JP3199818B2 - Microcapsules for epoxy resin curing agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microcapsule for an epoxy resin curing agent and an epoxy resin composition containing the same.

[0002]

2. Description of the Related Art Conventionally, amines have been widely used as curing agents for epoxy resins. These epoxy resins are useful as sealants, adhesives, paints, laminates, molding materials, casting materials, and the like.

[0003] Epoxy resins are cured by mixing and reacting an epoxy compound (hereinafter simply referred to as a prepolymer) with amines. At this time, the prepolymer and the curing agent start reaction easily upon contact with each other. Usually, a two-pack type mixing method is used just before use. The two-pack type is a preferred form in terms of storage stability, but has the inconvenience that it must be mixed before use.

A so-called one-pack type in which a prepolymer and a curing agent are filled in the same container is as follows: (1) As a curing agent, a comparative curing temperature of boron fluoride, an amine complex, dicyandiamide, an epoxy resin amine adduct, etc. (2) a method of adsorbing an amine-based curing agent on a molecular sieve or the like; (3) a method of sealing an active group with a blocking agent or the like; (4) a method of microencapsulating a prepolymer;
(5) Various methods such as a method of microencapsulating an amine-based curing agent have been proposed.

The methods (1) and (3) have good storage stability but require a high temperature for curing; the method (2) requires the use of a special release agent, and is not affected by moisture. The method (4) requires only a large amount of the capsule-forming agent, so that only a part of the method, such as a method using a diluent and a binder, is practically used; Has not been put to practical use due to insufficient stability of the capsule.

[0006]

SUMMARY OF THE INVENTION The present invention proposes a method for supplying stable microcapsules of amines, which has heretofore been difficult to form stable microcapsules, and a method thereof. In particular, an important object of the present invention is a one-pack type sealing, molding, casting, laminating, bonding or coating composition using an epoxy resin which is excellent in storage stability and can be cured at a low temperature. Another object of the present invention is to obtain a microcapsule of an amine-based curing agent for an epoxy resin, which is useful as a raw material.

[0007]

SUMMARY OF THE INVENTION The present invention provides a coating layer comprising a solid core substance containing amines as a main component and a polymer of a radical polymerizable monomer containing an organic acid having a polymerizable double bond. And a microcapsule for an epoxy resin curing agent.

Further, the present invention provides a method for dispersing a solid core material containing an amine as a main component in an organic solvent which does not dissolve the core material, and forming a radical containing an organic acid having a polymerizable double bond in the dispersion. The present invention relates to a microcapsule for an epoxy resin curing agent, characterized in that a polymerizable monomer monomer is radically polymerized to form a coating layer of a polymer on the surface of a core substance.

The core material used in the present invention is solid and contains amines as an essential component. Normally, solid amines may be used as they are as the core substance, but in addition to amines, a third component inert to amines or radical polymerizable monomers, for example, an adsorbent for amine, carrier, diluent, etc. May be included.

The amines used as the core substance in the present invention are preferably solid amines at the microencapsulation temperature. That is, in order to produce the core substance by the method of the present invention, it is necessary to disperse the core substance in the medium as solid fine particles. Therefore, the core material preferably has a melting point of 35 ° C. or higher. When the core substance is only amines, the amines themselves are solid and have a melting point of preferably 3
5 ° C. or higher. When, for example, zeolite or bentonite is used as a carrier, and amines are adsorbed thereon and used as a core substance, the amines themselves need not be solid. Typically, the core material is a 100% solid amine, which is preferred.

When the core material is dispersed in a liquid state during the production of microcapsules, the dispersed particles adhere, coalesce or agglomerate, making encapsulation incomplete or impossible.

Specific examples of amines include amines such as hexamethylenediamine, octamethylenediamine, decamethylenediamine, 3,9-bis (3-aminopropyl) 2,4,8,10-tetraspiro [5] .5] aliphatic amine compounds such as undecane and bis (4-aminocyclohexyl) methane; aromatic amine compounds such as metaphenylenediamine, diaminodiphenylmethane and diaminodiphenylsulfone; 2-methylimidazole;
-Ethyl-4-methylimidazole, 2-undecylimidazole, 2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2
-Phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 1-cyanoethyl-
2-undecyl imidazolium trimellitate, 2-
Methylimidazolium isocyanurate, 2-phenylimidazolium isocyanurate, 2,4-diamino-6- [2-methylimidazolyl- (1)] ethyl S-triazine, 2,4-diamino-6- [2- Undecyl imidazolyl- (1)] ethyl S-triazine, imidazole compounds such as 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 3-phenyl-1,1 -Dimethylurea, 3- (3,4-dichlorophenyl) -1,1-
Urea compounds such as dichlorourea, succinic hydrazide,
Hydrazide compounds such as adipic hydrazide and isophthalic hydrazide; dicyandiamide compounds such as dicyandiamide, o-tolylbiguanide and 2,5-dimethylbiguanide; diamino compounds such as diaminomaleonitrile, N-benzyldiaminomaleonitrile and N-isobutyldiaminomaleonitrile There are melamine compounds such as maleonitrile compounds, melamine and diallyl melamine, and curing agents for epoxy compounds such as amine compounds / epoxy compounds / adducts such as 2-methylimidazole / bisphenol A / adducts. The amines may be a mixture of two or more.

In the present invention, the polymer monomer forming the microcapsule coating layer is a radical polymerizable monomer, at least a part of which contains an organic acid having a polymerizable double bond.

The organic acid having a polymerizable double bond includes:
(Meth) acrylic acid, itaconic acid, maleic acid (may be anhydrous), crotonic acid, ethyl acrylic acid, allyl phthalate, allyl malate, allyl fumarate, mono (2
-Acryloyloxyethyl) maleate, polymerizable double bond-containing fatty acid such as mono (2-acryloyloxyethyl) phthalate, mono (2-acryloyloxyethyl)
Acid phosphate, mono (2-methacryloyloxyethyl) acid phosphate and other polymerizable double bond-containing phosphoric acid and vinyl sulfonic acid, styrene sulfonic acid, allyl sulfonic acid, sulfoethyl methacrylate, 2-acrylamido-2-methylpropane Examples thereof include polymerizable double bond-containing sulfonic acids such as sulfonic acid. Two or more of these may be included.

Other radically polymerizable monomers include:
Methyl acrylate, ethyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, glycerol monoacrylate, glycidyl methacrylate, phenoxy, polyoxyethylene methacrylate, methyl methacrylate, ethyl methacrylate,
Hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycerol monomethacrylate, glycidyl methacrylate, phenoxy / polyoxyethylene methacrylate and other (meth) acrylate monomers, vinyl acetate, styrene, vinyl toluene, methyl styrene, vinyl pyrrolidone, vinyl pyridine , Vinyl monomers such as vinyl ethyl ether, vinyl chloride,
Examples include halogen-based monomers such as vinylidene chloride, and nitrile-based monomers such as acrylonitrile, methacrylonitrile, and crotononitrile. These monomers are
They may be used alone or in combination of several types.

The capsule wall can be modified by adding a crosslinkable monomer such as divinylbenzene, ethylene diacrylate, polyethylene diacrylate, ethylene dimethacrylate, or polyethylene dimethacrylate. Among the radical polymerizable monomers used in the present invention, the polymerizable double bond-containing organic acid is preferably used in an amount of preferably 1 to 100% of the total amount of the monomer.
-100% by weight, more preferably 3-95% by weight, more preferably 5-75% by weight. However, 50 equivalent% or less of the amines used is preferable.

Other monomers are preferably used in an amount of preferably 5 to 99% by weight based on the total amount of the monomers. The total amount of the crosslinkable monomer is preferably 0.01 to 20% by weight, more preferably 0.1 to 5% by weight. In the present invention, by using an organic acid having a polymerizable double bond as a part of the radical polymerizable monomer, the organic acid is bonded to the surface of the solid amine fine particles, and the polymer film is used as a nucleus to form an amine particles. Formed on the surface.

The amount of the radical polymerizable monomer to be used is about 0.1 per 100 parts by weight of the amines to be microencapsulated.
It is preferably 1 to 60 parts by weight, more preferably 1 to 40 parts by weight. The ratio between the core and the wall material is 100/1 to 100/2 by weight.
It is preferably in the range of 00. The average particle size of the core material is not particularly limited, but if the average particle size is too large, the curability may be reduced or the mechanical properties of the cured product may be impaired. The average particle size is 100 μm or less, preferably 10 μm or less.

Examples of the solvent include solvents that do not dissolve amines, for example, hydrocarbon solvents such as aliphatic hydrocarbons such as hexane, heptane, isooctane, cyclohexane, and liquid paraffin; and aromatic hydrocarbons such as benzene, toluene, and xylene. Examples thereof include alcohol compounds such as methanol, ethanol and isopropyl alcohol, ether compounds such as diethyl ether, dioxane, and tetrahydrofuran; ester compounds such as methyl acetate, ethyl acetate and ethyl butyrate; ketone compounds such as acetone and methyl ethyl ketone; and silicon oil. . Two or more kinds of mixed solvents may be used.

The radical polymerization catalyst includes methyl ethyl ketone peroxide, cyclohexanone peroxide, 2,2-bis (t-butylperoxy) valate, di-
Organic peroxides such as t-butyl peroxide, dicumyl peroxide, octanoyl peroxide, benzoyl peroxide or 2,2-azobis (2,4-dimethylvaleronitrile), 2,2-azobis (2-methyl Butyronitrile), 1,1-azobis (cyclohexyl-1-
(Carbonitrile), VA-061 (Wako Pure Chemical Industries), VA
Azo compounds such as -080, VA-110 and V-601. The amount of the catalyst used is preferably 0.1 to 5 parts by weight based on 100 parts by weight of the monomer.

If necessary, the core material and the resulting microcapsules may be dispersed and stabilized by using a surfactant or a dispersant. Thereby, the particle size can be made uniform. Examples of the surfactant include anionic surfactants such as sodium alkyl sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, sodium alkyl phosphate, sodium dialkyl sulfosuccinate, sorbitan fatty acid esters, and glycerin fatty acid esters. Nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, alkyltrimethylammonium chlorides,
There are cationic surfactants such as base dialkyldimethylammonium and alkyldimethylbenzylammonium chloride. Examples of the dispersant include ethyl cellulose, polyvinylpyrrolidone, and maleic acid copolymer.

The amount of the surfactant used is 5% by weight or less, more preferably 1% by weight or less of the total amount of the core substance. If the amount of the surfactant is too large, a large amount of polymer-only fine particles containing no core substance are formed.

To produce the microcapsules of the present invention,
Either the solid amines or the solid core material to which the amines are adsorbed or mixed and other additives are atomized and dispersed in a medium in which the amines are not dissolved, or the core material is finely dispersed in the medium. The organic solvent used for the medium is preferably used in an amount of 1 to 20 times by volume, particularly 2 to 10 times by volume of the core substance. Although a mixed solvent may be used, it is essential that it has a boiling point higher than the radical polymerization temperature and does not dissolve amines used for the core substance. The term "insoluble in amines" means that the solubility of amines is 5% by weight or less, more preferably 2% by weight or less at a radical polymerization temperature.

The dispersion of the core substance may be performed by the action of stirring or ultrasonic waves. Stirring is performed with the dispersion particles of about 0.1 to 100.
The range may be set to a range in which the particles are stably dispersed at a particle size of μm, more preferably 0.1 to 10 μm.

Polymerization is carried out in the presence of a radical polymerization catalyst in a dispersion of amines while adding a radically polymerizable monomer. The catalyst is usually added to the dispersion. The polymerization temperature is generally 2
0 to 100 ° C, more preferably 30 to 80 ° C,
It is not limited to this. The radical polymerizable monomer may be mixed in advance in a predetermined monomer ratio and then gradually added to the dispersion, or a polymerizable double bond-containing organic acid may be separately added to the system. The addition of the polymerizable organic acid may be in any of the initial, middle and late stages. The polymerization is usually completed in about 2 to 10 hours.

The solvent is removed by filtration, centrifugation or the like, and if necessary, the solvent is completely distilled off under reduced pressure. The temperature at that time may be higher than the melting point of the amines.

A typical use of the microcapsules of the present invention is as a curing agent for epoxy resins. In this case, the microcapsules of the present invention may be blended into an epoxy compound to form a one-part adhesive.

Examples of the epoxy compound include glycidyl ether of bisphenol A, glycidyl ether of bisphenol F, glycidyl ether of glycerin, glycidyl ether of polyalkylene oxide, glycidyl ether of phenol novolak, glycidyl ether of orthocresol novolak, and glycidyl ether of brominated bisphenol A. Glycidyl ether epoxy resins such as glycidyl ether, cycloaliphatic epoxy resins such as alicyclic diepoxy acetal, alicyclic diepoxy adipate, and alicyclic diepoxycarboxylate, diglycidylyl phthalate, tetrahydrophthalic acid Glycidyl esters such as diglycidylyl ester, hexahydrodiglycidylyl ester and glycidyl diester dimer Glycidylamine resins such as N, N-diglycidylaniline, tetraglycidylaminodiphenylmethane, triglycidyl-p-aminophenol, heterocyclic epoxy resins, hydantoin type epoxy resins, and triglycidyl isocyanurate. You.

When the microcapsules of the present invention are mixed with an epoxy compound, other additives may be added according to the purpose of use. For example, toluene, solvents such as xylene, butyral resin, acrylic resin, nylon resin,
There are polymer compounds such as polyester resin, and inorganic compounds such as alumina, fine powder silica, titanium oxide, glass balloon, and glass fiber.

Hereinafter, the present invention will be described with reference to examples. Example 1 Microencapsulation Cureazole 2PZ- previously finely pulverized to an average particle size of 5 μm.
CN (1-cyanoethyl-2-phenylimidazole;
90 parts by weight of Shikoku Fine Chemical Co., Ltd.) were 2 parts by weight of methacrylic acid, 8 parts by weight of acrylonitrile and V-70.
Dispersed in 400 parts by weight of toluene / n-hexane (1/1) containing 0.1 part of (2,2-azobis (4-methoxy-2,4-dimethylvanitrile); manufactured by Wako Pure Chemical Industries, Ltd.) I let it. This dispersion was reacted at 50 ° C. for 3 hours under a nitrogen atmosphere. After the reaction, the dispersion was filtered and dried to obtain 98 parts by weight of a capsule containing methacrylic acid / acrylonitrile resin-coated curesol 2PZ-CN.

Storage stability 5 parts by weight of the microcapsules, 4 parts by weight of Aerogel 300 (titanium oxide; manufactured by Nippon Aerogel Co., Ltd.) and 100 parts by weight of Epicoat 828 (bisphenol A epoxy resin; manufactured by Yuka Shell Epoxy Co., Ltd.) Was mixed to form a one-pack type. This composition showed storage stability at 40 ° C. for 30 days or more. The bending strength of the molded product cured at 150 ° C. for 1 hour was 11.0 kg / mm ² .

Example 2 Microencapsulation Cureazole 2PHZ previously finely pulverized to an average particle size of 5 μm.
90 parts by weight of 2-phenyl-4,5-dihydroxymethylimidazole (manufactured by Shikoku Fine Chemical Co., Ltd.) are 2 parts by weight of methacrylic acid, 2 parts by weight of methyl methacrylate, 4 parts by weight of acrylonitrile and V-70 (2,2- Azobis
(4-methoxy-2,4-dimethylvanitrile); dispersed in 400 parts by weight of isopropyl alcohol containing 0.1 part by Wako Pure Chemical Industries, Ltd. This dispersion was reacted at 50 ° C. for 3 hours under a nitrogen atmosphere. After the reaction, the dispersion was filtered and dried to obtain 99 parts by weight of a capsule containing 2PHZ of Curazole.

Storage stability 5 parts by weight of the microcapsules, 4 parts by weight of Aerogel 300 (titanium oxide; manufactured by Nippon Aerogel Co., Ltd.) and 100 parts by weight of Epicoat 828 (bisphenol A type epoxy resin; manufactured by Yuka Shell Epoxy Co., Ltd.) The parts were mixed to form a one-pack type. This composition showed storage stability at 40 ° C. for 30 days or more. The bending strength of the molded product cured at 150 ° C. for 1 hour was 10.0 kg / mm ² .

[0034] Example 3 Microencapsulation monomer of mono (2-acryloyloxyethyl) acid phosphate 4 parts by weight of glycidyl methacrylate 3
The encapsulation was carried out in the same manner as in Example 2 except that the parts by weight were changed to 3 parts by weight of styrene.
99 parts by weight of a PHZ-encapsulated capsule were obtained.

Storage stability 5 parts by weight of the microcapsules, 4 parts by weight of Aerogel 300 (titanium oxide; manufactured by Nippon Aerogel Co., Ltd.) and 100 parts by weight of Epicoat 828 (bisphenol A epoxy resin; manufactured by Yuka Shell Epoxy Co., Ltd.) The parts were mixed to form a one-pack type. This composition showed storage stability at 40 ° C. for 30 days or more.

[0036] Example 4 Microencapsulation monomer and 2 parts by weight of 2-acrylamido-2-methylpropanesulfonic acid, acrylonitrile, 7 parts by weight, except for changing the 1 part by weight of styrene, encapsulated in the same manner as in Example 2 Was carried out to obtain 97 parts by weight of a capsule containing Curezole 2PHZ.

Storage stability 5 parts by weight of the microcapsules, 4 parts by weight of Aerogel 300 (titanium oxide; manufactured by Nippon Aerogel Co., Ltd.) and 100 parts by weight of Epikote 828 (bisphenol A epoxy resin; manufactured by Yuka Shell Epoxy Co., Ltd.) The parts were mixed to form a one-pack type. This composition showed storage stability at 40 ° C. for 30 days or more.

Example 5 Microencapsulation Encapsulation was performed in the same manner as in Example 1 except that the amine compound was changed to diaminodiphenylmethane.
99 parts by weight of diaminodiphenylmethane-containing capsules were obtained.

Storage stability 5 parts by weight of the microcapsules, 4 parts by weight of Aerogel 300 (titanium oxide; manufactured by Nippon Aerogel Co., Ltd.) and 100 parts by weight of Epikote 828 (bisphenol A type epoxy resin; manufactured by Yuka Shell Epoxy Co., Ltd.) The parts were mixed to form a one-pack type. This composition showed storage stability at 40 ° C. for 30 days or more.

Example 6 Encapsulation was carried out in the same manner as in Example 1 except that the amine compound was changed to 2,5-dimethylbiguanide. As a result, 97 parts by weight of capsules containing 2,5-dimethylbiguanide were obtained. Was.

Storage stability 5 parts by weight of the microcapsules, 4 parts by weight of Aerogel 300 (titanium oxide; manufactured by Nippon Aerogel Co., Ltd.) and 100 parts by weight of Epicoat 828 (bisphenol A epoxy resin; manufactured by Yuka Shell Epoxy Co., Ltd.) The parts were mixed to form a one-pack type. This composition showed storage stability at 40 ° C. for 30 days or more.

Comparative Example Storage stability : 4 parts by weight of 2-PZ-CN, 4 parts by weight of Aerogel 300 (titanium oxide; manufactured by Nippon Aerogel Co., Ltd.) and Epicoat 828 (bisphenol A type epoxy resin; manufactured by Yuka Shell Epoxy Co., Ltd.) ) 100 parts by weight were mixed to form a one-pack type. This composition was completely cured in 3 days at 40 ° C.

[0043]

The microcapsules of the present invention can be stably stored for a long period of time. Therefore, it can be blended with an epoxy compound and used as a curing agent for one-pack adhesives, sealants, molding agents, casting agents, laminating agents, paints, etc., which have excellent storage stability.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-208386 (JP, A) JP-A-2-292325 (JP, A) JP-A-5-93178 (JP, A) JP-A-3-302 182520 (JP, A) JP-A-1-287131 (JP, A) JP-A-50-27900 (JP, A) JP-A-62-161747 (JP, A) JP-A-62-103047 (JP, A) JP-B-46-17580 (JP, B1) JP-B-49-25000 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 59/50 C08G 59/40 B01J 13/02 -13/22

Claims (3)

(57) [Claims] 1. An epoxy resin hardened layer comprising a solid core material mainly composed of amines and a polymer of a radical polymerizable monomer containing an organic acid having a polymerizable double bond as a coating layer.
Microcapsules for agent . 2. A solid core material containing an amine as a main component is dispersed in an organic solvent which does not dissolve the core material, and a radical polymerizable monomer containing an organic acid having a polymerizable double bond is dispersed in the dispersion. A microcapsule for an epoxy resin curing agent , wherein a monomer is subjected to radical polymerization to form a coating layer of a polymer on the surface of a core material. 3. An epoxy resin composition comprising the microcapsule according to claim 1 and an epoxy compound.