JP5158088B2 - Microcapsule type latent curing agent for epoxy resin and method for producing the same, and one-part epoxy resin composition and cured product thereof - Google Patents

Description

  The present invention relates to a microcapsule-type latent curing agent for epoxy resin, a method for producing the same, and a one-pack epoxy resin composition and a cured epoxy resin.

  Epoxy resin has excellent performance in terms of mechanical properties, electrical properties, thermal properties, chemical resistance, adhesiveness, etc., and it can be used for paints, insulating materials for electrical and electronic materials, adhesives, etc. It is used for a wide range of applications. Many of the epoxy resin compositions generally used at present are so-called two-component compositions in which two components of an epoxy resin and a curing agent are mixed at the time of use.

  The two-part epoxy resin composition can be cured at room temperature, but it is necessary to store the epoxy resin and the curing agent separately and weigh and mix them as necessary. It is. In addition, since the pot life is limited, it cannot be mixed in a large amount in advance, the blending frequency increases, and the efficiency is unavoidable.

In order to solve the problem of such a two-part epoxy resin composition, several one-part epoxy resin compositions have been proposed so far. For example, there is an epoxy resin blended with a latent curing agent such as dicyandiamide, BF ₃ -amine complex, amine salt and modified imidazole compound.

In addition, studies have been made to impart latency to the curing agent by reacting the surface of the powdery amine compound with isocyanate to inactivate the surface of the amine compound (Patent Documents 1 to 5). Furthermore, a microcapsule type curing agent encapsulated by reacting a powdered amine compound with isocyanate in an epoxy resin has also been proposed (Patent Documents 6 to 8). For example, Patent Document 6 discloses a master batch type curing agent obtained by a method in which an amine curing agent as a core is dispersed in an epoxy resin, and an isocyanate and water are added thereto to form a shell. Other methods include mixing an epoxy resin and an amine curing agent and immediately freezing to stop the progress of the reaction, microencapsulating the amine curing agent, and adsorbing the curing agent on the molecular sieve. is there.
Japanese Patent Publication No.58-55970 JP 59-27914 A JP 59-59720 A European Patent Application No. 193068 JP-A-61-190521 JP-A-1-70523 JP 2004-269721 A JP 2005-344046 A

  However, in the case of conventional latent curing agents, those having excellent storage stability have low curability and require high temperature or a long time for curing. On the other hand, those having high curability have low storage stability and need to be stored at a low temperature such as -20 ° C. For example, a one-part epoxy resin composition containing dicyandiamide has a storage stability of 6 months or more when stored at room temperature, but requires a curing temperature of 170 ° C. or more. When a curing accelerator is used in combination to lower the curing temperature, curing at, for example, 130 ° C. to 150 ° C. is possible. However, in that case, since the storage stability at room temperature is insufficient, storage at a low temperature is unavoidable, and the pot life is shortened. As a result, the potential of dicyandiamide is not fully utilized. The epoxy resin composition used when manufacturing a film-shaped molded article or a product in which the base material is impregnated with the epoxy resin composition is often used in combination with a solvent or a reactive diluent. When a conventional latent curing agent is used in a compounded product, the storage stability is extremely lowered. For this reason, it is necessary to make the blended product substantially two-component, and improvement has been demanded.

  As in Patent Document 3, the method by blocking the surface functional group of an amine compound is not necessarily sufficient in terms of the properties required as a one-part epoxy resin composition, particularly in terms of storage stability. Further, when the one-component epoxy resin composition is actually used, its uniformity is also important. Therefore, generally, it is necessary to uniformly disperse the powdery curing agent in the epoxy resin with a roll or other equipment. However, even if any of the methods disclosed in Patent Documents 1 to 4 is used, the inactive surface layer once generated by the mechanical shearing force accompanying the dispersion operation at room temperature is destroyed, and as a result, it is practically used. There is also a problem that sufficient storage stability cannot be obtained in order to withstand.

  On the other hand, according to the method of freezing, microencapsulation, or molecular sieve described above, relatively good storage stability can be obtained, but performance, particularly cured product characteristics are not sufficient, and practical application has hardly been made. is the current situation.

  As described above, a one-component epoxy resin composition that can achieve both high curability and excellent storage stability has been strongly demanded. Particularly in recent years, in order to improve productivity in electronic material applications, further improvements in curing characteristics and storage stability have been demanded for one-part resin compositions.

  Then, an object of this invention is to provide the hardening | curing agent which enables coexistence of the low-temperature curability of the one-component epoxy resin composition, and the outstanding storage stability, and its manufacturing method. Another object of the present invention is to provide a one-part epoxy resin composition using the curing agent and a cured product thereof.

  In one aspect, the present invention relates to a microcapsule type latent curing agent having a core and a capsule covering the core. In the microcapsule type curing agent according to the present invention, the core includes an amine adduct, and the capsule includes a reaction product of an isocyanate and a compound having an active hydrogen group and / or water. At least a portion of the reaction product is bound to the core by reaction with the amine adduct. The microcapsule type curing agent according to the present invention is used to cure an epoxy resin. The microcapsule-type latent curing agent according to the present invention may be in a powder form.

  According to the microcapsule-type curing agent according to the present invention, it is possible to achieve both low temperature curability and excellent storage stability of the one-part epoxy resin composition.

  In order to make the effect of the present invention more remarkable, the core preferably contains 50 to 100% amine adduct in mass ratio.

  The ratio of the capsule is preferably 5 to 80% by mass based on the total mass of the microcapsule-type latent curing agent. This makes it possible to achieve both low-temperature curability and storage stability at a higher level.

  40-80 mass% may be sufficient as the ratio of a capsule. Thereby, the latent curing agent can have very good storage stability and solvent resistance. Further, excellent low temperature curability is also achieved. Therefore, for example, even when the latent curing agent is mixed with a solvent and left for a long time, the low temperature curability can be maintained without the core component of the microcapsule type latent curing agent being eluted by the solvent. .

  The ratio of the capsule may be 15 to 40% by mass. Thereby, the latent curing agent can have better storage stability and solvent resistance, can also have better low-temperature curability, and can have these characteristics at a very high level. Therefore, for example, even when a latent curing agent is mixed with an epoxy resin and left in a heated state such as about 40 ° C. for one week, the reaction with the epoxy resin proceeds to increase the viscosity, and its low temperature curing characteristics Is not lost, and good storage stability and good low-temperature curability can be exhibited.

  The ratio of the capsule may be 5 to 15% by mass. Thereby, the latent curing agent can have better storage stability and solvent resistance while having very good low-temperature curability.

  In another aspect, the present invention relates to a method for producing a microcapsule latent curing agent for epoxy resin. The production method according to the present invention includes a step of forming a capsule covering the core by reacting an amine adduct contained in the core, an isocyanate, a compound having an active hydrogen group and / or water in a dispersion medium. The production method according to the present invention may further include a step of taking out a powdery microcapsule-type latent curing agent having a core and a capsule from the mixture after the reaction.

  According to the production method of the present invention, it is possible to obtain a microcapsule-type curing agent capable of achieving both low temperature curability and excellent storage stability of a one-part epoxy resin composition while suppressing variation in characteristics. it can. The microcapsule-type latent curing agent according to the present invention may be obtained by the production method according to the present invention.

  In still another aspect, the present invention relates to a one-part epoxy resin composition. The one-component epoxy resin composition according to the present invention contains the above-described microcapsule type latent curing agent for epoxy resin according to the present invention and an epoxy resin.

  The one-part epoxy resin composition according to the present invention has low temperature curability and excellent storage stability.

  The microcapsule-type latent curing agent for epoxy resin may be heat-treated in epoxy resin. The one-part epoxy resin composition according to the present invention preferably contains 5 to 70 parts by mass of a microphone capsule type latent curing agent with respect to 100 parts by mass of the total amount of the epoxy resin and the microphone capsule type latent curing agent. .

  In yet another aspect, the present invention relates to a cured product of an epoxy resin composition. The cured product according to the present invention is formed by curing the one-component epoxy resin composition according to the present invention by heating. The cured product according to the present invention is particularly excellent in terms of electrical characteristics (insulating properties).

  According to the microcapsule type curing agent according to the present invention, it is possible to achieve both low temperature curability and excellent storage stability of a one-part epoxy resin composition. For this reason, the microcapsule type curing agent according to the present invention is preferably used in order to improve productivity in applications such as electronic materials.

The powdery microcapsule-type latent curing agent according to the present invention has an excellent effect in the following points.
(1) Since it is in a powder form, it can be easily and uniformly dispersed in an epoxy resin in accordance with the purpose in consideration of curing characteristics and physical properties of the cured product. Moreover, the freedom degree of the compounding ratio of the hardening | curing agent in an epoxy resin composition is also high.
(2) Since the capsule portion can be easily controlled, a latent curing agent having good curing characteristics and good storage stability can be easily achieved according to the purpose.
(3) Since a one-component epoxy resin composition can be easily produced, workability at the time of use is improved and high reliability of the product can be obtained.

  The microcapsule-type latent curing agent according to the present invention also has an effect that there is little change in performance even by a mechanical shear force applied when preparing a one-pack type epoxy resin composition.

  According to the production method of the present invention, it is possible to obtain a microcapsule-type curing agent that can achieve both low-temperature curability and excellent storage stability of a one-part epoxy resin composition while suppressing variation in characteristics. . In the case of a conventional production method in which a powdered amine compound is reacted with an isocyanate in an epoxy resin, for example, in order to increase the amount of a microcapsule type latent curing agent for the purpose of improving low-temperature curability, a large amount of powder is contained in the epoxy resin. It is necessary to add an amine compound. When the amount of the powdery amine compound is increased, the viscosity becomes high, so that it is difficult to perform a uniform encapsulation reaction. As a result, the variation in characteristics between lots becomes large, the defect rate of the product becomes high, and the degree of capsule formation is insufficient, so that sufficient storage stability cannot be obtained. In addition, if a component having high reactivity with an epoxy resin is used as a core material in order to enhance the curing characteristics, the curing reaction proceeds in the epoxy resin, and a latent curing agent having sufficient characteristics cannot be synthesized. There is also. According to the production method of the present invention, since the reaction between the core and the epoxy resin that causes an increase in viscosity and the reaction between the isocyanate, water, and the epoxy resin can be suppressed, a highly fluid one-component epoxy resin is obtained. be able to. In these respects, the production method according to the present invention has an advantageous effect as compared with the conventional method.

  According to the method for producing a microcapsule-type latent curing agent according to the present invention, compared with a method of forming a shell after blending a powdery amine compound as a curing agent in an epoxy resin, there is a curing reaction and an increase in viscosity. Since the amount is small, the reaction can proceed more easily and uniformly. As a result, characteristic variation between lots is reduced. Also, removal of by-products is easy. Furthermore, since it is not necessary to prepare a curing agent for each type of epoxy resin to be combined, the work efficiency is good and the range of selection of the epoxy resin is wide.

  Although the viscosity of the conventional masterbatch type curing agent is high and it is difficult to achieve sufficient fluidity of the epoxy resin composition, according to the present invention, a one-part epoxy resin having sufficiently high fluidity It is possible to obtain a composition. In recent years, especially in the field of electronic equipment, in order to cope with higher circuit density and improved connection reliability, one-part epoxy resin compositions used as one of connection materials are used to fill narrow gaps. It has become more important to have high fluidity.

  In the case of a method of forming a shell on the surface of a powdered amine curing agent by adding isocyanate and water in an epoxy resin, as a side reaction, a primary amine generated by the reaction of isocyanate and water reacts with the epoxy resin. Since the reaction is likely to occur, the reproducibility of the product is difficult to obtain. Moreover, since a hardening | curing agent was obtained in the state of a compound (master batch) with a specific epoxy resin, there also existed a problem that the freedom degree of a compounding was restrict | limited. The present invention is also advantageous in solving these problems.

  Taking advantage of the above effects, the microcapsule-type latent curing agent and one-component epoxy resin composition according to the present invention can be used in a wide range of applications. For example, as an adhesive, in the automotive field, headlights, gasoline tanks, hemin grunge parts such as bonnets, body and roof steel plates joined, in the electrical field, speaker magnets, impregnation and adhesion of motor coils, Adhesion of tape heads, battery cases, fluorescent lamp ballasts, die bonding adhesives, IC chip sealing agents, chip coating materials, chip mounting materials, printing substrate adhesives, film adhesives, The one-component epoxy resin composition according to the present invention can be used for applications such as a anisotropic conductive film and an anisotropic conductive paste. Other applications include powder paints, solder resist inks, conductive paints and the like in the paint field. The present invention can also be used for an electrical insulating material, a laminated structure, and the like. Particularly in recent years, in order to improve productivity in electronic material applications, further improvements in curing characteristics and storage stability have been demanded for one-part resin compositions.

  Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

  The microcapsule-type latent curing agent according to this embodiment has a particulate core and a capsule covering the core. The capsule is a film covering at least a part of the core surface.

  The core includes an amine adduct as a main component. More specifically, the core usually contains 50 to 100%, preferably 60 to 100%, of amine adducts by weight. If the mass ratio of the amine adduct is less than 50%, it tends to be relatively difficult to achieve both curing characteristics and storage stability.

  An amine adduct is a compound having an amino group obtained by a reaction between an epoxy resin and an amine compound.

  As an epoxy resin used for obtaining an amine adduct, either a monoepoxy compound or a polyvalent epoxy compound or a mixture thereof can be used. Examples of the monoepoxy compound include butyl glycidyl ether, hexyl glycidyl ether, phenyl glycidyl ether, allyl glycidyl ether, para-tert-butylphenyl glycidyl ether, ethylene oxide, propylene oxide, paraxyl glycidyl ether, glycidyl acetate, glycidyl butyrate. Glycidyl hexoate and glycidyl benzoate. Examples of the polyvalent epoxy compound include bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetramethylbisphenol A, tetramethylbisphenol F, tetramethylbisphenol AD, tetramethylbisphenol S, tetrabromobisphenol A and tetrachlorobisphenol A, tetra Bisphenol-type epoxy resin obtained by glycidylation of bisphenols such as fluorobisphenol A; Epoxy obtained by glycidylation of other dihydric phenols such as biphenol, dihydroxynaphthalene and 9,9-bis (4-hydroxyphenyl) fluorene Resin; 1,1,1-tris (4-hydroxyphenyl) methane, 4,4- (1- (4- (1- (4-hydroxyphenyl) -1-methylethyl) Epoxy resin obtained by glycidylation of trisphenols such as) phenyl) ethylidene) bisphenol; epoxy resin obtained by glycidylation of tetrakisphenols such as 1,1,2,2, -tetrakis (4-hydroxyphenyl) ethane A novolac type epoxy resin obtained by glycidylation of novolaks such as phenol novolak, cresol novolak, bisphenol A novolak, brominated phenol novolak, brominated bisphenol A novolak; epoxy resin obtained by glycidylation of polyhydric phenols, glycerin Aliphatic ether type epoxy resins obtained by glycidylation of polyhydric alcohols such as polyethylene glycol and polyethylene glycol; hydroxycarboxylic acids such as p-oxybenzoic acid and β-oxynaphthoic acid are glycidyl Ether ester type epoxy resin obtained by crystallization; ester type epoxy resin obtained by glycidylation of polycarboxylic acid such as phthalic acid and terephthalic acid; glycidylation of amine compounds such as 4,4-diaminodiphenylmethane and m-aminophenol And glycidyl type epoxy resins such as amine type epoxy resins such as triglycidyl isocyanurate and alicyclic epoxides such as 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate.

  As an epoxy resin, since the storage stability of an epoxy resin composition can be improved, a polyvalent epoxy compound is preferable. The polyvalent epoxy compound is preferably a glycidyl type epoxy resin because the productivity of the amine compound is overwhelmingly high. In view of excellent adhesion and heat resistance of the cured product, the polyvalent epoxy compound is more preferably a glycidylated product of a polyhydric phenol, and a bisphenol type epoxy resin is more preferable. In particular, a bisphenol A type epoxy resin which is an epoxy resin obtained by glycidylation of bisphenol A and a bisphenol F type epoxy resin which is an epoxy resin obtained by glycidylation of bisphenol F are preferred, and among these, a bisphenol A type epoxy resin is most preferred. These epoxy resins may be used alone or in combination.

  The amine compound used to obtain the amine adduct is preferably a compound having a primary amino group and / or a secondary amino group and no tertiary amino group, and a compound having a tertiary amino group and an active hydrogen group And chosen from. Examples of the compound having a primary amino group and / or a secondary amino group and not having a tertiary amino group include methylamine, ethylamine, propylamine, butylamine, ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, and triethylenetetramine. Primary amines such as ethanolamine, propanolamine, cyclohexylamine, isophoronediamine, aniline, toluidine, diaminodiphenylmethane and diaminodiphenylsulfone, and dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine , Dimethanolamine, diethanolamine, dipropanolamine, dicyclohexylamine, piperidine, piperidone, diphenylamine Secondary amines such as phenylmethyl amine, and phenylethylamine and the like.

  In the compound having a tertiary amino group and an active hydrogen group, examples of the active hydrogen group include a primary amino group, a secondary amino group, a hydroxyl group, a thiol group, a carboxylic acid, and a hydrazide group. Examples of the compound having a tertiary amino group and an active hydrogen group include 2-dimethylaminoethanol, 1-methyl-2-dimethylaminoethanol, 1-phenoxymethyl-2-dimethylaminoethanol, 2-diethylaminoethanol, 1- Amino alcohols such as butoxymethyl-2-dimethylaminoethanol, methyldiethanolamine, triethanolamine and N-β-hydroxyethylmorpholine; 2- (dimethylaminomethyl) phenol and 2,4,6-tris (dimethylaminomethyl) ) Aminophenols such as phenol; 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1-aminoethyl-2-methyl Imidazole, 1- (2-hydroxy-3-phenoxypropyl) -2-methylimidazole, 1- (2-hydroxy-3-phenoxypropyl) -2-ethyl-4-methylimidazole, 1- (2-hydroxy-3 -Imidazoles such as butoxypropyl) -2-methylimidazole and 1- (2-hydroxy-3-butoxypropyl) -2-ethyl-4-methylimidazole; 1- (2-hydroxy-3-phenoxypropyl)- 2-phenylimidazoline, 1- (2-hydroxy-3-butoxypropyl) -2-methylimidazoline, 2-methylimidazoline, 2,4-dimethylimidazoline, 2-ethylimidazoline, 2-ethyl-4-methylimidazoline, 2 -Benzylimidazoline, 2-phenylimidazoline, 2- (o- Tolyl) -imidazoline, tetramethylene-bis-imidazoline, 1,1,3-trimethyl-1,4-tetramethylene-bis-imidazoline, 1,3,3-trimethyl-1,4-tetramethylene-bis-imidazoline, 1,1,3-trimethyl-1,4-teramethylene-bis-4-methylimidazoline, 1,2-phenylene-bis-imidazoline, 1,3-phenylene-bis-imidazoline, 1,4-phenylene-bis-imidazoline Imidazolines such as 1,4-phenylene-bis-4-methylimidazoline; dimethylaminopropylamine, diethylaminopropylamine, dipropylaminopropylamine, dibutylaminopropylamine, dimethylaminoethylamine, diethylaminoethylamine, dipropylaminoethyl A , Tertiary aminoamines such as dibutylaminoethylamine, N-methylpiperazine, N-aminoethylpiperazine and diethylaminoethylpiperazine; 2-dimethylaminoethanethiol, 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, 2- Amino mercaptans such as mercaptopyridine and 4-mercaptopyridine; aminocarboxylic acids such as N, N-dimethylaminobenzoic acid, N, N-dimethylglycine, nicotinic acid, isonicotinic acid and picolinic acid; N, N- Mention may be made of aminohydrazides such as dimethylglycine hydrazide, nicotinic acid hydrazide and isonicotinic acid hydrazide.

  As the amine compound, a compound having a tertiary amino group and an active hydrogen group is preferable because the balance between storage stability and curability is excellent. Among these, imidazoles are more preferable, and 2-methylimidazole and 2-ethyl-4-methylimidazole are more preferable.

  The core may include one or more other components in addition to the amine adduct. Desired characteristics can be imparted by adding other components. For example, in order to enable curing at a lower temperature or in a shorter time, the core may contain a compound or a curing accelerator that is more reactive with an epoxy resin than an amine adduct. Additives necessary for the cured product may be added to the core in advance.

  The other components are preferably solid at room temperature (25 ° C.). Preferably it is solid at 40 ° C., more preferably it is solid at 60 ° C. When a liquid component is used at room temperature, encapsulation tends to be difficult, or the storage stability of the one-part epoxy resin composition tends to decrease.

  The amine adduct and other components are preferably mixed uniformly in the core. As a method to achieve uniform mixing, the amine adduct and other components are heated and melted together, mixed well, then cooled to room temperature and pulverized, or either one is heated and melted, and the other is dispersed and homogeneous. There is a method in which a dispersion is formed, cooled to room temperature, and pulverized.

  The core is preferably in the form of particles having an average particle size of 0.1 to 50 μm. The average particle diameter of the core is more preferably 0.5 to 10 μm, and further preferably 0.5 to 5 μm. If the average particle size of the core is less than 0.1 μm, it tends to be relatively difficult to achieve both curability and storage stability. Further, when the average particle diameter of the core is 50 μm or less, it becomes easy to obtain a uniform cured product. The average particle diameter refers to the median diameter. The average particle diameter of the core can be measured by a laser diffraction type particle size distribution measuring apparatus.

  The shape of the core is not particularly limited and may be either spherical or indeterminate, but spherical is preferable for reducing the viscosity of the one-component epoxy resin composition. Here, the term “spherical” includes not only a true sphere but also a shape having rounded irregular corners.

  The microcapsule type latent curing agent is a step of forming a capsule covering the core by reacting, for example, an amine adduct contained in the core, an isocyanate, a compound having an active hydrogen group and / or water in a dispersion medium. And a step of taking out the microcapsule type curing agent having the core and the capsule from the mixture after the reaction.

  Isocyanates are compounds having one or more isocyanate groups, preferably two or more isocyanate groups. Preferred isocyanates include aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, low molecular triisocyanates and polyisocyanates. Examples of aliphatic diisocyanates include ethylene diisocyanate, propylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate and trimethylhexamethylene diisocyanate. Examples of alicyclic diisocyanates include isophorone diisocyanate, 4-4′-dicyclohexylmethane diisocyanate, norbornane diisocyanate, 1,4-isocyanatocyclohexane, 1,3-bis (isocyanatomethyl) -cyclohexane and 1,3-bis. Mention may be made of (2-isocyanatopropyl-2-yl) -cyclohexane. Examples of aromatic diisocyanates include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylene diisocyanate and 1,5-naphthalene diisocyanate. Examples of low molecular weight triisocyanates include 1,6,11-undecane triisocyanate, 1,8-diisocyanate-4-isocyanate methyloctane, 1,3,6-hexamethylene triisocyanate, 2,6-diisocyanatohexane 2-isocyanatoethyl acid, 2,6-diisocyanatohexanoic acid-1-methyl-2-isocyanatoethyl aliphatic triisocyanate compound, tricyclohexylmethane triisocyanate, bicycloheptane triisocyanate and other alicyclic triisocyanates Examples thereof include aromatic triisocyanate compounds such as compounds, triphenylmethane triisocyanate and tris (isocyanatephenyl) thiophosphate. Examples of the polyisocyanate include polymethylene polyphenyl polyisocyanate, polyisocyanate derived from the above diisocyanate, and low molecular triisocyanate. Examples of the polyisocyanate derived from the diisocyanate and triisocyanate include isocyanurate type polyisocyanate, burette type polyisocyanate, urethane type polyisocyanate, allophanate type polyisocyanate, and carbodiimide type polyisocyanate. These isocyanates can be used alone or in combination of two or more.

  Due to the reaction between the active hydrogen group of the amine adduct and the isocyanate, the amine adduct and the isocyanate are bonded to form a product film on the core surface. And by making the compound and / or water which have an active hydrogen group in a reaction system, the film containing the reaction product of them and isocyanate grows and a capsule is formed. At least a part of the reaction product contained in the capsule is bonded to the core by a urethane bond generated by the reaction between the isocyanate and the amine adduct. It is considered that sufficient storage stability of the one-part epoxy resin composition can be obtained by using the microcapsule-type latent curing agent having a film thus grown.

  In the microcapsule-type latent curing agent, the ratio of capsules (inert film) is preferably 5 to 80% by mass based on the total mass of the microcapsule-type latent curing agent. The ratio of the capsule may be 40 to 80% by mass, 15 to 40% by mass, or 5 to 15% by mass depending on the desired use or purpose.

  The ratio of capsules is determined by, for example, measuring the mass M2 of the undissolved solid content by dispersing the microcapsule-type latent curing agent having a mass M1 in a solvent that selectively dissolves the core portion. : Capsule ratio (% by mass) = (M2 / M1) × 100. For example, methanol is used as the solvent for selectively dissolving the core.

  Examples of the active hydrogen group of the compound used to form the capsule include a primary amino group, a secondary amino group, a hydroxyl group, a thiol group, a carboxylic acid, and a hydrazide group. A compound having one or more active hydrogen groups in one molecule may be used, but a compound having two or more active hydrogen groups in one molecule is preferably used. By using a compound having two or more active hydrogen groups, a coating film on the core surface can be efficiently grown, and a microcapsule-type latent curing agent having particularly excellent storage stability can be produced. The compound which has an active hydrogen group can be used individually by 1 type or in combination of 2 or more types.

  The capsule formation reaction can be performed in a reaction solution in which a core is dispersed in a dispersion medium. The reaction is preferably carried out at a temperature below the melting point or softening point of the components (particularly amine adducts) constituting the core.

  The boiling point of the dispersion medium is preferably 150 ° C. or less at 1 atmosphere. If the boiling point of the dispersion medium is 150 ° C. or higher, it tends to be difficult to remove the dispersion medium from the reaction solution. The viscosity of the dispersion medium is preferably 1000 mPa · s or less at 25 ° C. When the viscosity of the dispersion medium is 1000 mPa · s or more, a uniform reaction becomes difficult, and the resulting microcapsule-type latent curing agent may aggregate to significantly reduce the curing characteristics. From the same viewpoint, more preferably, the boiling point of the dispersion medium is 50 to 120 ° C., and the viscosity of the dispersion medium is 0.2 to 10 mPa · s.

  The dispersion medium preferably does not have a substituent such as an active hydrogen group or an epoxy group that reacts with an amine adduct. These substituents may inhibit the capsule formation reaction. Specific examples of suitable dispersion media include cyclohexane (boiling point 80.7 ° C., viscosity 0.898 mPa · s: 25 ° C.) and hexane (boiling point 69 ° C., viscosity 0.299 mPa · s: 25 ° C.).

  After the capsule formation, the dispersion medium is removed from the mixture containing the microcapsule type latent curing agent and the dispersion medium. In the dispersion medium, unreacted isocyanate and by-products, water and / or a compound having an active hydrogen group may remain. However, by removing the dispersion medium, it is separated from the residue in the dispersion medium. Thus, the microcapsule type latent curing agent can be taken out. If unreacted substances are contained in the microcapsule-type latent curing agent, the storage stability may be lowered.

  The method for removing the dispersion medium is not particularly limited, but it is preferable to remove unreacted isocyanate, by-products, water, and a residue such as a compound having an active hydrogen group together with the dispersion medium. A preferred method includes filtration. It is preferable to wash the microcapsule-type latent curing agent after removing the dispersion medium by filtration or the like. The method for washing is not particularly limited, and after filtration, washing can be performed using a solvent that does not dissolve the microcapsule-type latent curing agent. As the solvent, the same kind as the dispersion medium may be used. By washing, unreacted compounds adhering to the surface of the microcapsule type latent curing agent can be removed. The filtered microcapsule-type latent curing agent is powdered by drying. The drying method is not particularly limited, but it is preferable to dry at a temperature below the melting point or softening point of the core. Such a method includes drying under reduced pressure. The powdery microcapsule-type curing agent can be easily applied for a wide variety of formulations in a one-part epoxy resin composition.

  In the case of the encapsulation method in the epoxy resin, the unreacted isocyanate, by-product, water and / or the compound having an active hydrogen group remain in the one-pack type epoxy resin composition, so that the storage stability is improved. descend. Moreover, when powdery amine adduct particles are added to the epoxy resin at a high concentration, the viscosity becomes remarkably high, a uniform reaction cannot be performed, and the difference in characteristics between lots becomes large, and the encapsulation reaction itself cannot be performed. Such a problem also occurs. In order to enhance the reactivity, if the core is added with a compound that is highly reactive with the epoxy resin or if the encapsulation is performed using a highly reactive epoxy resin as the dispersion medium, the reaction between the core and the epoxy resin is preferential. Therefore, it becomes difficult to produce a microcapsule type latent curing agent or a one-part epoxy resin composition.

  The capsule formation reaction may be performed twice or more if necessary. At this time, at least one reaction may be performed between the amine adduct, the isocyanate, the compound having an active hydrogen group, and / or water. In addition, the compound may be selected from the compound having the isocyanate, the active hydrogen group, and / or water. The reaction may be carried out using any one of them. The capsule formation reaction is preferably 5 times or less from the viewpoint of suppressing the production cost, and more preferably 3 times or less.

  The one-component epoxy resin composition according to this embodiment contains a microcapsule-type latent curing agent and an epoxy resin. The amount of the microcapsule type latent curing agent is not particularly limited, but is usually about 5 to 70 parts by mass with respect to 100 parts by mass of the total amount of the epoxy resin and the microphone capsule type latent curing agent. When this amount is less than 5 parts by mass, the epoxy resin tends to be hard to be cured sufficiently, or the curing tends to take a long time, and when it exceeds 70 parts by mass, the fluidity of the epoxy resin composition tends to decrease. is there.

  As the epoxy resin used in the one-component epoxy resin composition, an epoxy compound having an average of two or more epoxy groups can be preferably used. Specifically, bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetramethylbisphenol A, tetramethylbisphenol F, tetramethylbisphenol AD, tetramethylbisphenol S, tetrabromobisphenol A, tetrachlorobisphenol A and tetrafluorobisphenol A Bisphenol-type epoxy resin obtained by glycidylation of bisphenols such as bisphenol; Epoxy resin obtained by glycidylation of other dihydric phenols such as biphenol, dihydroxynaphthalene and 9,9-bis (4-hydroxyphenyl) fluorene 1,1,1-tris (4-hydroxyphenyl) methane and 4,4- (1- (4- (1- (4-hydroxyphenyl) -1-methylethyl) phenyl) Liden) Epoxy resin obtained by glycidylation of trisphenols such as bisphenol; Epoxy resin obtained by glycidylation of tetrakisphenols such as 1,1,2,2, -tetrakis (4-hydroxyphenyl) ethane; Phenol novolak , Novolak type epoxy resins obtained by glycidylation of novolaks such as cresol novolak, bisphenol A novolak, brominated phenol novolak and brominated bisphenol A novolak; epoxy resins obtained by glycidylation of polyhydric phenols, glycerin and polyethylene Aliphatic ether type epoxy resin obtained by glycidylation of polyhydric alcohol such as glycol; obtained by glycidylation of hydroxycarboxylic acid such as p-oxybenzoic acid and β-oxynaphthoic acid Ether ester type epoxy resins; ester type epoxy resins obtained by glycidylation of polycarboxylic acids such as phthalic acid and terephthalic acid; glycidylated products of triaminedyl compounds such as 4,4-diaminodiphenylmethane and m-aminophenol Examples thereof include glycidyl type epoxy resins such as amine type epoxy resins such as isocyanurate, and alicyclic epoxides such as 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate. Other examples of epoxy resins include modified epoxy resins such as urethane-modified epoxy resins, rubber-modified epoxy resins, and alkyd-modified epoxy resins. These epoxy resins may be used alone or in combination of two or more.

  The one-part epoxy resin composition further contains at least one curing agent selected from the group consisting of acid anhydrides, phenols, hydrazides, and guanidines in addition to the microcapsule-type latent curing agent. It may be. In addition, the one-part epoxy resin composition can be used as required by a filler, a reinforcing material, a filler, conductive fine particles, a pigment, an organic solvent, a reactive diluent, a non-reactive diluent, a resin, a crystalline alcohol, a cup. A ring agent or the like may be contained.

  Examples of the filler include, for example, coal tar, glass fiber, asbestos fiber, boron fiber, carbon fiber, cellulose, polyethylene powder, polypropylene powder, quartz powder, mineral silicate, mica, asbestos powder, slate powder, Kaolin, aluminum oxide trihydrate, aluminum hydroxide, chalk powder, gypsum, calcium carbonate, antimony trioxide, penton, silica, aerosol, lithopone, barite, titanium dioxide, carbon black, graphite, carbon nanotube, fullerene, iron oxide , Gold, silver, aluminum powder, iron powder, nano-sized metal crystals, intermetallic compounds, and the like. Any of these is effectively used according to the application.

  Examples of the conductive fine particles include, for example, solder particles, nickel particles, nano-sized metal crystals, metal particles coated with other metals, metal particles such as copper and silver inclined particles, and styrene resin, Examples thereof include particles obtained by coating resin particles such as urethane resin, melamine resin, epoxy resin, acrylic resin, phenol resin, and styrene-butadiene resin with a conductive thin film such as gold, nickel, silver, copper, and solder.

  Examples of the organic solvent include toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate and butyl acetate.

  Examples of reactive diluents include butyl glycidyl ether, N, N′-glycidyl-o-toluidine, phenyl glycidyl ether, styrene oxide, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, and 1,6-hexanediol diester. A glycidyl ether is mentioned. Examples of non-reactive diluents include dioctyl phthalate, dibutyl phthalate, dioctyl adipate, and petroleum solvents.

  Examples of the resins include polyester resins, polyurethane resins, acrylic resins, polyether resins, melamine resins, and phenoxy resins.

  Examples of the crystalline alcohol include 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, pentaerythritol, sorbitol, sucrose, and trimethylolpropane.

  The one-part epoxy resin composition preferably comprises a step of dispersing the microphone capsule type latent curing agent in a mixture of the microcapsule type latent curing agent and the epoxy resin, and a dispersed microcapsule type latent curing agent. It can obtain by a manufacturing method provided with the process of heat-processing.

  The microcapsule type latent curing agent can be dispersed in the epoxy resin by stirring the mixture of the microcapsule type latent curing agent and the epoxy resin using a mixer or a roll.

  By heat-treating the microcapsule-type latent curing agent in the epoxy resin, the epoxy resin is taken into the capsule and the storage stability is further improved. The temperature of the heat treatment is higher than room temperature (25 ° C.) and is preferably below the melting point or softening point of the amine adduct constituting the core. When the temperature is lower than room temperature, the effect of improving the storage stability tends to be small, and when the temperature is higher than the melting point or softening point of the amine adduct, the properties of the curing agent are likely to deteriorate due to the reaction with the epoxy resin. The treatment time is preferably 5 minutes to 72 hours from the viewpoint of productivity.

  The one-component epoxy resin composition according to this embodiment is cured by heating to form a cured product. Such a one-component epoxy resin composition includes, in addition to an adhesive and / or a bonding paste and a bonding film, a conductive material, an anisotropic conductive material, an insulating material, an encapsulant, a coating material, a coating composition, a prepreg, It is useful as a heat conductive material.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these.

(Examination 1)
1-1. Synthesis of amine adduct particles 1
In a 3000 mL three-necked separable flask equipped with a condenser, an isostatic dropping funnel, and a stirrer, 288 g of 2-methylimidazole was added to 824.2 g of 1-butanol and toluene mixed in 1/1 (wt / wt). In addition, the mixture was heated to 80 ° C. in an oil bath with stirring to dissolve 2-methylimidazole. Next, 946 g of bisphenol A type epoxy resin (epoxy equivalent 173 g / eq, amount of hydrolyzed chlorine 0.01 wt%) was dissolved in 300 g of a mixed solvent in which 1-butanol and toluene were mixed at 1/1 (wt / wt). The solution was added dropwise over 90 minutes using an isobaric dropping funnel. After completion of dropping, the mixture was heated at 80 ° C. for 5 hours. Thereafter, the temperature was raised to 180 ° C., and the pressure in the apparatus was finally reduced until the pressure became 10 mmHg or less. After the pressure became 10 mmHg or less, the solvent was distilled away by heating under reduced pressure for 2 hours to obtain a dark reddish brown viscous liquid. The viscous liquid was cooled to room temperature to obtain a dark reddish brown solid amine adduct. The amine adduct was pulverized with a jet mill to obtain amine adduct particles 1 having an average particle size of 1.96 μm.

Amine adduct particle 2
The average particle size of the bisphenol A-type epoxy resin was changed to 874 g of bisphenol F-type epoxy resin (epoxy equivalent 160 g / eq, hydrolyzed chlorine content 0.007 wt%) in the same manner as the amine adduct particles 1 except that 88 μm amine adduct particles 2 were obtained.

1-2. Synthesis of microcapsule type latent curing agent Microcapsule type latent curing agent 1
45.0 g of amine adduct particles 1 and 171.0 g of cyclohexane were added to a 500 mL three-necked separable flask equipped with a condenser, a thermocouple, and a stirrer, heated to 40 ° C., and then 1.2 g of water was added. After stirring for 10 minutes, 3.0 g of 4,4′-diphenylmethane diisocyanate was added and reacted at 40 ° C. for 2 hours. Subsequently, it heated up at 50 degreeC and made it react for 6 hours. After completion of the reaction, the dispersion was filtered, and the recovered powder was washed with cyclohexane heated to 50 ° C. The solvent was removed from the obtained powder by drying under reduced pressure for 24 hours at a pressure of 10 mmHg or less to obtain a microcapsule-type latent curing agent 1.

Microcapsule type latent curing agent 2
A microcapsule-type latent curing agent 2 was obtained in the same manner as in Example 1 except that the amine adduct particle 2 was used in place of the amine adduct particle 1.

Microcapsule type latent curing agent 3 (Recapsulation of microcapsule type latent curing agent 1)
To a 500 mL three-necked separable flask equipped with a condenser, a thermocouple, and a stirrer, 146.3 g of toluene and 2.5 g of 4,4′-diphenylmethane diisocyanate were added and heated to 50 ° C. in an oil bath. Next, 15.0 g of the microcapsule type latent curing agent (F) 1 was added and reacted at 50 ° C. for 3 hours. After completion of the reaction, the dispersion was filtered, and the recovered powder was washed with toluene heated to 50 ° C. The solvent was removed from the obtained powder by drying under reduced pressure for 24 hours at a pressure of 10 mmHg or less to obtain a microcapsule-type latent curing agent 3.

Microcapsule type latent curing agent 4 (with ethylene glycol added)
45.0 g of amine adduct particles 1 and 171.0 g of cyclohexane were added to a 500 mL three-necked separable flask equipped with a condenser, a thermocouple, and a stirrer, and heated to 40 ° C. Next, 2.0 g of tolylene diisocyanate was added and heated at 40 ° C. for 2 hours. The temperature was further raised to 50 ° C., and 3.0 g of ethylene glycol was added over 6 hours. After completion of the reaction, the dispersion was filtered, and the recovered powder was washed with cyclohexane heated to 50 ° C. The solvent was removed from the obtained powder by drying under reduced pressure for 24 hours at a pressure of 10 mmHg or less to obtain a microcapsule-type latent curing agent 4.

Microcapsule type latent curing agent 6
45.0 g of amine adduct particles 1 and 171.0 g of cyclohexane were added to a 500 mL three-necked separable flask equipped with a condenser, a thermocouple, and a stirrer, heated to 40 ° C., and then 1.2 g of water was added. After stirring for 10 minutes, 3.0 g of polymeric MDI (manufactured by Nippon Polyurethane Co., Ltd., trade name: Millionate MR-200) was added and reacted at 40 ° C. for 2 hours. Subsequently, it heated up at 50 degreeC and made it react for 6 hours. After completion of the reaction, the dispersion was filtered, and the recovered powder was washed with cyclohexane heated to 50 ° C. The solvent was removed from the obtained powder by drying under reduced pressure for 24 hours at a pressure of 10 mmHg or less to obtain a microcapsule-type latent curing agent 6.

1-3. Preparation Examples 1 to 3 of One-Part Epoxy Resin Composition
33 g of microcapsule type latent curing agent 1, 2 or 3 and 67 g of bisphenol F type epoxy resin (epoxy equivalent 160 g / eq, amount of hydrolyzed chlorine 0.007 wt%) were blended. A liquid epoxy resin composition was obtained.

Example 4
33 g of microcapsule type latent curing agent 4 and 67 g of bisphenol A type epoxy resin (epoxy equivalent 173 g / eq, hydrolyzed chlorine content 0.01 wt%) were blended to obtain a one-pack epoxy resin composition.

Example 5
45 g of the microcapsule type latent curing agent 3 and 55 g of bisphenol F type epoxy resin (epoxy equivalent 160 g / eq, hydrolyzed chlorine amount 0.007 wt%) were blended to obtain a one-pack epoxy resin composition.

Example 6
35 g of microcapsule type latent curing agent 3, 25 g of bisphenol A type epoxy resin (epoxy equivalent 160 g / eq, amount of hydrolyzed chlorine 0.007 wt%), resorcin diglycidyl ether (epoxy equivalent 117 g / eq, hydrolyzed chlorine) 40 g) was added to obtain a one-part epoxy resin composition.

Example 7
33 g of microcapsule-type latent curing agent 1 was added to a three-necked separable flask equipped with a condenser, a thermocouple, and a stirrer, and a bisphenol F-type epoxy resin (epoxy equivalent 160 g / eq, hydrolyzed chlorine content 0.007 wt. %) Was added and stirred at 50 ° C. for 24 hours to obtain a one-part epoxy resin composition.

Example 8
A one-part epoxy resin composition was obtained in the same manner as in Example 7 except that the microcapsule type latent curing agent 2 was used instead of the microcapsule type latent curing agent 1.

1-4. Characteristic Evaluation of Microcapsule Type Latent Curing Agent The curing characteristics and storage stability of the one-part epoxy resin compositions of Examples 1 to 8 and the average particle diameter of the amine adduct particles 1 and 2 were evaluated by the following methods. The results are summarized in Table 1.

Curing characteristics Using a Perkin-Elmer DSC7 differential calorimeter, the effect characteristics of the one-part epoxy resin composition were measured at a temperature rising rate of 10 ° C / min, a measurement temperature range of 30 ° C to 300 ° C, and a nitrogen atmosphere. “AA” if the temperature at the maximum peak of the peak derived from the heat of curing is less than 115 ° C., “A” if it is 115 ° C. or higher and lower than 120 ° C., “B” if it is 120 ° C. or higher and lower than 130 ° C. Was determined. It means that the lower the temperature of the peak maximum point derived from the curing heat generation, the better the low temperature curability of the resin composition.

Storage stability The same weight of bisphenol A type epoxy resin (epoxy equivalent: 173 g / eq, amount of hydrolyzed chlorine: 0.01% by weight) was added to the one-part epoxy resin composition and stored in a constant temperature bath at 40 ° C. The viscosity at 25 ° C. of the one-part epoxy resin composition at the initial stage and after 30 days was measured using an E-type viscometer. Storage stability was judged by the rate of increase in viscosity from the beginning after 30 days. Viscosity is measured using a 3 ° (angle) cone, 10 rpm when the viscosity is 3 to 40 Pa · s, 2.5 rpm when the viscosity is 40 to 200 Pa · s, and 0. The rotation was performed at 5 rpm. When the viscosity increase rate after 30 days was 25% or less, it was determined as “AA”, when it was 50% or less, “A”, when it was less than 100%, “B”, and when it was 100% or more, “C”.

Average Particle Size The average particle size of the amine adduct particles was measured three times using a laser diffraction particle size distribution analyzer (Mastersizer 2000: dry measurement unit Sciroco 2000) manufactured by Malvern. The average value of 50% diameter (median diameter) at this time was defined as the average particle diameter.

  Hereinafter, a microcapsule-type latent curing agent and a one-part epoxy resin composition for a comparative example were prepared.

Synthesis of Microcapsule Type Latent Curing Agent 5 Add 45.0 g of amine adduct particles 1 and 171.0 g of cyclohexane to a three-necked separable flask equipped with a condenser, thermocouple, and stirrer, and heat to 40 ° C. Stir for 10 minutes. Thereafter, 3.0 g of 4,4′-diphenylmethane diisocyanate was added and reacted at 40 ° C. for 2 hours. Subsequently, it heated up at 50 degreeC and made it react for 6 hours. After completion of the reaction, the dispersion was filtered, and the recovered powder was washed with cyclohexane heated to 50 ° C. The solvent was removed from the obtained powder by drying under reduced pressure for 24 hours at a pressure of 10 mmHg or less to obtain a microcapsule-type latent curing agent 5.

Comparative Example 1
33 g of microcapsule type latent curing agent 5 and 67 g of bisphenol F type epoxy resin (epoxy equivalent 160 g / eq, hydrolyzed chlorine amount 0.007 wt%) were blended to obtain a one-pack epoxy resin composition.

Comparative Example 2
45 g of amine adduct particles 1 and 55 g of bisphenol A type epoxy resin (epoxy equivalent 173 g / eq, amount of hydrolyzed chlorine 0.01 wt%) were added to a three-necked separable flask equipped with a condenser, a thermocouple, and a stirring device. After heating to 40 ° C., 0.5 g of water was added. After stirring for 10 minutes, 4.0 g of 4,4′-diphenylmethane diisocyanate was added and heated at 40 ° C. for 2 hours. Next, when the temperature was raised to 50 ° C. and heated for 6 hours, the curing reaction proceeded in the flask, and a one-component epoxy resin composition could not be obtained.

Comparative Example 3
33 g of amine adduct particles 1 and 67 g of bisphenol A type epoxy resin (epoxy equivalent 173 g / eq, amount of hydrolyzed chlorine 0.01 wt%) were added to a three-necked separable flask equipped with a condenser, a thermocouple, and a stirring device. After heating to 40 ° C., 0.5 g of water was added. After stirring for 10 minutes, 4.0 g of 4,4′-diphenylmethane diisocyanate was added and heated at 40 ° C. for 2 hours. Next, the temperature was raised to 50 ° C. and heated for 6 hours to obtain a one-component epoxy resin composition.

  The curing properties and storage stability of the one-component epoxy resin compositions of Comparative Examples 1 and 3 and the microcapsule-type latent curing agent 5 were evaluated by the same method as described above.

Comparison of characteristics variation between lots For the epoxy resin compositions of Examples 1 and 3 and Comparative Example 1, the same experiment was repeated five times from the synthesis of the microcapsule type latent curing agent to the preparation of the resin composition, and the initial viscosity variation It was investigated. In the one-component epoxy resin composition of Example 1, the value obtained by dividing the maximum value of the initial viscosity by the minimum value is 1.3, and the standard deviation when the minimum viscosity value is 1 is 0.012, which varies. It was small and good. In the one-component epoxy composition of Example 3, the value obtained by dividing the maximum value of the initial viscosity by the minimum value is 1.2, and the standard deviation when the minimum viscosity value is 1 is as small as 0.007. It was good. On the other hand, in the one-component epoxy resin composition of Comparative Example 3, the value obtained by dividing the maximum value of the initial viscosity by the minimum value is 3.6, and the standard deviation when the minimum viscosity value is 1 is 0.78. The variation was large.

  The evaluation results as described above are summarized in Table 1.

  As is apparent from the results shown in Table 1, by using the microcapsule-type latent curing agent according to the present invention, a one-part epoxy resin composition having sufficient low-temperature curing characteristics and excellent storage stability is obtained. It was confirmed that

Example 9
30 g of microcapsule type latent curing agent 1, 50 g of bisphenol A type epoxy resin (epoxy equivalent 173 g / eq., Hydrolyzable chlorine content 0.01% by mass) and bisphenol F type epoxy resin (epoxy equivalent 160 g / eq.). , Hydrolyzed chlorine amount 0.007 mass%) 20 g was added to obtain a one-part epoxy resin composition of Example 9.

Examples 10 and 11
30 g of microcapsule type latent curing agent 3 or 6; 50 g of bisphenol F type epoxy resin (epoxy equivalent 160 g / eq, hydrolyzed chlorine amount 0.007% by mass); and bisphenol A type epoxy resin epoxy equivalent 173 g / eq. , Hydrolyzable chlorine content 0.01 mass%) 20 g was blended to obtain one-part epoxy resin compositions of Examples 10 and 11.

Comparative Example 4
30 g of amine adduct particles 1 and 50 g of bisphenol A type epoxy resin (epoxy equivalent 173 g / eq., Hydrolyzable chlorine content 0.01% by mass) in a three-necked separable flask equipped with a condenser, a thermocouple and a stirrer 20 g of bisphenol F-type epoxy resin (epoxy equivalent 160 g / eq, hydrolyzed chlorine amount 0.007 mass%) was added and heated to 40 ° C., and then 0.5 g of water was added. After stirring for 10 minutes, 3.0 g of 4,4′-diphenylmethane diisocyanate was added and heated at 40 ° C. for 2 hours. Next, the temperature was raised to 50 ° C. and heated for 6 hours to obtain a one-component epoxy resin composition.

表２に示される結果から明らかなように、本発明に係るマイクロカプセル型潜在性硬化剤を用いることにより、十分な低温硬化特性及び優れた貯蔵安定性が得られるばかりでなく、同様な組成のエポキシ樹脂において比較したときに、アミンアダクト粒子よりも更に低い粘度が達成されること、すなわちより高い流動性が達成されることが確認された。Comparative Example 5
30 g of amine adduct particles 1 and 50 g of bisphenol F type epoxy resin (epoxy equivalent 160 g / eq, amount of hydrolyzed chlorine 0.007% by mass) and bisphenol A in a three-necked separable flask equipped with a condenser, thermocouple and stirrer Type epoxy resin Epoxy equivalent 173 g / eq. , Hydrolyzable chlorine content 0.01 mass%) 20 g was added and heated to 40 ° C., and then 0.5 g of water was added. After stirring for 10 minutes, 3.0 g of Polymeric MDI (manufactured by Nippon Polyurethane Co., Ltd., trade name: Millionate MR-200) was added and heated at 40 ° C. for 2 hours. Next, the temperature was raised to 50 ° C. and heated for 6 hours to obtain a one-component epoxy resin composition.

As is apparent from the results shown in Table 2, not only sufficient low-temperature curing characteristics and excellent storage stability can be obtained by using the microcapsule-type latent curing agent according to the present invention, but a similar composition can be obtained. When compared in epoxy resins, it was confirmed that even lower viscosities were achieved than amine adduct particles, i.e. higher flowability was achieved.

(Examination 2)
2-1. Synthesis of amine adduct particles Amine adduct particles 3
In a 3000 mL 3-neck separable flask equipped with a condenser, an isostatic dropping funnel, and a stirrer, 1-butanol and toluene were mixed in 1/1 (wt / wt) at 824.2 g and 2-methylimidazole 336. 4 g was added and heated to 80 ° C. in an oil bath with stirring to dissolve 2-methylimidazole. Next, a solution obtained by dissolving 945.8 g of bisphenol A type epoxy resin (epoxy equivalent 173 g / eq, amount of hydrolyzed chlorine 0.01 mass%) in 300 g of 1-butanol and toluene 1/1 (wt / wt) solution, etc. It dropped over 90 minutes using the pressure dropping funnel. After completion of dropping, the mixture was heated at 80 ° C. for 5 hours. Then, it heated up to 180 degreeC and pressure-reduced until the pressure finally became 10 mmHg or less inside the apparatus. The solvent was distilled off. After the pressure became 10 mmHg or less, the solvent was distilled away by heating under reduced pressure for 2 hours to obtain a dark reddish brown viscous liquid. The viscous liquid was cooled to room temperature to obtain a dark reddish brown solid amine adduct. The amine adduct was pulverized with a jet mill to obtain amine adduct particles 3 having an average particle diameter of 2.50 μm.

Amine adduct particle 4
The average particle size of 3.14 μm was the same as that of the amine adduct particle 1 except that the bisphenol A type epoxy resin was changed to 874 g of the bisphenol F type epoxy resin (epoxy equivalent 160 g / eq, hydrolyzed chlorine amount 0.007 mass%). The amine adduct particle 4 was obtained.

2-2. Synthesis of microcapsule type latent curing agent Microcapsule type latent curing agent 7
45.0 g of amine adduct particles 3 and 171.0 g of cyclohexane were added to a three- necked separable flask equipped with a condenser, a thermocouple, and a stirrer, heated to 40 ° C., and 1.1 g of water was added. After stirring for 10 minutes, 6.0 g of 4,4′-diphenylmethane diisocyanate was added and reacted at 40 ° C. for 2 hours. Subsequently, it heated up at 50 degreeC and made it react for 6 hours. After completion of the reaction, the dispersion was filtered, and the recovered powder was washed with cyclohexane heated to 50 ° C. The solvent was removed from the obtained powder by drying under reduced pressure for 24 hours at a pressure of 10 mmHg or less to obtain a powdery microcapsule-type latent curing agent 7. The proportion of capsules in the obtained microcapsule-type latent curing agent 7 was 14% by mass.

Microcapsule type latent curing agent 8
45.0 g of amine adduct particles 3 and 171.0 g of cyclohexane were added to a 500 mL three-necked separable flask equipped with a condenser, a thermocouple, and a stirrer. After heating to 40 ° C., 1.1 g of water was added. Subsequently, 3.0 g of 4,4′-diphenylmethane diisocyanate was added and reacted at 40 ° C. for 2 hours. Further, the temperature was raised to 50 ° C. and reacted for 6 hours. After completion of the reaction, the dispersion was filtered, and the collected powder was washed with toluene. The solvent was removed from the obtained powder by drying under reduced pressure for 24 hours at a pressure of 10 mmHg or less to obtain a powdery microcapsule-type latent curing agent 8. The proportion of capsules in the obtained microcapsule-type latent curing agent 8 was 9% by mass.

Microcapsule type latent curing agent 9
45.0 g of amine adduct particles 4 and 171.0 g of cyclohexane were added to a three-necked separable flask equipped with a condenser, a thermocouple, and a stirrer, heated to 40 ° C., and then 1.1 g of water was added. After stirring for 10 minutes, 6.0 g of 4,4′-diphenylmethane diisocyanate was added and reacted at 40 ° C. for 2 hours. Subsequently, it heated up at 50 degreeC and made it react for 6 hours. After completion of the reaction, the dispersion was filtered, and the recovered powder was washed with cyclohexane heated to 50 ° C. The solvent was removed from the obtained powder by drying under reduced pressure for 24 hours at a pressure of 10 mmHg or less to obtain a powdery microcapsule-type latent curing agent 9. The proportion of capsules in the obtained microcapsule type latent curing agent 9 was 15% by mass.

Microcapsule type latent curing agent 10 (Re-encapsulation of microcapsule type latent curing agent 7)
To a 500 mL three-necked separable flask equipped with a condenser, a thermocouple, and a stirrer were added 146.3 g of toluene and 3.7 g of 4,4′-diphenylmethane diisocyanate, and the mixture was heated to 50 ° C. in an oil bath. Next, 15.0 g of the microcapsule type latent curing agent 7 was added and reacted at 50 ° C. for 3 hours. After completion of the reaction, the dispersion was filtered, and the recovered powder was washed with toluene heated to 50 ° C. The solvent was removed from the obtained powder by drying under reduced pressure for 24 hours at a pressure of 10 mmHg or less to obtain a powdery microcapsule-type latent curing agent 10. The proportion of capsules in the obtained microcapsule type latent curing agent 10 was 45% by mass.

Microcapsule type latent curing agent 11 (Re-encapsulation of microcapsule type latent curing agent 7)
To a 500 mL three-necked separable flask equipped with a condenser, a thermocouple, and a stirrer, 146.3 g of toluene and 1.8 g of 4,4′-diphenylmethane diisocyanate were added and heated to 50 ° C. in an oil bath. Next, 15.0 g of the microcapsule type latent curing agent 7 was added and reacted at 50 ° C. for 3 hours. After completion of the reaction, the dispersion was filtered, and the recovered powder was washed with toluene heated to 50 ° C. The solvent was removed from the obtained powder by drying under reduced pressure for 24 hours at a pressure of 10 mmHg or less to obtain a powdery microcapsule-type latent curing agent 11. The ratio of the capsules of the obtained microcapsule type latent curing agent 11 was 28% by mass.

2-3. Preparation of one-part epoxy resin composition Examples 12-16
33 g of each of the microcapsule-type latent curing agents 7 to 11 and 67 g of a bisphenol F type epoxy resin (epoxy equivalent 160 g / eq, hydrolyzed chlorine amount 0.007% by mass) are blended, and one of Examples 12 to 16 A liquid epoxy resin composition was obtained.

Example 17
One-part epoxy resin composition of Example 17 containing 33 g of microcapsule type latent curing agent 10 and 67 g of bisphenol A type epoxy resin (epoxy equivalent 173 g / eq, hydrolyzed chlorine content 0.01 mass%) I got a thing.

Example 18
One-part epoxy resin composition of Example 18 containing 33 g of microcapsule type latent curing agent 10 and 67 g of naphthalene type epoxy resin (epoxy equivalent 142 g / eq, hydrolyzed chlorine amount 0.017 mass%). I got a thing.

Example 19
35 g of microcapsule type latent curing agent 10, 25 g of bisphenol F type epoxy resin (epoxy equivalent 160 g / eq, hydrolyzed chlorine amount 0.007% by mass), resorcin diglycidyl ether (epoxy equivalent 117 g / eq, water) A one-component epoxy resin composition of Example 19 was obtained by blending 40 g of cracked chlorine content 0.7 mass%).

2-4. Microcapsule type latent curing agent for comparison and synthesis of one-part epoxy resin composition microcapsule type latent curing agent 12 Amine adduct particle 3 in a three-neck separable flask equipped with a cooling tube, a thermocouple, and a stirring device 45.0 g and cyclohexane 171.0 g were added and heated to 40 ° C., followed by stirring for 10 minutes. Thereafter, 1.0 g of 4,4′-diphenylmethane diisocyanate was added and reacted at 40 ° C. for 2 hours. Subsequently, it heated up at 50 degreeC and made it react for 6 hours. After completion of the reaction, the dispersion was filtered, and the recovered powder was washed with cyclohexane heated to 50 ° C. The solvent was removed from the obtained powder by drying under reduced pressure for 24 hours at a pressure of 10 mmHg or less to obtain a microcapsule-type latent curing agent 12. The ratio of capsules of the obtained microcapsule type latent curing agent 12 was 3% by mass.

Comparative Example 6
One-part epoxy resin composition of Comparative Example 6 containing 33 g of microcapsule type latent curing agent 12 and 67 g of bisphenol F type epoxy resin (epoxy equivalent 160 g / eq, hydrolyzed chlorine content 0.007 mass%) I got a thing.

Comparative Example 7
45 g of amine adduct particles 3 and 55 g of bisphenol A type epoxy resin (epoxy equivalent 173 g / eq, amount of hydrolyzed chlorine 0.01% by mass) were added to a three-neck separable flask equipped with a condenser, a thermocouple, and a stirring device. After heating to 40 ° C., 0.5 g of water was added. After stirring for 10 minutes, 4.0 g of 4,4′-diphenylmethane diisocyanate was added and heated at 40 ° C. for 2 hours. Next, when the temperature was raised to 50 ° C. and heated for 6 hours, the curing reaction proceeded in the flask, and a one-component epoxy resin composition could not be obtained.

Comparative Example 8
45 g of amine adduct particles 3 and 55 g of bisphenol F type epoxy resin (epoxy equivalent 160 g / eq, amount of hydrolyzed chlorine 0.007% by mass) were added to a three-neck separable flask equipped with a condenser, a thermocouple, and a stirrer. However, the curing reaction proceeded in the flask, and a one-part epoxy resin composition could not be obtained.

2-5. Characteristic Evaluation of Microcapsule Type Latent Curing Agent The curing characteristics and storage stability of the one-part epoxy resin compositions of Examples and Comparative Examples and the average particle diameter of the amine adduct particles 3 and 4 were evaluated by the following methods. The results are summarized in Table 3.

Curing characteristics The curing characteristics of the one-part epoxy resin composition were measured using a Perkin-Elmer DSC7 differential calorimeter at a heating rate of 10 ° C / min, a measurement temperature range of 30 ° C to 300 ° C, and a nitrogen atmosphere. “AA” if the temperature at the peak maximum point derived from the heat generated by curing is less than 110 ° C., “A” if it is 110 ° C. or more and less than 125 ° C., “B” if it is 125 ° C. or more and less than 135 ° C., and if it is 135 ° C. or more. It was determined as “C”.

Storage Stability The storage stability of the epoxy resin composition and the average particle size of the amine adduct particles were measured according to the same measurement conditions and criteria as in Study 1.

Proportion of capsules A dispersion prepared by adding a sufficient amount of methanol to a microcapsule-type latent curing agent is stirred at room temperature for 6 hours, whereby a portion derived from amine adduct particles in the microcapsule-type latent curing agent is obtained. Dissolved in methanol. The dispersion was filtered, and the filtrate was dried at a temperature of 50 ° C. or lower to completely remove methanol. The weight of the filtrate after drying was weighed. The ratio of the weight of the filtrate to the total weight of the microcapsule type epoxy resin curing agent was regarded as the ratio of capsules.

Solvent resistance Toluene / ethyl acetate = 1/1 (wt / wt) was used as a solvent, and a one-part epoxy resin composition / solvent = 15 g / 3.5 g mixture was kept in a water bath at 40 ° C. The viscosity change of the mixture was observed. If the time when fluidity is lost is 0 to 3 hours, it is “C”, if it is 3 to 6 hours, “B”, if it is 6 to 10 hours, “A”, if it is 10 hours or more, “AA”. Judged.

2-6. Results The evaluation results of Examples and Comparative Examples are summarized in Table 3 below. In the table, the numerical value in parentheses is the blending ratio (parts by weight) of the one-component epoxy resin composition. The contents of the abbreviations in the table are as follows.
BisA: bisphenol A type epoxy resin (epoxy equivalent 173 g / eq, hydrolyzed chlorine content 0.01% by mass)
BisF: bisphenol F type epoxy resin (epoxy equivalent 160 g / eq, amount of hydrolyzed chlorine 0.007% by mass)
Nap: Naphthalene type epoxy resin (epoxy equivalent 142 g / eq, amount of hydrolyzed chlorine 0.017% by mass)
Res: Resorcin diglycidyl ether (epoxy equivalent 117 g / eq, amount of hydrolyzed chlorine 0.7 mass%)

  From the above experimental results, according to the present invention, it is possible to obtain a powdery microcapsule type latent curing agent for epoxy resin that satisfies both low-temperature curability and storage stability, a production method, and a one-part epoxy resin composition. Was confirmed.

Claims (11)

A step of forming capsules covering the core by reacting an amine adduct contained in the core, an isocyanate, a compound having an active hydrogen group and / or water in a dispersion medium ;
Removing the powdery microcapsule-type latent curing agent having a core and a capsule from the mixture after the reaction, and a method for producing a microcapsule-type latent curing agent for epoxy resin. The powdery microcapsule-type latent curing agent is taken out of the mixture by removing the dispersion medium together with the unreacted isocyanate and by-products, water and / or the compound having an active hydrogen group. 2. A process for producing a microcapsule type latent curing agent for epoxy resin according to 1. The method for producing a microcapsule type latent curing agent for epoxy resin according to claim 1 or 2, wherein the powdery microcapsule type latent curing agent is taken out of the mixture by removing the dispersion medium by filtration. The manufacturing method of the microcapsule type | mold latent hardener for epoxy resins as described in any one of Claims 1-3 in which the said dispersion medium contains a cyclohexane and / or hexane. The manufacturing method of the microcapsule type | mold latent hardener for epoxy resins as described in any one of Claims 1-4 with which the said core contains the said amine adduct of 50-100% by mass ratio. The production of the microcapsule type latent curing agent according to any one of claims 1 to 5, wherein the ratio of the capsule is 5 to 80% by mass based on the total mass of the microcapsule type latent curing agent . Way . The microcapsule-type latent hardening | curing agent for epoxy resins which can be obtained by the manufacturing method as described in any one of Claims 1-6 . A one-component epoxy resin composition comprising the microcapsule-type latent curing agent for epoxy resin according to claim 7 and an epoxy resin. The one-component epoxy resin composition according to claim 8 , wherein the microcapsule-type latent curing agent for epoxy resin is heat-treated in the epoxy resin. Said containing microphone capsule type latent curing agent 5-70 parts by mass relative to the total 100 parts by weight of the epoxy resin and the microphone capsule type latent curing agent, one-component epoxy resin composition according to claim 8 . A cured product formed by curing the one-component epoxy resin composition according to claim 8 by heating.