JPH0959557A - Thermosetting resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new thermosetting resin composition comprising specific three kinds of copolymers, excellent in storage stability, low-temperature curing properties, solvent resistance, stain removing properties and weather resistance besides acid resistance and scratching resistance. SOLUTION: This thermosetting resin composition comprises (A) a (meth) acrylic copolymer containing an α,β-dicarboxylic acid-monoesterified acid anhydride, having 250-3,000g/eq α,β-dicarboxylic acid monoester equivalent, (B) a (meth)acrylic copolymer containing an epoxy group and a hydroxyl group, having 200-700g/eq epoxy equivalent and 400-3,000g/eq hydroxyl equivalent and (C) a fluoroolefin-based copolymer containing an epoxy group and a hydroxyl group, having 300-2,000g/eq epoxy equivalent and 280-2,000 hydroxyl equivalent. The component A, for example, is obtained by polymerizing a dibasic acid monoesterified substance such as monomethyl maleate. The component C, for example, is obtained from a fluoroolefin such as tetrafluoroethylene, etc., an epoxy-containing ethylenic unsaturated monomer and a hydroxyalkyl vinyl ether.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a thermosetting resin composition, and more specifically, to storage stability, low temperature curability,
The present invention relates to a thermosetting resin composition for coatings, which is excellent in acid resistance, scratch resistance, stain resistance, weather resistance, and solvent resistance.

[0002]

2. Description of the Related Art Conventionally, an acrylic melamine-based coating has been widely used industrially as a top coat for automobile bodies because it is a one-pack type and has excellent coating workability and finishing workability and high cost performance. However, in recent years, acid rain has become a social problem, and the conventional acrylic melamine type has a drawback that the acid resistance of the cross-linking site of melamine is poor.

On the other hand, a resin composition obtained by crosslinking a hydroxyl group-containing fluororesin with a melamine resin has remarkably superior coating film performance as compared with an acrylic melamine-based paint, but since melamine is also used, a severe test condition of 70 ° C. or higher is required. Then, the problem of acid resistance remains.

In order to solve this problem, a novel curing system replacing melamine has been required, and a curing system utilizing a crosslinking reaction between an acid group and an epoxy group has been actively studied. For example, Japanese Patent Laid-Open Nos. 2-45577 and 3-
JP-A-287650 and JP-A-4-363374 disclose a thermosetting composition containing a copolymer in which an acid anhydride group as an acid group is half-esterified, a hydroxy compound and an epoxy compound, and an acid group. A thermosetting composition containing a copolymer obtained by half-esterifying the acid anhydride group, and a compound having an epoxy group and a hydroxyl group has been proposed. Further, JP-A-6-57077 discloses a fluororesin having an acid group and / or a hydroxyl group, a copolymer obtained by half-esterifying an acid anhydride group as an acid group, an epoxy group and a hydroxyl group having a specific structure. A thermosetting composition containing the resin has been proposed.

However, JP-A-2-45577, JP-A-3-287650 and JP-A-4-363374.
The thermosetting composition as disclosed in Japanese Patent Publication has a good acid resistance at the initial stage because it has an ester bond formed by the reaction of an acid group and an epoxy group as a crosslinking point, but the main component is an acrylic resin. Therefore, there is a problem that the acid resistance after weathering deterioration is lowered, and if the crosslink density is increased to improve the weather resistance, the scratch resistance of the coating film is lowered.

Further, the thermosetting composition as disclosed in JP-A-6-57077 contains a fluororesin having an acid group and / or a hydroxyl group and therefore has good scratch resistance and stain resistance. However, since such a fluororesin easily turns yellow, the coating color used as a paint is limited, and the low reactivity of the acid groups of the fluororesin makes it inferior in low-temperature curability and low in solvent resistance. Has the problem of being.

[0007]

DISCLOSURE OF THE INVENTION The present invention is a novel and useful coating which is excellent in storage stability, low temperature curing property, solvent resistance, stain resistance and weather resistance in addition to acid resistance and scratch resistance. A thermosetting resin composition for use is provided.

[0008]

SUMMARY OF THE INVENTION The present inventors have accomplished the present invention as a result of earnestly examining thermosetting resin compositions in view of the above problems of the prior art. That is, the thermosetting resin composition of the present invention has an α, β-dicarboxylic acid monoesterified acid anhydride group and an α, β-dicarboxylic acid monoester equivalent of 250 to 3000 g / eq ( It has a (meth) acrylic copolymer (A), an epoxy group and a hydroxyl group, and has an epoxy equivalent of 200 to 700 g.
/ Eq, a hydroxyl group equivalent of 400 to 3000 g / eq (meth) acrylic copolymer (B), and an epoxy group and a hydroxyl group, and an epoxy equivalent of 300 to 2000.
It is characterized by containing a fluoroolefin copolymer (C) having a g / eq and a hydroxyl equivalent of 280 to 2000 g / eq.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The (meth) acrylic copolymer (A) used in the thermosetting resin composition of the present invention is a monomer having an α, β-dicarboxylic acid monoesterified acid anhydride group. Obtained by polymerizing a polymerizable monomer mixture containing a polymer, or after polymerizing a polymerizable monomer mixture containing a monomer having a dibasic acid anhydride group, the acid anhydride group is monoester with an alkanol. And α, β-
Dicarboxylic acid monoester equivalent (1 gram equivalent of α, β
-Dicarboxylic acid monoesterified acid anhydride group-containing resin) is in the range of 250 to 3000 g / eq. This is because if the α, β-dicarboxylic acid monoester equivalent exceeds 3000 g / eq, a sufficient effect for improving low temperature curability cannot be obtained, and if it is less than 250 g / eq, the storage stability of the thermosetting resin composition decreases. Therefore, the range is preferably 300 to 2000 g / eq, and more preferably 350 to 1000 g / eq.

The (meth) acrylic copolymer (A) of the present invention has an acid value (mg of potassium hydroxide required to neutralize 1 g of the (meth) acrylic copolymer) of 30 to 30.
250 mg KOH / g, weight average molecular weight 1000-5
0000 is preferred. This is because when the acid value of the (meth) acrylic copolymer (A) is less than 30 mgKOH / g, the hardness and solvent resistance of the coating film tend to decrease due to insufficient curability, and 250 mgKOH / g. When it exceeds g, the viscosity of the copolymer remarkably increases, and further the gloss, water resistance and weather resistance of the coating film tend to decrease.
The range is more preferably 50 to 190 mgKOH / g, and further preferably 80 to 160 mgKOH / g. Further, if the weight average molecular weight of the (meth) acrylic copolymer (A) is less than 1000, the water resistance and weather resistance of the coating film tend to be lowered, and if it exceeds 50,000, the viscosity of the resin is remarkably increased. However, the cosmetic appearance of the coating film and the storage stability of the resin composition tend to decrease, and more preferably 2
000-30000, more preferably 3000-20
The range is 000.

Monomers used when the (meth) acrylic copolymer (A) of the present invention is obtained by polymerizing a monomer having an α, β-dicarboxylic acid monoesterified acid anhydride group. As, for example, monomethyl maleate,
Monoethyl maleate, monobutyl maleate, monooctyl maleate, monomethyl itaconate, monoethyl itaconate, monobutyl itaconate, monooctyl itaconate, mono-2-ethylhexyl itaconate, monomethyl fumarate, monoethyl fumarate, monobutyl fumarate, fumar Examples include monoesters of dibasic acid or acid anhydride monomers such as monooctyl acid and monoethyl citracone.

Further, after polymerizing the (meth) acrylic copolymer (A) of the present invention with a polymerizable monomer mixture containing a monomer having a dibasic acid anhydride group, the acid anhydride group is treated with an alkanol. Examples of the monomer having a dibasic acid anhydride group used when obtained by monoesterification include, for example, dibasic acid such as maleic acid anhydride, itaconic acid anhydride, fumaric acid anhydride and citraconic acid anhydride. Examples thereof include anhydrides, and examples of the alkanol include methanol, ethanol, i-
Propanol, t-butanol, i-butanol, n-
Butanol, methyl cellosolve, ethyl cellosolve, dimethylaminoethanol, diethylaminoethanol,
Examples include acetol, propargyl alcohol, allyl alcohol and the like. The monoesterification can be carried out by a usual method, if necessary, together with a reaction catalyst such as a quaternary ammonium salt such as tetrabutylammonium bromide or a tertiary amine such as triethylamine.

The type of the α, β-dicarboxylic acid monoesterified acid anhydride group contained in the (meth) acrylic copolymer (A) of the present invention may be one type or two types according to need. It may be more than one kind.

Further, the monomer unit having an α, β-dicarboxylic acid monoesterified acid anhydride group contained in the (meth) acrylic copolymer (A) of the present invention is α, β.
-Dicarboxylic acid monoester equivalent is 250-3000 g
/ Eq, for example, 3 to 40% by weight. This is because when the monomer unit having these dicarboxylic acid monoesterified acid anhydride groups is less than 3% by weight, a sufficient effect for improving the low-temperature curability cannot be obtained, and when it exceeds 40% by weight, the thermosetting resin composition. This is because the storage stability of the product decreases, and the range is preferably 5 to 35% by weight, more preferably 10 to 30% by weight.

Other polymerizable monomers used in the (meth) acrylic copolymer (A) of the present invention include, for example, methyl (meth) acrylate, ethyl (meth) acrylate and n-propyl (meth). ) Acrylate, n-
Butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, sec-
Butyl (meth) acrylate, n-pentyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, 2-ethylhexyl (meth)
(Meth) acrylic acid esters having a hydrocarbon substituent such as acrylate and cyclohexyl (meth) acrylate, styrene derivatives such as styrene, vinyltoluene and α-methylstyrene, and ethylenically unsaturated nitriles such as acrylonitrile and methacrylonitrile. N-alkoxy-substituted amides such as N-methoxymethylacrylamide, N-ethoxymethylacrylamide, N-butoxymethylacrylamide, ethylenically unsaturated basic such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate Mono- or di-basic acids such as monomers, methacrylic acid, acrylic acid, crotonic acid, vinyl benzoic acid, fumaric acid, itaconic acid, maleic acid, citraconic acid, 2-hydroxyethyl (meth) ) Relate adducts long chain carboxyl-containing monomers such as and the like.

When the (meth) acrylic copolymer (A) of the present invention is obtained by polymerizing a monomer having an α, β-dicarboxylic acid monoesterified acid anhydride group,
2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth)
Acrylate, (meth) acrylic acid ester having hydroxyalkyl group such as 6-hydroxyhexyl (meth) acrylate, γ-butyrolactone ring-opening adduct to 2-hydroxyethyl methacrylate, ε-caprolactone to 2-hydroxyethyl acrylate Ring-opening addition product, ring-opening addition product of ethylene oxide to methacrylic acid,
Ring-opening addition product of propylene oxide to methacrylic acid, 2
-Hydroxyethyl (meth) acrylate or 2-hydroxypropyl (meth) acrylate dimer or trimer having a hydroxyl group-terminated (meth) acrylic acid ester, 4-hydroxybutyl vinyl ether, p-hydroxystyrene, etc. Other hydroxyl group-containing polymerizable monomers such as other hydroxyl group-containing vinyl monomers can also be used in combination. These may be used alone or in combination of two or more as required.

The (meth) acrylic copolymer (B) used in the thermosetting resin composition of the present invention is obtained by copolymerizing a monomer having an epoxy group and a hydroxyl group in a specific ratio. , Its epoxy equivalent (g of resin containing 1 gram equivalent of epoxy group) is 200 to 700 g / e.
q and hydroxyl equivalent (the number of g of the resin containing 1 gram equivalent of hydroxyl group) are in the range of 400 to 3000 g / eq. This is because when the epoxy equivalent of the (meth) acrylic copolymer (B) exceeds 700 g / eq, the curability is insufficient and the hardness and solvent resistance of the coating film are reduced, resulting in 200 g / eq.
If it is less than eq, the resin composition tends to thicken or gel easily, and preferably 250 to 400 g / eq.
Range. Further, when the hydroxyl group equivalent of the (meth) acrylic copolymer (B) exceeds 3000 g / eq, the non-sand recoatability of the coating film decreases, and when it is less than 400 g / eq, the water resistance of the coating film decreases. Yes, preferably 450 to 2000 g / eq, more preferably 500 to
It is in the range of 1500 g / eq.

The (meth) acrylic copolymer (B) of the present invention preferably has a weight average molecular weight of 1,000 to 50,000. When the weight average molecular weight of the (meth) acrylic copolymer (B) is less than 1000,
The water resistance and weather resistance of the coating film tend to decrease, and
This is because when it exceeds 0, the viscosity of the resin remarkably increases and the appearance of the coating film tends to deteriorate, and more preferably 2
000-30000, more preferably 3000-20
The range is 000.

Examples of the epoxy group-containing monomer used in the (meth) acrylic copolymer (B) of the present invention include glycidyl (meth) acrylate, methylglycidyl (meth) acrylate and 3,4-epoxy. Cyclohexyl (meth) acrylate, allyl glycidyl ether, etc. are mentioned, and these can be used individually or in combination of 2 or more types as needed.

The amount of these epoxy group-containing monomers used is
The epoxy equivalent of the (meth) acrylic copolymer (B) is 2
The range is from 00 to 700 g / eq, for example, from 20 to 60% by weight. This is because when the amount of the epoxy group-containing monomer used is less than 20% by weight, the curability is insufficient, so that the hardness and solvent resistance of the coating film decrease, and when it exceeds 60% by weight, the resin composition thickens. This is because it tends to gel or gel, and the range is preferably from 35 to 55% by weight.

Examples of the hydroxyl group-containing monomer used in the (meth) acrylic copolymer (B) of the present invention include 2-hydroxyethyl (meth) acrylate and 2-hydroxyethyl (meth) acrylate.
It has a hydroxyalkyl group such as hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate ( Meta)
Acrylic esters, γ-butyrolactone ring-opening addition product to 2-hydroxyethyl methacrylate, ε-caprolactone ring-opening addition product to 2-hydroxyethyl acrylate, ethylene oxide ring-opening addition product to methacrylic acid, methacrylic acid Ring-opening adduct of propylene oxide, 2-hydroxyethyl (meth) acrylate or 2-hydroxypropyl (meth) acrylate dimer or trimer (meth) acrylic acid ester having a hydroxyl group at the terminal, 4- Hydroxybutyl vinyl ether, p
-Other hydroxyl group-containing vinyl monomers such as hydroxystyrene are included. These may be used alone or in combination of two or more as required.

The amount of these hydroxyl group-containing monomers used is such that the hydroxyl group equivalent of the (meth) acrylic copolymer (B) is 400 to
The range is 3000 g / eq, for example, 4 to
It is in the range of 50% by weight. This is because when the amount of the hydroxyl group-containing monomer used is less than 4% by weight, the non-sand recoatability of the coating film decreases, and when it exceeds 50% by weight, the water resistance of the coating film decreases, and preferably 6 to It is in the range of 40% by weight, and more preferably in the range of 8 to 30% by weight.

The other polymerizable monomers used in the (meth) acrylic copolymer (B) of the present invention include
For example, methyl (meth) acrylate, ethyl (meth)
Acrylate, n-propyl (meth) acrylate, n
-Butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, sec
-Butyl (meth) acrylate, n-pentyl (meth)
Acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, and other (meth) acrylic acid esters having a hydrocarbon substituent, styrene, vinyltoluene, α- Styrene derivatives such as methylstyrene, ethylenically unsaturated nitriles such as acrylonitrile and methacrylonitrile, N-alkoxy-substituted amides such as N-methoxymethylacrylamide, N-ethoxymethylacrylamide and N-butoxymethylacrylamide, dimethylaminoethyl (Meta)
Examples thereof include ethylenically unsaturated basic monomers such as acrylate and diethylaminoethyl (meth) acrylate, and these can be used alone or in combination of two or more as required.

The (meth) acrylic copolymers (A) and (B) of the present invention can be produced by a known polymerization method such as a solution polymerization method, a bulk polymerization method and an emulsion polymerization method. It is preferably manufactured by a legal method. When the (meth) acrylic copolymer is produced by the solution polymerization method, the monomer mixture is copolymerized in the presence of an organic solvent and a polymerization initiator.

As the organic solvent used in the solution polymerization, aromatic hydrocarbons such as toluene and xylene, ketones such as methyl ethyl ketone and methyl isobutyl ketone, esters such as ethyl acetate and n-butyl acetate are used. And the like, and alcohols such as isopropanol and n-butanol may be used depending on the case.

As the polymerization initiator used,
2,2-azobisisobutyronitrile, 2,2-azobis (2,4-dimethylvaleronitrile), 2,2-azobis (2-methylbutyronitrile), benzoyl peroxide, cumene hydroperoxide, lauryl per It can be selected from commonly used polymerization initiators such as oxide and di-t-butyl peroxide. If necessary, a chain transfer agent such as 2-mercaptoethanol and n-octylmercaptan can be used.

When the (meth) acrylic copolymer is produced by the solution polymerization method, it is generally preferable to carry out the polymerization in the range of 80 to 160 ° C., more preferably 100 to 160 ° C., in order to control the molecular weight. It is in the range of 140 ° C.

The fluoroolefin copolymer (C) used in the thermosetting resin composition of the present invention is a fluoroolefin, an ethylenically unsaturated monomer having an epoxy group, an ethylenically unsaturated monomer having a hydroxyl group. , Other ethylenically unsaturated monomers are copolymerized in a specific ratio, and the epoxy equivalent thereof is 300 to 2000 g / e.
q and hydroxyl equivalent are in the range of 280 to 2000 g / eq. This is because when the epoxy equivalent of the fluoroolefin copolymer (C) exceeds 2000 g / eq, the crosslinking density becomes insufficient, and the weather resistance, acid resistance, and chemical resistance decrease, and when it becomes less than 300 g / eq, the crosslinking density decreases. Is too high, and it becomes hard and brittle as a practical coating film, causing a problem in flexibility. It is preferably in the range of 400 to 1200 g / eq.

If the hydroxyl equivalent of the fluoroolefin copolymer (C) exceeds 2000 g / eq, the compatibility between the fluoroolefin copolymer (C) and the acrylic copolymer (B) will decrease. In addition, the curability, the transparency of the coating film, and the smoothness are lowered, and when it is less than 280 g / eq, the fluoroolefin copolymer (C) is soluble only in the polar solvent, and the solubility in the aromatic hydrocarbon cannot be secured. This is because. It is preferably in the range of 350 to 1200 g / eq.

The fluoroolefin copolymer (C) of the present invention has a weight average molecular weight of 6000 to 10000.
It is preferably in the range of 0. This is because when the weight average molecular weight of the fluoroolefin-based copolymer (C) is less than 6000, the weather resistance of the coating film tends to decrease.
When it exceeds 0000, the coating workability and the finished appearance tend to be deteriorated, and more preferably 8000 to
It is in the range of 50,000.

The fluoroolefin used in the fluoroolefin copolymer (C) of the present invention has the general formula CF
A compound represented by ₂ = CFZ (wherein Z is hydrogen, chlorine, fluorine, a perfluoroalkyl group having 1 to 3 carbon atoms or a perfluoroalkoxy group having 1 to 3 carbon atoms) is preferably adopted. Specific examples include tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, perfluoropropyl vinyl ether and the like. Fluoroolefins may be used alone or in combination of two or more.

The ethylenically unsaturated monomer having an epoxy group, the ethylenically unsaturated monomer having a hydroxyl group, and other ethylenically unsaturated monomer used in the fluoroolefin copolymer (C) of the present invention. As the ethylenically unsaturated monomer in the body, ethyl ether unsaturated monomers such as vinyl ethers, allyl ethers, isopropenyl ethers, vinyl esters, allyl esters and olefins are preferably used, and their solvents Solubility, control of coating hardness, alternating copolymerizability from the viewpoint of weather resistance,
Vinyl ethers are particularly preferable from the viewpoint of polymerization yield and the like. Specific examples thereof include alkyl vinyl ethers and cycloalkyl vinyl ethers having an alkyl group or a cycloalkyl group having about 2 to 8 carbon atoms such as ethyl vinyl ether and cyclohexyl ether.

The epoxy group-containing ethylenically unsaturated monomer used in the fluoroolefin copolymer (C) of the present invention includes, for example, fats such as glycidyl vinyl ether, glycidyl allyl ether and glycidyl (meth) acrylate. Group epoxy group-containing ethylenically unsaturated monomer, 3,4-epoxycyclohexyl vinyl ether, 3,4-epoxycyclohexylmethyl (meth)
Examples thereof include alicyclic epoxy group-containing ethylenically unsaturated monomers such as acrylates, and these can be used alone or in combination of two or more as required. Further, for the same reason as described above, as the ethylenically unsaturated monomer having an epoxy group, a vinyl ether type is preferable.

The amount of the ethylenically unsaturated monomer having an epoxy group used is in a range such that the epoxy equivalent of the fluoroolefin copolymer (C) is 300 to 2000 g / eq, for example, 5 to 40. It is in the range of% by weight. This is because when the amount of the ethylenically unsaturated monomer having an epoxy group used is less than 5% by weight, the crosslink density is insufficient, and the acid resistance and chemical resistance including weather resistance are reduced, and when it exceeds 40% by weight, crosslinking occurs. This is because the density is too high and the coating film becomes hard and brittle as a practical coating film, which causes a problem in flexibility.
-30% by weight.

Examples of the ethylenically unsaturated monomer having a hydroxyl group used in the fluoroolefin copolymer (C) of the present invention include hydroxyalkyl vinyl ethers such as hydroxybutyl vinyl ether and hydroxyethyl vinyl ether, and hydroxyalkyl vinyl ethers. Examples thereof include hydroxyalkyl (meth) acrylates such as ethyl (meth) acrylate, hydroxyalkyl allyl ethers such as hydroxyethyl allyl ether, hydroxyalkyl isopropenyl ethers such as hydroxybutyl isopropenyl ether, and allyl alcohol.
These may be used alone or in combination of two or more as required.

Of these, hydroxyalkyl vinyl ethers and hydroxyalkyl isopropenyl ethers are preferable, and hydroxyalkyl vinyl ethers are particularly preferable in terms of copolymerizability with fluoroolefins. The amount of the ethylenically unsaturated monomer having a hydroxyl group used is in such a range that the hydroxyl equivalent of the fluoroolefin copolymer (C) is 280 to 2000 g / eq, for example, 5 to 40% by weight. Is. This is because the amount of the ethylenically unsaturated monomer having a hydroxyl group is 5% by weight.
If it is less than 40% by weight, the crosslink density is insufficient, and the acid resistance and chemical resistance including weather resistance are deteriorated. If it exceeds 40% by weight, the fluoroolefin copolymer (C) is soluble only in a polar solvent, and the aromatic hydrocarbon This is because the solubility cannot be secured. Preferably it is in the range of 10 to 30% by weight.

Examples of other ethylenically unsaturated monomers used in the fluoroolefin copolymer (C) of the present invention include olefins such as ethylene, propylene and isobutylene, vinyl chloride and vinylidene chloride. And the like, unsaturated carboxylic acid esters such as methyl methacrylate, allyl ethers, allyl esters and the like. These may be used alone or in combination of two or more as required.

The fluoroolefin copolymer (C) of the present invention acts on a monomer mixture in a predetermined ratio with a polymerization initiator or a polymerization initiation source such as ionizing radiation in the presence or absence of a polymerization catalyst. Can be manufactured.

As the polymerization initiator to be used, a water-soluble or oil-soluble one can be appropriately selected and used according to the polymerization type or the polymerization medium. Specifically, as the water-soluble initiator, a persulfate such as potassium persulfate, hydrogen peroxide, or a redox initiator comprising a combination of these with a reducing agent such as sodium bisulfite and sodium thiosulfate, Small amounts of iron in these redox initiators,
Inorganic initiators such as ferrous salts and silver nitrate coexisting systems, dibasic acid oxides such as disuccinic acid peroxide and monosuccinic acid peroxide, and organic initiators such as azobisisobutylamidine dibasic acid salt It can be illustrated. Further, as the oil-soluble initiator, peroxyester type peroxides such as t-butylperoxyisobutyrate and t-butylperoxyacetate, diisopropyl peroxydicarbonate, benzoyl peroxide, azobisisobutyronitrile Etc. can be illustrated.

The amount of the polymerization initiator used can be appropriately changed depending on the type of the polymerization initiator, the conditions of the copolymerization reaction, etc.
Normally 0.005 with respect to the total amount of monomers to be copolymerized
˜5 wt%, especially about 0.05 to 5 wt%.

In the above-mentioned polymerization reaction, the reaction mode is not particularly limited, and bulk polymerization, suspension polymerization, emulsion polymerization, solution polymerization and the like can be adopted. For ease of polymer separation, emulsion polymerization in an aqueous medium, alcohols such as t-butanol, esters, saturated halogenated hydrocarbons containing at least one fluorine atom, aromatics such as xylene, etc. Solution polymerization using a hydrocarbon or the like as a solvent is preferably adopted.

When carrying out the copolymerization reaction in an aqueous medium, it is preferable to add a basic buffer so that the pH value of the liquid during the polymerization does not fall below 4, preferably 6. The addition of the basic substance is also effective in the case of solution polymerization. Further, it goes without saying that the above-mentioned polymerization can be carried out by operations such as a batch system, a semi-continuous system and a continuous system.

In the above polymerization reaction, the polymerization reaction temperature is −
The optimum value is appropriately selected in the range of 30 to 150 ° C depending on the polymerization initiation source, the type of the polymerization medium, etc., but when the polymerization reaction is carried out in an aqueous medium, 0 to 100 ° C, preferably 10 to 9 ° C.
The reaction temperature is selected in the range of 0 ° C. The reaction pressure can be appropriately selected, but is usually in the range of 1 to 100 kg / cm ² , preferably ² to 50 kg / cm ² . Further, if necessary, a chain transfer agent can be used during the polymerization reaction.

The (meth) acrylic copolymer (A), the (meth) acrylic copolymer (B) and the fluoroolefin copolymer (C) which are the constituents of the thermosetting resin composition of the present invention. Means that the total of the epoxy groups in the components (B) and (C) is 0.5 to 2 with respect to 1 mol of the acid group in the component (A).
It is preferable to mix them in such a ratio that they are in a molar range.
Outside of this range, unreacted functional groups tend to reduce the water resistance and weather resistance of the coating film, which is not preferable. More preferably, it is in the range of 0.7 to 1.8 mol.

Further, the (meth) acrylic copolymer (B)
And the fluoroolefin copolymer (C) are the components (B)
It is preferable to mix the epoxy group in the component (C) in the thermosetting resin composition of the present invention in a ratio of 0.05 to 2 mol per 1 mol of the epoxy group therein. This is because when the ratio of the epoxy groups in the component (C) is less than 0.05 mol, the water resistance and weather resistance of the coating film tend to decrease, and when it exceeds 2 mol, the storage stability of the resin composition is high. This is because the heat-resistant yellowing of the coating film tends to decrease, and the range of 0.1 to 1 mol is more preferable.

The thermosetting resin composition of the present invention contains, if necessary, an acrylic resin used in a general coating composition,
One or more kinds of polyester resin, amino resin, epoxy resin, polyurethane resin and the like can be mixed. These can be added in an appropriate amount as long as the storage stability of the resin composition and the coating film performance are not impaired.
It is preferably 20% by weight or less based on the total amount of the acrylic copolymers (A) and (B) and the fluoroolefin copolymer (C). This is because when the amount added exceeds 20% by weight, the acid resistance of the coating film tends to decrease and the coating film tends to yellow.

The thermosetting resin composition of the present invention may contain a catalyst to accelerate curing. The curing catalyst may be a known one used for the esterification reaction of acid groups and hydroxyl groups, and examples thereof include organic amines, organic metal compounds, metal chelates, quaternary ammonium salts, and quaternary phosphonium salts.

Furthermore, in the thermosetting resin composition of the present invention, if necessary, organic bentonite, crosslinked polymer particles,
Rheology modifiers such as microgels and waxes, surface modifiers, UV absorbers, light stabilizers, antioxidants, color pigments, metallic pigments, extender pigments, etc. are appropriately blended using known means as necessary. can do.

The thermosetting resin composition of the present invention is preferably used by dissolving or dispersing it in an organic solvent or water, and can be used as a solid color paint, a metallic paint and a clear paint.

When the thermosetting resin composition of the present invention is used as a clear coat paint for automobile coating, the thermosetting resin composition of the present invention can be used as the base coat layer in contact with the clear coat layer. However, a known curable resin can be appropriately used if necessary. These thermosetting resins include diluents composed of volatile organic solvents, curing agents composed of amino resins or polyisocyanate compounds, aluminum pastes, mica, brightening agents such as flake iron oxide, titanium oxide, carbon black. , Inorganic pigments such as quinacridone and organic pigments, polyester resins, epoxy resins, addition resins such as cellulose resins, surface modifiers, ultraviolet absorbers, antioxidants and other additives using known means as necessary. It can be blended appropriately.

[0051]

EXAMPLES The present invention will be described in more detail below with reference to examples. In addition, "part" in the following Examples and Comparative Examples means "part by weight". The evaluations in the examples and comparative examples were performed by the following methods.

(1) Nonvolatile matter 1 g of the (meth) acrylic copolymer solution was sampled and dried at 150 ° C. for 1 hour to measure the nonvolatile matter.

(2) Weight average molecular weight It was measured by gel permeation chromatography using polystyrene as a reference.

(3) Storage stability The state after observing the coating material at 30 ° C. for 72 hours was observed. ◎: No abnormality ○: Viscosity slightly increased, no problem in practical use △: Thickened, problem in practical use ×: Gelled, unusable

(4) Acid resistance 10 wt% sulfuric acid aqueous solution 0.3 cc is spotted on the coated surface,
After leaving at 70 ° C. for 1 hour and washing with water, the edge depth of the spot portion was measured with a three-dimensional surface roughness meter.

(5) Scratch resistance A felt soaked with a cleanser was made to reciprocate 50 times on the coated surface under a load of 500 g, and the gloss retention rate was calculated from the initial gloss and the scratch gloss.

(6) Contamination resistance Carbon black is dispersed in water at a concentration of 0.1% by weight, sprayed on a coated plate and baked at 60 ° C for 20 minutes. This operation was set as one cycle, and the stain removal property after 5 cycles was visually evaluated. ◯: Stain is well removed Δ: Part of the stain remains ×: Stain remains considerably

(7) Weather resistance The gloss retention of the coating film after exposure for 3000 hours with a sunshine weather meter was indicated.

(8) Solvent Resistance Methyl ethyl ketone was dipped in gauze and subjected to a 50-way reciprocating rubbing test to visually determine the appearance of the coating film.

(9) Low Temperature Curing Property A coated plate baked at 120 ° C. was subjected to the above solvent resistance test using xylene, and the appearance of the coating film after the test was visually judged.

The solvent resistance and the low temperature curability were visually determined according to the following criteria. ⊚: The coating film quality after the performance test does not change from that before the test, and excellent coating film performance is maintained. ◯: The quality of the coating film after the performance test is slightly lower than that before the test, but it has sufficient practical performance. B: The quality of the coating film after the performance test is lower than that before the test, which is a problem in practice. X: The coating film quality after the performance test is significantly lower than that before the test,
It is practically unusable.

(1) Production Example of Base Coat Paint (M-1) 10 parts of n-butanol and 90 parts of toluene as a solvent were added to a container equipped with a stirrer, a temperature controller and a condenser, and heated to 100 ° C. with stirring. After that, with a vinyl monomer consisting of 40 parts of methyl methacrylate, 30 parts of ethyl acrylate, 15 parts of n-butyl acrylate, 12 parts of 2-hydroxyethyl methacrylate, 3 parts of methacrylic acid, and 1 part of azobisisobutyronitrile. After the mixture of the polymerization initiator was dropped into the solvent over 4 hours, the mixture was polymerized at the same temperature for 3 hours to give a (meth) acrylic copolymer (D-
1) was synthesized. The nonvolatile content of the obtained (meth) acrylic copolymer (D-1) was 50% by weight, and the weight average molecular weight was 40,000.

Further, 100 parts of this (meth) acrylic copolymer (D-1), Uban 20SE-60 (manufactured by Mitsui Toatsu Chemicals, Inc., butylated melamine resin, solid content 60)
%) 25 parts, Alpaste # 1700NL (manufactured by Toyo Aluminum Co., Ltd., aluminum paste, solid content 65)
%) 14 parts to obtain a base coat coating composition.

Next, this base coat coating composition was diluted with a mixed solvent consisting of ethyl acetate / toluene / Solvesso # 150 (produced by Esso, aromatic hydrocarbon) = 40/30/30 (wt%) to obtain a base coat coating composition. Adjust the viscosity of the product with Ford Cup # 4 to 13 seconds,
A silver metallic base coat paint (M-1) was obtained.

(2) (Meth) acrylic copolymer (A-
1) to (A-3), (A-10), (A-12) Synthesis 20 parts of butyl acetate as a solvent in a container equipped with a stirrer, a temperature control device, and a condenser, Solvesso # 100 (Esso Co., aroma) 50 parts of group petroleum derivative) and heated to 100 ° C. with stirring, and then 30 parts of n-butyl acetate and the polymerizable monomer shown in Table 1 and the weight average molecular weight shown in Table 1 as a radical polymerization initiator. A mixture of such an amount of 2,2-azobis (2-methylbutyronitrile) was dropped into the solvent over 4 hours, and the internal temperature of the flask was adjusted to 1
The reaction is terminated at a temperature of 00 ° C and the conversion rate to the resin is sufficiently increased, and the (meth) acrylic copolymer (A-
1) to (A-3), (A-10) and (A-12) were synthesized. The characteristic values of the obtained (meth) acrylic copolymer are shown in Table 1.

(3) (Meth) acrylic copolymer (A-
4) to (A-9), (A-11) synthesis 20 parts of butyl acetate as a solvent in a container equipped with a stirrer, a temperature control device, and a condenser, 50 parts of Solvesso # 100 (Aromatic petroleum derivative manufactured by Esso). Was added and heated to 100 ° C. with stirring, and then 30 parts of n-butyl acetate and the polymerizable monomer described in Table 1 and a radical polymerization initiator in an amount of 2, such that the weight average molecular weight shown in Table 1 was obtained. A mixture of 2-azobis (2-methylbutyronitrile) was dropped into the solvent for 4 hours, and the inner temperature of the flask was adjusted to 1
It was kept at 00 ° C to sufficiently increase the conversion rate to resin. Then, the temperature inside the flask was lowered to 80 ° C., and the mixture of methanol and triethylamine shown in Table 1 was added,
After reacting at 0 ° C. for 7 hours, the disappearance of the acid anhydride group was confirmed by IR to terminate the reaction, and (meth) acrylic copolymers (A-4) to (A-9) and (A-11) ) Was synthesized. The characteristic values of the obtained (meth) acrylic copolymer are shown in Table 1.

[0067]

[Table 1]

(4) (Meth) acrylic copolymer (B-
1) to (B-12) Synthesis In a container equipped with a stirrer, a temperature controller, and a condenser, 30 parts of n-butanol as a solvent, Solvesso # 100.
(Esso Co., aromatic petroleum derivative) (70 parts) was added, and the mixture was heated to 120 ° C. with stirring, so that the polymerizable monomers shown in Table 2 and the radical polymerization initiator had the weight average molecular weights shown in Table 2. A mixture of 2,2-azobis (2-methylbutyronitrile) in an appropriate amount was dropped into the solvent over 4 hours, and the internal temperature of the flask was maintained at 120 ° C. to obtain a sufficient conversion rate to resin. Stop the reaction when you raise it,
(Meth) acrylic copolymers (B-1) to (B-12)
Was synthesized. The characteristic values of the obtained (meth) acrylic copolymer are shown in Table 2.

[0069]

[Table 2]

(5) Fluoroolefin copolymer (C
Synthesis of -1) to (C-4) Polymerization of monomer mixture shown in Table 3 by appropriately adding radical polymerization initiator t-butylperoxypivalate so that the weight average molecular weight shown in Table 3 is obtained. I went. The resin characteristic values of the obtained copolymer are shown in Table 3. However,
(C-1) is obtained by copolymerizing the monomer components in the table and then acid-modifying a part of the hydroxyl groups in the copolymer with succinic anhydride.

[0071]

[Table 3]

(6) Preparation of clear coat coating composition The (meth) acrylic copolymers and fluoroolefin copolymers shown in Tables 1, 2 and 3 were blended in the composition ratios shown in Tables 4 to 6. After mixing with stirring, a mixed solvent (Solvesso # 100 / cellosolve acetate = 50/50 (weight ratio)) was added and diluted so that the paint viscosity was 25 seconds (using Ford cup No. 4, measurement temperature 20 seconds). Then, a clear coat paint was prepared.

[0073]

[Table 4]

[0074]

[Table 5]

[0075]

[Table 6]

[Examples 1 to 23 and Comparative Examples 1 to 13]
A steel sheet (30 cm × 90 cm) treated with zinc phosphate was coated with a cationic electrodeposition paint for automobiles and baked at 180 ° C. for 30 minutes. Further, an amino alkyd resin-based intermediate coating material was applied and baked at 160 ° C. for 30 minutes, and then the coating film was water-polished and dried. On this coating film, first, a base coat paint (M-1) was applied to a dry film thickness of 15 μm, and after leaving it for 5 minutes, the clear coat paint prepared in (6) above was applied to a dry film thickness of 30 μm. Was repeatedly applied by the wet-on-wet method. After leaving the undried coating film for 15 minutes at room temperature, it is baked for 30 minutes in a hot air dryer at 140 ° C. (sample for low temperature curability evaluation is 12
Baking at 0 ° C. for 25 minutes) A multi-layer coating film was formed by a 2-coat 1-baking method. The coating performances of the obtained multilayer coatings are shown in Tables 7-9.

[0077]

[Table 7]

[0078]

[Table 8]

[0079]

[Table 9]

As is clear from the results of the above Examples and Comparative Examples, the thermosetting resin composition of the present invention (Examples 1 to 1)
23) has excellent storage stability and low-temperature curing property, and is also excellent in coating film performance such as acid resistance, scratch resistance, stain resistance, weather resistance and solvent resistance. On the other hand, the thermosetting resin compositions of Comparative Examples 1 to 13, which did not satisfy the conditions defined by the present invention, had low storage stability, low temperature curability, and various coating film performances.

[0081]

INDUSTRIAL APPLICABILITY The thermosetting resin composition of the present invention is excellent in storage stability and low temperature curability, and by using it, it is also excellent in coating film performance such as acid resistance and scratch resistance. It is possible to provide a coating film, which is very useful industrially.

Front Page Continuation (72) Inventor Takeshi Kato 4-chome, Sunadabashi, Higashi-ku, Aichi Prefecture, Aichi Prefecture 60-72, Product Development Laboratory, Mitsubishi Rayon Co., Ltd. (72) Akio Iwamoto 4-chome, Sunadabashi, Higashi-ku, Aichi Prefecture, Aichi Prefecture Mitsubishi Rayon Co., Ltd. Product Development Laboratory (72) Inventor Isao Kimura 3-474 Tsukakoshi 2 Sachi-ku, Kawasaki-shi, Kanagawa Asahi Glass Co., Ltd. Tamagawa Branch Office (72) Inventor Shunichi Kodama 3-474 Tsukakoshi, Sachi-ku, Kawasaki-shi, Kanagawa Address 2 Asahi Glass Co., Ltd. Tamagawa Branch Room (72) Inventor Nobuyuki Miyazaki 3-chome Tsukagoshi, Sachi-ku, Kawasaki City, Kanagawa Prefecture 2 Address 2 Asahi Glass Co. Ltd. Tamagawa Branch Room (72) Yasuyuki Sasao 3-474 Tsukagoshi, Saikoku-ku, Kawasaki City, Kanagawa Prefecture Address 2 Asahi Glass Co., Ltd. Tamagawa Branch Office

Claims (1)

[Claims] 1. A (meth) acrylic copolymer (having an α, β-dicarboxylic acid monoesterified acid anhydride group and an α, β-dicarboxylic acid monoester equivalent of 250 to 3000 g / eq. A), a (meth) acrylic copolymer (B) having an epoxy group and a hydroxyl group, an epoxy equivalent of 200 to 700 g / eq and a hydroxyl group equivalent of 400 to 3000 g / eq, and an epoxy group and a hydroxyl group. A thermosetting resin composition comprising a fluoroolefin copolymer (C) having an epoxy equivalent of 300 to 2000 g / eq and a hydroxyl equivalent of 280 to 2000 g / eq.