JP3270774B2 - Latent curing agent for spherical epoxy resin and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates to a spherical particle of a latent curing agent for an epoxy resin. More particularly, the present invention relates to a latent curing agent for an epoxy resin or a latent curing accelerator spherical particle for a high-temperature curing type curing agent, which has a low production cost and excellent storage stability at room temperature and excellent curing performance. is there.

(Prior art) Epoxy resin cured products are excellent in adhesiveness, mechanical properties, thermal properties and electrical properties, so that they are widely used as paints, adhesives, and electrical / electronic insulating materials. It is used for Epoxy resin formulations used for these applications are broadly divided into one-component and two-component systems.

[0003] The most commonly used epoxy resin formulations are of the two-component type. The two-component compound is composed of an epoxy resin compound and a curing agent or a compound thereof, and these are stored separately, and both are measured and mixed as necessary for use. Such disadvantages are pointed out. (1) It is difficult to always obtain a homogeneous cured composition by avoiding measurement errors. (2) Variations in performance due to imperfect mixing and defoaming are likely to occur. (3)
The reaction between the epoxy resin and the curing agent starts at the same time as mixing,
The viscosity of the system gradually increases until it hardens through gelation. The viscosity of the formulation changes over time, making its application to automation impossible. (4) The pot life of the compound is determined by the chemical structure and composition of the epoxy resin and the curing agent. Generally, the faster the curing speed, the shorter the pot life. If the cure rate is the main focus, room-temperature or low-temperature curing compounding is possible, but the working time is inevitably shortened, and it is unavoidable that the working efficiency is greatly reduced, such as the necessity of frequently compounding a small amount.

On the other hand, in the case of the one-component system, since the curing agent is previously added to the epoxy resin, all problems associated with the two-component system are eliminated. However, in order to prepare a one-component epoxy resin composition having good storage stability at room temperature, a latent curing agent is required as a curing agent. Several latent curing agents have been proposed for this purpose. The simplest latent curing agents are solid at room temperature and do not dissolve in the epoxy resin, but disperse latent curing agents that dissolve when heated to near the melting point and start the reaction rapidly, such as dicyandiamide, phenol novolak, and adipin Acid dihydrazide, diallyl melamine, diamino maleonitrile, boron trifluoride-amine complex,
Examples include amine salts and imidazole derivatives. Although they are excellent in storage stability at room temperature, most of them are high-temperature curing types, and have a drawback that they require high-temperature curing at 160 ° C. or higher for a long time. Similarly, an acid anhydride curing agent, for example, methylhexahydrophthalic anhydride liquid at room temperature is also a kind of high-temperature curing type curing agent, reflecting its curing reaction mechanism, having a low hydroxyl group concentration. The compound with the liquid epoxy resin is relatively stable at room temperature, but has a disadvantage that the reaction rate is extremely slow, and the reaction hardly proceeds even when heated to about 160 ° C.

When using these high-temperature curing type curing agents,
Usually, tertiary amines represented by tris (dimethylaminomethyl) phenol,
It is known to use a curing accelerator such as an imidazole compound represented by ethyl-4-methylimidazole in combination. However, when a curing accelerator is added, the curing temperature becomes 12
Although it is possible to lower the temperature to 0 to 150 ° C., on the other hand, the storage stability is significantly impaired, and the potential advantage of the high-temperature curing type curing agent cannot be exhibited.

Other latent curing agents include, for example, amine imide compounds activated by thermal decomposition, ketimine compounds activated by contact with moisture, aromatic diazonium salt compounds activated by light irradiation, diallyliodonium Salt compounds, triallylsulfonium salts or selenium salt compounds, hardeners microencapsulated with materials that are destroyed by mechanical pressure or heat, and the like. Among them, the most advanced is a curing agent in which solid particles of an amine compound / epoxy compound adduct are treated with a polyfunctional isocyanate compound in the presence of a liquid epoxy resin to greatly improve the potential thereof. These techniques are disclosed in Japanese Unexamined Patent Publication No. 64-70523 and Japanese Unexamined Patent Publication No. Hei 1-113480. In this case, it is presumed that an encapsulation film is formed on the surface of the hardener particles.

The amine compound / epoxy compound adduct is
It is obtained by reacting an amine compound and an epoxy compound.The disadvantages of amine compound curing agents, such as volatility, which is a problem in handling, as well as hygroscopicity that greatly affects curability and compatibility with epoxy resins, etc. Not only is it significantly improved, but also control of the melting point is possible. In terms of performance,
Anionic polymerization catalyzed curing agents, such as tertiary amine adducts, which are not susceptible to metal corrosion, are preferred. Particularly suitable for this purpose in practical use is an imidazole compound / epoxy resin adduct, as disclosed in JP-A-58-13623 and JP-A-61-1986.
No. 268721.

[0008] According to these conventional methods, the amine compound / epoxy compound adduct is first obtained as a mass by reacting the amine compound with the epoxy resin in an organic solvent and then removing the solvent from the system. Next, this is pulverized and classified to take out hardener particles of a desired size. In this case, the size of the adduct curing agent particles is important, and the smaller the size, the higher the curing speed but the lower the storage stability. Conversely, as the particle size increases, the storage stability is improved, but the low-temperature curability tends to be impaired, and it is difficult to obtain a curing agent that is sufficiently satisfactory in both curability and storage stability. In addition, there is a limit to grinding, and a Stokes diameter of 3μ
It is industrially extremely difficult to produce fine particles of m or less. In addition, a great deal of energy is required to remove the solvent and finely crush and classify the product, and the production process is long and complicated, which not only results in extremely high production costs, but also limits the pulverization by crushing and its crushing. It is pointed out that there are various disadvantages caused by the shape of the resin, such as bulkiness, which is inconvenient for packaging and transportation, and a large contribution to the viscosity of the epoxy resin cured composition.

Furthermore, in order to impart a potential to the pulverized and classified adduct particles having a small average particle diameter, which is considered to have a high curing speed, conventionally, the adduct particles are dispersed in a liquid epoxy resin and heated to a polyfunctional state. By adding and reacting a reactive isocyanate compound, a master batch of a desired curing agent is produced. However, in this state, a side reaction such as polymerization of the dispersion medium epoxy resin inevitably occurs, so that the obtained curing agent master batch often has a very high viscosity, is difficult to handle, and has an epoxy resin cured composition. It is not preferable because it lowers the degree of freedom in the formulation design.

(Problems to be Solved by the Invention) As described above, the amine compound / epoxy compound adduct particles are
Despite having excellent advantages as a curing agent for epoxy resins, one-component cured compositions have not been fully utilized due to the various problems described above.

In order to make use of the advantages of the one-component epoxy resin cured composition, the production process is simplified, the production cost is low, and the particle size can be easily controlled. There is a great demand for a latent curing agent fine powder having excellent physical properties of the resulting cured product.

From the above viewpoints, the present inventors have overcome the problems of the prior art amine compound / epoxy compound adduct particles and have a curing agent capable of fully utilizing the advantages of the one-component epoxy resin cured composition. As a result of intensive research to develop, first, in the addition reaction of an amine compound and an epoxy compound in an organic solvent in the prior art, the amine compound and the epoxy compound are dissolved as the organic solvent, but the adduct is obtained. Spherical amine compound / epoxy compound adduct particles whose particle size is controlled by selecting those that do not dissolve, and further coexisting with a suitable dispersion stabilizer, and stably dispersing the adduct particles formed without agglomeration. Can be obtained in one step, and the obtained spherical amine compound / epoxy compound adduct particles are extremely useful as a curing agent for a latent epoxy resin. It found to be use, and filed a patent application (applicant's JP Gantaira 2-138176).

The invention of the present application is disclosed in Japanese Patent Application No. 2-138176.
The invention described in the item (1) is further improved.

(Means for Solving the Problems) The present inventors have conducted further intensive studies on spherical amine compound / epoxy compound adduct particles useful as a curing agent for a latent epoxy resin. In the addition reaction of the amine compound and the epoxy compound in such an organic solvent,
Further, the reaction is carried out in the presence of an excess of a polyfunctional epoxy compound, or after the completion of the addition reaction, by treatment with a polyfunctional isocyanate compound, or in the presence of an excess of a polyfunctional epoxy compound, and the reaction is carried out. It has been found that the treatment with a polyfunctional isocyanate compound after the completion has further improved the potential of the spherical adduct particles according to the preceding invention, and has completed the present invention.

That is, in one embodiment, the method for producing a curing agent for a latent epoxy resin according to the present invention comprises the steps of: combining an amine compound and an epoxy compound with each other in the presence of a dispersion stabilizer; In a method of producing adduct particles having a spherical shape by reacting in an organic solvent in which the adduct formed from both dissolves but the adduct formed from both does not dissolve, the adduct is further increased during the course of the reaction between the amine compound and the epoxy compound. The present invention is characterized in that a functional epoxy compound is present or a further multifunctional epoxy compound is added after the completion of the reaction to further react. The adduct obtained by such a method is characterized in that the shape synthesized from the amine compound and the epoxy compound has an encapsulating layer formed by a polyfunctional epoxy compound on the surface of the spherical adduct, The presence of the encapsulating layer significantly improves its potential.

In another aspect, the present invention also includes a method for producing spherical adduct particles, wherein a polyfunctional isocyanate compound is further allowed to act on the adduct obtained as described above. Is what you do. According to such a production method, the shape synthesized from the amine compound and the epoxy compound has an encapsulating layer formed of an epoxy resin on the surface of the spherical adduct, and the epoxy encapsulating layer further has a multifunctional structure. Spherical adduct particles having a further excellent potential as a latent curing agent for an epoxy resin, characterized by having an encapsulating layer formed of an isocyanate compound or a mixed encapsulating layer thereof, are obtained.

Further, in another aspect, the present invention provides a method for dissolving an amine compound and an epoxy compound together with the amine compound and the epoxy compound in the presence of a dispersion stabilizer. The present invention relates to a method for producing adduct particles having a spherical shape by reacting in an organic solvent which does not dissolve, wherein a predetermined amount of a polyfunctional isocyanate compound is further reacted after completion of the reaction. According to this production method, the shape synthesized from the amine compound and the epoxy compound is a spherical adduct, and further has an encapsulating layer formed of a polyfunctional isocyanate compound on the surface thereof. Thus, spherical adduct particles having more excellent potential as a latent curing agent for epoxy resins can be obtained.

According to such a production method, operations such as fine pulverization, classification and kneading of high viscosity are not required as compared with the conventional method of preparing a latent curing agent by a pulverization / master batch method. This is considerably simplified, and the manufacturing cost can be greatly reduced. In addition, spherical adduct particles have advantages such as a higher bulk density than pulverized particles and a small contribution to the viscosity of the epoxy resin compound.
Further, according to the present invention, the potential of the amine compound / epoxy compound adduct spherical particles as a latent curing agent for an epoxy resin may be determined by using any of the treatments described above in the course of the reaction between the amine compound and the epoxy compound. Only by itself, the curing performance and cured physical properties of the epoxy resin formulation are greatly improved without impairing.

Hereinafter, the present invention will be described in more detail.

First, the amine compound and the epoxy compound which are the raw materials of the adduct constituting the latent curing agent of the present invention are selected in consideration of the properties of the adduct as a curing agent. Important are the chemical structure that promotes anionic polymerization curing, the melting point, the excellent compatibility with the compounded epoxy resin to be cured in the molten state, the rapid curing properties, and the effect of addition (high curing reactivity with a small amount of addition).

Although all types of amine compounds can be used for this purpose, they are restricted by the type of epoxy compound to be combined therewith. because,
This is because, in order to synthesize a pure adduct, it is necessary to avoid polymerization and stop the addition reaction.

Although it is possible to combine all types of amine compounds with the monofunctional epoxy compound, the combination with the polyfunctional epoxy compound is as follows.
Only amine compounds having only one active hydrogen contributing to the reaction with the epoxy group are obtained. In any case, the presence of a tertiary amino group having no active hydrogen may be included. Rather, its presence is preferred for increasing the concentration of amino groups contributing to the curing reaction of the adduct, that is, for increasing the effect of addition as a curing agent. Furthermore, if the conditions for this combination are satisfied, one or more amine compounds may be used in combination.

Specific examples of the amine compound which can be combined with the polyfunctional epoxy compound include imidazole compounds represented by 2-methylimidazole and 2,4-dimethylimidazole, imidazoline compounds represented by imidazoline and 2-methylimidazoline, and the like. Piperazine compounds represented by N-methylpiperazine and N-hydroxyethylpiperazine, anabasin compounds represented by anabasin,
Examples include pyrazole compounds represented by 3,5-dimethylpyrazole, purine compounds represented by tetramethylguanidine and purine, and triazole compounds represented by 1,2,4-triazole.

All kinds of epoxy compounds can be used as the other raw material. For example, monofunctional epoxy compounds include n-butyl glycidyl ether, styrene oxide, phenylglycidyl ether, and bifunctional epoxy compounds include bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, and bisphenol S diglycidyl. ether,
Phthalic acid diglycidyl ester, trifunctional epoxy compound as triglycidyl isocyanurate, triglycidyl paraaminophenol, tetrafunctional epoxy compound as tetraglycidyl metaxylenediamine,
Tetraglycidyl diaminodiphenylmethane and epoxy compounds having a higher functional group include cresol novolak polyglycidyl ether and phenol novolak polyglycidyl ether. However, it is the same as described for the amine compound that it is restricted by the type of the amine compound to be combined. That is,
An amine compound having only one active hydrogen can be combined with all kinds of epoxy compounds, but an amine compound having two or more active hydrogens can be combined only with a monofunctional epoxy compound. is there.

The epoxy compound is selected in consideration of the melting point of the adduct to be produced and the compatibility with the epoxy resin to be cured in the molten state. Bisphenol A diglycidyl ether occupies an overwhelming amount as the epoxy resin to be cured. Therefore, as an epoxy compound as a raw material of the adduct, this epoxy compound has excellent compatibility with the epoxy compound and is advantageous in cost. Compounds are commonly used.
In an epoxy compound, the epoxy concentration is represented by the reciprocal of the epoxy equivalent (grams per equivalent). The lower the epoxy equivalent, the higher the epoxy group concentration. A high epoxy group concentration is desirable in order to increase the concentration of the tertiary amino group contained in the adduct formed by the addition reaction with the amine as much as possible to enhance the effect of addition as a curing agent. Therefore, it is desired that the epoxy equivalent of the epoxy compound be as small as possible. Usually, 1000 or less, preferably 500 or less epoxy compounds are used.

The melting point of the amine compound / epoxy compound adduct is determined by the chemical structure of the raw materials used, the mode of addition, the structure of the adduct, and the ratio of epoxy resin to amine compound added. With their proper choice,
According to the purpose, it is possible to synthesize an adduct having a low melting point to a high melting point. The higher the melting point, the easier it is to handle,
Conversely, the curing reaction initiation temperature of the formulation increases. Therefore, although the melting point has not been lowered from the viewpoint of curability, a melting point of at least 50 ° C. is required in consideration of handleability, especially handling in summer.

The amine compound / epoxy compound adduct is
Usually, it is synthesized under the condition of equivalence or amine excess,
When a monofunctional epoxy compound is used, the melting point of the resulting adduct decreases when the epoxy content is excessive. Conversely, when a polyfunctional epoxy compound is used, if the epoxy content is excessive, the addition reaction and the polymerization reaction occur competitively, and the melting point of the adduct increases. The reaction equivalent ratio between the epoxy compound and the amine compound in producing the spherical amine compound / epoxy compound adduct in the present invention is not particularly limited, but is based on the stoichiometric amount.

In one embodiment of the present invention, the encapsulating layer is formed on the surface of the adduct by allowing a further excess amount of the polyfunctional epoxy compound to act on the basis of the ratio. The amount of the additional polyfunctional epoxy compound varies depending on the particle size of the adduct particles to be formed, but is generally 1 to 100 parts by weight per 100 parts by weight of the adduct, and 5 to 50 parts by weight. Parts by weight are preferred. When the amount is less than 1 part by weight, the potential as a latent curing agent for an epoxy resin is not sufficient, and the storage stability of a one-pack type epoxy resin cured composition to which such a curing agent is added becomes insufficient. Also, 10
If the amount exceeds 0 parts by weight, the low-temperature curability is impaired, which is not practical.

The additional polyfunctional epoxy compound forming the encapsulating layer may be a polyfunctional epoxy compound, and the epoxy compound which reacts with an amine compound to form an adduct is a polyfunctional epoxy compound. May be the same as or different from the epoxy compound forming the adduct. The timing of adding the further polyfunctional epoxy compound may be before the start of the adduct formation reaction (that is, at the stage of charging the reaction raw materials), during the reaction, or after the end of the reaction. When the epoxy compound for forming an adduct and the multifunctional epoxy compound for forming an encapsulation are the same, the spherical adduct particles having the encapsulating layer of the present invention can be produced by using an excess amount of the epoxy compound in advance. Can be.

In another embodiment of the present invention, the spherical adduct particles are formed by reacting the above-described amine compound / epoxy compound in an approximately equivalent ratio as described above, or after an excess amount of the spherical adduct particles is formed. After the spherical adduct particles having the encapsulating layer formed by the polyfunctional epoxy compound are formed by the action of the polyfunctional epoxy compound, the adduct is treated with a polyfunctional isocyanate compound to thereby form the adduct. An encapsulating layer formed by a polyfunctional isocyanate or a mixed encapsulating layer of both is formed on the surface of the particles. By forming such an encapsulating layer, the potential of the spherical adduct particles as a latent curing agent is further improved.

The encapsulating layer forming reaction by the polyfunctional isocyanate compound is performed after the reaction rate of the formation reaction of the adduct or the encapsulating layer forming reaction by the further polyfunctional epoxy compound reaches 100%. Examples of the polyfunctional isocyanate compound used for this purpose include mononuclear and polynuclear products of toluene diisocyanate and methylene diphenyl diisocyanate, hydrogenated methylene diphenyl diisocyanate, 1,5-naphthalenediisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate. Isocyanate, hydrogenated xylylene diisocyanate, tetramethyl xylene diisocyanate, 1,3,6-hexamethylene triisocyanate,
Examples include lysine diisocyanate, triphenylmethane triisocyanate, tris (isocyanatephenyl) thiophosphate, and a polyfunctional isocyanate compound formed by an addition reaction of these with another active hydrogen-containing compound. Such a polyfunctional isocyanate compound is selected from those which dissolve in the solvent used in the production reaction of the adduct particles, and one or more of them are used in combination. The amount added to the adduct particles varies depending on the particle size of the adduct particles, but the volume average particle diameter is 0.05%.
adduct particles 1 for particles in the range of
The amount is 0.1 to 100 parts by weight, preferably 1 to 50 parts by weight based on 00 parts by weight. If the amount is less than 0.1 part by weight, sufficient storage stability cannot be obtained. If the amount exceeds 100 parts by weight, a considerably long reaction time is required, and the curing reactivity is lowered.

The formation of the spherical adduct particles according to the present invention can be realized only by the precipitation or dispersion addition reaction proposed by the present inventors in Japanese Patent Application No. 2-138176. That is, the formation of the spherical adduct particles of the present invention is carried out by using an amine compound and an epoxy compound as an organic solvent, and selecting an amine compound and an epoxy compound that dissolves but does not dissolve the obtained adduct, and further provides an appropriate dispersion stability. The method is carried out by allowing the agent to coexist and stably dispersing the resulting adduct particles without agglomeration. By this method, spherical amine compound / epoxy compound adduct particles having a controlled particle diameter can be obtained in one step. The most important factor in carrying out this reaction is the selection of a solvent used in the reaction. Basically, it is necessary to use a solvent that dissolves an amine compound and an epoxy compound as raw materials of the adduct and a dispersion stabilizer described below, and precipitates the addition product as particles without dissolving. Generally speaking, substances dissolve in solvents of similar polarity. A solubility parameter (unit: [cal / cm ³ ] ^1/2 ) is often used as a measure of the polarity of a solvent. According to this display method, the epoxy compound, the amine compound, and the amine compound / epoxy compound adduct have solubility parameters of 8 to 11, 8 or more, and 1 respectively.
Dissolve in 1-16 solvents. Therefore, to carry out the precipitation or dispersion addition reaction of the present invention, a solvent having a solubility parameter of 8 to 11 is suitable.

The solvent used in the reaction of the present invention includes:
For example, methyl ethyl ketone, methyl isobutyl ketone,
Methyl isopropyl ketone, acetone, n-butyl acetate, isobutyl acetate, ethyl acetate, methyl acetate, tetrahydrofuran, 1,4-dioxane, cellosolve, ethylene glycol monomethyl ether, diethylene glycol dimethyl ether, anisole, toluene, p-xylene, benzene, cyclohexane, Examples include methylene chloride, chloroform, trichloroethylene, chlorobenzene, pyridine and the like. These are used alone or in combination of two or more. Even if the solubility parameter of the solvent is out of the range of 8 to 11, it is also possible to use the solvent after adjusting the solubility parameter within the range specified by a combination of two or more kinds.
However, since a suitable solvent naturally differs somewhat depending on the chemical structures of the amine compound and the epoxy compound, it is important to select strictly according to each case.

In the precipitation or dispersion addition reaction of the present invention,
In order to stably disperse the precipitated adduct particles in a solvent to obtain spherical particles, it is necessary to coexist an appropriate dispersion stabilizer. If such a dispersion stabilizer is not present, the generated adduct particles will aggregate with each other during the reaction to cause phase separation, and the desired spherical particles cannot be obtained. As the dispersion stabilizer for this purpose, an amphiphilic polymer compound having a high affinity for both the formed adduct and the organic solvent is suitable. Alternatively, a polymer compound which does not initially show amphipathic properties but can be converted to amphiphilicity by a functional group conversion reaction may be used. In terms of chemical structure, it may be any of a graft copolymer, a block copolymer, a random copolymer, and another polymer.

Examples of the graft copolymer include poly ((methyl methacrylate-co-methacrylic acid) -g
-Styrene), poly ((methyl methacrylate-co-)
2-hydroxyethyl methacrylate) -g-styrene), poly ((methyl methacrylate-co-glycidyl methacrylate) -g-styrene), poly ((styrene-co-glycidyl methacrylate) -g-styrene), poly (2-hydroxy Ethyl methacrylate-g
-Styrene), poly (2,3-dihydroxypropyl methacrylate-g-styrene), poly (acrylamide-2-methylpropanesulfonic acid-g-styrene), poly (vinyl acetate-g-styrene), poly (methacrylic acid- g-styrene), poly (acrylamide-g-styrene), poly (ethylene oxide-g-styrene), poly (4-vinyl-N-ethylpyridium bromide-g-styrene), poly ((methyl methacrylate-co-methacryl) Acid) -g-alkyl methacrylate (R = C ₁ -C
₁₂ )), poly ((methyl methacrylate-co-fluoroalkyl acrylate) -g-methyl methacrylate), poly ((methyl methacrylate-co-glycidyl methacrylate) -g-methyl methacrylate), poly ((styrene-co-glycidyl methacrylate) )-
g-methyl methacrylate), poly (vinyl alcohol-g-methyl methacrylate), poly ((methyl methacrylate-co-glycidyl methacrylate) -g-methacrylic acid), poly (butadiene-g-methacrylic acid), poly (methyl methacrylate) g-2-hydroxyethyl methacrylate), poly (methyl methacrylate-gN-methylolacrylamide), poly (2-
Hydroxyethyl methacrylate-g-N-methylolacrylamide), poly (methyl methacrylate-g-)
12-hydroxystearic acid), poly ((ethyl acrylate-co-methacrylic acid) -g-12-hydroxystearic acid), poly ((methyl acrylate-co
-Methacrylic acid) -g-12-hydroxystearic acid), poly ((styrene-co-methacrylic acid) -g-
12-hydroxystearic acid), poly ((ethyl acrylate-co-methacrylic acid) -g-lauryl methacrylate), poly (vinyl acetate-g-2-ethylhexyl acrylate), poly (chloroprene-g-2-ethylhexyl acrylate) and the like Is mentioned.

Examples of the block copolymer include poly (vinyl acetate-b-styrene) and poly (styrene-b-styrene).
Dimethylsiloxane), poly (styrene-b-methacrylic acid), poly (lauryl methacrylate-b-methacrylic acid), poly (ethylene oxide-b-styrene-b-
Ethylene oxide), poly (12-hydroxystearic acid-b-ethylene oxide-b-12-hydroxystearic acid) and the like.

Examples of the random copolymer include poly (vinyl acetate-co-vinyl alcohol), poly (N-vinyl pyrrolidone-co-vinyl acetate), poly (N-vinyl pyrrolidone-co-methyl methacrylate), Poly (long chain methacrylate or acrylate-c
o-N-vinylpyrrolidone) and the like. Furthermore,
Examples of other polymers include carboxylic acid-modified polyphthalic acid glycol ester and quaternized amine-modified polyester.

As the dispersion stabilizer used in the present invention, there are various structural stabilizers as described above, and there are various molecular weights from low molecular weight to high molecular weight. The conversion effect naturally depends on the chemical structure of the amine compound / epoxy compound and the nature of the solvent. In practice, it requires trial and error selection. Of course, these dispersion stabilizers may be used alone or in combination of two or more depending on the purpose.

In the formation reaction of the adduct and the curing agent particles of the present invention, by selecting an appropriate solvent and a dispersion stabilizer, the formation of aggregates can be avoided to avoid the addition reaction and the multifunctional epoxy compound or polyfunctional isocyanate. Although the encapsulating layer forming reaction by the compound can smoothly proceed up to a reaction rate of 100%, it is important to control the particle size of the adduct and the curing agent particles that proceed stably without generating aggregates and the resulting adducts. It is.

First, a stable reaction is governed by the raw material concentration, dispersion stabilizer concentration, reaction temperature, stirring conditions, reaction rate or reaction time. In the formation reaction of the adduct particles, it is necessary to add an appropriate dispersion stabilizer in order to form a stable dispersion. The addition amount of the dispersion stabilizer is usually 1 to 40% by weight, preferably 5 to 30% by weight, based on the total amount of the amine compound and the epoxy compound. Even if a sufficient dispersion stabilizer is present, when the concentration of the raw material and the reaction temperature are increased, the rate of the addition reaction is increased, but aggregates are easily formed, and the system becomes unstable. Therefore, the raw material concentration is usually 2 to 40% by weight, preferably 5 to 30% by weight in the solvent. The reaction temperature is usually 40 to 90 ° C, preferably 50 to 70 ° C.
Use ° C.

The stability of the reaction system is further related to the stirring conditions and the reaction rate. The appropriate stirring speed differs depending on the composition, reaction conditions and the shape of the stirring blade, and cannot be stated unconditionally.However, too fast stirring promotes the formation of aggregates, while too slow stirring results in spherical particles. Not suitable for Trial and error experiments are required for each system, but usually 50 to 1000 rpm, preferably 100 to 1000 rpm.
Use 500 rpm. Although depending on the reaction conditions, in general, aggregates tend to be generated as the reaction rate increases. As described above, as described above, the higher the raw material concentration and the reaction temperature, the lower the concentration of the dispersion stabilizer, and the smaller the size of the adduct particles to be formed, the lower the reaction rate at which aggregates are formed. start. By adjusting the conditions, 1
It is possible to reach a conversion of 00%.

After the formation of the adduct particles was advanced at a yield of 100%, the particles were used in the formation reaction of the adduct in the encapsulation layer forming reaction with a further polyfunctional epoxy compound or polyfunctional isocyanate compound. Reaction conditions (raw material concentration, reaction temperature) and stirring conditions can be applied. However, since the encapsulating layer forming reaction by the polyfunctional isocyanate compound occurs even at a low temperature, the reaction temperature is from room temperature to 9
0 ° C, preferably 50-70 ° C is used. The reaction time of the encapsulation layer forming reaction varies depending on the amount of the polyfunctional epoxy compound or the polyfunctional isocyanate compound used and the reaction temperature, and generally, the yield of the recovered curing agent particles is 1%.
The time to reach 00% is defined as the end point of the reaction. The end point of the reaction can also be determined by analyzing the reaction solution by infrared spectroscopy and quantifying the remaining amount of unreacted substances.

The particle size of the resulting hardener particles is governed by the particle size of the adduct particles used and the amount of the polyfunctional epoxy compound or polyfunctional isocyanate compound added.

The particle size of the adduct particles is governed by the types of the raw materials and the solvent, the reaction conditions, the chemical structure and molecular structure of the dispersion stabilizer, and the amount added. Critical of these factors are the chemical and molecular structure of the dispersion stabilizer. For example, in a precipitation or dispersion addition reaction of 2-methylimidazole and bisphenol A diglycidyl ether in methyl isobutyl ketone, poly ((methyl methacrylate-co-methacrylic acid) -g-styrene)
When the graft copolymer is used as a dispersion stabilizer, micron-sized particles are provided, whereas a quaternized amine-modified polyester dispersion stabilizer provides submicron-sized particles. Further, although depending on the chemical structure of the dispersion stabilizer, generally, the smaller the molecular weight of the dispersion stabilizer, the larger the particle size of the obtained adduct particles. Next, the reaction conditions have a great influence on the formation of particles. Generally speaking, the higher the concentration of the dispersion stabilizer, the higher the reaction temperature and the higher the stirring speed, and the lower the concentration of the raw material and the conversion, the smaller the particles produced. By appropriately combining these factors, the volume average particle diameter of the resulting adduct or curing agent particles can be controlled to 0.05 to 100 μm.

After the formation of the adduct particles having a desired particle size, an encapsulating layer is formed on the surface of the adduct particles by further adding a polyfunctional epoxy compound or a polyfunctional isocyanate compound. The polyfunctional epoxy compound is polymerized on the particle surface by the catalytic action of the adduct to form a polymerized epoxy resin film. In addition, the polyfunctional isocyanate compound reacts with hydroxyl groups, adsorbed moisture and other active hydrogen functional groups present on the surface of the adduct particles to form a polyurethane,
It is thought that it is converted into a polymer such as polyurea to form an encapsulated film. Therefore, by forming these encapsulating layers, the volume average particle diameter of the obtained latent curing agent becomes larger than the volume average particle diameter of the original adduct particles.

Since the thickness of the encapsulating layer is determined by the volume average particle diameter of the adduct particles before the reaction and the amount of the polyfunctional epoxy compound or polyfunctional isocyanate compound used for the surface reaction, the final thickness is obtained. The volume average particle size of the obtained curing agent is also controlled by these factors. For the range of the volume average particle diameter of the adduct particles, the excess addition amount of the polyfunctional epoxy compound and the addition amount of the polyfunctional isocyanate compound, the volume average particle diameter of the obtained curing agent of the present invention is: 0.1 to 200 μm.

The volume average particle diameter referred to here is the value described in 6.3.multidot. Of "Powder, Theory and Application" (Maruzen, 1979 edition).
It refers to the volume-based mean Stokes diameter of particles obtained by gravity or centrifugal sedimentation method shown in Section 4 and Sections 6 ・ 3 ・ 6 (hereinafter simply referred to as “volume-average particle diameter”).

A predetermined amount of a solvent was charged into a reactor, and the selected amine compound, epoxy compound and dispersion stabilizer were dissolved therein. The mixture was heated to a predetermined temperature while stirring and continued to be heated. The reaction solution becomes opaque with the formation of the adduct particles. As the reaction proceeds, the opacity of the system gradually increases, and the milky white color peculiar to the dispersion comes to appear. At this stage, when the amount ratio of the amine compound to the epoxy compound is equivalent, the amine compound / epoxy compound adduct spherical particles are formed, and the polyfunctional epoxy compound is used for the amine compound. In addition, when the equivalent of the polyfunctional epoxy compound is in excess, the spherical adduct particles having an encapsulating layer formed by the polyfunctional epoxy compound on the surface of the amine compound / epoxy compound adduct spherical particles are formed. It is formed. In the former case, the encapsulation layer of the polyfunctional epoxy compound can be formed on the surface of the adduct particles by adding and mixing a further polyfunctional epoxy compound at this point and continuing the reaction. . Further, after the formation of the adduct and the formation of the encapsulating layer, a polyfunctional isocyanate compound is added and the reaction is further continued, so that the surface of the adduct particles or the encapsulating layer of the polyfunctional epoxy compound is formed. An encapsulating layer of a polyfunctional isocyanate compound or a mixed encapsulating layer composed of both can be further formed.

After these reactions are completed, the dispersion is cooled to room temperature and spray-dried with a spray drier for an organic solvent, or collected by forced sedimentation and dried to obtain the desired powder of spherical hardener particles. Is obtained immediately.

Recovery of hardener particles by spray drying is most efficient. By using a cooling device attached to the spray dryer, almost 100% of the solvent used in the reaction can be recovered and can be recycled for the next reaction. Therefore, one of the major features of this process is that almost no solvent is used for the raw material cost. When a spray dryer is not used, the hardener particles are dispersed quite stably in the solvent and the particle size is small, so that it is extremely difficult to recover the particles by a normal filtration method or a natural sedimentation method. In this case, a hardening agent particle can be separated from the solvent by adding a solvent exhibiting an aggregating action to the dispersion system, coagulating and sedimenting the dispersed particles, and filtering or centrifuging. Further drying at a predetermined temperature can recover almost 100% of the particles. The solvent used can be reused by fractional distillation in the same manner as in the spray drying method.

Hereinafter, the present invention will be described in more detail with reference to Comparative Examples and Examples.

The fine powder of the hardener particles used in the comparative examples and examples was prepared by the following method. In order to examine the properties of the obtained curing agent particles as an epoxy resin curing agent, it was blended with Epicoat 828, which is a general-purpose epoxy resin, so as to have substantially the same amine concentration, and was uniformly kneaded in a mortar to obtain a cured composition. In order to examine the properties of the high-temperature curing type curing agent as a curing accelerator, Epicoat 828 was used.
To prepare a cured composition. At that time, dicyandiamide (Dicy) and methylhexahydrophthalic anhydride (MHHPA) were used as a high-temperature curing type curing agent,
The amounts added were 8 phr and 85 phr, respectively.

For the cured composition, an initial viscosity at 25 ° C.
The curing time at each temperature and the viscosity increase factor after storage at 40 ° C. for one week were measured. Further, a part of the cured composition was heated and cured at 100 ° C. for 1 hour and then at 150 ° C. for 3 hours to prepare a cured product, and its glass transition temperature (Tg) and water absorption in boiling water were measured.

The measuring method or the apparatus used was as follows.

Volume average particle diameter : Ultracentrifugal automatic particle size distribution analyzer (CAPA-700, Horiba) Viscosity : B type viscometer (Tokyo Keiki Co., Ltd.).

Curing time : The sample was placed on an aluminum plate for about 0.
1 g of the mixture was dropped, placed in a ventilation circulation oven previously adjusted to a predetermined temperature, heated and cured, and the time required to develop a hardness of H or more in a pencil hardness test was measured.

Tg : Measured by a penetration method using a thermomechanical analyzer (TMA, manufactured by Seiko Denshi Kogyo KK).

Boiling water absorption : about 40 mm in diameter and about 4 m in thickness
m was immersed in boiling water at 100 ° C. for 1 hour, and the weight increase was measured.

Comparative Example 1 600 g of xylene and 300 g of 2-methylimidazole (2MZ) were placed in a 3,000 ml four-neck round bottom flask equipped with a thermometer, a reflux condenser, a dropping funnel and a steel propeller-type stirrer. (3.654 eq.), And the temperature was raised to 120 ° C. while stirring to completely dissolve 2MZ. Then, while stirring, 68 g of xylene was added to 300 g of xylene.
A solution of 0 g of a bisphenol A diglycidyl ether type epoxy resin having an epoxy equivalent of 186 (manufactured by Yuka Shell Epoxy Co., Ltd., Epicoat 828, abbreviated as “EP828”, 3.656 equivalents) was dissolved at a temperature of 120 ° C.
Was added from the dropping funnel over 90 minutes. Since the produced adduct was insoluble in xylene, it was deposited as a viscous candy with the progress of the reaction. The reaction was continued for another 2 hours, and the conversion reached almost 98% or more. Next, the temperature of the content was lowered to room temperature to stop stirring, the xylene in the upper layer was removed by a gradient method, and then the content of the flask was heated to 140 ° C. to remove residual xylene by 10 mm.
Distilled off under reduced pressure of Hg. Next, the molten adduct was poured into a shallow dish and cooled at room temperature to obtain a red-brown adduct mass. This was crushed with a hammer, crushed repeatedly with a jet mill, and finally classified to obtain a yellow fine powder. The volume average particle diameter of this fine powder was 2.9 μm.

Comparative Example 2 325 g of methyl isobutyl ketone (MIBK) was placed in a 1,000-ml four-necked round-bottomed flask equipped with a thermometer, a reflux condenser, a dropping funnel and a steel propeller-type stirrer.
And 162.5 g of 2-phenylimidazole (2PZ)
(0.4514 equivalents) and the temperature was increased to 10 while stirring.
The temperature was raised to 0 ° C. to completely dissolve 2PZ. Next, a solution prepared by dissolving 195.2 g of bisphenol A diglycidyl ether having an epoxy equivalent of 173 (manufactured by Dow Chemical Co., Ltd., DER332, 0.4514 equivalent) in 195 g of MIBK while stirring was added while maintaining the temperature at 100 ° C.
Added via dropping funnel over 0 minutes. Since the produced adduct was insoluble in MIBK, it was precipitated as a viscous candy with the progress of the reaction. The reaction was continued for another 4 hours, and the conversion reached almost 98% or more. Next, the temperature of the contents was lowered to room temperature to stop stirring, and the upper MIB
After removing K by a decanting method, the content of the flask was
The mixture was heated to 140 to 140 ° C., and the remaining MIBK was distilled off under a reduced pressure of 10 mmHg. Next, the molten adduct was poured into a shallow dish and cooled at room temperature to obtain a brown adduct mass. This was ground and classified in the same manner as in Comparative Example 1 to obtain a yellow fine powder, and the volume average particle diameter of the powder was 4.5 μm.

Comparative Example 3 In a 500 ml beaker equipped with a thermometer, a band heater and a steel propeller type stirring device, 276.8 g was placed.
Of DER332 (1.60 equivalents) was heated with a band heater while stirring the contents. Content temperature is 7
When the temperature reaches 0 to 75 ° C, the heating is stopped and the liquid 2-
Ethyl-4-methylimidazole (EMI-24) 17
6.3 g (1.60 equivalents) are added at once, and 500 rpm
The contents were uniformly mixed while stirring at a high speed. The temperature of the contents once dropped to about 60 ° C., but shortly thereafter, heat generation due to the addition reaction was observed, and the temperature rapidly increased to 23 ° C.
The temperature reached about 0 ° C. When the temperature was lowered gradually to 140 ° C while stirring the contents, the adduct formed became a viscous candy, which was poured into a shallow dish and cooled to room temperature to obtain a red-brown adduct mass. Was. This was ground and classified in the same manner as in Comparative Example 1 to obtain a yellow fine powder, and the powder had a volume average particle size of 4.3 μm.

Comparative Example 4 A 1,000-ml three-necked round-bottomed flask equipped with a thermometer, a reflux condenser, and a Teflon half-moon type stirring device was prepared.
28.0 g of 2-methylimidazole (2MZ, 0.3
4 equivalents) and poly ((styrene-c
4.54 g of o-glycidyl methacrylate) -g-methyl methacrylate) graft copolymer (Reseda GP-300, manufactured by Toagosei Co., Ltd.) was charged, and 542.
After adding 53 g of MIBK, the temperature was increased to 70 ° C. to completely dissolve. Then 50% MI of Epicoat 828
125.60 g (0.34 equivalent) of the BK solution was added, and the contents were reacted at 70 ° C. for 9 hours while stirring at a speed of 300 rpm. The initially colorless and transparent reaction liquid gradually changed to a milky white and opaque liquid as the reaction time elapses, and became a creamy milky white dispersion at the end of the reaction.

When the reaction rate reaches 100% in a reaction at 70 ° C. for 9 hours, the reaction mixture is cooled to room temperature, spray-dried with a spray dryer for organic solvent system (manufactured by Yamato Scientific Co., Ltd., Model GS-31), and cured. The particles were collected. The spray drying conditions were as follows.

Drying chamber inlet temperature: 100 ° C. Drying chamber outlet temperature: 74 ° C. Condenser outlet temperature: 16 ° C. Spray nozzle diameter: 0.4 mm Spray pressure: 1.2 kg / cm ² Hot air flow rate: 0.5 m ³ / min Speed: 10 g / min By this spray drying, almost the theoretical amount of hardener particles was recovered as a white dry powder. Observation with a scanning electron microscope revealed that the hardener particles were recovered as almost primary particles. The volume average particle diameter of the obtained hardener particles was 2.8 μm, as measured by an ultracentrifugal automatic particle size distribution analyzer (CAPA-700, manufactured by Horiba, Ltd.).
Met. The recovery rate of MIBK as a solvent is 99.
2%.

Comparative Example 5 A 1,000-ml three-necked round-bottomed flask equipped with a thermometer, a reflux condenser, and a Teflon half-moon stirring device was prepared.
40.37 g of 2-phenylimidazole (2PZ,
0.280 equiv.) And 4.44 g of Reseda GP-300.
And then add 543.6 g of MIBK to it,
The temperature was raised to 70 ° C. to completely dissolve. Then DER3
96.88 g (0.280 equivalent) of a 50% MIBK solution of 32 was added, and the contents were reacted at 70 ° C. for 15 hours with stirring at a speed of 300 rpm. The initially colorless and transparent reaction liquid gradually turned into a milky white and opaque liquid as the reaction time passed, and became a creamy uniform and stable dispersion at the end of the reaction. The dispersion of the hardener particles thus synthesized was transferred to a 2,000 ml beaker, and about 50 ml of n-hexane was gradually added while stirring the contents.
The dispersed particles were coagulated and settled. The particles were separated by filtration through a glass filter and further dried under vacuum at 50 ° C. for 2 days to obtain a creamy white powder in a yield of 95.5%. The volume average particle diameter of the obtained curing agent particles was 3.8 μm.

Comparative Example 6 A 1,000-ml three-necked round-bottomed flask equipped with a thermometer, a reflux condenser, and a Teflon half-moon stirring device was prepared.
Charge 20.00 g of 2-ethyl-4-methylimidazole (EMI-24, 0.182 equivalents) and 2.57 g of Reseda GP-300, and add 310.4 g of MIB
After K was added, the temperature was raised to 70 ° C. to completely dissolve. Then, a 50% MIBK solution of DER332, 62.8.
3 g (0.182 equivalents) were added, and the content was reduced to 300 rpm.
The reaction was carried out at 70 ° C. for 15 hours while stirring at a speed of. The initially yellow and transparent reaction liquid gradually changed to a yellow-brown and opaque liquid as the reaction time passed, and became a yellow-brown uniform and stable dispersion at the end of the reaction. The dispersion of the hardener particles thus synthesized was subjected to coagulation, sedimentation and recovery of the dispersed particles with n-hexane in the same manner as in Comparative Example 5, and the particles were separated by filtration through a glass filter, and further vacuum-dried at 45 ° C. for 2 days to obtain yellow. Was obtained in a yield of 70.0%. The volume average particle diameter of the obtained curing agent particles was 4.1 μm.

In the reactions of Comparative Examples 1 to 6, the amine compound / epoxy compound adduct particles were synthesized stoichiometrically, in which case no modification reaction was performed.

Example 1 A three-necked, round-bottomed flask having an inner volume of 1,000 ml equipped with a thermometer, a reflux condenser and a Teflon half-moon type stirring device was prepared.
28.0 g of 2-methylimidazole and 4.99 g of Reseda GP-300 were charged, and 593.95 g of M was added thereto.
After IBK was added, the temperature was raised to 70 ° C. to completely dissolve. Next, a 50% MIBK solution 1 of Epikote 828
43.74 g was added, and the contents were reacted at 70 ° C. for 10 hours while stirring at a speed of 300 rpm, and the reaction rate was almost 1%.
00%. At the end of the reaction, a uniform and stable dispersion was obtained which was almost the same in appearance as Comparative Example 4. The dispersion of the hardener particles thus synthesized was spray-dried under the same conditions as in Comparative Example 4 to quantitatively obtain a dried white powder. The volume average particle diameter of the obtained curing agent particles is 2.8 μm.
m.

In the present example, the curing agent particles were synthesized by a one-step method in which the polyfunctional epoxy compound was added in an excess of 9% as compared with Comparative Example 4 in the first stage of charging.

Example 2 A 1,000-ml three-necked round-bottomed flask equipped with a thermometer, a reflux condenser and a Teflon half-moon type stirring device was prepared.
26.0 g of 2-methylimidazole and 5.06 g of Reseda GP-300 were charged, and 599.47 g of M was added thereto.
After IBK was added, the temperature was raised to 70 ° C. to completely dissolve. Next, a 50% MIBK solution 1 of Epikote 828
50.40 g was added, and the contents were reacted at 70 ° C. for 11 hours while stirring at a speed of 300 rpm, and the reaction rate was almost 1%.
00%. At the end of the reaction, a uniform and stable dispersion was obtained which was almost the same in appearance as Comparative Example 4. The dispersion of the hardener particles thus synthesized was spray-dried under the same conditions as in Comparative Example 4 to quantitatively obtain a dried white powder. The volume average particle diameter of the obtained curing agent particles is 2.9 μ.
m.

In this example, the curing agent particles were synthesized by a one-step method in which the polyfunctional epoxy compound was added in an excess of 19% as compared with Comparative Example 4 in the first stage of charging.

Example 3 A 1,000-ml three-necked round-bottomed flask equipped with a thermometer, a reflux condenser, and a Teflon half-moon type stirring device was prepared.
23.0 g of 2-methylimidazole and 4.95 g of Reseda GP-300 were charged, and 584.17 g of M was added thereto.
After IBK was added, the temperature was raised to 70 ° C. to completely dissolve. Next, a 50% MIBK solution 1 of Epikote 828
52.06 g was added thereto, and the contents were reacted at 70 ° C. for 12 hours while stirring at a speed of 300 rpm.
00%. At the end of the reaction, a uniform and stable dispersion was obtained which was almost the same in appearance as Comparative Example 4. The dispersion of the hardener particles thus synthesized was spray-dried under the same conditions as in Comparative Example 4 to quantitatively obtain a dried white powder. The volume average particle diameter of the obtained curing agent particles is 3.0 μm.
m.

In this example, the curing agent particles were synthesized by a one-step method by adding a 33% excess of the polyfunctional epoxy compound as compared with Comparative Example 4 in the first stage of charging.

Example 4 A 1,000 ml three-necked round-bottomed flask equipped with a thermometer, a reflux condenser and a Teflon half-moon type stirring device was prepared.
24.0 g of 2-methylimidazole and 3.90 g of Reseda GP-300 were charged into which 465.03 g of M were added.
After IBK was added, the temperature was raised to 70 ° C. to completely dissolve. Next, a 50% MIBK solution 1 of Epikote 828
07.66 g was added, and the contents were reacted at 70 ° C. for 9 hours while stirring at a speed of 300 rpm. Further, 51.01 g of a 50% MIBK solution of Epicoat 828 and 21.43 g of MIBK for washing were added, and the mixture was further reacted at the same temperature for 4 hours to reach a reaction rate of almost 100%. At the end of the reaction, a uniform and stable dispersion which was almost the same in appearance as in Example 3 was obtained. The dispersion of the hardener particles thus synthesized was spray-dried under the same conditions as in Comparative Example 4 to quantitatively obtain a dried white powder. The volume average particle diameter of the obtained curing agent particles was 3.0 μm.

In this example, the curing agent particles were synthesized by a two-step method by synthesizing the same particles as in Comparative Example 4 with a yield of 100%, and then adding an excess of 33% of a polyfunctional epoxy compound. Things.

Example 5 A 1,000-ml three-necked round-bottomed flask equipped with a thermometer, a reflux condenser, and a Teflon half-moon stirring device was prepared.
40.37 g of 2-phenylimidazole (2PZ,
0.280 equiv.) And 4.44 g of Reseda GP-300.
Was added, and 543.6 g of MIBK was added thereto, and then the temperature was increased to 70 ° C. to completely dissolve. Then DE
96.88 g of a 50% MIBK solution of R332 (0.28
0 equivalent) and the contents were reacted at 70 ° C. for 18 hours with stirring at a speed of 300 rpm. The initially colorless and transparent reaction liquid gradually changed to a milky white and opaque liquid as the reaction time elapsed, and became a creamy uniform and stable dispersion. To this, 44.50 g of 50% MIBK solution of Epikote 828 and 20.0 g of MIBK for cleaning were added.
Next, the mixture was added and reacted at the same temperature for 6 hours. At the end of the reaction, a cream-colored uniform and stable dispersion was obtained. The dispersion of the hardener particles synthesized in this manner was subjected to coagulation sedimentation and recovery of the dispersed particles with n-hexane in the same manner as in Comparative Example 5, and the particles were separated by a glass filter.
It was vacuum-dried at 2 ° C. for 2 days to obtain a creamy white powder almost quantitatively. The volume average particle diameter of the obtained curing agent particles was 4.1 μm.

In this example, the curing agent particles were prepared by synthesizing the same particles as in Comparative Example 5 at a yield of almost 100%, and then adding a 25% excess of a polyfunctional epoxy compound by a two-step method. It was done.

Example 6 A 1,000-ml three-necked round-bottomed flask equipped with a thermometer, a reflux condenser and a Teflon half-moon type stirring device was prepared.
Charge 20.00 g of 2-ethyl-4-methylimidazole (EMI-24, 0.182 equivalents) and 2.57 g of Reseda GP-300, and add 310.4 g of MIB
After K was added, the temperature was raised to 70 ° C. to completely dissolve. Then, a 50% MIBK solution of DER332, 62.8.
3 g (0.182 equivalents) were added, and the content was reduced to 300 rpm.
The reaction was carried out at 70 ° C. for 15 hours while stirring at a speed of. The initially yellow and transparent reaction liquid gradually changed to a yellow-brown and opaque liquid as the reaction time passed, and became a yellow-brown uniform and stable dispersion at the end of the reaction. To this, 31.42 g of 50% MIBK solution of Epikote 828 and 20.0 g of MIBK for washing were added secondarily, and further reacted at the same temperature for 6 hours. At the end of the reaction, a dark cream uniform and stable dispersion was obtained. Was. The dispersion of the hardener particles thus synthesized was subjected to coagulation, sedimentation and collection of the dispersed particles with n-hexane in the same manner as in Comparative Example 5, and the particles were separated by filtration through a glass filter, and further dried in vacuo at 45 ° C. for 2 days to obtain a yellow liquid. A powder was obtained with a yield of 87.1%. The volume average particle diameter of the obtained curing agent particles was 4.4 μm.

In this example, the curing agent particles were obtained by synthesizing the same particles as in Comparative Example 6 and then adding a polyfunctional epoxy compound in an excess of 31% in a two-step method.

Example 7 In a 1,000 ml four-necked round-bottomed flask equipped with a thermometer, a reflux condenser, a dropping funnel and a Teflon half-moon stirring device, 24.0 g of 2-methylimidazole and 3. 90g of Reseda GP-300 is charged, and 46
After adding 5.03 g of MIBK, the temperature was increased to 70 ° C. to completely dissolve. Then 50% of Epikote 828
107.66 g of MIBK solution was added, and the contents were
The reaction was carried out at 70 ° C. for 9 hours while stirring at a speed of pm.
Methylene diphenyl diisocyanate (MD
I, Millionate M, manufactured by Nippon Polyurethane Industry Co., Ltd.
49.04 g of a 10% MIBK solution of T) was slowly dropped from the funnel, and after the completion of the dropping, the mixture was further reacted at the same temperature for 5 hours to reach a reaction rate of almost 100%. At the end of the reaction, a slightly dark cream color was obtained, but a uniform and stable dispersion was obtained. The dispersion of the hardener particles thus synthesized was spray-dried under the same conditions as in Comparative Example 4 to quantitatively obtain a dried cream-white powder. The volume average particle diameter of the obtained curing agent particles was 2.9 μm.

In this example, as the curing agent particles, the same adduct particles as in Comparative Example 4 were synthesized at a yield of 100%, and then a polyfunctional isocyanate compound was added at 6% to the adduct particles. It was prepared by

Example 8 In a 1,000 ml four-neck round bottom flask equipped with a thermometer, a reflux condenser, a dropping funnel and a Teflon half-moon stirring device, 24.0 g of 2-methylimidazole and 3. 90g of Reseda GP-300 is charged, and 46
After adding 5.03 g of MIBK, the temperature was increased to 70 ° C. to completely dissolve. Then 50% of Epikote 828
107.66 g of MIBK solution was added, and the contents were
The reaction was carried out at 70 ° C. for 9 hours while stirring at a speed of pm.
Further, a 50% MIBK solution 13.1 of Epicoat 828 is used.
6 g was added and further reacted at the same temperature for 4 hours to reach a reaction rate of almost 100%. Next, 1 of methylene diphenyl diisocyanate (MDI, millionate MT)
49.04 g of a 0% MIBK solution was slowly added dropwise from the funnel, and after completion of the addition, the mixture was further reacted at the same temperature for 5 hours. At the end of the reaction, a uniform and stable dispersion which was almost the same in appearance as in Example 7 was obtained. The dispersion of the hardener particles thus synthesized was spray-dried under the same conditions as in Comparative Example 4 to quantitatively obtain a creamy white powder. The volume average particle diameter of the obtained curing agent particles was 3.0 μm.

In this example, the curing agent particles were synthesized by a two-step method in which the polyfunctional epoxy compound was similarly added in an excess of 8%, and then the polyfunctional isocyanate compound was added by 6% to the adduct particles. It was prepared by

[0084]

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5] One embodiment of the present invention is characterized in that when an amine compound / epoxy compound adduct is synthesized, an excess of a polyfunctional epoxy compound is treated in the course of the reaction. The effect is shown in Table 2. ing. As a comparative example, a case where no processing is performed is shown in Table 1. Further, as a second aspect, after the above-mentioned adduct is synthesized, it is treated with a polyfunctional isocyanate compound.
Is characterized in that after the treatment with the excess polyfunctional epoxy compound, the composition is further treated with a polyfunctional isocyanate compound. The effects thereof are shown in Table 3. These tables show the preparation conditions and results of the hardener particles and the properties as the hardener. The properties of dicyandiamide (Dicy) and acid anhydride (MHHPA) as curing accelerators are shown in Tables 4 and 5, respectively.

As is clear from Table 1, the usual solution addition reaction (synthesis in a solvent, Comparative Examples 1 and 2) and the bulk addition reaction (synthesis without a solvent, Comparative Example 3), followed by solvent removal, pulverization,
The stoichiometry was determined by the method of classification (referred to as “pulverization method”) and the method of precipitation or dispersion addition reaction in an organic solvent proposed by the present applicant (referred to as “Comparative Examples 4, 5, 6, and“ Precipitation method ”). Epoxy resin cured compositions prepared from crushed or spherical hardener particles of an amine compound / epoxy compound adduct that has been synthesized and not subjected to any treatment have a temperature of 100 ° C. regardless of the shape of the hardener particles. 120 ° C
, And shows good cured properties, but has a disadvantage that storage stability is extremely poor. In the case of hardener particles crushed at 40 ° C. (Comparative Examples 1, 2, and 3), gelation occurs in only one day, and in the case of spherical hardener particles (Comparative Examples 5 and 6), they are slightly improved. Gelled in two days. Table 1
As can be seen from the above, spherical hardener particles synthesized by the precipitation method give an epoxy resin cured composition having a relatively lower viscosity than crushed hardener particles prepared by the pulverization method. Also, the potential is improved (especially Comparative Example 4), probably because the specific surface area of the spherical particles is relatively small,
It is also considered that the polymer dispersion stabilizer used for the reaction was fixed on the surface of the particles to form a kind of encapsulating film.

On the other hand, as can be seen from Table 2, when synthesizing the amine compound / epoxy compound adduct, an excessive amount of the polyfunctional epoxy compound was added in the course of the reaction (excess amount at the start of the reaction). The epoxy resin cured composition prepared from the curing agent particles (the present invention) obtained by the reaction in a one-stage method of adding, or a two-stage method of adding an excess amount during the reaction or after the end of the adduct formation reaction) is described in Table 1. Compared with Comparative Example 1, if the amine concentration is the same, the curing performance and the cured physical properties at the ordinary curing temperature (120 to 150 ° C.) are almost the same and good, but the storage stability is considerably improved. I have. Literature (A. Farkas and PFStrohm, J.
Appl.Polym.Sci., 12 , 159 (1968) and JMBarton and PMS
According to hepherd, Makromol. Chem., 176 , 919 (1975)), it is suggested that the addition reaction occurs before the polymerization reaction during the curing reaction of the epoxy resin with the amine compound. Therefore, in the course of the adduct formation reaction in the present invention, an excessive amount of the polyfunctional epoxy compound is added at an arbitrary stage, so that the adduct particles are formed first, and then an excessive amount of the polyfunctional epoxy compound is formed on the surface thereof. It is considered that the encapsulating layer of the polymerized epoxy resin is formed by the reactive epoxy compound. It is considered that this encapsulating layer contributes to the improvement of the potential of the curing agent, and it is observed that the higher the added amount of the polyfunctional epoxy compound used in the reaction, the more the potential is improved. Examples 1-3). Further, when the excess amount of the polyfunctional epoxy compound is large (Examples 3 to 6) reflecting this, the curability is slightly slowed at 100 ° C. or less, but the storage stability is extremely long at room temperature and 40 ° C. , Indicating that the potential is extremely excellent. Further, the particle size of the obtained curing agent particles shows a tendency to increase, though slightly, as the amount of the polyfunctional epoxy compound added increases, and the particle yield hardly changes, and the yield is almost 100%. Can be recovered. Further, although there is almost no difference depending on the reaction system, hardener particles obtained by a one-stage method in which an excessive amount of a polyfunctional epoxy compound is excessively added at the initial stage of the preparation (Example 3, Gel Time = 122 sec / 10)
(0 ° C.) compared with (0 ° C.) hardener particles obtained by a two-step method in which an excess amount of a polyfunctional epoxy compound is added after formation of adduct particles (Example 4, Gel Time = 105 sec / 100 ° C.)
Seems to be relatively reactive.

Table 3 shows the effects of the second and third embodiments of the present invention. By treating the curing agent particles of the amine compound / epoxy compound adduct with the polyfunctional isocyanate compound, it is considered that an encapsulation layer is formed on the surface of the adduct particles due to the formation of urethane resin, and the potential of the curing agent Contributes to the improvement of Further, when the polyfunctional epoxy compound is excessively added and reacted, and then further treated with a polyfunctional isocyanate compound, a further synergistic effect is expected. As shown in Table 3, the curing agent particles obtained by further treating with the polyfunctional isocyanate compound after completion of the addition reaction were compared with the curing agent particles of the adduct that had not been treated at all (comparatively 4). In Example 7), the potential is improved as in the case where the polyfunctional epoxy compound is excessively added. The curing agent particles (Example 8) obtained by excessively adding and reacting the polyfunctional epoxy compound and then further treating with the polyfunctional isocyanate compound have a normal curing temperature (120 to 15).
At 0 ° C.), the epoxy resin is quickly cured to give excellent physical properties, and the storage stability of the epoxy resin cured composition prepared from such a curing agent is greatly improved. It was found that it did not thicken and exhibited a pot life of one year or more at room temperature.

Tables 4 and 5 show the properties when the curing agent particles obtained in Examples 3 to 8 were used as a curing accelerator for a high-temperature curing type curing agent in comparison with Comparative Examples 4 to 6. ing. As is evident from the table, the hardener particles prepared according to the invention consist of dicyandiamide (Table 4) and acid anhydride (MH).
When used as a curing accelerator in HPA, Table 5), 120
The curing temperature could be lowered to 100 ° C. as well as the temperature above 100 ° C., and the epoxy resin could be cured at 100 ° C. in a short time of 15 to 20 minutes. In addition, it was observed that the viscosity was hardly increased even after storage at 40 ° C. for one week, and that the storage stability was considerably superior to that of the comparative example. Further, the obtained cured product also exhibited good cured physical properties.

(Effects of the Invention) As described above, when synthesizing spherical amine compound / epoxy compound adduct particles by precipitation or dispersion addition reaction, (a) excess polyfunctional epoxy compound, (b) polyfunctional epoxy compound By treating with either a functional isocyanate compound or (c) an excess of a polyfunctional epoxy compound and a polyfunctional isocyanate compound, an encapsulating film is formed on the surface of the particles by polymerization of an epoxy resin or generation of a urethane resin. To be formed,
As a curing agent for an epoxy resin of the obtained adduct particles, curing performance at a normal curing temperature (120 to 150 ° C.)
Without impairing the cured properties, the potential can be greatly improved, and when used as a high-temperature curing type curing agent, for example, a dicyandiamide or acid anhydride curing accelerator, low-temperature fast-curing, storage stability It was also possible to provide an epoxy resin cured composition having excellent cured physical properties.

The production and recovery processes of the latent hardener particle fine powder according to the present invention are considerably simplified as compared with the conventional pulverization method, as is clear from the examples, so that the production cost is reduced. There is expected. Further, since the obtained curing agent particles are spherical fine powder, (1) high bulk density contributes to reduction of packaging and transportation costs; (2) good dispersibility in epoxy resin and more uniform curing Imparts structure; (3) the viscosity rise of the compound is small and the degree of freedom in compounding design can be increased; (4) the hardener itself is a fine powder, so that it does not deteriorate even if it is stored at room temperature over time. Show the benefits. Furthermore, since it has the above-mentioned excellent performance, it is considered that the advantages of the one-component epoxy resin cured composition can be fully utilized.

Taking advantage of this property, the spherical latent curing agent particles of the present invention can provide a one-component epoxy resin cured composition to a wide range of fields. Expected areas of application include structural adhesives, such as vehicle assembly adhesives, optical machine assembly adhesives, and electronic and electrical equipment assembly adhesives;
Paint field, for example powder paint, baking paint, etc .; electronic field, for example, printed circuit board glass cloth impregnating material, IC
Chip sealing material, conductive paint, solder resist ink,
Die bonding adhesives, printed circuit board adhesives, conductive adhesives, etc .; in the electrical field, for example, electrical insulating materials, coil impregnating materials, battery case adhesives, tape head adhesives, etc.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-47-33200 (JP, A) JP-A-58-13623 (JP, A) JP-A-61-268721 (JP, A) JP-A-59-33 49223 (JP, A) JP-A-1-113480 (JP, A) Patent 3098760 (JP, B2) Patent 3168016 (JP, B2) Patent 2914390 (JP, B2) (58) Fields investigated (Int. Cl. ⁷⁾ , DB name) C08G 59/50 C08G 59/40

Claims (10)

(57) [Claims] An epoxy resin characterized in that it is a spherical adduct synthesized from an amine compound and an epoxy compound, and further has an encapsulating layer formed of a polyfunctional epoxy compound on its surface. For latent curing agent. 2. An epoxy resin which is a spherical adduct synthesized from an amine compound and an epoxy compound, and further has an encapsulating layer formed of a polyfunctional isocyanate compound on the surface thereof. For latent curing agent. 3. An adduct having a spherical shape synthesized from an amine compound and an epoxy compound, further comprising an encapsulation layer formed of a polyfunctional epoxy compound on the surface thereof, and further comprising the epoxy encapsulation. A latent curing agent for an epoxy resin, comprising an encapsulating layer formed of a polyfunctional isocyanate compound on the layer, or a mixed encapsulating layer thereof. 4. An amine compound and an excess amount of a polyfunctional epoxy compound with respect to the amine compound are dissolved together in the presence of a dispersion stabilizer to form the amine compound and the epoxy compound. 2. The adduct is reacted in an insoluble organic solvent.
The method for producing a latent curing agent for an epoxy resin according to the above. 5. An amine compound and an epoxy compound are reacted in the presence of a dispersion stabilizer in an organic solvent which dissolves both the amine compound and the epoxy compound but does not dissolve an adduct formed from both. The method for producing a latent curing agent for an epoxy resin according to claim 1, wherein a further polyfunctional epoxy compound is added during or after the reaction to further react. 6. After reacting an amine compound and an epoxy compound in an organic solvent which dissolves both the amine compound and the epoxy compound in the presence of a dispersion stabilizer but does not dissolve an adduct formed from both. 3. The method for producing a latent curing agent for an epoxy resin according to claim 2, wherein a polyfunctional isocyanate compound is added to cause a further reaction. 7. An amine compound and an excess amount of a polyfunctional epoxy compound with respect to the amine compound are dissolved together in the presence of a dispersion stabilizer to form the amine compound and the epoxy compound. The method for producing a latent curing agent for an epoxy resin according to claim 3, wherein after reacting the adduct in an organic solvent in which the adduct is not dissolved, a polyfunctional isocyanate compound is added to further react. 8. An amine compound and an epoxy compound are reacted in the presence of a dispersion stabilizer in an organic solvent which dissolves both the amine compound and the epoxy compound but does not dissolve an adduct formed from both. 4. The method according to claim 3, wherein a further polyfunctional epoxy compound is added during the reaction or after the completion of the reaction to further carry out the reaction, and then a polyfunctional isocyanate compound is further added to carry out the reaction. A method for producing a latent curing agent for an epoxy resin according to the above. 9. A one-component thermosetting composition comprising the latent curing agent for epoxy resin according to claim 1 and an epoxy resin as main components. 10. A one-pack type composition comprising an epoxy resin and a high-temperature curing type curing agent as main components, and the latent curing agent for an epoxy resin according to claim 1 as a curing accelerator. Thermosetting composition.