acid, linolenic acid, monoctic acid, parinaric acid, arachidonic acid, sardine oil acid, hiragasira acid, nisic acid, large Examples include soybean oil fatty acids and tall oil fatty acids.

As the drying accelerator (b), fatty acid manganese salts are preferred from the viewpoint of easily obtaining a coating film with better bubble resistance, and in particular, manganese neodecanoate compounds, manganese octylate compounds, Manganese isononanoate compounds and manganese naphthenate compounds are preferred, and manganese neodecanoate compounds are more preferred since a coating film with better weather resistance can be easily obtained.

The content of the drying accelerator (b) is 100 parts by mass of the modified (meth)acrylic resin (a) from the viewpoint of easily obtaining a coating film with excellent curability and bubble blistering resistance. The amount is preferably 0.01 to 5 parts by weight, more preferably 0.01 to 1 part by weight.

<Other ingredients>
The present composition is not particularly limited as long as it contains the modified (meth)acrylic resin (a) and the drying accelerator (b), and if desired, the modified (meth)acrylic resin ( In addition to a) and the drying accelerator (b), other components such as plasticizers, pigments, color separation inhibitors, anti-sagging agents (anti-settling agents), antifoaming agents, and solvents may be used.
Commercially available products may be used for these other components.
These other components may be used alone or in combination of two or more.

Although an anti-skinning agent may be used in the present composition, since the composition does not cause skinning even without the use of the anti-skinning agent, considering the impact on the human body and the environment, it is Preferably, no anti-tension agent is used.
Note that as the anti-skinning agent, an antioxidant such as an oxime compound or a phenol compound is used. Commercially available products of such anti-skinning agents include "MEK Oxime" (manufactured by Ube Industries, Ltd.), which is an oxime compound.

<Plasticizer>
The present composition preferably contains a plasticizer from the viewpoints of improving crack resistance and water resistance, and improving adhesion to the object to be coated, especially the undercoat film.
The plasticizers may be used alone or in combination of two or more.

Plasticizers are not particularly limited, but include, for example, chlorinated paraffins, phthalates, adipates, trimellitates, phosphates, citric esters, sebacic esters, azelaic esters, maleic esters, and benzoic acid. Examples include esters, acrylic resins (excluding modified (meth)acrylic resin (a)), polyester resins, and epoxy resins.

When a plasticizer is added to this composition, the amount of plasticizer added is determined from the viewpoint of easily obtaining a coating film with excellent adhesion to the object to be coated, especially the undercoat film. The amount is preferably 0.5 to 10% by weight based on 100% by weight of solid content.

<Pigment>
The pigment is not particularly limited, but may include coloring pigments, extender pigments, functional pigments, etc., and may be appropriately selected and used depending on desired physical properties.
The pigments may be used alone or in combination of two or more.

Examples of colored pigments include carbon black, titanium oxide, iron oxide, phthalocyanine, azo compounds, and fused polycyclic compounds.
Examples of extender pigments include barium sulfate, (colloid) calcium carbonate, talc, mica, and silica.
Examples of functional pigments include conductive pigments, fluorescent pigments, aluminum pigments, and stainless steel pigments.

When a pigment is blended into the present composition, the pigment volume concentration (PVC) in the present composition is preferably 15 to 45%, more preferably 15 to 45%, from the viewpoint of providing a well-balanced and excellent toughness and gloss of the resulting coating film. Preferably it is 18 to 40%, particularly preferably 20 to 38%.
If the PVC is too low, the bubble blistering resistance of the coating film tends to decrease, and if it is too high, the adhesion to the object to be coated tends to decrease.

Note that PVC in this specification refers to the total volume concentration of pigments in the coating composition with respect to the volume of the solid content in the coating composition, and specifically, it is determined by the following formula.
PVC (%) = total volume of pigments in the paint composition/volume of solids in the paint composition x 100
For PVC, more specifically, the mass and true density of the heating residue of the coating composition are measured based on the above-mentioned JIS K 5601-1-2, and the pigment is further separated from the heating residue. , can be calculated by measuring the mass and true density of the separated pigment.

<Anti-sagging agent (anti-settling agent)>
The anti-sagging agent (anti-settling agent) is not particularly limited, and conventionally known anti-sagging agents (anti-settling agent) can be used.
The anti-sagging agents (anti-settling agents) may be used alone or in combination of two or more.

Examples of anti-sagging agents (settling prevention agents) include organic thixotropic agents such as amide wax-based thixotropic agents, hydrogenated castor oil-based thixotropic agents, oxidized polyethylene-based thixotropic agents, clay minerals such as bentonite, and synthetic thixotropic agents. Examples include inorganic thixotropic agents such as finely divided silica, and preferred are amide wax-based thixotropic agents, oxidized polyethylene-based thixotropic agents, synthetic finely divided silica, and clay minerals such as bentonite.

When an anti-sagging agent (anti-settling agent) is added to the composition, the amount thereof is preferably 0.1 to 10% by weight based on 100% by weight of the composition.

<Defoaming agent>
The antifoaming agent is not particularly limited, and conventionally known antifoaming agents can be used.
The antifoaming agents may be used alone or in combination of two or more.
Examples of antifoaming agents include acrylic (excluding modified (meth)acrylic resin (a)), vinyl ether, silicone, butadiene, olefin, and fluorine compounds.
When an antifoaming agent is added to the composition, the amount thereof is preferably 0.01 to 5% by weight based on 100% by weight of the composition.

<solvent>
The solvent is not particularly limited, but for example, toluene, xylene, "Ipsol 100" (manufactured by Idemitsu Kosan Co., Ltd.), "Swasol 1000" (manufactured by Maruzen Petrochemical Co., Ltd.), "Solvesso 100", "Solvesso 150" (manufactured by ExxonMobil), "LAWS" (manufactured by Shell), etc., aromatic hydrocarbon solvents, ethylene glycol monobutyl ether (butyl cellosolve), isopropyl alcohol, n-butanol, etc. alcohol solvents, ethyl acetate, butyl acetate, Ester solvents such as isobutyl acetate, aliphatic hydrocarbon solvents such as n-hexane, n-octane, 2,2,2-trimethylpentane, isooctane, n-nonane, cyclohexane, methylcyclohexane, methyl isobutyl ketone, methyl ethyl ketone, Examples include ketone solvents such as methyl isobutyl ketone and petroleum solvents such as mineral spirit.

≪Laminated coating film≫
The laminated coating film according to the present invention is a laminated coating film of an epoxy resin base coat anticorrosive coating film (A) and a top coat coating film (B) formed from the present composition.
Such a laminated coating film is formed by forming an undercoat anticorrosion coating film (A) using the epoxy paint below, and forming a topcoat coating film (B) using the present composition on the undercoat anticorrosion coating film (A). Specifically, the step of coating a base material with an epoxy paint, drying and curing the painted paint to form an undercoat anticorrosion coating film (A), and It can be produced by a method including the steps of coating the present composition on the undercoat anticorrosion coating (A), drying and curing the coated composition to form the topcoat coating (B). In the latter method, a coated substrate is produced.

The base material is not particularly limited, but examples of the material include steel, aluminum, and FRP (fiber reinforced plastic). In particular, the base material is preferably a (large) steel structure, from the viewpoint that the effects of the present invention are more effectively exhibited, and specifically, ships, bridges, tanks, plants, marine buoys, etc. Examples include underwater pipelines. In particular, the outer surfaces of hulls (vessels) such as passenger ships, cargo ships, and tankers (particularly areas such as the outer side, waterline, deck, and superstructure of ships) have anti-bubble, anti-yellowing, Since water whitening resistance, weather resistance, etc. are required, it is preferable to use the present composition on the outer surface because the effects of the present invention can be more effectively exhibited.

In addition, before applying the epoxy paint below, the surface of the base material may be treated if necessary. Specifically, rust, oil, moisture, dust, etc. that have already occurred or adhered to the surface of the base material to be painted can be treated. The deposits on the surface of the base material may be cleaned and removed, or a sealer, binder, primer, etc. may be applied in advance depending on the material of the base material.
That is, the base material includes a base material coated with a sealer, a binder, a primer, or the like.

The method of applying the epoxy paint or this composition described below is not particularly limited, and conventionally known methods such as spray painting, brush painting, and roller painting can be used. Among these, spray coating is preferred because it can easily coat large (large area) substrates.
When painting, it may be diluted with various solvents as necessary before painting. The solvent is not limited as long as it has good compatibility and drying properties, and for example, the solvents exemplified in the column of other components can be used. Note that the descriptions in this specification other than this paragraph relate to the present composition, epoxy paint, etc. before dilution.

Although it depends on the desired use and the situation at the painting site, the present composition may be applied after a certain period of time (interval) after forming the undercoat anticorrosive coating (A).

The method for drying and curing the following epoxy paint and this composition is not particularly limited, and may be dried and cured by heating at about 5 to 60°C to shorten the curing time, but usually at room temperature or in the atmosphere. The applied epoxy paint or this composition is allowed to dry and harden by leaving it for about 1 to 14 days.

The thickness of the undercoat anticorrosive coating (A) is not particularly limited, but is usually 50 to 500 μm, preferably 100 to 350 μm.
When forming a coating film with such a thickness, the coating film with the desired thickness may be formed with one coating, or the coating with the desired thickness may be formed with two coatings (or more if necessary). A thick coating film may be formed.

The thickness of the top coat (B) is also not particularly limited, but is usually 20 to 350 μm, preferably 30 to 150 μm.

<Epoxy resin anti-corrosion coating>
The undercoat anticorrosive coating film (A) is a coating film formed from an epoxy resin-based anticorrosive coating composition (also referred to as "epoxy paint"). The epoxy paint is not particularly limited, and conventionally known epoxy resin-based anticorrosive paint compositions can be used, but the corrosion resistance and adhesion to the base material of the undercoat anticorrosive film (A) formed from the paint are From these points, it is preferable to contain the following epoxy resin (p) and curing agent for epoxy resin (q).

<Epoxy resin (p)>
The epoxy resin (p) is not particularly limited, but includes polymers or oligomers having two or more epoxy groups in the molecule, and polymers or oligomers in which the epoxy groups undergo a ring-opening reaction. Examples of such epoxy resins include glycidyl ether type epoxy resins, glycidyl ester type epoxy resins, glycidylamine type epoxy resins, bisphenol type epoxy resins, phenol novolak type epoxy resins, cresol type epoxy resins, and dicyclopentadiene type epoxy resins. , aliphatic epoxy resins, alicyclic epoxy resins, and fatty acid-modified epoxy resins.
The epoxy resin (p) may be used alone or in combination of two or more.

Among these, bisphenol-type epoxy resins are preferred because they can easily form coating films with excellent corrosion resistance and adhesion to substrates, and bisphenol-A, bisphenol-AD, and bisphenol-F epoxy resins are preferred. More preferably, it is one or more selected from resins, and particularly preferably bisphenol A type epoxy resin.

The weight average molecular weight and epoxy equivalent of the epoxy resin (p) cannot be absolutely determined depending on the coating curing conditions of the obtained epoxy paint (e.g. air-drying painting or baking painting, etc.), but they were determined by the GPC method. The weight average molecular weight is usually 350 to 20,000, and the epoxy equivalent is usually 150 to 1,000.

The content of the epoxy resin (p) is usually 10 to 60% by mass, preferably 100% by mass, based on 100% by mass of the epoxy paint containing a solvent etc., from the viewpoint of easily obtaining a coating film with excellent corrosion resistance. The amount is usually 10 to 70% by weight, preferably 20 to 60% by weight, based on 100% by weight of the solid content of the epoxy paint.

<Curing agent for epoxy resin (q)>
The curing agent (q) for epoxy resin is not particularly limited, but specifically includes amine curing agents and acid anhydride curing agents, with amine curing agents being preferred.
Examples of the amine curing agent include aliphatic amine curing agents, alicyclic amine curing agents, aromatic amine curing agents, heterocyclic amine curing agents, other amine curing agents such as polyether diamine, and these amines. Examples include modified products of curing agents (e.g. polyamides, polyamidoamines [polyamide resins], amine adducts with epoxy compounds, Mannich compounds [e.g. Mannich-modified polyamideamines], Michael adducts, ketimines, aldimines, phenalkamines).
Specific examples of the amine curing agent include, for example, the curing agent described in JP 2018-44162A.
The curing agent (q) may be used alone or in combination of two or more.

The active hydrogen equivalent of the amine curing agent is preferably 50 to 1,000, more preferably 80 to 400, from the viewpoint of obtaining an anticorrosive undercoat coating (A) with excellent corrosion resistance.

When an amine curing agent is used as the curing agent (q) in the epoxy paint, the equivalent ratio (amount of curing agent used/active hydrogen equivalent)/(amount of epoxy resin used/epoxy equivalent) is preferably 0.20 to 0. .9, more preferably 0.25 to 0.75.

Examples of acid anhydride curing agents include phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, 3,6-endomethylenetetrahydrophthalic anhydride, hexachloroendomethylenetetrahydrophthalic anhydride, and methyl-3,6-endomethylenetetrahydrophthalic anhydride. - Endomethylenetetrahydrophthalic anhydride.

<Additive>
In addition to the epoxy resin (p) and the curing agent (q), the epoxy paint may contain additives such as a curing accelerator, pigment, anti-sagging agent (anti-settling agent), antifoaming agent, and solvent. Also, from the viewpoint of adhesion of the obtained coating film to the substrate, it is preferable to contain a pigment.
As the additive, the same components as those described in the column of other components may be used.
These additives may be used alone or in combination of two or more.

The volume fraction (VS) of the solid content of the epoxy paint, measured according to ISO 3233, is preferably 50 to 100%, more preferably 55 to 90%, particularly preferably 60 to 85%.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

The weight average molecular weight (Mw), acid value (mgKOH/g) and iodine value (solid content equivalent value) of the obtained resin were measured using the test method described below, and the solid content in the modified (meth)acrylic resin solution was measured. (% by mass) was measured.

<Weight average molecular weight (Mw)>
The weight average molecular weight was determined by the GPC method using an apparatus (manufactured by Tosoh Corporation, HLC-8220GPC), columns (SuperH2000+SuperH4000 (manufactured by Tosoh Corporation, inner diameter 6 mm each/length 15 cm each)), column temperature (40 ° C.), Measurement was performed under the following conditions: eluent (tetrahydrofuran), flow rate (0.50 mL/min.), detector (RI), and standard substance (polystyrene).

<Solid content>
After drying the modified (meth)acrylic resin solution in a hot air dryer at 108° C. for 3 hours, the heating residue (synonymous with “solid content”) was measured and calculated from the following formula.
Solid content (mass%) = (mass of the heated residue/mass of the resin solution before heating) x 100 (%)

<Acid value>
Accurately weigh 1 to 5 g of resin in a conical beaker, add 30 to 50 ml of toluene/ethanol = 7/3 (volume ratio) mixed solution to dissolve the resin, add 2 drops of phenolphthalein-ethanol solution as an indicator, Titration was performed with N/10 potassium hydroxide-ethanol solution. The end point of the titration was when the redness of the liquid did not disappear for 30 seconds, and the acid value was calculated using the following formula.
Acid value=(B×f×5.61)/S
(B: Amount of potassium hydroxide-ethanol solution used (ml), f: Factor of potassium hydroxide-ethanol solution, S: Mass of resin (g))

<Iodine value>
0.2 to 5 g of resin was accurately weighed into a flask with a stopper, 10 ml of carbon tetrachloride was added to dissolve the resin, and 25 ml of Wies' solution was further added accurately. After capping, the container was left in a dark place at room temperature for 30 minutes. Next, 20 ml of a 10 W/V% potassium iodide aqueous solution and 100 ml of water were added and mixed by shaking. Titrate the resulting solution with an N/10 aqueous sodium thiosulfate solution, and after the solution turns slightly yellow, add a few drops of starch solution and continue the titration while shaking well. The end point is when the blue color due to starch disappears. This test was conducted by doing this. In parallel with the main test, a blank test similar to the main test was conducted except that no resin was used.
The iodine value was calculated using the following formula. The iodine value in terms of solid content was calculated from the calculated iodine value and the solid content.
Iodine value = ((AB) x f x 1.269)/S
(A: Amount of N/10 sodium thiosulfate aqueous solution used in blank test (ml), B: Amount of N/10 sodium thiosulfate aqueous solution used in main test (ml), f: Factor of N/10 sodium thiosulfate aqueous solution, S : Mass of resin (g))

[Synthesis Example 1] Synthesis of alkyd resin solution (K1) In a reactor, 311.55 parts by mass of soybean oil fatty acid, 230.70 parts by mass of phthalic anhydride, 82.05 parts by mass of glycerin, and 98.55 parts by mass of pentaerythritol. Parts by mass, 27.15 parts by mass of benzoic acid, and 22.50 parts by mass of xylene as a refluxing solvent were charged.
The temperature of the resulting mixed solution was raised to 220° C. under a nitrogen stream, kept at the temperature for 3 hours, and then cooled. Thereafter, 650.80 parts by mass of xylene was added to prepare an alkyd resin solution (K1).
The solid content in the alkyd resin solution (K1) was 50.0% by mass. Furthermore, the Mw of the alkyd resin in the alkyd resin solution (K1) was 16,000, and the acid value was 6.4 mgKOH/g.

[Production Example 1] Preparation of modified (meth)acrylic resin solution (a1) In a reactor, 10.00 parts by mass (5.00 parts by mass in terms of solid content) of the alkyd resin solution (K1) obtained above and , 52.67 parts by mass of xylene and 9.00 parts by mass of toluene were charged as a solvent to obtain a mixed solution. After heating the mixture to 125° C. (reaction temperature) under a nitrogen stream, a mixture of monomer components (styrene: 38.00 parts by mass, methyl methacrylate (MMA): 18.00 parts by mass, n -Butyl acrylate (BA): 29.50 parts by mass, 2-hydroxyethyl methacrylate (2-HEMA): 8.45 parts by mass, and methacrylic acid (MAA): 1.05 parts by mass) 95 parts by mass, and starting A mixed solution with 1.00 parts by mass of agent (t-butyl peroxybenzoate) was added dropwise over 3 hours while maintaining the temperature at 125°C. After the dropwise addition, the mixture was kept at the same temperature (125°C) for 1 hour, and then 0.3 parts by mass of t-butyl peroxybenzoate was added. After keeping the temperature for 2 hours, it was cooled and 33.33 parts by mass of xylene was added to prepare a modified (meth)acrylic resin solution (a1).
The solid content in the modified (meth)acrylic resin solution (a1) was 50.0% by mass. Furthermore, the Mw of the modified (meth)acrylic resin in the modified (meth)acrylic resin solution (a1) is 34,000, the acid value is 3.9 mgKOH/g, and the iodine value (solid content equivalent value) is 2. It was .8.

[Production Example 2] Preparation of modified (meth)acrylic resin solution (a2) In a reactor, 3.40 parts by mass (1.70 parts by mass in terms of solid content) of the alkyd resin solution (K1) obtained above and , 55.99 parts by mass of xylene and 9.00 parts by mass of toluene were charged as a solvent to obtain a mixed solution. After heating the mixture to 125°C (reaction temperature) under a nitrogen stream, a mixture of monomer components (styrene: 39.32 parts by mass, methyl methacrylate (MMA): 18.00 parts by mass, n -Butyl acrylate (BA): 31.15 parts by mass, 2-hydroxyethyl methacrylate (2-HEMA): 8.69 parts by mass, and methacrylic acid (MAA): 1.14 parts by mass) 98.30 parts by mass. , and 1.66 parts by mass of an initiator (t-butyl peroxybenzoate) was added dropwise over 3 hours while maintaining the temperature at 125°C. After the dropwise addition, the mixture was kept at the same temperature (125°C) for 1 hour, and then 0.3 parts by mass of t-butyl peroxybenzoate was added. After keeping the temperature for 2 hours, it was cooled and 35.23 parts by mass of xylene was added to prepare a modified (meth)acrylic resin solution (a2).
The solid content in the modified (meth)acrylic resin solution (a2) was 50.1% by mass. Furthermore, the Mw of the modified (meth)acrylic resin in the modified (meth)acrylic resin solution (a2) is 25,711, the acid value is 4.7 mgKOH/g, and the iodine value (solid content equivalent value) is 1. It was .0.

[Production Example 3] Preparation of modified (meth)acrylic resin solution (a3) In a reactor, 17.40 parts by mass (8.70 parts by mass in terms of solid content) of the alkyd resin solution (K1) obtained above and 48.99 parts by mass of xylene and 9.00 parts by mass of toluene were charged as a solvent to obtain a mixed solution. After heating the mixture to 125°C (reaction temperature) under a nitrogen stream, a mixture of monomer components (styrene: 36.52 parts by mass, methyl methacrylate (MMA): 16.72 parts by mass, n -Butyl acrylate (BA): 28.93 parts by mass, 2-hydroxyethyl methacrylate (2-HEMA): 8.07 parts by mass, and methacrylic acid (MAA): 1.06 parts by mass) 91.30 parts by mass. , and 1.54 parts by mass of an initiator (t-butyl peroxybenzoate) was added dropwise over 3 hours while maintaining the temperature at 125°C. After the dropwise addition, the mixture was kept at the same temperature (125°C) for 1 hour, and then 0.3 parts by mass of t-butyl peroxybenzoate was added. After keeping the temperature for 2 hours, it was cooled and 35.15 parts by mass of xylene was added to prepare a modified (meth)acrylic resin solution (a3).
The solid content in the modified (meth)acrylic resin solution (a3) was 49.8% by mass. Furthermore, the Mw of the modified (meth)acrylic resin in the modified (meth)acrylic resin solution (a3) is 35,042, the acid value is 4.7 mgKOH/g, and the iodine value (solid content equivalent value) is 5. It was .0.

[Production Example 4] Preparation of modified (meth)acrylic resin solution (a4) In a reactor, 35.00 parts by mass (17.50 parts by mass in terms of solid content) of the alkyd resin solution (K1) obtained above and , 40.19 parts by mass of xylene and 9.00 parts by mass of toluene were charged as solvents to obtain a mixed solution. After heating the mixture to 125° C. (reaction temperature) under a nitrogen stream, a mixture of monomer components (styrene: 33.00 parts by mass, methyl methacrylate (MMA): 15.33 parts by mass, n -Butyl acrylate (BA): 26.30 parts by mass, 2-hydroxyethyl methacrylate (2-HEMA): 7.00 parts by mass, and methacrylic acid (MAA): 0.87 parts by mass) 82.50 parts by mass. , and 1.39 parts by mass of an initiator (t-butyl peroxybenzoate) was added dropwise over 3 hours while maintaining the temperature at 125°C. After the dropwise addition, the mixture was kept at the same temperature (125°C) for 1 hour, and then 0.3 parts by mass of t-butyl peroxybenzoate was added. After keeping the temperature for 2 hours, it was cooled and 35.00 parts by mass of xylene was added to prepare a modified (meth)acrylic resin solution (a4).
The solid content in the modified (meth)acrylic resin solution (a4) was 49.7% by mass. Furthermore, the Mw of the modified (meth)acrylic resin in the modified (meth)acrylic resin solution (a4) is 47,341, the acid value is 4.6 mgKOH/g, and the iodine value (solid content equivalent value) is 10. It was .0.

[Example 1]
45.5 parts by mass of the modified (meth)acrylic resin solution (a1) prepared in Production Example 1 was added to the container as the modified (meth)acrylic resin (a). Next, 1 part by mass of a plasticizer was added, 20 parts by mass of titanium white, 3.5 parts by mass of colloidal calcium carbonate, and 9.5 parts by mass of barium sulfate. Next, 3.2 parts by mass of n-butanol, 2 parts by mass of butyl cellosolve, 4.3 parts by mass of xylene, and 7.1 parts by mass of "Ipsol 100" were added.

Thereafter, glass beads GB605M (manufactured by Potter's Ballotini Co., Ltd.) were added, and these ingredients were mixed using a paint shaker (manufactured by Asada Tekko Co., Ltd.). Next, the glass beads were removed, and 0.2 parts by mass of calcium carbonate, 3 parts by mass of anti-sagging agent, 0.5 parts by mass of antifoaming agent, and 0.2 parts by mass of "Mn Dryer 1" as drying accelerator (b) were added. % and mixed with a disper "HOMODISPER MODEL 2.5" (manufactured by Primix Co., Ltd.) to prepare a modified (meth)acrylic resin coating composition.

[Examples 2 to 4, Comparative Examples 1 to 3]
Modified (meth)acrylic resin coating compositions were prepared in the same manner as in Example 1, except that the types and amounts of each component were changed as shown in Table 1. The amounts (parts by mass) of the modified (meth)acrylic resin solutions (a1) and (a2) in Table 1 indicate the values of the solutions.
Table 3 shows details of each component used in Examples and Comparative Examples.

<Bubble blistering resistance test>
At an environmental temperature of 23°C, the following epoxy resin anti-corrosion coating was applied to a sandblasted steel plate (150mm x 70mm x 2.3mm, Sa2.5 or higher) using an air spray coating machine (W-77, manufactured by Anest Iwata Co., Ltd.). The coating composition (P1) was applied to a wet film thickness of about 200 μm. After drying for one day under the environmental conditions of a temperature of 23°C and a humidity of 55%, a modified (meth)acrylic resin was applied onto the resulting epoxy resin anticorrosive coating using an airless spray coating machine (X Force, manufactured by Graco). The coating composition was applied to a wet film thickness of about 400 μm. Next, after drying for one day under the environmental conditions of a temperature of 23°C and a humidity of 55%, a modified (meth)acrylic resin was further applied onto the resulting modified (meth)acrylic resin coating using an airless spray coating machine (X Force). A coated steel plate for the bubble blistering resistance test was prepared by applying a resin coating composition to a wet film thickness of about 400 μm and drying it for 7 days under environmental conditions of a temperature of 23° C. and a humidity of 55%.

A process of holding the obtained painted steel plate for the bubble-proof blistering test in a constant temperature and humidity chamber at a temperature of 70°C and a humidity of 70% for 4 hours, followed by a process of holding it in a constant temperature and humidity chamber at a temperature of 23°C and a humidity of 70%. A total of 14 cycles were performed, with one cycle consisting of a step of holding the sample in a container for 4 hours (8 hours in total).
After 14 cycles, the coating film on the painted steel plate for the bubble blistering resistance test was visually checked to see if there was any blistering, and the evaluation was rated as ○ if there was no blistering, and × if there was blistering. The results are shown in Table 1.

・Epoxy resin anticorrosive paint composition (P1)
In a container, 5 parts by mass of epoxy resin "E-001-75X" (manufactured by Ohtake Meishin Chemical Co., Ltd., bisphenol A type epoxy resin) and 5 parts by mass of epoxy resin "E-834-85X" (manufactured by Ohtake Meishin Chemical Co., Ltd.) , bisphenol A type epoxy resin) was added. Next, as pigments, 3 parts by mass of "R-5N" (manufactured by Sakai Chemical Industry Co., Ltd., titanium white), 0.1 parts by mass of "MA-100" (manufactured by Mitsubishi Chemical Corporation, carbon black), " 22 parts by mass of "TTK Talc" (manufactured by Takehara Chemical Industry Co., Ltd.) and 18 parts by mass of "Ceramic Powder OF-T" (manufactured by Kinseimatec Co., Ltd., potassium feldspar) were added. Furthermore, as additives, 0.3 parts by mass of "KBM-403" (manufactured by Shin-Etsu Chemical Co., Ltd., γ-glycidoxypropyltrimethoxysilane), "DISPARON 6650" (manufactured by Kusumoto Kasei Co., Ltd., fatty acid amide wax) ) 1 part by mass was added. Next, as a solvent, 4 parts by mass of "methoxypropanol" (manufactured by Daicel Chemical Industries, Ltd.), 7.9 parts by mass of xylol (manufactured by Daishin Chemical Co., Ltd.), and n-butanol (manufactured by Dow Chemical Japan Co., Ltd.) were used. 1 part by mass (manufactured by ) was added.
Thereafter, glass beads GB605M were added, and these ingredients were mixed using a paint shaker (manufactured by Asada Tekko Co., Ltd.). Next, the glass beads were removed to produce a main component of an epoxy resin anticorrosive paint composition (P1).

In a separate container from the one in which the main ingredient was produced, 7.9 parts by mass of "PA-66" (manufactured by Ohtake Meishin Chemical Co., Ltd., polyamide amine) and "PA-290 (A)" were added as an amine curing agent. (manufactured by Ohtake Meishin Kagaku Co., Ltd., polyamide amine) and 3 parts by mass of "Cardrite NX-4918" (manufactured by Cardrite Co., Ltd., modified aliphatic polyamine) were added, and then as a curing accelerator, Add 0.1 part by mass of "Ankamin K-54" (manufactured by Air Products Co., Ltd., tertiary amine) and mix the mixture uniformly with a disper "HOMODISPER MODEL 2.5" to obtain an epoxy resin anticorrosive paint composition. A curing agent component (P1) was produced.

86 parts by mass of the main agent component and 14 parts by mass of the curing agent component were mixed to form an epoxy resin anticorrosive coating composition (P1), which was then coated. In this case, the equivalent ratio = (amount of curing agent used/active hydrogen equivalent)/(amount of epoxy resin used/epoxy equivalent) is 0.49, and the solid state of the epoxy resin anticorrosive coating composition (P1) The volume fraction (VS) was 73%.

<Yellowing resistance test>
A modified (meth)acrylic resin coating composition was applied to a degreased tin plate using an applicator (gap 0.3 mm) and dried at 23° C. for one week to form a coating film. The color b* of the formed coating film was measured using SPECTROPHOTOMETER CM-3700A (light source: C, field of view: 2°) manufactured by Konica Minolta Japan, and the b* increase rate was calculated from the following formula. Calculated. The results are shown in Table 1.
b*Increase rate (%) = (b* in each test - b* in Comparative Example 3) x 100/b* in Comparative Example 3

<Weather resistance test>
A modified (meth)acrylic resin coating composition was applied to a degreased tin plate using an applicator (gap 0.3 mm) and dried at 23° C. for one week to form a coating film. Thereafter, the formed coating film was irradiated with light for 350 hours using a super xenon weather meter (manufactured by Suga Test Instruments Co., Ltd.) in accordance with JIS K 5600-7-7. Note that the irradiance was 180 W/m ² .
The 60° specular gloss (G1) of the coating film formed using micro-TRI-gloss manufactured by BYK (the coating film before light irradiation) and the 60° specular gloss (G2) of the coating film after light irradiation. The gloss retention rate was calculated from the following formula. The results are shown in Table 1.
Gloss retention rate (%) = (G2/G1) x 100
In addition, using SPECTROPHOTOMETER CM-3700A (light source: C, field of view: 2°) manufactured by Konica Minolta Japan, Inc., the color difference between the formed coating film (coating film before light irradiation) and the coating film after light irradiation ( ΔE) was measured. The results are shown in Table 1.

[Examples 5 and 6 and Comparative Examples 4 to 8]
Modified (meth)acrylic resin coating compositions were prepared in the same manner as in Example 1, except that the types and amounts of each component were changed as shown in Table 2. Note that the blending amounts (parts by mass) of the modified (meth)acrylic resin solutions (a1) to (a4) in Table 2 indicate the values of the solutions.
Table 3 shows details of each component used in Examples and Comparative Examples.

<Bubble resistance test and weather resistance test>
A bubble resistance test and a weather resistance test (60° gloss retention) were conducted in the same manner as above. The results are shown in Table 2.

<Water whitening resistance test>
A modified (meth)acrylic resin coating composition was applied to a degreased tin plate using an applicator (gap 0.3 mm) and dried at 23° C. for one week to form a coating film. Thereafter, the formed coating film was immersed in warm water at 50° C. for 3 hours to whiten the coating film.
60° specular gloss (initial gloss, G3) of the paint film formed using micro-TRI-gloss manufactured by BYK (paint film before whitening), and 60° specular gloss (gloss after whitening) of the paint film after whitening. , G4) were measured, and the gloss retention rate was calculated from the following formula. The results are shown in Table 2.
Gloss retention rate (%) = (G4/G3) x 100
In addition, using SPECTROPHOTOMETER CM-3700A (light source: C, field of view: 2°) manufactured by Konica Minolta Japan, Inc., the brightness difference (ΔL) between the formed coating film (paint film before whitening) and the coating film after whitening *) was measured. The results are shown in Table 2.

Table 1 shows the results of using a white composition to confirm yellowing resistance, and Table 2 shows the results of using a black composition to confirm water whitening resistance. In addition, Comparative Examples 1 and 2 corresponding to Examples 1 and 3 and 4, and Comparative Examples 4 and 5 corresponding to Example 5, were designed so that the metal content in the drying accelerator used was the same. It is a composition adjusted to.
By using a modified (meth)acrylic resin (a) with an iodine value of less than 4 and a drying accelerator containing manganese (b), a coating film with excellent blistering resistance, yellowing resistance, weather resistance, and water whitening resistance A modified (meth)acrylic resin coating composition capable of forming the following was obtained.
Since the modified (meth)acrylic resin coating composition obtained in the example uses a modified (meth)acrylic resin (a) with an iodine value of less than 4, it can be coated without using a harmful anti-skinning agent. It is considered not to do so.

Although the present invention has been described above with reference to Examples, the present invention is not limited to such Examples, and, for example, without departing from the gist of the present invention as described in the claims. Design changes are allowed.

Claims (7)

A modified (meth)acrylic resin coating composition containing a modified (meth)acrylic resin (a) having an iodine value of less than 4 and a drying accelerator (b) containing manganese. The modified (meth)acrylic resin coating composition according to claim 1, wherein the drying accelerator (b) is a fatty acid manganese salt. Furthermore, it contains pigment,
The pigment volume concentration (PVC) in the modified (meth)acrylic resin coating composition is 15 to 45%,
The modified (meth)acrylic resin coating composition according to claim 1. A laminated coating film comprising an epoxy resin undercoat anticorrosive coating film and a topcoat coating formed from the modified (meth)acrylic resin coating composition according to any one of claims 1 to 3. A base material with a coating film, comprising the laminated coating film according to claim 4 and a base material. The coated base material according to claim 5, wherein the base material is a steel structure. A method for producing a coated base material, including the following steps 1 and 2.
Step 1: A step of applying an epoxy resin-based anticorrosive coating composition to a base material to form an undercoat anticorrosion coating (A). Step 2: Applying any one of claims 1 to 3 on the undercoat anticorrosion coating (A). A step of coating the modified (meth)acrylic resin coating composition according to item 1 to form a topcoat film (B).