JPH07133340A - Curable resin composition - Google Patents

Abstract

PURPOSE:To obtain a curable resin compsn. excellent in low-temp. curability and storage stability by compounding a polyepoxide, a specific curative, and a specific latent cure catalyst as the essential components. CONSTITUTION:A curable resin compsn. contains a polyepoxide, a curative having a carboxyl and/or cyclic acid anhydride group or groups (e.g. a low mol.wt. compd. such as tetra hydrophthalic acid, or trimellitic acid, or a polycarboxylic acid resin based on a vinyl polymer or a polyester), and a latent cure catalyst comprising an onium salt (e.g. a quaternary ammonium salt such as tetraethylammonium chloride) and an acidic phosphoric ester (e.g. dimethyl phosphate or diethyl phosphate). A pref. curative is a polycarboxylic acid.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel curable resin composition.

[0002]

2. Description of the Related Art Conventionally, in curing an epoxy resin with a curing agent such as polycarboxylic acid anhydride, a curing catalyst such as a tertiary amine or a quaternary ammonium salt has been used.

However, since the curing catalyst has a great effect of promoting the reaction between the epoxy resin and the curing agent, there is a problem that the storage stability is poor and the pot life is short.

The present invention was made for the purpose of developing a curable resin composition having excellent low temperature curability and good storage stability.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in order to solve the above problems. As a result, they have found that a latent curing catalyst composed of an onium salt and an acidic phosphoric acid ester as a curing catalyst for polyepoxide provides a resin composition that solves all the above problems, and completes the present invention. Came to.

That is, the present invention relates to (A) polyepoxide,
A curable resin composition containing (C) a latent curing catalyst composed of (B) a carboxyl group and / or cyclic acid anhydride group-containing curing agent, (a) an onium salt, and (b) an acidic phosphoric acid ester as essential components. Related to things.

The (A) polyepoxide used in the present invention is 1
It is a resin having an average of about 2 or more epoxy groups in the molecule. As the (A) polyepoxide, a conventionally known one can be used, but a weight average molecular weight of about 6,000 to 15.0 having an average of about 2 to 50 epoxy groups in one molecule.
It is desirable to use the acrylic resin of No. 00 because it gives a cured coating film with good performance such as finished appearance and outdoor weather resistance.

Examples of the acrylic resin include an epoxy group-containing monomer having one epoxy group and one (meth) acryloyl group in one molecule, represented by glycidyl (meth) acrylate, and other polymerizable unsaturated compounds. Those obtained by a radical copolymerization reaction with a monomer are included.

It is desirable that the epoxy group-containing monomer is contained in the resin in an amount of about 5 to 60% by weight, preferably about 20 to 50% by weight, as a constituent of the resin.

Other polymerizable unsaturated monomers include
For example, (meth) acryl such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, and lauryl (meth) acrylate. Acid alkyl esters; (meth) acrylic acid cycloalkyl esters such as cyclohexyl (meth) acrylate; hydroxy groups such as hydroxyethyl (meth) acrylate, hydroxybutyl (meth) acrylate and adducts of these with ε-caprolactone Containing ethylenically unsaturated monomers; isononylethyl (meth) acrylate,
(Meth) acrylic acid fluoroalkyl esters such as perfluorooctyl (meth) acrylate: vinyl aromatic compounds such as styrene and vinyltoluene; nitrile compounds such as (meth) acrylonitrile; tetrafluoroethylene, trifluoroethylene chloride Fluoroolefins such as vinylidene difluoride and vinyl fluoride, vinyl esters, olefin compounds and the like are included.

The acrylic resin can be produced by any known method such as a solution polymerization method, a suspension polymerization method and an emulsion polymerization method without any particular limitation.

The curing agent (B) used in the present invention is a curing agent containing a carboxyl group and / or a cyclic acid anhydride group. The curing agent is a polycarboxylic acid curing agent containing two or more carboxyl groups in one molecule, a cyclic acid anhydride curing agent containing one or more cyclic acid anhydride groups in one molecule, and a carboxyl group in one molecule. And a carboxyl group-containing cyclic acid anhydride curing agent containing one or more cyclic acid anhydride groups, respectively.

As the polycarboxylic acid curing agent, low molecular weight substances such as tetrahydrophthalic acid, hexahydrophthalic acid and trimellitic acid, polycarboxylic acid resins such as vinyl type and polyester type (usually having an average molecular weight of about 500 to 8).
10,000) and the like are included.

Examples of the above-mentioned vinyl-based polycarboxylic acid resin include, for example, a carboxyl group-containing ethylenically unsaturated monomer ((meth) acrylic acid, an adduct of the hydroxyl group-containing vinyl monomer and hymic acid anhydride) and, if necessary, (Co) polymer obtained by radical polymerization of other ethylenically unsaturated monomers; carboxyl group-containing ethylenically unsaturated monomers (itaconic anhydride, maleic anhydride, etc.) and, if necessary, the other ethylenically unsaturated One obtained by half-esterifying a (co) polymer obtained by radical polymerization of monomers with an esterifying agent (acetol, allyl alcohol, propargyl alcohol, methanol, etc.); the above-mentioned ethylenically unsaturated monomer containing an anhydrous carboxyl group and the above-mentioned ester A monomer obtained by half-esterifying the agent A (co) polymer obtained by radically polymerizing the other ethylenically unsaturated monomer, if necessary; the hydroxyl group-containing ethylenically unsaturated monomer as an essential component, and if necessary, the other ethylenically unsaturated monomer. Examples thereof include those obtained by half-esterifying a hydroxyl group-containing (co) polymer obtained by radical (co) polymerization with carboxylic acid anhydride (succinic anhydride, etc.).

The polyester-based polycarboxylic acid resin is mainly an esterified product of a polybasic acid and a polyhydric alcohol, and examples of the polybasic acid include (anhydrous) phthalic acid, isophthalic acid, terephthalic acid, (anhydrous). ) Succinic acid, adipic acid, fumaric acid, (anhydrous) maleic acid, tetrahydro (anhydrous) phthalic acid, hexahydro (anhydrous) phthalic acid, (anhydrous) trimellitic acid, methylcyclohexene tricarboxylic acid, (anhydrous) pyromellitic acid, etc. Examples of the polyhydric alcohol include dihydric or higher polybasic acids. Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, diethylene glycol,
Butanediol, neopentyl glycol, cyclohexanedimethanol, 1,6-hexanediol, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, bis (hydroxyethyl)
Examples thereof include terephthalate, (hydrogenated) bisphenol, polyisocyanate polyol, triethanolamine and the like.

As the curing agent containing a cyclic acid anhydride group,
Maleic anhydride, succinic anhydride, dodecyl succinic anhydride, tetrahydrophthalic anhydride, 3-methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, hymic acid anhydride, hettic anhydride, phthalic anhydride 1,2-carboxylic acid anhydride such as acid, and the above-mentioned carboxyl group-containing ethylenically unsaturated monomer and optionally other ethylenically unsaturated monomer (co) polymer (normally average) And a molecular weight of about 500 to 80,000).

Examples of the carboxylic group-containing cyclic acid anhydride curing agent include compounds such as trimellitic anhydride, the above-mentioned carboxylic group-containing ethylenically unsaturated monomer, carboxylic anhydride group-containing ethylenically unsaturated monomer and, if necessary, other compounds. A copolymer obtained by radically polymerizing an ethylenically unsaturated monomer (usually, an average molecular weight of 500 to 8).
10,000) and the like.

The (C) latent curing catalyst used in the present invention is
It is composed of (a) onium salt and (b) acidic phosphoric acid ester, and both may be a mixture or may be reacted. (A) An onium salt is a compound containing an element having a lone electron pair such as nitrogen, phosphorus, and sulfur, in which a compound in the proton or other cation form is coordinate-bonded to these lone electron pairs. is there.

Specific examples of the above-mentioned (a) onium salt include a quaternary ammonium salt represented by the general formula (I) (R ₁ R ₂ R ₃ R ₄ N) X, and a general formula (II) (R ₁ R ₂ R ₃ R ₄
P) quaternary phosphonium salt represented by the general formula (II
I) A tertiary sulfonium salt represented by (R ₁ R ₂ R ₃ S) X and the like can be mentioned.

In the above general formulas (I) to (III), R
₁ , R ₂ , R ₃ and R ₄ are hydrocarbons and may be the same or different. The hydrocarbon group may be substituted with a halogen or a hydroxyl group. Further, the hydrocarbon group includes a linear or branched alkyl group, a cycloalkyl group, an aryl group (phenyl, tolyl group, etc.), an aralkyl group (benzyl group, etc.) and the like.

X is an acid group or hydroxyl group of an inorganic acid such as hydrochloric acid, sulfuric acid or phosphoric acid, or an organic acid such as acetic acid, citric acid, butyric acid, malonic acid or chlorinated acetic acid.

Typical examples of the (a) onium salt include tetraethylammonium chloride, tetraethylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium bromide, diethyldibutylammonium bromide, dimethyldioleylammonium chloride, dimethylbenzyllaurylammonium chloride, dimethyl. Examples thereof include dicyclohexylammonium bromide, tetraethylphosphonium bromide, tetraethylphosphonium bromide, tetrabutylphosphonium chloride, dimethylbenzyllaurylphosphonium bromide and triethylsulfonium chloride.

(B) The acidic phosphoric acid ester is an organic acidic (sub) phosphoric acid ester obtained by substituting a part of hydrogen atoms of an inorganic phosphorus compound of phosphoric acid, phosphorous acid and a condensate thereof with an alkyl group or an aryl group. is there. The alkyl group may be linear or branched, and examples thereof include methyl, ethyl, n-propyl, iso-propyl and n.
-Butyl, iso-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, 2-
Examples include groups such as ethylhexyl and n-decyl.

Specific examples of the above-mentioned (b) acidic phosphoric acid ester include dimethyl phosphate, diethyl phosphate, dipropyl phosphate, monobutyl phosphate, dibutyl phosphate, mono-2-ethylhexyl phosphate, di-2-ethylhexyl phosphate,
Examples thereof include monophenyl phosphate and mono-2-ethylhexyl phosphite.

The mixing ratio of the (a) onium salt and the (b) acidic phosphoric acid ester is about 2 to 90% by weight, preferably about 25 to 75% by weight of the (a) onium salt in terms of the total amount of both components.
% And (b) the acidic phosphate ester is in the range of about 10-98% by weight, preferably about 25-75% by weight.
When the blending ratio of (a) onium salt is less than about 2% by weight, and (b) the acid phosphate exceeds about 98%, the low temperature curability of the resin composition decreases, while the blending of (a) onium salt. When the amount is more than about 90% by weight and the amount of the acid phosphate (b) is less than about 10% by weight, the storage stability of the resin composition is deteriorated, which is not preferable.

The mixing ratio of the above components (A) to (C) is (B) based on 100 parts by weight of the (A) polyepoxide.
A range of about 10 to 200 parts by weight of the curing agent, preferably about 30 to 100 parts by weight and about 0.5 to 10 parts by weight of the (C) latent curing catalyst, preferably about 2 to 6 parts by weight. If the compounding ratio of the curing agent (B) is out of the above range, the performance such as finish and acid resistance is deteriorated, which is not preferable. Also,
If the compounding ratio of the latent curing catalyst (C) is less than about 0.5 parts by weight, the low temperature curability will be poor, whereas if it exceeds about 10 parts by weight, the effect of improving the low temperature curability will be small, such being undesirable.

The curable resin composition of the present invention can be used in the form of powder or dissolved or dispersed in an organic solvent.

In the present invention, the above (A) to (C)
In addition to the components, if necessary, color pigments, fillers, organic polymers, fine particles, organic solvents, fluidity modifiers, ultraviolet absorbers,
A light stabilizer or the like can be blended.

The curable resin composition of the present invention is a one-pack type which is excellent in low-temperature curability, and can form a coating film excellent in finished appearance and acid resistance, and is therefore useful as an automotive top coating composition. Examples of the automobile top coating include solid color and 2 coat 1 bake, 2 coat 2 bake,
It can be used as a clear for metallic colors such as 3 coat 1 bake and 3 coat 2 bake.

[0030]

INDUSTRIAL APPLICABILITY In the curable resin composition of the present invention, the onium salt and the acidic phosphoric acid ester used as the curing catalyst for the polyepoxide do not function as a catalyst at room temperature, but a so-called catalyst function is newly generated by heating. It is considered to act as a latent curing catalyst. By using the curing catalyst, the curable resin composition of the present invention exhibits an excellent storage stability.

[0031]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 Polyepoxide (methyl methacrylate / n-butyl methacrylate / n-butyl acrylate / styrene / glycidyl methacrylate = 2/46/10/2/40% by weight copolymer, weight average molecular weight of about 10,000, Fifty
(% By weight toluene solution) 130 parts by weight of polycarboxylic acid (I) 70 parts by weight of solution of polycarboxylic acid (I) (Halfester compound of 2 mol of hexahydrophthalic anhydride in 1 mol of neopentyl glycol, 50% by weight methyl isobutyl ketone solution), tetraethylammonium bromide A mixture of 1 part by weight and 2 parts by weight of bis (ethylhexyl) phosphate.

Example 2 100 parts by weight of polyepoxide (the same as in Example 1), polycarboxylic acid (II) (methyl methacrylate / n)
-Butyl methacrylate / n-butyl acrylate / styrene / acrylic acid = 2/50/30/3/15% by weight
Copolymer, weight average molecular weight 10,000, 50% by weight
Xylene solution) 100 parts by weight, tetrabutylammonium bromide 1 part by weight, and bis (ethylhexyl) phosphate 1 part by weight.

Comparative Example 1 The composition of Example 1 containing no tetraethylammonium bromide and bis (ethylhexyl) phosphate.

Comparative Example 2 The composition of Example 1 containing no bis (ethylhexyl) phosphate.

Comparative Example 3 The composition of Example 1 containing no tetraethylammonium bromide.

Examples and Comparative Examples Table 1 shows the performance of each Example and Comparative Example.

Storage stability was tested by the following method. Ford cup No. The sample diluted with 4 to have a viscosity of 30 seconds (20 ° C.) was used as a sample. After storing the sample in a sealed state at 60 ° C. for 16 hours, the viscosity of the sample was measured and evaluated according to the following criteria. ◎
Indicates a viscosity increase of 0 to 5 seconds, and ○ indicates a viscosity increase of 6 to 10 seconds.
Seconds, Δ indicates 11 seconds or more, and x indicates gelation.

The preparation of the test plate and the performance test in Table 1 were conducted under the following conditions.

Preparation of test plate An epoxy resin-based cationic electrodeposition coating was applied (25 μm) to a chemical conversion treated dull steel plate and heat-cured at 170 ° C. for 30 minutes, and then as an intermediate coating, “Rugabake AM” (trade name, A polyester resin / melamine resin-based automotive coating manufactured by Kansai Paint Co., Ltd.) was applied so as to have a dry film thickness of 30 μm, and heat-cured at 140 ° C. for 30 minutes.
Then, the coated surface was water-polished with # 400 sandpaper, drained and dried, and the coated surface was wiped with petroleum benzine as a material.

Next, "Magiclon # 1000 Base Coat (Silver)" (trade name, manufactured by Kansai Paint Co., Ltd.,
Acrylic resin / melamine resin) is spray-coated on the above material so that the dry film thickness is about 15 μm, and after splashing off, the compositions of Examples and Comparative Examples are sprayed so that the dry film thickness is about 40 μm. It was painted and baked at 140 ° C. for 30 minutes.

Performance test Appearance: The surface of the cured product was visually evaluated. O indicates that there is no abnormality on the surface, Δ indicates that blurring is observed due to tingling and the like, and X indicates that the surface is extremely glossy and has low gloss.

Curability: The appearance of the cured product after visually wiping the surface of the cured product with xylene impregnated ten times with a fingertip was visually evaluated. O indicates that the surface has no abnormalities and good curability, Δ indicates that the surface is slightly scratched and the curability is poor, and X indicates that the surface is dissolved in xylene and the curability is significantly poor.

Acid resistance: A 40% by weight aqueous solution of sulfuric acid (0.4 cm ^{3) was} dropped on the surface, heated at 60 ° C. for 15 minutes in a hot air drier, washed with water and visually evaluated. O indicates that there is no abnormality, Δ indicates that spots, whitening or blisters are slightly observed, and X indicates that spots, whitening or blisters are markedly observed.

[0045]

[Table 1]

Claims (2)

[Claims] 1. A latent curing catalyst (C) composed of (A) polyepoxide, (B) carboxyl group and / or cyclic acid anhydride group-containing curing agent, (a) onium salt and (b) acidic phosphoric acid ester. A curable resin composition comprising: as an essential component. 2. The curable resin composition according to claim 1, wherein the curing agent (B) is a polycarboxylic acid.