JP2000234069A - Resin composition for thermosetting paint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin compsn. for a thermosetting paint capable of using in conventional painting method and thermosetting method, having a low viscosity and excellent in workability without using an org. solvent, capable of high solidification, and having environmental compatibility. SOLUTION: This compsn. contains as essential components a multifunctional (meth)acrylate (A) having at least 2 (meth)acryloyl groups in a molecule and a mol.wt., per (meth)acryloyl group, of 84-980, and a resin (B) comprising a polyester resin (B1) having at least a functional group contg. an active hydrogen in a molecule and a number average mol.wt. of 2,000-20,000 and/or an acrylic resin (B2).

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 such solvent-based paints due to global environmental problems or the safety of health caused by the work environment. Water-based paints (for example, JP-A-63-248874), powder paints (for example, JP-A-8-313395), UV-curable paints (for example, JP-A-2-289611) are proposed as corresponding paints. Have been.

[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 has at least two (meth) acryloyl groups in a molecule,
The molecular weight per acryloyl group is 84 to 1,000.
(A) having at least one active hydrogen-containing group in the molecule and having a number average molecular weight of 2,0
A resin composition for a thermosetting paint, characterized by comprising, as essential components, a resin (B) composed of 100 to 20,000 of a polyester resin (B1) and / or an acrylic resin (B2); It is a metal can coated with a paint comprising the composition.

[0005]

The resin composition for a thermosetting paint of the present invention is heated, for example, to a temperature of 150 ° C. or more, so that the (meth) acryloyl group of the polyfunctional (meth) acrylate (A) and the resin (B) By reacting with active hydrogen (Michael reaction) to form a three-dimensional crosslinked structure and thermally polymerizing the (meth) acryloyl groups of (A), a coating film having an excellent balance between hardness and flexibility can be obtained. Form. That is, in the state of the composition, the (A) has a sufficiently low viscosity because it functions as a reactive diluent, does not require dilution with an organic solvent, and is used as it is or with a small amount (30% by mass or less) of water or the like. It can be used in a diluted high concentration (so-called non-sol type or high solid type).

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, polyfunctional (meth)
The molecular weight per (meth) acryloyl group of the acrylate (A) is usually from 84 to 1,000, preferably from 95 to 1,000.
600, particularly preferably 110 to 400. If the molecular weight per (meth) acryloyl group is less than 84, 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 (A) includes, for example, those having 2 to 2 carbon atoms.
12 aliphatic dihydric alcohols (ethylene glycol, propylene glycol, 1,2-, 1,3-, 2,3- or 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6 -Hexanediol, 3-methyl-1,5-pentanediol, 2-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, etc.), an alicyclic dihydric alcohol having 6 to 15 carbon atoms [1,4-cyclohexylene glycol, 1,
4-cyclohexanedimethanol, 2,2-bis (4,
4'-hydroxycyclohexyl) propane, 4,4 '
-Dihydroxycyclohexylsulfone, 4,4'-dihydroxycyclohexylmethane, etc.], having 8 to 1 carbon atoms
Aromatic dihydric alcohols (e.g., xylylene glycol), alkylene oxide adducts of these dihydric alcohols (addition moles 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.) Di (meth) acrylates of diols; aliphatic trihydric alcohols having 3 to 6 carbon atoms (glycerin, trimethylolethane, trimethylolpropane, 1,2,6-hexanetriol, etc.) and alkylenes of these trihydric alcohols Di- or tri (meth) acrylates of triols such as oxide adducts (addition moles 1 to 20 or more); aliphatic tetrahydric alcohols having 5 to 10 carbon atoms (pentaerythritol, diglycerin, methyl glucooxide, etc.) ) And their tetravalent a Di-, tri- or tetra (meth) acrylates of tetraols, such as alkylene oxide adducts of coal (addition moles 1 to 20 or more); 5 to 12 or more valent fats having 6 to 30 carbon atoms Polyhydric alcohol (dipentaerythritol,
Sorbitol, sucrose, polyglycerin (polymerization degree 3 to 10), etc.] and poly (2-12 functional) of polyols such as alkylene oxide adducts of these polyhydric alcohols (1 to 20 or more moles added) ( Meth) acrylates; and mixtures of two or more thereof. Of these, preferred are di (meth) acrylates of alkylene oxide adducts of aliphatic dihydric alcohols (addition moles 1 to 10) and alkylene oxide adducts of aliphatic trihydric alcohols (addition moles 1 to 1).
10) Tri (meth) acrylate and alkylene oxide adduct of aliphatic tetrahydric alcohol (addition mole number 1 to 1)
0) tetra (meth) acrylate and a mixture of two or more thereof, more preferably aliphatic 2
Di (meth) acrylate of alkylene oxide adduct of polyhydric alcohol (addition mole number 1 to 10), alkylene oxide adduct of aliphatic tetrahydric alcohol (addition mole number of 1)
10) to tetra (meth) acrylate and combinations thereof.

In the above and the following, 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 method for producing (A) is not particularly limited, and for example, the following method can be exemplified. 1 mol of the above-mentioned polyhydric alcohol and 2 to 12 mol or more of (meth) acrylic acid are optionally subjected to a dehydration esterification reaction in the presence of a dehydration co-solvent (eg, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone) ( Reaction temperature 90 ~ 150 ℃, normal pressure ~ 200mmH
g), if necessary, a method of removing unreacted (meth) acrylic acid by washing with alkaline water or the like; 1 mol of the above-mentioned polyhydric alcohol and alkyl (1 to 4 carbon atoms) ester of (meth) acrylic acid 2 １２12 mol or more of the ester exchange reaction (reaction temperature 90-1
50 ° C., normal pressure to 200 mmHg), if necessary, removing by-produced alcohol and unreacted alkyl (meth) acrylate by distillation or the like;

In the esterification or transesterification, a catalyst (eg, dibutyltin dilaurate, tin octylate, paratoluenesulfonic acid, lithium naphthenate, etc.) and a radical polymerization inhibitor (eg, hydroquinone, etc.) , Hydroquinone monomethyl ether, copper oleate, air, etc.) can also be used.

In the present invention, as the resin (B) having at least one active hydrogen-containing group, a polyester resin (B
1), an acrylic resin (B2) and a combination thereof.

Examples of the active hydrogen-containing functional group include a carboxyl group, a hydroxyl group, an active methylene group, and an amide group, preferably a carboxyl group and a hydroxyl group, and particularly preferably a carboxyl group.

The number average molecular weight of the resin (B) is usually 2,0
00 to 20,000, preferably 5,000 to 18.0
00, more preferably 7,500 to 15,000. If the number average molecular weight is less than 2,000, the flexibility (workability) of the obtained coating film becomes insufficient, and if it exceeds 20,000, the viscosity of the coating material becomes high and the workability is reduced.

Compounds (B1) constituting the polyester resin (B1) and providing a carboxyl group to the (B1)
1) is an aliphatic or alicyclic dicarboxylic acid having 2 to 10 carbon atoms [oxalic acid, succinic acid, malonic acid, adipic acid, glutaric acid, azelaic acid, sebacic acid, hexahydrophthalic acid, nadic acid) , Maleic acid, fumaric acid, itaconic acid, tetrahydrophthalic acid, etc.]; an aromatic divalent carboxylic acid having 8 to 18 carbon atoms [phthalic acid, isophthalic acid, terephthalic acid, etc.]; Aliphatic or alicyclic polycarboxylic acid [methylcyclohexenetricarboxylic acid, cyclopentanetetracarboxylic acid, butanetetracarboxylic acid, etc.];
A trivalent or higher polyvalent aromatic carboxylic acid [trimellitic acid,
Pyromellitic acid, benzophenonetetracarboxylic acid, etc.]; their ester-forming derivatives [acid anhydrides, lower alkyl (1 to 4 carbon atoms) esters, etc.]; and combinations of two or more of these. Of these, preferred are aliphatic divalent carboxylic acids, aromatic divalent carboxylic acids,
Or higher polyvalent aromatic polycarboxylic acids (anhydrides) and a combination of two or more thereof, more preferably aliphatic divalent carboxylic acids, aromatic divalent to tetravalent carboxylic acids and combinations thereof, Particularly preferred are a combination of adipic acid and / or sebacic acid and an aromatic polycarboxylic acid selected from isophthalic acid, terephthalic acid and (trimellitic anhydride) [weight ratio (20 to 50): (80 to 5).
0)].

The compound (B12) which constitutes (B1) and imparts a hydroxyl group to (B1) includes the polyfunctional (meth) compound
Polyhydric alcohols exemplified in the section of the acrylate (A),
These alkylene oxide adducts and alkylene oxide adducts of dihydric phenols are exemplified. Of these, preferred are aliphatic dihydric alcohols, aliphatic trihydric alcohols, aliphatic tetrahydric alcohols and combinations of two or more of these. More preferred are neopentyl glycol, 2-butyl-2-ethyl. -1,3-
A combination of a dihydric alcohol selected from propanediol and 1,6-hexanediol with trimethylolpropane and / or pentaerythritol.

In addition to the above (B11) and (B12), if necessary, a monocarboxylic acid and / or a monoalcohol (B1
One or more of 3) may be polycondensed. Examples of the monocarboxylic acid include an aliphatic saturated monocarboxylic acid having 2 to 20 carbon atoms (acetic acid, propionic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, castor oil fatty acid, stearic acid, etc.), carbon number And 10 to 20 aliphatic unsaturated monocarboxylic acids (oleic acid, ricinoleic acid, linoleic acid, linolenic acid, eriostearic acid and the like). Examples of the monoalcohols include aliphatic monoalcohols having 1 to 20 carbon atoms (such as methanol, ethanol, propanol, 1-butanol, 2-butanol, 1-octanol, 2-ethylhexanol, and lauryl alcohol), and alkylenes of these monoalcohols. Oxide adducts (number of added moles 1 to 20) and the like. Of these, preferred are monocarboxylic acids, and more preferred are combinations of saturated monocarboxylic acids and unsaturated monocarboxylic acids [weight ratio (3 to 90):
(97-10)]. The amount of (B13) used is (B13)
11), usually 10 mol% or less, preferably 0.5 to 5 mol%, based on the sum of (B12) and (B13).

The number average molecular weight of (B1) is usually 2,000
0 to 15,000, preferably 3,000 to 12,000
0, more preferably 5,000 to 10,000. If the number average molecular weight is less than 2,000, the flexibility (workability) of the obtained coating film becomes insufficient, and if it exceeds 20,000, the viscosity of the coating material becomes high and the workability is reduced.

The method for producing (B1) is not particularly limited.
It can be produced by a usual esterification method or transesterification method. The reaction temperature is usually 100 to 200 ° C. In the reaction, a catalyst commonly used for polyester (for example, dibutyltin dilaurate, tin octylate, paratoluenesulfonic acid, lithium naphthenate, etc.) may be used.

The acrylic resin includes a copolymer of at least one monomer (B21) having an active hydrogen-containing group and a monomer (B22) having no active hydrogen-containing group.

The above (B21) includes unsaturated carboxylic acids [unsaturated monocarboxylic acids [(meth) acrylic acid, crotonic acid, etc.]], unsaturated dicarboxylic acids [(anhydrous) maleic acid, fumaric acid, (anhydrous) itacone Acid etc.], monoalkyl (1-5 carbon atoms) ester of unsaturated dicarboxylic acid [monomethyl maleate, monoethyl maleate, monobutyl itaconate etc.] etc.]; hydroxyl group-containing monomer [2 carbon atoms To 12 aliphatic dihydric alcohols (e.g., ethylene glycol, propylene glycol,
1,2-, 1,3- or 1,4-butanediol,
1,5-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, 1,9-nonanediol, 2,2 -Diethyl-1,
Mono (meth) acrylate of 3-propanediol, etc .; mono (meth) acrylate of alkylene oxide adduct of the dihydric alcohol (addition mole number 1 to 20) [for example, polyethylene glycol (polymerization degree 2 to 20) mono (meth) acrylate] A) acrylate, polypropylene glycol (degree of polymerization 2 to 20) mono (meth) acrylate, etc.], 3
~ 8 or more aliphatic polyhydric alcohols (e.g., glycerin, trimethylolpropane, diglycerin,
Mono (meth) acrylates of triglycerin, pentaerythritol, sorbitol, dipentaerythritol, etc., mono (meth) acrylates of alkylene oxide adducts of the above polyhydric alcohols (addition moles 1 to 20), unsaturated monocarboxylic acids Acid lactones (3 to 1 carbon atoms)
2) Adduct (1 to 10 moles of addition) [for example, 1 to 5 moles of ε-caprolactone of (meth) acrylic acid]
Active methylene group-containing monomer [acetoacetic ester of the above-mentioned aliphatic dihydric alcohol mono (meth) acrylate [for example, (meth) acryloyloxyethyl acetyl acetate, (meth) acryloyloxypropyl acetyl acetate, etc.]]; Amide group-containing monomers [eg, (meth) acrylamide, N-methylol (meth) acrylamide, N-butyl (meth) acrylamide, etc.]. Of these, preferred are unsaturated carboxylic acids and combinations of unsaturated carboxylic acids with hydroxyl-containing monomers, and more preferred are (meth) acrylic acid, maleic acid and one or more of these and C2-C2. 6
In combination with at least one kind of an aliphatic dihydric alcohol or an adduct thereof of 1 to 20 mol of an alkylene oxide (ethylene oxide and / or propylene oxide).

A monomer having no active hydrogen-containing group (B2
As 2), a (cyclo) alkyl (meth) acrylate having 1 to 20 carbon atoms in the alkyl group [for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (Meth) acrylate, hexyl (meth)
Acrylate, cyclohexyl (meth) acrylate,
2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, etc.]; aromatic ring-containing (meth) acrylate [eg, benzyl (meth) acrylate]; styrene compounds [eg, styrene, α-methylstyrene, ethylstyrene, dimethylstyrene] Glycidyl group-containing compounds such as glycidyl (meth) acrylate, allyl glycidyl ether, etc .; nitrile group-containing compounds such as (meth) acrylonitrile, etc .; vinyl ester monomers [ For example, vinyl acetate, vinyl propionate, etc.]; halogen-containing monomers [eg, vinyl chloride, vinyl fluoride, vinylidene chloride, vinylidene fluoride, etc.]; olefinic monomers [eg, ethylene, propylene, butadiene, isoprene, etc.] and this And a combination of two or more thereof. Among them, preferred are at least one alkyl (meth) acrylate having an alkyl group having 1 to 10 (preferably 1 to 8) carbon atoms in view of imparting hardness and water resistance of the obtained coating film to a styrene-based resin. It is a combination with a compound, and particularly preferred are one or more selected from methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate and (2-ethylhexyl (meth) acrylate), and styrene, α- It is used in combination with one or more selected from methylstyrene and α-methylstyrene dimer.

The weight ratio of (B21) to (B22) is usually (2-30) :( 98-70), preferably (5-2).
0): (95 to 80).

The number average molecular weight of (B2) is usually 5,000
0 to 20,000, preferably 7,000 to 15,000
0, particularly preferably 8,000 to 13,000.
If the number average molecular weight is less than 5,000, the flexibility (workability) of the obtained coating film is reduced, and if it exceeds 20,000, the viscosity of the coating material is increased and the workability is reduced.

The method for producing (B2) is not particularly limited.
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 azobisisobutyronitrile, azobisisovaleronitrile,
Azo compounds such as azobisisovaleric acid; organic peroxides such as benzoyl peroxide, t-butyl hydroperoxide, lauroyl peroxide, cumene hydroperoxide; potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, etc. And two or more of these inorganic peroxides. The amount of the polymerization initiator used is usually 0.1 to 5% by mass based on the total amount of the monomers.
It is. Examples of the chain transfer agent include mercaptans (butyl mercaptan, dodecyl mercaptan, etc.), α
-Methylstyrene dimer, chloroform and the like. The amount of the chain transfer agent is usually 5 to the total amount of the monomer.
% By mass or less, preferably 0.1 to 3% by mass. Examples of the organic solvent include alcohols (methanol, ethanol, propanol, isopropanol, n
-, Sec- or t-butanol, ethyl cellosolve, butyl cellosolve, ethyl carbitol, propylene glycol monoethyl ether, etc.), esters (ethyl acetate, butyl acetate, isoamyl acetate, cellosolve acetate, etc.); ethers (dioxane, etc.), Ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.); aliphatic or alicyclic hydrocarbons (n-hexane, n-heptane, cyclohexane, etc.); aromatic hydrocarbons (toluene, xylene, trimethylbenzene, etc.) And mixtures of two or more of these. Of these, ketones and aromatic hydrocarbons are preferred. The organic solvent may be removed by a method such as distillation after polymerization.

The total of the acid value and the hydroxyl value of the resin (B) is usually 10 to 200 mgKOH / g, preferably 20 to 200 mgKOH / g.
-150 mgKOH / g, particularly preferably 50-130 mgKOH / g
mg KOH / g. The sum of the acid value and the hydroxyl value is 1
If it is less than 0 mgKOH / g, the reaction of the polyfunctional (meth) acrylate (A) with the (meth) acryloyl group becomes insufficient, and the hardness of the obtained coating film decreases, and
If it exceeds H / g, the flexibility of the resulting coating film will be reduced, and workability such as deep drawing will be reduced. The ratio of the acid value in the total of the acid value and the hydroxyl value is usually 50 to 100%, preferably 70 to 100%.

The carboxyl groups in the resin (B) may be partially or entirely neutralized with a volatile base.
Examples of the volatile base include ammonia; a primary, secondary or tertiary monoamine having 1 to 4 carbon atoms of alkyl [eg, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, dibutylamine, etc.]; alkanol ( C2-4) amine [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 in view of the odor of the paint and the water resistance of the coating film, and particularly preferred are diethanolamine and N-amine.
It is methyldiethanolamine. In particular, when water is used as a diluent for the paint (for example, in an amount exceeding 15% by weight based on the total weight 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 such a case is usually at least 50 equivalent%, preferably at least 80 equivalent% of the carboxyl group. The timing of neutralization is not particularly limited, but is usually performed after polymerization.

The mass ratio of (A) :( B) in the composition of the present invention is usually (2-8) :( 8-2), preferably (3-7) :( 7-3). If the ratio of (A) is less than 2, the viscosity of the coating material increases and the workability decreases. If the ratio exceeds 8, the flexibility of the coating film obtained decreases, and the workability such as deep drawing decreases.

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

Examples of the amino resin (C1) include an alkyl (C1-8) etherified melamine resin, an alkyl (C1-8) etherified benzoguanamine resin, and an alkyl (C1-8) etherified urea resin. , Spiroguanamine resin, 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 polymerization degree of (C1) is usually from 1.1 to 5, preferably from 1.3 to 3, and particularly preferably from 1.4 to 2. If the degree of polymerization is less than 1.1, the volatile components during heat curing will increase, and if it exceeds 5, the viscosity will increase and the workability will tend to decrease.

Examples of the polyepoxy compound (C2) (the number of epoxy groups is 2 to 10) include polyhydric phenols (monocyclic dihydric phenols (resorcinol, pyrocatechol, hydroquinone, etc.) and 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 (1,5-hydroxynaphthalene, etc.), 2 to 10-valent condensed polyphenols (phenol novolak, cresol Novolak, phenol-dicyclopentadiene copolymer, etc.), polyglycidyl ethers obtained by adding epichlorohydrin in the presence of an alkali, hydrogenated products thereof, and mixtures of two or more of these. Among them, preferred is diglycidyl ether obtained by adding epichlorohydrin to bisphenol A.

The epoxy equivalent of (C2) is usually 180
5,000, preferably 220-3,000, particularly preferably 400-1,500. Epoxy equivalent is 1
If it is less than 80, the flexibility of the obtained coating film is reduced, so that workability such as deep drawing is reduced. If it is more than 5,000, the viscosity of the coating material is increased, and the workability tends to be reduced.

When (C) is used, the compounding amount is usually 100% by mass or less, preferably 50% by mass or less, more preferably 30% by mass or less, based on the total mass of (A) and (B). is there. If the content exceeds 100% by mass, the flexibility of the obtained coating film is reduced, so that workability such as deep drawing is reduced.
Said (C) may be previously mixed with the mixture consisting of (A) and (B), or may be mixed at the time of use.

The coating resin composition of the present invention may optionally contain other known thermosetting resins (acrylic resin, polyester resin, epoxy resin, phenolic resin, urethane resin, etc.). The amount of these compounds is usually 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass, based on the total mass of (A) and (B).
% By mass or less.

The coating resin composition of the present invention may contain, if necessary, known additives usually used in coating materials (eg, curing catalysts, pigments, leveling agents, defoamers, antioxidants, ultraviolet absorbers, etc.). Can be appropriately blended. The amount of the additive is usually 20% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less, based on the total mass of (A) and (B).

[0036] The resin composition for paints of the present invention may optionally contain a diluent, if necessary. Water as a diluent; alcohols (methanol, ethanol, n-propanol, isopropanol, n-, sec- or t-butanol, 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.]; aliphatic or alicyclic hydrocarbons [n-hexane, n-heptane, cyclohexane, etc.]; aromatic hydrocarbons [Toluene, xylene, trimethylbenzene, etc.] and a mixture of two or more of these.Preferred are water and alcohols, and particularly preferred is water. And the total mass of (B) And generally 30 wt% or less, preferably 20 wt%
Or less, particularly preferably 10% by mass or less.

The coating composition comprising the resin composition of the present invention generally has a nonvolatile content of 70% by mass or more, preferably 80 to 100%.
%, More preferably 90 to 100% by mass.
The viscosity (20 ° C.) is usually 500 to 5,000 mPa
S, preferably 1,000 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 ° C. to 250 ° C., preferably 190 ° C. to 230 ° C., and a time of usually 10 seconds to 5 minutes, preferably 1 minute to 2 minutes. Form a coating.

Metals are suitable as the coating substrate to which the coating comprising the resin composition of the present invention is applied, for example, aluminum, steel, various chemical treatments (for example, 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).

[0040]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.
In the following, parts and% are based on mass unless otherwise specified.

Production Example 1 In a four-necked flask equipped with a thermometer, a stirrer, a water separation tube and an air blowing tube, 100 parts of toluene, 50 parts of 1,4-butanediol and 1 part of paratoluenesulfonic acid were charged. Acrylic acid 5 while introducing air while stirring.
0 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 viscosity was 20 mPa.
-The polyfunctional acrylate (A-1) of s / 20 degreeC was obtained.

Production Example 2 The procedure of Production Example 1 was repeated except that 100 parts of toluene, 55 parts of a 2-mol addition product of pentaerythritol ethylene oxide, 1 part of paratoluenesulfonic acid and 45 parts of acrylic acid were used. , Viscosity 200mPa · s
/ 25 ° C. to obtain a polyfunctional acrylate (A-2).

Production Example 3 A four-necked flask equipped with a thermometer, a stirrer, a water separation tube and a nitrogen gas injection tube was charged with 10 parts of toluene, 5 parts of methyl isobutyl ketone (MIBK), 24 parts of neopentyl glycol, 11 parts of butyl-2-ethyl-1,3-propanediol, 13 parts of 1,6-hexanediol, 2 parts of pentaerythritol, 14 parts of sebacic acid, 37 parts of isophthalic acid and 8 parts of trimellitic anhydride were charged, and nitrogen gas was charged. After the dehydration esterification was performed at a temperature of 180 ° C. while stirring while introducing MIBK, MIBK was distilled off under reduced pressure to obtain an acid value of 6.
A liquid polyester resin (B1-1) having 0 mg KOH / g, a hydroxyl value of 60 mg KOH / g, and a number average molecular weight (according to GPC; the same applies hereinafter) of 7,500 was obtained.

Production Example 4 7 parts of acrylic acid, 7 parts of hydroxyethyl acrylate, α
-1 part of methylstyrene dimer, butyl methacrylate 3
5 parts and 50 parts of ethyl acrylate were weighed in a glass container, and mixed and stirred to obtain a monomer solution. In another glass container, 50 parts of MIBK and tertiary butyl peroxy-2-
One part of ethyl hexanoate was 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.
After the above-mentioned monomer solution and polymerization initiator solution were simultaneously added dropwise at 117 ° C. over 4 hours, stirring was continued at the same temperature for 1 hour, and 1 part of tert-butylperoxy-2-ethylhexanoate was further added. After continuing stirring at the same temperature for 2 hours, MIBK was distilled off under reduced pressure to obtain an acid value of 55 mgKOH /
g, hydroxyl value 34 mgKOH / g, number average molecular weight 10,
000 liquid acrylic resin (B2-1) was obtained.

Production Example 5 In Production Example 4, a monomer solution comprising 20 parts of methacrylic acid, 1 part of α-methylstyrene dimer, 20 parts of 2-ethylhexyl acrylate, 30 parts of butyl methacrylate and 40 parts of ethyl acrylate was mixed with methyl An acid value of 130 mgKOH / g and a number average molecular weight of 11,000 were obtained in the same manner as in Production Example 4 except that a polymerization initiator solution of 50 parts of isobutyl ketone and 2 parts of tert-butylperoxy (2-ethylhexanoate) was used. Liquid acrylic resin (B2-
2) was obtained.

Examples 1 to 6, Comparative Examples 1 to 3 Polyfunctional (meth) acrylates obtained in Production Examples 1 and 2, resins obtained in Production Examples 3 to 5, and Cymer manufactured by Mitsui Cytec as amino resin. No. 303 (CY303), 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 in the proportions shown in Table 1 to obtain thermosetting paints, respectively. Was. Table 2 shows the evaluation results of these paints. These paints were applied on a chromium-treated aluminum plate using a bar coater so that the dry coating thickness was 5 μm, and various evaluations were performed on the coating after heating and curing for 150 seconds in a circulating drier at 230 ° C. . Table 3 shows the evaluation results.

[0047]

[Table 1]

[0048]

[Table 2]

[Evaluation Method] Paint appearance: The condition of the paint was visually evaluated according to the following criteria. ；: No abnormalities in paint, △: Separated solution, ×: 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 applied paint after the roll was rotated for 10 seconds under the condition of rpm / min.

[0050]

[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 delamination by increasing the weight drop height at 5 cm intervals in a DuPont impact test (500 g, 1/2 inch). 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

[0052]

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 167/00 C09D 167/00

Claims (6)

[Claims] 1. A polyfunctional (meth) acrylate (A) having at least two (meth) acryloyl groups in the molecule and having a molecular weight of 84 to 1,000 per (meth) acryloyl group, and containing active hydrogen. At least one functional group in the molecule
Thermosetting characterized by comprising, as an essential component, a resin (B) comprising a polyester resin (B1) and / or an acrylic resin (B2) having a number average molecular weight of 2,000 to 20,000. Resin composition for conductive paint. 2. The composition according to claim 1, wherein the active hydrogen-containing functional group (B) is a carboxyl group and / or a hydroxyl group. 3. The total of the acid value and the hydroxyl value of (B) is 1
The composition according to claim 2, wherein the composition is 0 to 200 mgKOH / g. 4. The mass ratio of (A) :( B) is (2-8):
The composition according to any one of claims 1 to 3, which is (8 to 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: