JP2001002981A - Resin composition for thermoset coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition for a thermoset coating material, usable by a conventionally used coating method, and heating and hardening method, having a low viscosity excellent in operability without using an organic solvent, capable of being hybridized and having environmental compatibility. SOLUTION: This resin composition for a thermoset coating material consists essentially of (A) a single-functional and/or polyfunctional (meth)acrylate having 80-1,000 molecular weight per (meth)acryloyl group, and (B) an acrylic resin having at least one alkoxyalkylamide group in the molecule, and 5,000-100,000 weight average molecular weight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a resin composition for a thermosetting coating. More specifically, the present invention relates to a resin composition for a thermosetting paint, which is particularly suitable for a paint for coating the outer surface of a metal can.

[0002]

2. Description of the Related Art In recent years, strict regulations have been imposed on the use of solvent-based paints due to global environmental problems or the safety of health caused by the work environment. As a corresponding paint, a water-based paint (for example, JP-A-63-24887)
No. 4), powder coatings (for example, JP-A-8-3113)
No. 95), UV-curable paints (for example,
No. 89611) has been proposed.

[Problems to be solved by the invention]

However, in the above-mentioned method, a considerable amount (for example, 30% by mass) of a water-soluble organic solvent must be contained in order to impart a film-forming property to the paint, so that environmental problems and safety of the working environment are required. It is not always possible to respond sufficiently to the above. In addition, the above methods require special equipment and have a problem that it is difficult to obtain a coating film having sufficient performance. In recent years, it has been strongly desired to increase the concentration (high solid) of the paint in order to reduce the amount of transport and storage of the paint. The object of the present invention is that it has no problems such as pollution, safety and health, ignition and explosion, can be used in a conventionally used coating method and curing method, can be applied to a wide range of uses, and contains substantially no organic solvent. An object of the present invention is to provide a thermosetting resin composition for a coating material which can be made into a high solid.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to obtain a thermosetting paint capable of achieving the above object, and as a result, have reached the present invention. That is, the present invention relates to a monofunctional and / or polyfunctional (meth) acrylate (A) having a molecular weight of 80 to 1,000 and a hydroxyl value of 0.5 to 50 mgKOH / g per (meth) acryloyl group, A resin composition for a thermosetting paint, comprising an acrylic resin (B) having at least one alkylamide group in the molecule and having a weight average molecular weight of 5,000 to 100,000 as an essential component; And a metal can coated with a paint comprising the composition.

[0005]

The resin composition for a thermosetting coating composition of the present invention is heated, for example, to a temperature of 150 ° C. or more, so that the hydroxyl group and the (meth) acryloyl group of the monofunctional and / or polyfunctional (meth) acrylate (A) can be obtained. And the alkoxyalkylamide groups in the resin (B) react with each other to form a three-dimensional crosslinked structure, and the (meth) acryloyl groups in (A) are also thermally polymerized, so that the balance between hardness and flexibility is excellent. A coated film is formed. That is, in the state of the composition, (A) has a sufficiently low viscosity to function as a reactive diluent, and does not require dilution with an organic solvent.
Alternatively, it can be used in a high concentration (so-called non-sol type or high solid type) diluted with a small amount (30% by mass or less) of water or the like.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, monofunctional and / or
Alternatively, the molecular weight per (meth) acryloyl group of the polyfunctional (meth) acrylate (A) is usually from 80 to 1,000.
0, preferably 95-600, particularly preferably 110-600
400. If the molecular weight per (meth) acryloyl group is less than 80, the flexibility of the obtained coating film is reduced, so that the processability such as deep drawing is reduced. If it exceeds 1,000, the hardness of the obtained coating film is reduced. I do.

The hydroxyl group of (A) is usually 0.5 to 50 mgK
OH / g, preferably 1 to 30 mgKOH / g.
When the hydroxyl value is less than 0.5 mgKOH / g, the reactivity with the alkoxyacrylamide group decreases, and the
If it exceeds g, the flexibility of the coating film decreases

(A) is a hydroxyl group-containing (meth) acrylate or a mixture of (meth) acrylates containing at least a hydroxyl group-containing (meth) acrylate. The (meth) acrylate is, for example, a fatty acid having 2 to 12 carbon atoms. Group linear or branched dihydric alcohols (ethylene glycol, propylene glycol, 1,2-, 1,3-,
2,3-, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol,
-Methyl-2,4-pentanediol, 2,2-diethyl-1,3-propanediol, 2-ethyl-1,3-
Hexanediol, 2,2,4-trimethyl-1,3-
Pentanediol, 2-butyl-2-ethyl-1,3-
Propanediol, 1,9-nonanediol, 1,12
-Dodecanediol), alicyclic 2 having 6 to 15 carbon atoms
Dihydric alcohol [1,4-cyclohexylene glycol,
1,4-cyclohexanedimethanol, 2,2-bis (4,4′-hydroxycyclohexyl) propane,
4,4'-dihydroxycyclohexyl sulfone, 4,
4'-dihydroxycyclohexylmethane], aromatic dihydric alcohols having 8 to 15 carbon atoms (such as xylylene glycol), alkylene oxide adducts of these dihydric alcohols (addition moles of 1 to 20 or more) and 2 Alkylene oxide adducts (2 to 20 or more moles of addition) of polyhydric phenols (monocyclic dihydric phenols (hydroquinone, resorcin, catechol, etc.), bisphenols (bisphenol A, bisphenol S, bisphenol, etc.), etc.) Mono- and / or di (meth) acrylates of diols; aliphatic trihydric alcohols having 3 to 6 carbon atoms (glycerin, trimethylolethane, trimethylolpropane, 1,2,6-
Hexanetriol, etc.) and alkylene oxide adducts of these trihydric alcohols (addition moles 1 to 20).
Mono-, di-, and / or tri (meth) acrylates of triols; aliphatic tetrahydric alcohols having 5 to 10 carbon atoms (pentaerythritol, diglycerin, methyl glucoxide, etc.) and these tetrahydric alcohols Tetraol mono, such as an alkylene oxide adduct (addition mole number 1 to 20 or more),
Di-, tri- and / or tetra (meth) acrylates; aliphatic polyhydric alcohols having 6 to 30 carbon atoms and having 5 to 12 or more [dipentaerythritol, sorbitol, sucrose, polyglycerin (degree of polymerization 3 to 3)
10 or more) and alkylene oxide adducts of these polyhydric alcohols (addition mole number 1-2)
Mono- and / or poly (2-12 functional) (meth) acrylates of polyols, such as 0 or more), and mixtures of two or more thereof. Among them, polyfunctional (meth) acrylates [di (meth) acrylates of alkylene oxide adducts of aliphatic dihydric alcohols (addition moles 1 to 10), aliphatic 3
Di and tri (meth) acrylates of alkylene oxide adducts of polyhydric alcohols (addition moles 1 to 10) and di, tri and tetra (meth) acrylates of alkylene oxide adducts of aliphatic tetrahydric alcohols (addition moles 1 to 10) A) acrylates, and mixtures of two or more of these, particularly di (meth) acrylates of alkylene oxide adducts of aliphatic dihydric alcohols (addition moles 1 to 10) and alkylene oxide adducts of aliphatic tetrahydric alcohols (additions) 1-10 moles of tetra (meth) acrylate and a mixture of two or more of these), or a mixture of the above-mentioned polyfunctional / monofunctional (meth) acrylates (further, an alkylene oxide adduct of an aliphatic dihydric alcohol ( Mono- and di (meth) acrylates having an addition mole number of 1 to 10),
Mono, di and tri (meth) of alkylene oxide adduct of aliphatic trihydric alcohol (number of moles added: 1 to 10)
Acrylates, mono-, di-, tri- and tetra (meth) acrylates of alkylene oxide adducts of aliphatic tetrahydric alcohols (addition moles 1 to 10) and mixtures of two or more thereof, especially alkylene oxides of aliphatic dihydric alcohols Mono- and di (meth) acrylates of adducts (addition moles 1 to 10), mono-, di-, tri- and tetra (meth) acrylates of alkylene oxide adducts of aliphatic tetrahydric alcohols (addition moles 1 to 10) and Mixture of two or more of these]. The equivalent ratio of the polyfunctional / monofunctional (meth) acrylate mixture is usually 80/2
0-99.9 / 0.1, preferably 85 / 15-99.
5 / 0.5.

In the above and below, the alkylene oxide is an alkylene oxide having 2 to 4 carbon atoms in the alkylene group, for example, ethylene oxide, propylene oxide, 1,2-, 1,3-, 2,3- or 1,4-. Butylene oxide and a combination system of two or more of these (block and / or random). Preferred are ethylene oxide and / or propylene oxide.

The ratio between the hydroxyl group-containing (meth) acrylate and the hydroxyl group-free (meth) acrylate is usually 0.1 / 9.
9.9 to 50/50, preferably 0.5 / 99.5 to 3
0/70.

Although there is no particular limitation on the production method of (A),
For example, the following method can be exemplified. The above polyvalent (divalent to 12-valent or higher functional group)
1 mol of alcohol and 1 to 12 mol of (meth) acrylic acid are optionally subjected to a dehydration esterification reaction (reaction temperature of 90 to 90) in the presence of a dehydration co-solvent such as toluene, xylene, methyl ethyl ketone or methyl isobutyl ketone. A method of removing unreacted (meth) acrylic acid by washing with alkaline water or the like, if necessary, after 150 ° C., normal pressure to 200 mmHg); the above-mentioned polyvalent (divalent to 12-valent or more functional group)
After 1 mole of alcohol and 1 to 12 moles or more of alkyl (meth) acrylic acid ester (1 to 4 carbon atoms) are subjected to transesterification (reaction temperature: 90 to 150 ° C., normal pressure to 200 mmHg), necessary Of alcohol by-produced by the method and unreacted alkyl (meth) acrylate by distillation or the like.

In the esterification reaction or transesterification reaction, a catalyst [organic acid metal salt (for example, dibutyltin dilaurate, tin octylate, lithium naphthenate, etc.), an organic acid (for example, paratoluene sulfone) is used in order to smoothly carry out the reaction. Acid)) and radical polymerization inhibitors (eg, hydroquinone, hydroquinone monomethyl ether, copper oleate, air, etc.).

In the present invention, the weight average molecular weight (measurement method: GPC method) of the acrylic resin (B) is usually from 5,000 to
100,000, preferably 10,000 to 50,000
0, more preferably 15,000 to 40,000. If the weight average molecular weight is less than 5,000, the flexibility (workability) of the resulting coating film becomes insufficient, and if it exceeds 100,000, the viscosity of the coating material increases and the workability decreases.

As the acrylic resin (B), at least one kind of a monomer (B1) having an alkoxyalkylamide group and a monomer (B2) having no alkoxyalkylamide group
And copolymers thereof.

As (B1), an alkoxyalkylacrylamide represented by the following general formula (1) can be mentioned. ^{_{H 2 C = CR 1 C (}} O) NH-A-OR 2 (1) [ wherein, R ¹ represents a hydrogen or a methyl group, A is 1 to 3 carbon atoms
And R ² represents an alkyl group having 1 to 4 carbon atoms]

In the general formula (1), A includes a methylene group, an ethylene group, an n-, i-propylene group and the like. R ² is a methyl group, an ethyl group, n-,
Examples thereof include an i-propyl group, n-, i- and t-butyl groups. Specific examples of (B1) include N-methoxymethyl (meth) acrylamide and N-ethoxymethyl (meth)
Acrylamide, N-butoxymethyl (meth) acrylamide, N-isobutoxymethyl (meth) acrylamide, and a combination of two or more of these are exemplified. Of these, N-methoxymethyl (meth) acrylamide, N-isobutoxymethyl (meth) acrylamide and a combination of two or more of these are preferred.

As (B2), unsaturated carboxylic acids [unsaturated monocarboxylic acids [(meth) acrylic acid, crotonic acid, etc.]], unsaturated dicarboxylic acids [maleic acid, fumaric acid,
Itaconic acid, etc.], unsaturated carboxylic anhydrides [anhydrides such as maleic acid, itaconic acid, etc.], monoalkyl (1-5 carbon atoms) esters of unsaturated dicarboxylic acids [monomethyl maleate, monoethyl maleate] , Monobutyl itaconate, etc.]; a hydroxyl-containing monomer [aliphatic dihydric alcohol having 2 to 12 carbon atoms (eg, ethylene glycol, propylene glycol,
1,2-, 1,3-, 1,4-butanediol, 1,5
-Pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, 1,
Mono (meth) acrylates of 9-nonanediol, 2,2-diethyl-1,3-propanediol, etc., and mono (meth) acrylates of alkylene oxide adducts of the dihydric alcohols (addition moles 1 to 20) [ For example, polyethylene glycol (polymerization degree 2 to 20) mono (meth)
Acrylate, polypropylene glycol (polymerization degree 2
20) Mono (meth) acrylate, etc.], trihydric to octahydric or higher aliphatic polyhydric alcohols (for example, glycerin, trimethylolpropane, diglycerin, triglycerin, pentaerythritol, sorbitol, dipentaerythritol, etc.) Mono (meth) acrylate,
Mono (meth) acrylate of alkylene oxide adduct of polyhydric alcohol (addition mole number 1 to 20), lactone (C3 to C12) addition of unsaturated monocarboxylic acid (addition mole number of 1 to 10) [for example An active methylene group-containing monomer [acetoacetate ester of the above aliphatic dihydric alcohol mono (meth) acrylate [for example, (meth) acryloyloxy] Ethyl acetyl acetate, (meth) acryloyloxypropyl acetyl acetate, etc.]; amide group-containing monomers [eg, (meth) acrylamide, N-methylol (meth) acrylamide, N-butyl (meth) acrylamide, etc.];
(Cyclo) alkyl (C1-20) (meth) acrylate [for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate ) Acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, etc.]; aromatic ring-containing (meth) acrylate [eg, benzyl (meth) acrylate]; styrene-based monomer [eg, styrene] , Α-methylstyrene, ethylstyrene,
Dimethylstyrene, vinyltoluene, α-methylstyrene dimer, etc.]; glycidyl group-containing compound [eg, glycidyl (meth) acrylate, allyl glycidyl ether]; nitrile group-containing monomer [eg, (meth) acrylonitrile, etc.); vinyl ester type Monomers [eg, vinyl acetate, vinyl propionate, etc.]; halogen-containing monomers [eg, vinyl chloride, vinyl fluoride, vinylidene chloride, vinylidene fluoride, etc.]; olefinic monomers [eg, ethylene, propylene, butadiene, And a combination of two or more of these. Preferred among these are unsaturated carboxylic acids and alkyl (meth) acrylates in which the alkyl group has 1 to 10 (preferably 1 to 8) carbon atoms from the viewpoint of imparting hardness and water resistance to the resulting coating film. And at least one of the styrene-based monomers, and particularly preferred are (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate and (2-ethylhexyl ( At least one selected from meth) acrylates, styrene, α-methylstyrene and α
-Methylstyrene dimer is used in combination with one or more kinds (mass ratio is usually 99.9 / 0.1 to 60/40, preferably 99/1 to 70/30).

The mass ratio of (B1) to (B2) is usually 2/9
It is 8-30 / 70, preferably 5 / 95-20 / 80.

The method for producing the acrylic resin (B) is not particularly limited, and it can be produced by a usual radical polymerization method (bulk polymerization, solution polymerization, emulsion polymerization, etc.). In the polymerization, a known radical polymerization initiator, chain transfer agent, organic solvent, or the like may be used. Examples of the polymerization initiator include, for example, azo compounds such as azobisisobutyronitrile, azobisisovaleronitrile, and azobisisovaleric acid; benzoyl peroxide, t-butyl hydroperoxide, lauroyl peroxide, cumene hydroperoxide and the like. Organic peroxides; inorganic peroxides such as potassium persulfate, sodium persulfate, ammonium persulfate, and hydrogen peroxide; and combinations of two or more thereof. Preferred among these are organic peroxides and inorganic peroxides. The amount of the polymerization initiator used is usually 0.01 to 5% by mass based on the total amount of the monomers. Examples of the chain transfer agent include mercaptan (butyl mercaptan, dodecyl mercaptan, etc.), α-methylstyrene dimer, chloroform and the like. Of these, α-methylstyrene dimer is preferred. The amount of the chain transfer agent to be used is generally 5% by mass or less, preferably 0.1 to 3% by mass, based on the total amount of the monomers. Examples of the organic solvent include alcohols (methanol, ethanol,
n-, i-propanol, n-, i-, t-butanol); glycol ethers (such as ethyl cellosolve, butyl cellosolve, ethyl carbitol, and propylene glycol monoethyl ether); esters (ethyl acetate,
Butyl acetate, isoamyl acetate, cellosolve acetate, etc.); ethers, such as dioxane; ketones, such as acetone, methyl ethyl ketone, methyl isobutyl ketone; aliphatic or alicyclic hydrocarbons, such as n-hexane;
n-heptane, cyclohexane, etc.); aromatic hydrocarbons (toluene, xylene, trimethylbenzene, etc.) and mixtures of two or more of these. Of these, alcohols, ketones and aromatic hydrocarbons are preferred. The organic solvent may be removed by a method such as distillation after polymerization.

The resin (B) can also be obtained by copolymerizing (meth) acrylamide and (B2), followed by alkoxyalkylation. As a method of alkoxyalkylation, (form) aldehyde and an alkali catalyst are added to a copolymer of (meth) acrylamide and (B2) to form a methylol under a basic condition (for example, pH 9), and then the reaction is carried out in the presence of an acidic catalyst. A method of performing alkoxylation by adding an alcohol is exemplified.

The molecular weight per one alkoxyalkylamide group of the resin (B) is usually from 500 to 15,000, preferably from 600 to 15,000 from the viewpoint of the flexibility and hardness of the coating film obtained.
It is 10,000, particularly preferably 700 to 8,000.

When the resin (B) contains a carboxyl group, a part or all of the carboxyl group may be neutralized with a volatile base. As the volatile base, ammonia; primary, secondary or tertiary monoamine having 1 to 4 carbon atoms in the alkyl group [eg, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, dibutylamine, etc.]; alkanol ( 2 carbon atoms
4) amines [monoethanolamine, diethanolamine, N-methyldiethanolamine, triethanolamine, diisopropanolamine, etc.]; cyclic amines [morpholine, N-ethylmorpholine, etc.] and a combination of two or more thereof. Among these, alkanolamines are preferred from the viewpoints of the odor of the paint and the water resistance of the coating film, and diethanolamine and N-methyldiethanolamine are particularly preferred. In particular, when water is used as a diluent for the paint (for example, an amount exceeding 15% by mass based on the total mass of (A) and (B)), at least a part of the carboxyl groups of (B) is neutralized with a base. It is desirable that the degree of neutralization in this case is usually 50 equivalent% or more of carboxyl groups, preferably 80 to 99 equivalent% or more. The timing of neutralization is not particularly limited, but is preferably performed after polymerization.

The mass ratio of (A) / (B) in the composition of the present invention is usually 2/2 from the viewpoint of paint viscosity and flexibility of the coating film.
8 to 8/2, preferably 3/7 to 7/3.

The composition of the present invention has sufficient thermosetting properties as it is, but may contain a crosslinking agent (C) if necessary. Examples of the (C) include an amino resin (C1), a polyepoxy compound (C2), and a combination thereof.

Examples of the amino resin (C1) include alkyl (C1-8) etherified melamine resin, alkyl (C1-8) etherified benzoguanamine resin, alkyl (C1-8) etherified urea resin, Examples thereof include a spiroguanamine resin, an alkyl (C1-8) etherified resin of diguanamine in which two triazine rings are bonded to a phenylene nucleus, and / or a mixture of two or more thereof. Of these, alkyl etherified melamine resins and alkyl etherified benzoguanamine resins are preferred, and alkyl etherified benzoguanamine resins are particularly preferred.

The degree of polymerization of the amino resin (C1) is usually from 1.1 to 5, preferably from 1.3 to 3, and particularly preferably from 1.4 to 2, from the viewpoints of the viscosity of the coating composition and the volatile components during heat curing.

Examples of the polyepoxy compound (C2) (2 to 10 epoxy groups) include polyhydric phenols (monocyclic dihydric phenols (resorcinol, pyrocatechol,
Hydrophenols, bisphenols (bisphenol A, halogenated bisphenol A, bisphenol B, bisphenol S, bisphenol AD, bisphenol F, 4,4'-dihydroxybiphenyl, 4,
4′-dihydroxy-2,2 ′, 4,4′-tetramethylbiphenyl, etc.), polynuclear phenols (eg, 1,5-hydroxynaphthalene), 2 to 10-valent condensed polynuclear phenols (phenol novolak, cresol novolak, Phenol-dicyclopentadiene copolymer, etc.)
And polyglycidyl ethers obtained by adding epichlorohydrin in the presence of an alkali, hydrogenated products thereof, and mixtures of two or more thereof. Among them, preferred is diglycidyl ether obtained by adding epichlorohydrin to bisphenol A.

The epoxy equivalent of (C2) is usually from 180 to 5,000, preferably from 220 to 3,000, particularly preferably from 400 to 1, from the viewpoint of paint viscosity and flexibility of the coating film.
500.

When (C) is used, the compounding amount is usually 100% by mass or less, preferably 50% by mass or less, from the viewpoint of the flexibility of the coating film, based on the total mass of (A) and (B). More preferably, it is 3 to 20% by mass or less. Said (C) may be previously mixed with the mixture consisting of (A) and (B), or may be mixed at the time of use.

If necessary, other known thermosetting resins (acrylic resin, polyester resin, epoxy resin, phenolic resin, urethane resin, etc.) can be added to the resin composition for coating of the present invention. The amount of these components is usually 30% by mass or less, preferably 20% by mass or less, more preferably 3 to 10%, based on the total mass of (A) and (B), from the viewpoints of the viscosity of the paint and the hardness of the resulting coating film. % By mass or less.

The resin composition for paints of the present invention may contain, if necessary, known additives usually used in paints (eg, curing catalysts, pigments, leveling agents, defoamers, antioxidants, ultraviolet absorbers, etc.). Can be appropriately blended. The amount of the additive is usually 20 to 60% by mass, preferably 30 to 50% by mass for the pigment, and usually 20% by mass for the other additives exemplified above, based on the total mass of (A) and (B). %, Preferably 10% or less, more preferably 0.1% by mass.
01 to 5% by mass or less.

The coating resin composition of the present invention may optionally contain a diluent, if necessary. Water as the diluent; alcohol (methanol, ethanol, n-, i-
Propanol, n-, i-, t-butanol, etc., glycol ethers (ethyl cellosolve, butyl cellosolve, ethyl carbitol, propylene glycol monoethyl ether, etc.); ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.); esters (ethyl acetate) , Butyl acetate, cellosolve acetate, etc.);
Examples thereof include aliphatic or alicyclic hydrocarbons (such as n-hexane, n-heptane, and cyclohexane); aromatic hydrocarbons (such as toluene, xylene, and trimethylbenzene); and mixtures of two or more thereof. Among these, water and alcohol are preferred, and water is particularly preferred. The amount of the diluent is usually 30% by mass or less from the viewpoint of suppressing volatile components with respect to the total mass of (A) and (B).
Preferably 20% by mass or less, particularly preferably 10% by mass
It is as follows.

The nonvolatile content of the coating composition comprising the resin composition of the present invention is usually 70% by mass or more, preferably 80 to 100% by mass, more preferably 90 to 1 from the viewpoint of environmental problems.
00% by mass. The viscosity (20 ° C.) is usually 50 to 5,000 mPa · s, preferably 1 to 50 mPa · s from the viewpoint of paintability.
It is 00 to 3,000 mPa · s.

The method for applying the coating composition comprising the resin composition of the present invention to a coating substrate includes a spray coating method, a knife coating method, a roll coating method, a flow coating method, and the like. It is. The coating amount is appropriately selected according to the purpose, but the dry film thickness is usually 3 to 30 μm.
Is the amount The coating applied to the metal is cured by heat treatment at a temperature of usually 150 to 250 ° C., preferably 190 to 230 ° C., and a time of usually 10 seconds to 5 minutes, preferably 1 to 3 minutes. Form a coating.

The coating substrate to which the coating composition comprising the resin composition of the present invention is applied is preferably a metal, such as aluminum, steel, various chemical treatments (eg, chromium treatment), aluminum, various chemical treatment steels, polyesters, etc. Steel, tinned steel, galvanized steel, copper, brass and the like.
Among them, it is suitably used for the outer surface coating of metal used for deep drawing metal cans (chemical conversion aluminum, chemical conversion steel, steel laminated with polyester, etc., which is obtained by molding or punching a flat plate into a cylindrical shape).

[0036]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
In the following, parts and% are based on mass unless otherwise specified.

Production Example 1 100 parts of toluene, 35 parts of 1,4-butanediol and 1 part of paratoluenesulfonic acid were charged into a four-necked flask equipped with a thermometer, a stirrer, a water separation tube and an air blowing tube. Acrylic acid 6 while introducing air while stirring.
5 parts were charged and dehydration esterification was performed at a temperature of 120 ° C. for 8 hours. The temperature was cooled to 60 ° C., excess acrylic acid was neutralized with an aqueous sodium hydroxide solution, and then removed together with the aqueous phase. Further, toluene was distilled off under reduced pressure, and the hydroxyl value was 5 mgK.
A polyfunctional acrylate (A-1) having an OH / g and a viscosity of 20 mPa · s / 20 ° C. was obtained.

Production Example 2 The procedure of Production Example 1 was repeated, except that 100 parts of toluene, 50 parts of an adduct of 5 mol of pentaerythritol with ethylene oxide, 1 part of paratoluenesulfonic acid and 50 parts of acrylic acid were used. , Hydroxyl value 2mgKOH
/ G, a polyfunctional acrylate (A-2) having a viscosity of 150 mPa · s / 20 ° C.

Production Example 3 10 parts of methacrylic acid, α-methylstyrene dimer 1
Parts, N-methoxymethylacrylamide 10 parts, butyl acrylate 18 parts, 2-ethylhexyl acrylate 3
One part and 30 parts of ethyl acrylate were weighed in a glass container, and mixed and stirred to obtain a monomer solution. In a separate glass container, 50 parts of MIBK and 1 part of t-butylperoxy-2-ethylhexanoate were weighed and mixed and stirred to obtain a polymerization initiator solution. Next, 50 parts of MIBK was charged into a four-necked flask equipped with a thermometer, a stirrer and a nitrogen gas injection tube, and stirred while introducing nitrogen gas.
At 7 ° C., the above monomer solution and polymerization initiator solution are simultaneously
After dropping over time, stirring was continued for 1 hour at the same temperature,
Further, 0.1 part of t-butylperoxy-2-ethylhexanoate was added, and stirring was continued at the same temperature for 2 hours. Then, MIBK was distilled off under reduced pressure, and the weight average molecular weight was 25,000.
0, a liquid acrylic resin (B-1) having a molecular weight of 1300 per methoxymethylacrylamide group was obtained.

Production Example 4 In Production Example 3, 1 part of α-methylstyrene dimer,
Monomer solution consisting of 10 parts of N-methoxymethylacrylamide, 47 parts of butyl acrylate, and 42 parts of ethyl acrylate, 50 parts of methyl isobutyl ketone, and tert-butyl peroxy (2-ethylhexanoate) 1
Liquid acrylic resin (B-2) having a weight average molecular weight of 25,000 and a molecular weight per one methoxymethyl acrylamide group of 1200 was obtained in the same manner as in Production Example 3 except that the polymerization initiator solution in parts was used.

Examples 1-4, Comparative Example 1 The polyfunctional (meth) acrylates (A-1) and (A-2) obtained in Production Examples 1 and 2, and the resins obtained in Production Examples 3 and 4 ( (B-1) and (B-2), Cymel 303 (CY30) manufactured by Mitsui Cytec as amino resin.
3) Epicoat 1001 (EP1001) manufactured by Yuka Shell Epoxy Co., Ltd. as an epoxy resin and water or ethylene glycol monobutyl ether (buticello) as a diluent were blended in the proportions shown in Table 1 to obtain thermosetting paints. Table 2 shows the evaluation results of these paints. These paints were applied on a chrome-treated aluminum plate with a bar coater so that the dry coating thickness was 5 μm, and the coating after heating and curing for 120 seconds in a circulating drier at 230 ° C.
Various evaluations were made. Table 3 shows the evaluation results.

[0042]

[Table 1]

[0043]

[Table 2]

[Evaluation method] Paint appearance: The condition of the paint was visually evaluated according to the following criteria. ；: No abnormality of paint, Δ: Separation, ×: Solidified over time Paint viscosity: Viscosity at 20 ° C. (m
Pa · s) was measured. Misting property: 10 g of paint is applied to an incometer (manufactured by Yasuda Seiki Co., Ltd.), and 2,000 at roll temperature of 40 ° C.
The ratio of the amount scattered around to the amount of applied paint after rotating the roll for 10 seconds under the condition of rpm / min.

[0045]

[Table 3]

[Evaluation Method] Appearance of coating film: The surface condition of the coating film was visually evaluated according to the following criteria.
；: No abnormality of coating film, Δ: Whitening of coating film or disorder of coating film Pencil hardness: Measured based on JIS K 5400.6.14. Hardness in hot water: After immersing the coated plate in hot water of 80 ° C for 30 minutes,
The pencil hardness was measured in hot water. Impact resistance: The highest height without peeling when the weight drop height of the Dupont impact test (300 g, 1/2 inch) is increased at intervals of 5 cm. Retort resistance: After treating the coated plate at 130 ° C. for 30 minutes,
The state of the coating film was visually evaluated according to the following criteria. ；: No abnormality of coating film, Δ: Whitening of coating film or disorder of coating film Adhesion: After retort treatment, cross-cut peeling was performed and evaluated according to the following criteria. ○: no peeling, △: partial peeling, ×: full peeling

[0047]

The resin composition for thermosetting paints of the present invention comprises:
It has the following effects as compared with conventional water-based paints and the like. (1) To give a coating film excellent in adhesion to metal, retort resistance, balance between hardness and flexibility of the coating film, and the like. (2) Even if the conventional coating method and heat curing method are used, the workability is excellent and the organic solvent is not dissipated, so that the environment for the installation place of the coating equipment and the surroundings can be remarkably improved. (3) The paint can be made non-solvable or highly solid, and the storage and transportation efficiency of the paint as well as the safety can be greatly improved. Because of the above-mentioned effects, the coating composed of the resin composition of the present invention is extremely useful as a metal coating, particularly as an outer coating for metal cans (aluminum cans, steel cans, resin laminate cans, etc.).

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 163/00 C09D 163/00 F term (Reference) 4D075 CA47 DA06 DB01 DC42 EA05 EB22 EB45 EB52 EB55 EB56 4J038 CG021 CG022 CG061 CG062 CG081 CG082 CG141 CG142 CG161 CG162 CG171 CG172 CH031 CH032 CH041 CH042 CH081 CH082 CH121 CH122 CJ031 CJ032 CJ061 CJ062 DA132 DA162 DA172 DB002 FA111 FA112 FA151 FA152 GA03 GA09 KA03 B06

Claims (6)

[Claims] 1. A (meth) acryloyl group having a molecular weight of 80 to 1,000 and a hydroxyl value of 0.5 to 50 m
gKOH / g monofunctional and / or polyfunctional (meth) acrylate (A) and at least one alkoxyalkylamide group in the molecule and having a weight average molecular weight of 5,000
A resin composition for a thermosetting paint, comprising an acrylic resin (B) of from 100 to 100,000 as an essential component. 2. The composition according to claim 1, wherein (A) is a polyfunctional (meth) acrylate or a polyfunctional / monofunctional (meth) acrylate mixture. 3. An alkoxyalkylamide group 1 of (B)
The composition according to claim 1 or 2, wherein the molecular weight per unit is from 500 to 15,000. 4. The mass ratio of (A) / (B) is 2/8 to 8 /
The composition according to any one of claims 1 to 3, which is 2. 5. The composition according to claim 1, further comprising a crosslinking agent (C) comprising an amino resin (C1) and / or a polyepoxy compound (C2). 6. A metal can coated with a paint comprising the composition according to claim 1. Description: