JPH08337633A - Microcapsule type curing agent or curing accelerator, epoxy resin composition containing the same, curing method and cured epoxy resin - Google Patents

Abstract

(57) [Abstract] [Purpose] A microcapsule type curing agent or curing accelerator excellent in storage stability and mechanical strength, which can be used for a one-pack type epoxy resin composition, an epoxy resin composition, and a curing method and Provide a cured product. [Structure] A microcapsule in which a cured product and a curing accelerator are included in a wall film containing a polyurea-based polymer as a main component. By mixing this with an epoxy resin, a one-pack type epoxy resin composition is obtained. To do. When this composition is heated to a predetermined temperature or higher, the wall film is rapidly dissolved and the inclusion is released.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a microcapsule type curing agent or curing accelerator which is excellent in storage stability and mechanical strength, and is excellent in the release property of inclusions upon heat activation, and an epoxy resin composition containing the same. , And a curing method and an epoxy resin cured product.

[0002]

BACKGROUND OF THE INVENTION Epoxy resins are used in a wide variety of applications such as adhesives, paints, coating agents, encapsulants and laminates. Further, these epoxy resins usually contain various curing agents and curing accelerators.

The widely used epoxy resin composition includes
There is a so-called two-pack type composition in which a curing agent or a curing accelerator such as an amine, a Lewis acid, or an acid anhydride is mixed with an epoxy resin immediately before it is used. In such a two-component type, the epoxy resin and the curing agent are separately stored and used by mixing them as needed, but since the pot life after mixing is relatively short, a large amount should be mixed. Can not be kept, and therefore
When it is used in a large amount, it is necessary to mix it in small amounts many times, resulting in extremely poor work efficiency.

On the other hand, as a means for solving such a problem, a latent curing agent is used, which does not cause a curing reaction even if preliminarily compounded in an epoxy resin and causes a curing reaction by light irradiation or heating. Various one-pack types have been proposed. However, even if these latent curing agents are used, those having excellent storage stability when blended with an epoxy resin are
It is necessary to carry out the curing reaction under relatively high temperature conditions, and those that cure under low temperature conditions have the problem of poor storage stability, and those that have a good balance of both storage stability and curability The reality is that it has not been developed yet.

In recent years, a method has been proposed in which one of the constituent components of the epoxy resin composition is microencapsulated and stored as one liquid. Specifically, Japanese Patent Publication No. 54-314
No. 68, JP-A-1-242616, and JP-A-2
-292325, JP-A-3-182520, JP-A-5-123565, and JP-A-6-731.
Japanese Patent Laid-Open No. 63-128545 and Japanese Patent Laid-Open No. 6-128545 disclose a technique in which a microcapsule containing a curing agent or a curing accelerator is mixed with an epoxy resin. As the wall film material of the microcapsule disclosed in these publications, various polymers such as epoxy resin cured product, polystyrene, polymethacrylic acid methyl ester, ethylene-vinyl acetate copolymer, polyvinyltoluene and acrylic rubber, and vinylidene chloride. And a polymer obtained by using an ethylene-based monomer such as acrylonitrile or methacrylic acid as a main component monomer.

[0006]

The one-pack type epoxy resin composition using the microcapsules as described above is
It is necessary to satisfy well-balanced storage stability during storage, curability during heating, and excellent physical properties of the cured product, and these properties are greatly influenced by the material constituting the wall film of the microcapsule. For example, when a cross-linked resin such as the above-mentioned epoxy resin cured product is adopted for the wall film, the storage stability during storage is improved, but the curing agent or the like included during heating is less likely to be diffused and released outside the wall film, As a result, the curability may be poor.

Further, various polymers such as polystyrene, polymethacrylic acid methyl ester, ethylene-vinyl acetate copolymer, polyvinyltoluene and acrylic rubber, and ethylene-based monomers such as vinylidene chloride, acrylonitrile and methacrylic acid are main components. When a plastic polymer such as a polymer obtained as a monomer is used for the wall film, the curability upon heating is good, but the storage stability during storage remains a problem. In order to improve this point, when the polyfunctional monomer is copolymerized during the preparation of the wall film material to improve the storage stability by slightly cross-linking the wall film, the curability at the time of heating and use is reduced, It was difficult to get a well-balanced one.

Furthermore, in the one-pack type epoxy resin composition using the conventional microcapsules, the epoxy resin is cured by heating, and then the material forming the wall film is dispersed in the cured product to make a foreign substance ( Since it is contained as an impurity), various physical properties such as heat resistance and water resistance of the obtained cured product may be adversely affected. Therefore, in reality, no one has yet been obtained that satisfies the properties of one-liquid storability at room temperature, curability upon heating and excellent physical properties of the cured product in a well-balanced manner.

[0009]

The inventors of the present invention have conducted extensive studies to solve the problems of the above-mentioned conventional epoxy resin compositions. As a result, a polymer having a specific structural unit was used as a wall film material. It has been found that a one-component type epoxy resin composition that is relatively well-balanced as compared with the conventional product can be obtained by using the main component of (1), and the present invention has been completed.

That is, the present invention is a microcapsule type curing in which a curing agent or a curing accelerator is included in a wall film containing a polymer having a structural unit represented by the following general formula [Chemical Formula 2] as a main component. To provide an agent or a curing accelerator.

[0011]

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In a particularly preferred embodiment, the above curing agent and curing accelerator are curing agents and curing accelerators for epoxy resins.

The present invention also provides an epoxy resin composition containing the above-mentioned microcapsule type curing agent and an epoxy resin. Further, the above-mentioned microcapsule type curing accelerator, a curing agent for an epoxy resin, and an epoxy resin. An epoxy resin composition containing a resin is provided.

Further, according to the present invention, the above-mentioned epoxy resin composition is heated to a predetermined temperature or higher to release the curing agent or curing accelerator contained therein to the outside of the wall film, a method for curing an epoxy resin composition, An epoxy resin cured product obtained by the curing method is provided.

The wall film in the microcapsule type curing agent or curing accelerator of the present invention is mainly composed of a polymer having a structural unit represented by the above [Chemical formula 2].
It is a polymer called polyurea. The polymer having such a structural unit can be practically obtained by a polyaddition reaction between a polyvalent isocyanate and a polyvalent amine or a reaction between a polyvalent isocyanate and water.

The polyisocyanates may be compounds having two or more isocyanate groups in the molecule, specifically, m-phenylene diisocyanate and p-.
Phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, naphthalene-1,4-diisocyanate, diphenylmethane-4,4'-diisocyanate, 3,3'-dimethoxy-4,4'-biphenyl diisocyanate , 3,3'-
Dimethyldiphenylmethane-4,4'-diisocyanate, xylylene-1,4-diisocyanate, 4,4 '
-Diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate,
Propylene-1,2-diisocyanate, butylene-
1,2-diisocyanate, cyclohexylene-1,2
-Diisocyanates, diisocyanates such as cyclohexylene-1,4-diisocyanate, triisocyanates such as p-phenylene diisothiocyanate, xylylene-1,4-diisothiocyanate and ethylidyne diisothiocyanate, 4,4'-dimethyl Tetraisocyanates such as diphenylmethane-2,2 ′, 5,5′-tetraisocyanate, an adduct of hexamethylene diisocyanate and hexanetriol, 2,4-
Addition product of tolylene diisocyanate and prenzcatechol, addition product of tolylene diisocyanate and hexanetriol, addition product of tolylene diisocyanate and trimethylol propane, addition product of xylylene diisocyanate and trimethylol propane, hexamethylene diisocyanate and tri Isocyanate prepolymers such as trimers of aliphatic polyisocyanates such as methylol propane adducts, triphenyl dimethylene triisocyanate, tetraphenyl trimethylene tetraisocyanate, pentaphenyl tetramethylene pentaisocyanate, lysine isocyanate, hexamethylene diisocyanate And the like, and these can be used alone or in combination of two or more.

Among the above-mentioned polyisocyanates, from the viewpoint of film-forming property and mechanical strength when preparing microcapsules, tolylene diisocyanate and trimethylol propane adduct, xylylene diisocyanate and trimethylol propane adduct, It is preferable to use an isocyanate prepolymer represented by polymethylene polyphenyl isocyanate such as triphenyl dimethylene triisocyanate.

On the other hand, the polyvalent amines to be reacted with the above polyisocyanates may be compounds having two or more amino groups in the molecule, specifically, diethylenetriamine, triethylenetetramine, tetraethylenepenta. Min, 1,6-hexamethylenediamine, 1,8
-Octamethylenediamine, 1,12-dodecamethylenediamine, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, o-xylylenediamine, m-xylylenediamine, p-xylylenediamine, menthanediamine, bis (4-amino-3-methylcyclohexyl) methane, isophoronediamine, 1,
Examples thereof include 3-diaminocyclohexane and spiroacetal-based diamines, which can be used alone or in combination of two or more.

In the reaction between the polyvalent isocyanate and water, first, an amine is formed by hydrolysis of the polyvalent isocyanate, and the amine reacts with an unreacted isocyanate group (so-called self-polyaddition reaction). By doing so, a polyurea-based polymer having the structural unit is formed.

Further, in the present invention, as the curing agent or curing accelerator to be encapsulated in the microcapsules composed of the above wall film, any curing agent or curing accelerator capable of curing the polymer or having an action of promoting the curing reaction can be used. There is no particular limitation, and those used for applications such as adhesives, paints, coating agents, and encapsulating materials can be used. The microcapsule type curing agent or curing accelerator of the present invention can suitably exhibit its effect in a one-pack type epoxy resin composition.
In this case, from the viewpoint of workability when preparing the microcapsules and the characteristics of the obtained microcapsules, a curing agent or curing accelerator that is liquid at room temperature is preferable. In addition, in the present invention, the liquid at room temperature means that the property of the curing agent or the curing accelerator itself is liquid at room temperature, and even if it is solid at room temperature, it is dissolved or dispersed in any organic solvent to be liquid. It includes those that have been done.

Examples of such curing agents include acid anhydrides such as methylhymic acid anhydride, phthalic anhydride, benzophenonetetracarboxylic acid anhydride, phenols such as bisphenol A and phenol resin, tributylamine, and the like. Aliphatic tertiary amines, benzyldimethylamine, 2- (dimethylamino) phenol, 2,4
Aromatic tertiary amines such as 6-tris (diaminomethyl) phenol and alicyclic tertiary amines, or modified amines thereof, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole , 2-
Imidazoles such as isopropylimidazole, 2-dodecylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, and these imidazoles Lewis acid such as imidazole carboxylic acid salt of boron and acetic acid, lactic acid, salicylic acid, benzoic acid, adipic acid, phthalic acid, citric acid, tartaric acid, maleic acid, trimellitic acid, boron trifluoride, phosphorus pentafluoride, etc. Can be used. Of these, from the viewpoint of curing reactivity during heating, it is preferable to use a catalyst type curing agent such as a tertiary amine or imidazole. Further, in the present invention, an arbitrary amount of a known curing accelerator that is usually used may be blended so that the curing reaction sufficiently occurs even if a small amount of these curing agents is blended.

On the other hand, specific examples of the curing accelerator that can be used in the present invention include alkyl-substituted guanidines such as ethylguanidine, trimethylguanidine, phenylguanidine and diphenylguanidine;
(3,4-dichlorophenyl) -1,1-dimethylurea, 3-phenyl-1,1-dimethylurea, 3- (4-
3-substituted phenyl-1,1-dimethylureas such as chlorophenyl) -1,1-dimethylurea, 2-methylimidazoline, 2-phenylimidazoline, 2-undecylimidazoline, 2-imidazole such as 2-heptadecylimidazoline, Monoaminopyridines such as 2-aminopyridine, N, N-dimethyl-N- (2-hydroxy-
3-aryloxypropyl) amine-N'-lactoimide and other amine imides, ethylphosphine, propylphosphine, butylphosphine, phenylphosphine,
Phosphorus compounds such as trimethylphosphine, triethylphosphine, tributylphosphine, trioctylphosphine, triphenylphosphine, tricyclohexylphosphine, triphenylphosphine / trichiphenylborane complex, tetraphenylphosphonium tetraphenylborate, 1,8-diazabicyclo [5,5] 4,0] Undecene, 7,1,4-diazabicyclo [2,2,2]
A DBU compound such as octane can be used. The compounds exemplified as the curing agent can also be used as the curing accelerator.

The organic solvent that can be included in the wall film of the microcapsule is not particularly limited as long as it is liquid at room temperature, but it is necessary to select at least one that does not dissolve the wall film. Specifically, in addition to organic solvents such as ethyl acetate, methyl ethyl ketone, acetone, methylene chloride, xylene, toluene and tetrahydrofuran, oils such as phenylxylylethane and dialkylnaphthalene can be used.

The above-mentioned microcapsule type curing agent and curing accelerator of the present invention can be prepared by a conventionally known method. In particular, when a wall film is formed by interfacial polymerization, microcapsules are formed. It is preferable from the viewpoint of homogenizing the wall film and adjusting the wall film thickness. Specifically, the above-mentioned curing agent or curing accelerator that is liquid at room temperature is used as a core substance, and polyvalent isocyanates are dissolved therein. Since the solution thus obtained is oily, it is dispersed in the water phase as an oil phase in the form of oil droplets to prepare an O / W type (oil phase / water phase type) emulsion. At this time, the particle size of each oil drop is 0.05 to 50.
From the viewpoint of the stability of the emulsion during polymerization, it is preferably 0 μm, preferably 0.05 to 50 μm.
When a solid curing agent or curing accelerator is dissolved in the organic solvent to form a core substance, an S / O / W type (solid phase / oil phase / water phase) type emulsion is obtained. Further, in the above emulsion type, the curing agent and the curing accelerator are lipophilic, but when it is hydrophilic, it is difficult to obtain the above emulsion type, but in this case, the solubility is adjusted so that the O / O type or Interfacial polymerization may be performed as an S / O / O type emulsion type.

Next, a polyvalent amine is added to and dissolved in the water phase of this emulsion to cause interfacial polymerization with the polyvalent isocyanate in the oil phase to carry out a polyaddition reaction,
A wall film of a microcapsule made of a polyurea-based polymer having the structural unit represented by the above [Chemical Formula 2] is formed. As another method, by heating the emulsion, the polyisocyanate in the oil phase reacts with water at the interface with the water phase to produce an amine, and subsequently the self-polyaddition reaction is caused to cause The wall film of the microcapsule made of a polyurea-based polymer having the structural unit shown in 2] is formed. In addition, in the present invention, these two reactions may be simultaneously advanced to form a wall film.

In the above wall film forming step, when the core substance is liquid, free diffusion of polyvalent amine and water from the aqueous phase to the oil phase, and free polyvalent isocyanate from the oil phase to the aqueous phase. Since diffusion occurs smoothly, a dense and highly isolated wall film is formed.However, if a solid core material is used as it is, free diffusion does not occur smoothly, so a dense wall film is obtained. It is difficult to obtain the film and the film thickness is not uniform.

The thus-obtained microcapsules have a wall film made of a polyurea-based polymer and a curing agent or curing accelerator as a core substance enclosed therein. For example, it can be isolated by means of drying after drying by centrifugation or spray drying.
At this time, if necessary, the organic solvent in the microcapsules can be removed together with a means such as drying under reduced pressure.

In the microcapsule type curing agent or curing accelerator of the present invention obtained as described above, the amount of the curing agent or curing accelerator contained in the wall film is preferably 10 to 95% by weight of the total weight. Is in the range of 30 to 80% by weight. If the amount of inclusion is less than 10% by weight, the curing reaction takes too long and the reactivity becomes poor, and the amount of inclusion is 95% by weight.
If it exceeds, the wall film may be too thin, resulting in poor isolation of the core substance and mechanical strength.

The particle size of the above-mentioned microcapsule type curing agent or curing accelerator of the present invention is not particularly limited, but is usually 0.05 in view of uniform dispersibility in an epoxy resin or the like. ~ 500 μm, preferably 0.1-30 μm
It is about m.

The first epoxy resin composition of the present invention contains the above-mentioned microcapsule type curing agent in an amount of 1 to 80 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the epoxy resin. Blend with. The second aspect of the present invention
The epoxy resin composition is added in an amount of 0.1 to 30 parts by weight, preferably 1 to 20 parts by weight, based on 100 parts by weight of the heat-curable curing agent to which the microcapsule-type curing accelerator is added separately.

The epoxy resin used to obtain such an epoxy resin composition may be liquid or solid, and usually has an epoxy equivalent of about 100 to 3500 and has an average of 1 molecule per molecule. Those having two or more epoxy groups can be preferably used. Specifically, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, cycloaliphatic epoxy resin, hydantoin epoxy resin, hydroquinone type epoxy resin, resorcinol type epoxy resin, phenol novolac type epoxy resin, cresol novolac. -Type epoxy resin, naphthalene-type epoxy resin, glycidyl ether-type epoxy resin such as triglycidyl ether triphenylmethane, glycidyl ester-type epoxy resin such as hexahydrophthalic acid glycidyl ester, glycidylamine-type epoxy resin such as tetraglycidylaminodiphenylmethane, 4 , 4'-bis (glycidyloxy) -3,3'-diallylbiphenyl and other biphenyl type epoxy resins, aldehi other than formalin Phenol resins obtained by condensation reaction using an epoxy resin can be mentioned based, it can be used in combination singly or two or more kinds. Of these, bisphenol A is used from the viewpoint of prompt destruction during heating of the wall material forming the microcapsules.
Type, cresol novolac type, and biphenyl type epoxy resins are preferably used.

As the heat-curable curing agent to be mixed with the epoxy resin together with the microcapsule type curing accelerator of the present invention, a curing agent generally used for heat curing as a curing agent for epoxy resin can be used. Dicyandiamide type, imidazole type, phenol type, acid anhydride type, acid hydrazide type, fluorinated boron compound type,
Examples thereof include amine imide-based and amine-based epoxy resin curing agents, and these can be used alone or in combination of two or more kinds. These heat-curable curing agents are added and mixed in an amount of 1 to 200 parts by weight, preferably 5 to 100 parts by weight, based on 100 parts by weight of the epoxy resin.

Further, as a filler which can be contained in the epoxy resin composition of the present invention as required, silica, clay, gypsum, calcium carbonate, barium sulfate,
Quartz powder, glass fiber, kaolin, mica, alumina, hydrated alumina, aluminum hydroxide, talc, dolomite, zircon, titanium compounds, molybdenum compounds, antimony compounds and the like, silane coupling agents and pigments, antioxidants, Other optional additive components can be appropriately blended depending on the purpose and application. These fillers can be contained in the epoxy resin composition in an amount of 90% by weight or less, preferably 0.1 to 85% by weight.
Also, copper, zinc, nickel, cadmium, stainless steel,
It is also possible to add metal powder such as aluminum or silver to impart conductivity to the composition of the present invention. In the case of imparting conductivity, 2 parts of the above metal powder is added to the epoxy resin composition.
It is preferable to add 5% by weight or more.

The epoxy resin composition of the present invention containing the above components can be obtained by uniformly dispersing and mixing at room temperature using a roll, a mixer, a Henschel mixer, a ball mill, a kneader, a disper and the like.

The above-mentioned epoxy resin composition is heated to a predetermined temperature or higher to release the curing agent or the curing accelerator in the microcapsules to the outside of the wall film and cure the epoxy resin to obtain the desired cured product. . Such heat release phenomenon in the curing method of the present invention is not due to diffusion permeation through the wall film of the microcapsule as disclosed in JP-A-1-242616, but due to physical change. is there. In other words, the encapsulating curing agent and curing accelerator are released due to the shape change of the microcapsules and the dissolution of the wall film component in the epoxy resin. The dissolution of the wall membrane in this case can be both complete and partial dissolution.

In the curing method of the present invention, surprisingly, even if the wall film component has a relatively strong crosslinked structure, the above-mentioned microcapsule has a phenomenon of heating dissolution (destruction) at 80 to 150 ° C.
Occurs at such an extremely low temperature as described above, and the curability (releasability of the core substance from the inside of the microcapsules) does not deteriorate even if the wall film becomes thick. Such a dissolution phenomenon does not occur even if the microcapsule type curing agent or curing accelerator of the present invention is heated alone to a temperature of about 90 to 200 ° C. without being compounded in the composition, and oil or the like is used. It does not occur when heated in a liquid medium. That is, the above-mentioned curing reaction occurs when the polymer having a specific structure that constitutes the wall film of the microcapsule type curing agent or curing accelerator of the present invention is compounded with the epoxy resin composition.

Although the mechanism of action in the curing method of the present invention as described above is not clear, the structural unit of the wall film having the specific structure in the present invention causes a dissociation reaction at a relatively low temperature when an epoxy resin coexists. It is estimated that there is.
The temperature at which this dissociation reaction occurs can be controlled by the structure (composition) of the polymer forming the wall film and the type of epoxy resin coexisting. The structure of the polymer that constitutes the wall film can be changed by changing the type of polyvalent isocyanate or polyvalent amine used when forming the wall film by interfacial polymerization, or by using two or more types of polyvalent isocyanate. . The breaking temperature of the wall film in the microcapsules mentioned here is measured by the rising temperature of the exothermic peak obtained by DSC measurement.

[0038]

INDUSTRIAL APPLICABILITY As described above, the present invention uses a microcapsule type curing agent or curing accelerator containing a curing agent or a curing accelerator in a wall film made of a polyurea polymer having a specific structure. Therefore, not only the storage stability during storage is good, but also when the epoxy resin composition is blended with an epoxy resin, the storage stability during storage is good, and moreover, when heated to a predetermined temperature or higher. The curing reactivity is good, and the wall film component when the encapsulating curing agent is released dissolves by forming a covalent bond with the epoxy resin. ) And does not adversely affect the physical properties such as heat resistance and water resistance. Therefore, the epoxy resin composition of the present invention is suitable for various uses such as an adhesive, an adhesive sheet, a molding material, a casting material, a laminated board, a liquid coating material, a powder coating material, and an adhesive material.

[0039]

EXAMPLES The present invention will be specifically described below with reference to examples. In the following, parts and% in the text mean parts by weight and% by weight.

Example 1 10 parts of an adduct of 3 mol of xylylene diisocyanate and 1 mol of trimethylolpropane was used as a curing agent.
An oil phase was prepared by uniformly dissolving it in a mixed solution of 10 parts of benzyl-2-phenylimidazole and 30 parts of diisopropylnaphthalene.

An aqueous phase consisting of 95 parts of distilled water and 5 parts of polyvinyl alcohol was separately prepared, and the above-prepared oil phase was added to this, which was emulsified with a homomixer to give an emulsion state, which was refluxed with stirring. A polymerization reactor equipped with a machine and a dropping funnel was charged.

On the other hand, 13 parts of an aqueous solution containing 3 parts of triethylenetetramine was prepared, placed in a dropping funnel equipped with the above polymerization reactor, added dropwise to the emulsion in the reactor and allowed to stand at 70 ° C. for 3 hours for interface. Polymerization was performed to prepare the microcapsule type curing agent of the present invention.

The microcapsule type curing agent thus obtained was separated by centrifugation as free-flowing powdery particles after repeating the separation and washing with water. The average particle size of the particles was 5 μm. A scanning electron micrograph of the particle structure of the obtained microcapsule type curing agent is shown in FIG.

12 parts of the microcapsule type curing agent obtained as described above was added to 100 parts of a bisphenol A type epoxy resin (epoxy equivalent of about 190, weight average molecular weight of 380, viscosity of 125 poise at 25 ° C.) and mixed. The mixture was kneaded in a kettle at room temperature for 1 hour and further passed through a three-roll mill to obtain the epoxy resin composition of the present invention.

Comparative Example 1 An epoxy resin composition was prepared in the same manner as in Example 1 except that 4 parts of 1-benzyl-2-phenylimidazole was added instead of the microcapsule type curing agent obtained in Example 1. Got

Comparative Example 2 20 parts of polystyrene resin (produced by Denki Kagaku, trade name Denkastyrol) and 10 parts of 1-benzyl-2-phenylimidazole as a curing agent were uniformly dissolved in 180 parts of methylene chloride. , An oil phase was prepared.

950 parts of distilled water and polyvinyl alcohol 5
An aqueous phase consisting of 0 parts was separately prepared, the above-prepared oil phase was added thereto, and the mixture was emulsified with a homomixer to give an emulsion state, which was transferred into a rotary evaporator,
The organic solvent, methylene chloride, was distilled off to prepare a microcapsule type curing agent.

The microcapsule type curing agent thus obtained was separated by centrifugal separation and washed with water, and then dried to be isolated as free-flowing powdery particles. The average particle size of the particles was 9 μm.

An epoxy resin composition was obtained in the same manner as in Example 1, using the microcapsule type curing agent obtained as described above.

Comparative Example 3 A monomer mixture consisting of 35 parts of acrylonitrile, 13 parts of methacrylic acid methyl ester and 2 parts of divinylbenzene, 0.2 part of lauroyl peroxide and 1-benzyl-2-phenylimidazole 25 as a curing agent. A part was dissolved uniformly to prepare an oil phase.

475 parts of distilled water and polyvinyl alcohol 2
An aqueous phase consisting of 5 parts was prepared separately, and the above-prepared oil phase was added to this and emulsified with a homomixer to give an emulsion state, which was subjected to a polymerization reaction equipped with a reflux tube, a stirrer and a dropping funnel. I put it in a container.

Next, the inside of the reactor was replaced with nitrogen, and then 7
In situ polymerization was performed at 0 ° C. for 3 hours to prepare a microcapsule type curing agent.

The microcapsule type curing agent thus obtained was separated by centrifugation as a free-flowing powdery particle after repeating separation and washing with water. The average particle size of the particles was 8 μm.

Using the microcapsule type curing agent obtained as described above, an epoxy resin composition was obtained in the same manner as in Example 1.

Example 2 The same procedure as in Example 1 was carried out except that 1-benzyl-2-methylimidazole was used in place of 1-benzyl-2-phenylimidazole used in Example 1, and the microinvention of the present invention was performed. A capsule type curing agent was prepared. The average particle size of this microcapsule type curing agent was 5 μm.

Using the obtained microcapsule type curing agent, an epoxy resin composition of the present invention was obtained in the same manner as in Example 1.

Comparative Example 4 An epoxy resin composition was prepared in the same manner as in Example 2 except that 4 parts of 1-benzyl-2-methylimidazole was added instead of the microcapsule type curing agent obtained in Example 2. Got

Example 3 Mixture of 6.7 parts of an adduct of 3 mol of tolylene diisocyanate and 1 mol of trimethylolpropane, a mixture of 7.5 parts of triphenylphosphine as a curing accelerator and 12.5 parts of diisopropylnaphthalene. An oil phase was prepared by uniformly dissolving it in the oil phase.

An aqueous phase consisting of 95 parts of distilled water and 5 parts of polyvinyl alcohol was separately prepared, and the above-prepared oil phase was added thereto and emulsified with a homomixer to obtain an emulsion state, which was refluxed and stirred. A polymerization reactor equipped with a machine and a dropping funnel was charged.

On the other hand, 14.7 parts of an aqueous solution containing 4.7 parts of triethylenetetramine was prepared, placed in a dropping funnel provided in the above polymerization reactor, added dropwise to the emulsion in the reactor and heated to 70 ° C. Was interfacially polymerized for 3 hours to prepare the microcapsule type curing accelerator of the present invention.

The microcapsule type curing accelerator thus obtained was separated by centrifugation as a free-flowing powdery particle after repeated separation and washing with water. The average particle size of this particle is 3 μm
Met. A scanning electron micrograph of the particle structure of the obtained microcapsule type curing accelerator is shown in FIG.

4.6 parts of the microcapsule type curing accelerator obtained as described above was added to an orthocresol novolac type epoxy resin (epoxy equivalent of about 190, softening point of 65 ° C.).
100 parts and phenol novolac resin (hydroxyl equivalent 1
No. 05, softening point 98 ° C.) 53 parts, and further melt-kneaded through a hot roll mill to obtain an epoxy resin composition of the present invention.

Comparative Example 5 An epoxy resin composition was obtained in the same manner as in Example 3 except that 1.5 parts of triphenylphosphine was added instead of the microcapsule type curing accelerator obtained in Example 3. .

Example 4 Instead of the adduct of 3 mol of tolylene diisocyanate and 1 mol of trimethylol propane as a wall film material for microcapsules, an adduct of 3 mol of xylylene diisocyanate and 1 mol of trimethylol propane was used. A microcapsule type curing accelerator and an epoxy resin composition of the present invention were prepared in the same manner as in Example 3 except that the above was used.

Example 5 Instead of an adduct of 3 mol of tolylene diisocyanate and 1 mol of trimethylol propane as a wall film material for microcapsules, 3 mol of a hydrogenated compound of xylylene diisocyanate and 1 mol of trimethylol propane were used. A microcapsule type curing accelerator and an epoxy resin composition of the present invention were prepared in the same manner as in Example 3 except that an additive was used.

Example 6 Example 3 was repeated except that 5 parts of trimethylenetetraphenylisocyanate was used in place of the adduct of 3 mol of tolylene diisocyanate and 1 mol of trimethylolpropane as a wall film material for microcapsules. Similarly, the microcapsule type curing accelerator and the epoxy resin composition of the present invention were prepared.

Example 7: Instead of the adduct of 3 mol of tolylene diisocyanate and 1 mol of trimethylol propane as a wall film material for microcapsules, an adduct of 3 mol of tolylene diisocyanate and 1 mol of trimethylol propane. 35 copies,
A microcapsule type curing accelerator and an epoxy resin composition of the present invention were prepared in the same manner as in Example 3 except that a mixture of 3.35 parts of an adduct of 3 moles of xylylene diisocyanate and 1 mole of trimethylolpropane was used. Prepared.

Example 8 Instead of an adduct of 3 mol of tolylene diisocyanate and 1 mol of trimethylol propane as a wall film material for microcapsules, an adduct of 3 mol of tolylene diisocyanate and 1 mol of trimethylol propane. 69 copies,
A microcapsule type curing accelerator and an epoxy resin composition of the present invention were prepared in the same manner as in Example 3 except that a mixture of 3 mol of xylylene diisocyanate and 2.01 part of an adduct of 1 mol of trimethylolpropane was used. Prepared.

Comparative Example 6 An oil phase was prepared by uniformly dissolving 20 parts of triphenylphosphine and 40 parts of diisopropylnaphthalene.

An aqueous solution consisting of 194 parts of distilled water and 6 parts of isobutylene / maleic anhydride copolymer was prepared, and an aqueous citric acid solution was added thereto to separately prepare an aqueous phase having a pH of 3.6. The prepared oil phase was added, and the mixture was emulsified with a homomixer to give an emulsion state.
It was charged in a polymerization reactor equipped with a stirrer and a dropping funnel.

Next, 15 parts of a melamine-formaldehyde initial condensate was added to the reactor and heated at 70 ° C. for 3 hours to form a film consisting of a reaction product of methylolmelamine around the oil phase, followed by microcapsule type curing. An accelerator was made.

The microcapsule type curing accelerator thus obtained was separated by centrifugation as a free-flowing powdery particle after being repeatedly separated and washed with water. The average particle size of this particle is 8 μm
Met.

An epoxy resin composition was obtained in the same manner as in Example 3, using the microcapsule type curing accelerator obtained as described above.

Example 9 A mixed solution of 6 parts of an adduct of 3 mol of xylylene diisocyanate and 1 mol of trimethylolpropane and 10 parts of diisopropylnaphthalene was added to 3- (3, 3 having an average particle diameter of 3 μm as a curing accelerator. 4-dichlorophenyl) -1,
An oil phase was prepared by uniformly dissolving 1-dimethylurea.

An aqueous phase consisting of 95 parts of distilled water and 5 parts of polyvinyl alcohol was separately prepared, and the oil phase prepared above was added to this, which was emulsified with a homomixer to give an emulsion state. A polymerization reactor equipped with a machine and a dropping funnel was charged. On the other hand, triethylenetetramine 4.7
14.7 parts of an aqueous solution containing 1 part was prepared, placed in a dropping funnel provided in the above-mentioned polymerization reactor, added dropwise to the emulsion in the reactor and subjected to interfacial polymerization at 70 ° C. for 3 hours to obtain the solution of the present invention. A microcapsule type curing accelerator was prepared.

The microcapsule type curing accelerator thus obtained was separated by centrifugation as a free-flowing powdery particle after repeating separation and washing with water. The average particle size of this particle is 8 μm
Met.

5 parts of the microcapsule type curing accelerator obtained as described above was mixed with a bisphenol A type epoxy resin (epoxy equivalent: about 190, weight average molecular weight: 380, 25).
100 parts of a viscosity of 125 poise at ℃) and 8 parts of dicyandiamide are kneaded in a mixing pot at room temperature for 1 hour, and further 3
The epoxy resin composition of the present invention was obtained through this roll mill.

Comparative Example 7 3- (3,4-dichlorophenyl) -1,1-dimethylurea was used in place of the microcapsule type curing accelerator obtained in Example 9 and compounded in an epoxy resin composition. An epoxy resin composition was obtained in the same manner as in Example 9 except that the number of parts was 1.

The properties of the epoxy resin compositions obtained in the above Examples and Comparative Examples were measured according to the test methods shown below, and the results are shown in Table 1.

<Curing Property> The curing time at 150 ° C. or 200 ° C. was measured by the hot plate gel time measuring method. In addition, about Example 1, 2, 9, and Comparative Examples 1-4, 7, the measurement temperature was 150 degreeC, and other than that, it measured at 200 degreeC.

<Storage Stability> The epoxy resin compositions obtained in the respective examples and comparative examples were stored at 40 ° C.,
Observe the change with time of viscosity or the change with time of gel time, and confirm that it is more than 3 times the initial viscosity or 50
The number of days required to reach% was measured. In addition, with respect to Examples 1, 2, and 9 and Comparative Examples 1 to 4 and 7, changes in viscosity with time were examined, and in other cases, changes with time in gel time were examined.

<Reaction Initiation Temperature (Microcapsule Breaking Temperature)> With respect to the epoxy resin compositions obtained in the respective examples and comparative examples, the temperature at which the exothermic peak begins to rise (curing reaction) using a differential thermal analysis (DSC) meter. The onset temperature) was measured. FIG. 3 shows a DSC thermogram for the epoxy resin composition obtained in Example 3, and FIG. 4 shows a DSC thermogram for the epoxy resin composition obtained in Comparative Example 5.

As is clear from the comparison between FIG. 3 and FIG. 4, the epoxy resin composition of the present invention is superior in the isolation property of the microcapsules as compared with the comparative product, so that a rapid curing reaction occurs at the same time when the capsules are broken. ing.

<Observation of Fracture Behavior of Microcapsule Type Hardener> The epoxy resin composition was placed under a temperature rising rate condition of 10 ° C./min, and the morphological change of the microcapsules was observed by an optical microscope. The results are shown in FIG. And shown in FIG. FIG. 5 shows micrographs of the epoxy resin composition obtained in Example 1 at various temperatures, and FIG. 6 shows micrographs of the epoxy resin composition obtained in Comparative Example 6 at various temperatures.

As is clear from the comparison between FIGS. 5 and 6, the epoxy resin composition of the present invention causes deformation of the capsule and dissolution of the wall film in the epoxy resin at around 120 to 160 ° C. It can be seen that in the product, the capsule shape does not change even at around 200 ° C., and the balance between the isolation property and the curing reactivity is poor.

<Physical Properties of Cured Epoxy Resin> The functions of the epoxy resin compositions obtained in the respective examples and comparative examples as an adhesive were measured by the following methods.

According to JIS-K6854, a steel plate (SPCC: 200 × 25 × 0.8 ^t mm) is used as an adherend, and an adhesive has a thickness of 150 μm and a pulling speed of 200 mm.
The T-peel adhesion was measured in / sec. The curing condition is 1
It was set to 50 ° C. × 1 hour.

In the product of the present invention, since the wall film component reacts with the epoxy resin after curing, the adhesive strength is excellent and the brittleness of the cured epoxy resin product can be improved.

[0089]

[Table 1]

[Brief description of drawings]

FIG. 1 is a scanning electron micrograph (1000 showing a particle structure of a microcapsule type curing agent obtained in Example 1.
Times).

2 is a scanning electron micrograph showing the particle structure of the microcapsule type curing accelerator obtained in Example 3 (250
0 times).

FIG. 3 D of the epoxy resin composition obtained in Example 3
An SC thermogram is shown.

FIG. 4 D of the epoxy resin composition obtained in Comparative Example 4
An SC thermogram is shown.

FIG. 5 is an optical micrograph showing fracture behavior of particles (wall film) of the microcapsule type curing agent by heating the epoxy resin composition obtained in Example 1.

FIG. 6 is an optical micrograph showing fracture behavior of particles (wall film) of the microcapsule type curing accelerator by heating the epoxy resin composition obtained in Comparative Example 6.

Claims (8)

[Claims] 1. A microcapsule type curing agent in which a curing agent is included in a wall film containing a polymer having a structural unit represented by the following general formula [Chemical Formula 1] as a main component. Embedded image 2. The microcapsule type curing agent according to claim 1, wherein the curing agent is a curing agent for epoxy resin. 3. A microcapsule type curing accelerator having a curing accelerator encapsulated in a wall film containing a polymer having a structural unit represented by the general formula [Chemical Formula 1] as a main component. 4. The microcapsule type curing accelerator according to claim 3, wherein the curing accelerator is an epoxy resin curing accelerator. 5. An epoxy resin composition containing the microcapsule type curing agent according to claim 2 and an epoxy resin. 6. An epoxy resin composition containing the microcapsule type curing accelerator according to claim 4, a curing agent for an epoxy resin, and an epoxy resin. 7. An epoxy resin composition, characterized in that the epoxy resin composition according to claim 5 or 6 is heated to a predetermined temperature or higher to release the encapsulating curing agent or curing accelerator outside the wall film. How to cure things. 8. An epoxy resin cured product obtained by the curing method according to claim 7.