JP4711721B2 - Method for producing latent curing agent - Google Patents

Description

  The present invention relates to the technical field of adhesives, and more particularly to the technical field of latent curing agents used in adhesives.

  Conventionally, a latent curing agent in which a curing agent is contained in a microcapsule has been widely used to improve the storage stability of an adhesive. Since the latent hardener microcapsules are solid at room temperature and the hardener is protected by the microcapsules, the adhesive does not harden at room temperature, but when the adhesive is heated, the microcapsules dissolve or break. The curing agent is released into the adhesive, the thermosetting resin in the adhesive is polymerized by the curing agent, and the adhesive is cured.

  Microcapsules are generally made of resin, and the latent curing agent is produced by mixing the curing agent with the microcapsule resin raw material to form a curing agent droplet, and then heating it to the surface of the droplet. The adhering resin material is polymerized to form microcapsules that cover the droplets with a polymer of the resin material.

  However, if a curing agent that reacts chemically with the resin material is used, the reaction between the curing agent and the resin material starts when the curing agent and the resin material are mixed, and the curing agent is chemically modified. . If the curing agent is chemically modified, even if the curing agent can be microencapsulated, the reactivity of the adhesive to the thermosetting resin is reduced. Accordingly, the types of the curing agent and the resin raw material are limited to those that do not react with each other.

  For example, isocyanate is widely used as a resin material for microcapsules. Polymers of isocyanate (polyurea resin, polyurethane resin) are solid at room temperature, but are easily dissolved or destroyed by heating, so they are suitable for microcapsules. Isocyanate is an excellent curing agent for thermosetting resins (epoxy resins), but is highly reactive with imidazoles, amines, and phenols. Could not be microencapsulated.

There is also known a method in which imidazole is chemically modified, and then the modified product (for example, epoxy adduct product) is mixed with a resin raw material and microencapsulated, but the modified product is compared with imidazole before modification. The reactivity of the adhesive to the thermosetting resin is low, and the curing rate when the adhesive is cured is reduced.
Japanese Unexamined Patent Publication No. 2000-230039 JP 2004-142174 A JP 2004-246231 A

  The present invention has been made to solve the above-mentioned problems, and its purpose is to create a latent curing agent without reducing the reactivity of the curing agent even if the resin raw material reacts with the curing agent. A possible manufacturing method is provided.

  As a result of intensive studies by the present inventors, if a metal chelate is used as a curing agent and a droplet containing the metal chelate and isocyanate is cured, porous particles containing the metal chelate are formed inside. I found out that

  Since the metal chelate does not react with the isocyanate, the reactivity of the adhesive to the thermosetting resin does not decrease. However, in order to use the metal chelate as a curing agent, it is necessary to add a large amount of a silane coupling agent to the adhesive. Moreover, the reactivity with a thermosetting resin is also inferior compared with imidazole.

  As a result of further studies by the present inventors, the resin particles are formed without adding the aluminum chelate, and even if the resin particles and the curing agent are mixed, the curing agent is contained inside the resin particles. I understood.

The invention according to claim 1 made based on such knowledge forms a resin particle composed of a second resin component which is a reaction product by reacting a first resin component, and the resin particle includes the second resin component. A method for producing a latent curing agent that reacts with one resin component, contacts a solution of a curing agent component that does not react with the second resin component, and impregnates the curing agent component inside the resin particle , Isocyanate is used as the first resin component, and one or more compounds of imidazole, polyamine, tertiary amine, or phenol are used as the curing agent component, and a part of the isocyanate is hydrolyzed. The latent curing agent is produced by producing an amine and reacting the amine with another isocyanate to produce a polyurea resin as the second resin component .
Invention of Claim 2 is a manufacturing method of the latent hardening | curing agent of Claim 1, Comprising: Formation of the said resin particle is a dispersion | distribution solvent using the raw material liquid by which said 1st resin component was melt | dissolved in the raw material solvent. This is a method for producing a latent curing agent, in which liquid droplets of the raw material liquid are formed and dispersed, and the dispersion solvent in which the droplets are formed is heated to react the first resin component.
According to a third aspect of the invention, a method for producing a latent curing agent according to any one of claims 1 or claim 2, wherein the raw material solvent is a method for producing a latent curing agent is ethyl acetate .
Invention of Claim 4 is a manufacturing method of the latent hardening | curing agent of any one of Claim 1 thru | or 3 , Comprising: It is 40 of the said raw material solvent with respect to 11 weight part of said 1st resin components. It is a manufacturing method of the latent hardener using the said raw material liquid which has a weight part or more.
Invention of Claim 5 is a manufacturing method of the latent hardener of any one of Claim 1 thru | or 4 , Comprising: The latent hardener which adds alcohol to the said solution made to contact with the said resin particle It is a manufacturing method.
Invention of Claim 6 is a manufacturing method of the latent hardening | curing agent of Claim 5, Comprising: The latency which makes the density | concentration of the said hardening | curing agent component contacted with the said resin particle 30 to 40 weight% It is a manufacturing method of a hardening | curing agent.
The invention of claim 7, wherein, there is provided a method for producing a latent curing agent according to any one of claims 1 to 6, formation of the resin particles, the average particle diameter of the resin particles or higher 2μm This is a method for producing a latent curing agent.

  The present invention is configured as described above, and after forming the resin particles without adding the curing agent component to the first resin component, the curing agent component is in contact with the resin particles. The components are impregnated inside the resin particles without being chemically changed.

  The resin particles may contain other organic or inorganic substances other than the second resin component. The second resin component may be a homopolymer produced by homopolymerizing the first resin component, or may be produced by copolymerization of the first resin component and another resin component. Copolymers may also be used.

  As the dispersion solvent, the first resin component or a raw material solvent that dissolves the first resin component is used, and the raw material liquid can be dispersed in a larger amount (volume ratio) of the dispersion solvent than the raw material liquid. For example, droplets of the raw material liquid are formed in the dispersion solvent.

  When a solvent is added to the solution of the curing agent component, if a solvent that does not dissolve the second resin component is used, the resin particles are not dissolved when the solution of the curing agent component is brought into contact with the resin particles. The shape and internal porous structure are maintained. Examples of the solvent that does not dissolve the second resin solvent include alcohol when the second resin component is a polyurea resin.

  Even if the curing agent component reacts with the first resin component, since the curing agent component is impregnated inside the resin particles after the first resin component is polymerized, Activity does not decrease. Therefore, even if the latent curing agent is prepared without chemically modifying the curing agent component, the reactivity of the adhesive to the thermosetting resin does not decrease. According to the present invention, since the latent curing agent can be created regardless of the type and reactivity of the first resin component and curing agent, the type of curing agent and the type of first resin component are not limited, and curing conditions The latent curing agent can be freely designed according to the thermosetting resin and the bonding purpose. Imidazole is highly reactive with an epoxy resin, which is a thermosetting resin, and the polymer of isocyanate is solid at room temperature but dissolves easily by heating. Therefore, imidazole is used as the curing agent, and isocyanate is used as the first resin component. If a latent curing agent is prepared by using it, it will be cured at a low heating temperature when added to the adhesive, and the curing rate will be faster.

  Below, the manufacturing method of the latent hardening | curing agent of this invention is demonstrated in detail. A first resin component, which is a resin raw material for resin particles described later, is dissolved in a raw material solvent in which the first resin component can be dissolved to prepare a raw material liquid.

  Using a dispersion solvent that does not dissolve both the first resin component and the raw material solvent in the raw material liquid, when the raw material liquid is placed in the dispersion solvent and heated with stirring, droplets of the raw material liquid are formed in the dispersing solvent by stirring. By heating, the first resin component in the droplets reacts to cure the droplets, and resin particles of the second resin component, which is a reaction product of the first resin component, are formed.

  For example, when the first resin component is an isocyanate and the dispersion solvent is water, as shown in the following reaction formulas (1) and (2), a part of the isocyanate is hydrolyzed to form an intermediate product. A certain amine is produced, and the amine reacts with other isocyanate as shown in the reaction formula (3) to produce a polyurea resin.

  Since the raw material solvent in the droplet does not react with the first and second resin components, the raw material solvent is taken into the resin particles when the droplet is cured. When the resin particles are filtered off from the dispersion solvent, washed and dried, the raw material solvent taken into the resin particles at the time of drying evaporates, and after the raw material solvent evaporates, it remains as pores, with pores inside. A large number of formed porous resin particles can be obtained.

  When the resin particles are immersed in the solution of the curing agent component and the solution of the curing agent component is brought into contact with the resin particles, the solution of the curing agent component penetrates through the pores of the resin particles, and the curing agent component is inside the resin particles. Impregnated into.

  Here, the curing agent component is imidazole, and imidazole chemically reacts with the first resin component isocyanate, but does not react with the second resin component polyurea resin. The impregnated imidazole does not change chemically. Therefore, the imidazole is retained by the resin particles without deactivating the reactivity to the thermosetting resin described later.

  After the curing agent solution is stirred for a predetermined time and the resin particles are impregnated with a sufficient amount of the curable component, the resin particles are washed with a small amount of polar solvent, filtered, collected, and dried. A latent curing agent containing a curing agent component is obtained.

  Next, an example of an adhesive using this latent curing agent will be described. An adhesive is prepared by mixing a thermosetting resin that is an epoxy resin, the latent curing agent, and conductive particles. A diluent such as an organic solvent may be further added to the adhesive to form a paste adhesive, or a paste adhesive may be applied and dried to form a film adhesive (adhesive film).

  The second resin component constituting the resin particles does not dissolve at room temperature (35 ° C. or lower), and the adhesive does not cure while the adhesive is stored at room temperature, but when the adhesive is heated to a temperature exceeding room temperature. The second resin component is dissolved, and the curing agent component inside the resin particles is released into the adhesive.

  When the curing agent component is released into the adhesive, the thermosetting resin is polymerized. When the curing agent component is imidazole and the thermosetting resin is an epoxy resin, imidazole functions as a curing catalyst, and the epoxy resin is polymerized to cure the adhesive.

<Resin particles>
11 parts by weight of isocyanate as the first resin component was dissolved in 60 parts by weight of ethyl acetate as the raw material solvent to prepare a raw material liquid.
The isocyanate used here is a trade name “D-109” manufactured by Mitsui Takeda Chemical Co., Ltd., which is trimethylolpropane (1 mol) and methylenediphenyl-4,4-diisocyanate (3 mol). Is an adduct added.

  Dispersion in which 0.05 part by weight of a surfactant (trade name “Newlex RT” manufactured by Nippon Oil & Fats Co., Ltd.) and 4 parts by weight of a dispersant (polyvinyl alcohol) are added to 800 parts by weight of distilled water. The raw material liquid was added to the solvent, and the mixture was stirred with a homogenizer while heating at 80 ° C. to produce resin particles.

  An electron micrograph of the resin particles is shown in FIG. Furthermore, the particle size distribution of the resin particles was determined in terms of volume. The measurement results are shown in FIG. The horizontal axis of FIG. 2 indicates the particle diameter (particle size, unit μm), one vertical axis indicates the frequency (unit%) of the line graph, and the other vertical axis indicates the integrated amount (unit%) of the bar graph. The resin particles produced under the above conditions had a maximum particle size of 5 μm and a distribution with a particle size of 2.29 μm was the maximum.

<Example>
A curing agent solution containing 30% by weight of imidazole was prepared by dissolving imidazole (trade name “Cureazole 2MZ” manufactured by Shikoku Kasei Kogyo Co., Ltd.) as a curing agent component in ethanol as a curing agent solvent.

The resin particles were added to the curing agent solution so as to have a content of 2% by weight, stirred at 40 ° C. for 6 hours, and then stirred overnight at room temperature. The resin particles impregnated with the curing agent component were washed with a small amount of polar solvent, filtered, and then naturally dried to obtain a latent curing agent. An electron micrograph of the latent curing agent is shown in FIG.
Epoxy resin (trade name “EP807” manufactured by Japan Epoxy Resin Co., Ltd.) and the above-mentioned latent curing agent were mixed at a weight ratio of 100: 30 to prepare adhesives of Examples.

<Comparative example>
A comparative adhesive was prepared under the same conditions as in the Examples except that the imidazole was used without microencapsulation instead of the latent curing agent.

  The differential scanning calorimetry was performed on the adhesives of the above Examples and Comparative Examples, and the results are shown in FIG. 4 and FIGS. 5 to 8 described later, the horizontal axis indicates temperature (° C.), and the vertical axis indicates heat flow (mW). 4 indicates a DSC (Differential Scanning Calibration) curve of the example, and symbol M indicates a DSC curve of the comparative example.

  The comparative example had an exothermic peak at a low temperature of 85 ° C., the exothermic peak width was wide, and the maximum calorific value (maximum value of the heat flow mW) was low. On the other hand, the Example had an exothermic peak at 103 ° C., and the exothermic peak shifted to a higher temperature side than the comparative example, but the width of the exothermic peak was narrowed accordingly, and the maximum calorific value was as large as 26.42 mW.

  When the DSC curve rises in the direction of heat generation, the curing reaction of the adhesive starts, and the larger the amount of heat generated, the faster the curing reaction of the adhesive proceeds. It is estimated that the curing rate is faster than that.

<Concentration of curing agent component>
When a curing agent solution was prepared in which the imidazole concentration was changed to 20%, 30%, 40%, and 50% by weight, when the imidazole concentration was 50% by weight, the imidazole was not completely dissolved in ethanol and precipitated. It was. Therefore, when the curing agent component is imidazole, the concentration of the curing agent component in the curing agent solution is maximum at less than 50% by weight. Three types of latent curing agents were prepared under the same conditions as in the above examples except that the curing agent solution was changed to a curing agent solution having an imidazole concentration of 20 wt% to 40 wt%.

  Furthermore, in place of the epoxy resin of Example 1, the trade name “EP807” manufactured by Japan Epoxy Resin Co., Ltd. and the trade name “EP828EL” manufactured by Japan Epoxy Resin Co., Ltd. are 75:25 (weight ratio). Using the mixture, 30 parts by weight of the above-mentioned three kinds of latent curing agents were added to 100 parts by weight of the mixture to prepare three kinds of adhesives.

  The differential scanning calorimetry was performed on the three types of adhesives. The results are shown in FIG. 5 and the measured maximum heat generation amount and the temperature when the maximum heat generation amount is reached (exothermic peak temperature) are shown in Table 1 below. Show.

  Symbols La, Lb, and Lc in FIG. 5 indicate DSC curves when the imidazole concentrations in the curing agent solution were 20 wt%, 30 wt%, and 40 wt%, respectively, and the imidazole concentration was 30 When the weight percentage is 40% by weight, the maximum heat generation amount is larger and the curing start temperature is lower than when the weight percentage is 20% by weight. Therefore, when imidazole is used as the curing agent component, it is understood that the imidazole concentration should be 30% by weight or more if it is desired to lower the curing start temperature of the adhesive and increase the curing rate.

  Also, when the imidazole concentration is as high as 40% by weight, the maximum calorific value is conversely smaller than when it is 30% by weight, and when the imidazole concentration is further higher than 40% by weight, it is estimated that the maximum calorific value is further reduced. Therefore, when the curing agent component is imidazole, an adhesive having a high curing rate can be obtained by setting the upper limit of the concentration of the curing agent component to 40% by weight.

<Average particle diameter of resin particles>
Three types of resin particles having different average particle diameters were prepared. When the average particle diameter of these resin particles was measured, they were 3.05 μm, 2.29 μm, and 1.88 μm, respectively, in terms of volume.

  Next, using the above three types of resin particles, three types of adhesives were prepared under the same conditions as in the above examples except that the same epoxy resin as in the above-mentioned “curing agent component concentration” test was used. Differential scanning calorimetry was performed on the adhesive. The results are shown in FIG. 6, and the measured maximum calorific value and the temperature at which the maximum calorific value is reached are shown in Table 2 below together with the average particle diameter of the resin particles.

  The code | symbol Ld of FIG. 6, the code | symbol Le, and the code | symbol Lf have shown the DSC curve when the average particle diameters of the resin particle were 3.05 micrometer, 2.29 micrometer, and 1.88 micrometer, respectively, 3 types of adhesion | attachment Both of the agents had a low curing start temperature and a sufficiently large maximum calorific value, but the maximum calorific value was particularly large when the average particle size was 2.29 μm and 3.05 μm. Therefore, it is understood that the average particle diameter should be 2 μm or more when it is desired to increase the curing rate of the adhesive.

<Combination ratio of first resin component and raw material solvent>
Three kinds of resin particles are produced by changing the blending amount of the raw material solvent with respect to 11 parts by weight of the first resin component to 30 parts by weight, 40 parts by weight, and 60 parts by weight. Three types of adhesives were prepared under the same conditions as in the above example except that the same epoxy resin as in the “Concentration of agent component” test was used, and differential scanning calorimetry was performed on the three types of adhesives. The results are shown in FIG. 7, and the measured maximum calorific value and the temperature when the maximum calorific value is reached are shown in Table 3 below together with the blending amount of the raw material solvent.

  Symbols Lg, Lh, and Li in FIG. 7 show DSC curves when the amounts of the raw material solvent are 30 parts by weight, 40 parts by weight, and 60 parts by weight, respectively, and both types of adhesives are cured. The starting temperature was low and the maximum heat generation was sufficiently high.

  However, when the blending amount of the raw material solvent was 30 parts by weight, the maximum calorific value was slightly smaller than when the blending amount of the raw material solvent was 40 parts by weight and 60 parts by weight. This is presumably because if the blending amount of the raw material solvent is too small, the crosslinking density of the second resin component constituting the resin particles becomes high, and the curing agent component is hardly released from the resin particles during heating. From these, it is understood that if it is desired to increase the curing rate of the adhesive, 11 parts by weight of the first resin component may be dissolved in 40 parts by weight or more of the raw material solvent.

<Impregnation temperature>
3 under the same conditions as in the above example except that the resin particles were immersed and stirred in the curing agent solution, and the curing agent component and the resin particles were impregnated at 30 ° C., 40 ° C., and 50 ° C. Three types of latent hardeners were prepared, and these three types of latent hardeners and three types of adhesives were used under the same conditions as in the above examples except that the same epoxy resin as in the above-mentioned “Concentration of hardener component” test was used. It was created.

  Differential scanning calorimetry was performed on these three types of adhesives. The result is shown in FIG. Symbols Lj, Lk, and Ll in FIG. 8 indicate DSC curves when the stirring temperature is 30 ° C., 40 ° C., and 50 ° C., respectively, and each DSC curve has a large maximum heat generation amount. It is estimated that the type of adhesive has a fast curing rate. Therefore, it can be seen that an adhesive having a high curing rate can be obtained if the temperature at which the curing agent component is impregnated into the resin particles is in the range of at least 30 ° C. and 50 ° C. or less.

Next, another embodiment of the present invention will be described in detail.
The time for dipping and stirring the resin particles in the curing agent solution is not particularly limited, and the dipping time can be shortened to about 3 hours by changing the temperature at the time of dipping, the amount of resin particles added, and the stirring conditions. Is also possible.

  The method for bringing the curing agent solution into contact with the resin particles is not particularly limited, and the resin particles may be put into the curing agent solution, or conversely, the curing agent solution may be put into the resin particles. May be sprayed onto the resin particles.

  The curing agent component is not particularly limited as long as it does not react with the second resin component even if it reacts with the first resin component. For example, when the first resin component is an isocyanate, In addition, amines such as polyamines and tertiary amines, and compounds having one or more hydroxyl groups in the chemical structure such as phenol can be used. One of these compounds may be used alone for the curing agent component, or two or more of these compounds may be used together for the curing agent component.

  In addition, even when the curing agent does not react with the first and second resin components, it reacts with an intermediate product that is produced until the second resin component is produced from the first resin component. Moreover, the manufacturing method of the latent hardening | curing agent of this invention is applicable.

  For example, when the first resin component is an isocyanate and the second resin component is a polyurea resin, an amine is generated as an intermediate product as described above, but the intermediate product is present in the resin particles of the second resin component. Since it does not remain, a curing agent that reacts with an amine can also be used.

  The curing agent solvent is not particularly limited as long as it can dissolve the curing agent component and does not react with the curing agent component, but it has excellent solubility in the curing agent component, low boiling point, polarity. It is preferable that the resin particles satisfy the condition that the resin particles can swell. As a material satisfying such conditions, there is an alcohol when the curing agent component is imidazole, and ethanol is particularly suitable among the alcohols in consideration of the safety of the working environment.

  Since the resin particles are produced using a so-called interfacial polymerization method, the shape thereof is spherical, and the particle diameter (diameter) is preferably 0.5 μm or more and 100 μm or less from the viewpoint of curability and dispersibility. However, in order to increase the amount of the curing agent component impregnated in the resin particles and increase the curing rate of the adhesive, the particle diameter is desirably 2 μm or more. In addition, the size of the pores inside the resin particles is preferably 5 nm or more and 150 nm or less from the viewpoint of curability and latency.

  In addition, the latent curing agent has a tendency that if the degree of cross-linking of the second resin component is too small, the potential is lowered, and if it is too large, the thermal responsiveness tends to be lowered. It is preferable to use an adjusted porous resin. Here, the degree of crosslinking of the porous resin can be measured by a micro compression test.

  The latent curing agent of the present invention contains substantially no organic solvent (raw material solvent, dispersion solvent) used during the interfacial polymerization, specifically 1 ppm or less, in terms of curing stability. Is preferable.

It is presumed that resin particles having a porous structure can be obtained even if the type of isocyanate contained in the first resin component is changed.
The isocyanate used for the first resin component is preferably a compound having two or more isocyanate groups in one molecule, more preferably three isocyanate groups in one molecule. As a more preferred example of such a trifunctional isocyanate compound, a TMP adduct of the following formula (1) obtained by reacting 3 mol of a diisocyanate compound with 1 mol of trimethylolpropane, and the following formula (3) The isocyanurate body of 2) and the burette body of following formula (3) which the remaining 1 mol diisocyanate condensed with the diisocyanate urea obtained from 2 mol of 3 mol of diisocyanate compounds are mentioned.

  In the above formulas (1) to (3), the substituent R is a portion excluding the isocyanate group of the diisocyanate compound. Specific examples of such diisocyanate compounds include toluene 2,4-diisocyanate, toluene 2,6-diisocyanate, m-xylylene diisocyanate, hexamethylene diisocyanate, hexahydro-m-xylylene diisocyanate, isophorone diisocyanate, methylene diphenyl-4. , 4'-diisocyanate.

  As described above, the type of isocyanate is not particularly limited. However, if the type of isocyanate is changed, the porous structure of the resin particles is also changed, which affects the properties as a latent curing agent. Potential curing agent based on the optimum conditions determined in each evaluation test of “concentration of agent component”, “average particle diameter of resin particles”, “mixing ratio of first resin component and raw material solvent”, and “impregnation temperature” In the case of preparation, it is preferable to use an adduct of methylenediphenyl-4,4-diisocyanate (3 mol) and trimethylolpropane (1 mol).

  In the porous resin obtained by interfacial polymerization of such a polyfunctional isocyanate compound, part of the isocyanate group undergoes hydrolysis during the interfacial polymerization to become an amino group, and the amino group reacts with the isocyanate group. It is a polyurea that is polymerized by generating urea bonds and has many pores inside. When the latent curing agent composed of such a porous resin and the curing agent component held in the pores is heated for curing, the clear reason is unknown, but the retained curing agent component Is released into the adhesive so that it can come into contact with the thermosetting resin, and the polymerization reaction of the thermosetting resin can proceed.

  The raw material solvent for dissolving the first resin component is preferably a volatile organic solvent having a boiling point of 100 ° C. or lower under atmospheric pressure. Here, the reason for using the volatile organic solvent is as follows. That is, when a high boiling point solvent having a boiling point exceeding 300 ° C. as used in a normal interfacial polymerization method is used, the organic solvent does not volatilize during the interfacial polymerization, so the contact probability with isocyanate-water does not increase. This is because the degree of progress of interfacial polymerization between them becomes insufficient.

  Therefore, it is difficult to obtain a polymer having good shape retention even when interfacial polymerization is performed, and even when it is obtained, a high boiling point solvent is still taken into the polymer, and when blended in an adhesive, it has a high boiling point. This is because the solvent adversely affects the physical properties of the cured product of the adhesive.

  As such a volatile organic solvent, it is a good solvent with a polyfunctional isocyanate compound (the solubility of each is preferably 0.1 g / ml (organic solvent) or more), and it is substantially soluble in water. (The solubility of water is 0.5 g / ml (organic solvent) or less) and the boiling point at atmospheric pressure is 100 ° C. or less. Specific examples of such volatile organic solvents include alcohols, acetate esters, ketones and the like. Among these, ethyl acetate is preferable in terms of high polarity, low boiling point, and poor water solubility.

  The viscosity of the solution that becomes the oil phase can be lowered by using a relatively large amount of the raw material solvent within the range of the raw material solvent used. The oil phase droplets in the system can be made finer and uniform, and the particle size distribution is monodispersed while the resulting latent curing agent particle size is controlled to a size of submicron to several microns. It becomes possible. The viscosity of the oil phase solution is preferably set to 1 mPa · s or more and 2.5 mPa · s or less.

When the first resin component is dissolved in the raw material solvent to prepare the raw material solution, it may be simply mixed and stirred at room temperature under atmospheric pressure, but may be heated as necessary.
The raw material liquid is put into an aqueous phase (dispersing solvent) containing a dispersing agent and subjected to interfacial polymerization by heating and stirring. At this time, if a surfactant or a dispersant is added to the dispersion solvent, the dispersibility of the droplets is improved, so that the droplets have a uniform particle size, and as a result, resin particles having a uniform particle size can be obtained.

  Here, as a dispersing agent, what is used in normal interfacial polymerization methods, such as polyvinyl alcohol, carboxymethylcellulose, gelatin, can be used. The amount of the dispersant used is usually 0.1% by weight or more and 10.0% by weight or less of the aqueous phase.

  When PVA (polyvinyl alcohol) is used as the dispersant, the hydroxyl group of PVA reacts with the polyfunctional isocyanate compound, so that by-products adhere around the resin particles as foreign substances, and the particle shape itself is It may be deformed. Since the polyfunctional isocyanate compound has a higher reaction rate (interfacial polymerization) with the amine formed by hydrolysis than the reaction rate with the hydroxyl group of PVA, if water is used as the dispersion solvent, the reaction probability with PVA is lowered. be able to.

  The blending amount of the raw material liquid with respect to the dispersion solvent is polydispersed if the raw material liquid is too small, and if it is too large, aggregation occurs due to miniaturization. is there.

  As the emulsification conditions in the interfacial polymerization, stirring conditions (stirring apparatus homogenizer; stirring speed of 8000 rpm or more) such that the size of the droplets that are the oil phase is preferably 0.5 μm or more and 100 μm or less are usually obtained under atmospheric pressure. The temperature of the dispersion | distribution solvent in which the oil phase was disperse | distributed can be 30 degreeC or more and 80 degrees C or less, and the conditions which heat-stir for 2 hours or more and 12 hours can be mentioned. After the completion of interfacial polymerization, the polymer fine particles are filtered off from the second dispersion and naturally dried to obtain the latent curing agent of the present invention.

  According to the production method of the present invention described above, the curing characteristics of the latent curing agent can be controlled by changing the type and amount of the first resin component and the interfacial polymerization conditions. For example, if the polymerization temperature is lowered, the curing temperature can be lowered, and conversely, if the polymerization temperature is raised, the curing temperature can be raised.

  The latent curing agent of the present invention can be used in the same applications as conventional imidazole-based latent curing agents, and preferably, when used in combination with a thermosetting resin, a low-temperature fast-curing thermosetting adhesive Agent can be given.

  If the content of the latent curing agent in the thermosetting adhesive is too small, it will not be cured sufficiently, and if it is too large, the resin properties (for example, flexibility) of the cured product of the adhesive will decrease. 1 part by weight or more and 70 parts by weight or less, preferably 1 part by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the conductive resin.

  As the thermosetting resin, a thermosetting urea resin, a thermosetting melamine resin, a thermosetting phenol resin, etc. can be used in addition to the thermosetting epoxy resin, as long as it can be cured by reacting with the curing agent component. Can be used. Among these, a thermosetting epoxy resin can be preferably used in consideration of a good adhesive strength after curing.

  Such a thermosetting epoxy resin may be liquid or solid, and preferably has an epoxy equivalent of usually 100 or more and 4000 or less and having two or more epoxy groups in the molecule. For example, a bisphenol A type epoxy compound, a phenol novolac type epoxy compound, a cresol novolac type epoxy compound, an ester type epoxy compound, an alicyclic epoxy compound, or the like can be preferably used. These compounds include monomers and oligomers.

  The thermosetting adhesive may contain a filler such as silica and mica, a pigment, an antistatic agent, a coupling agent, a coloring agent, an anti-aging agent, and the like as necessary. In addition, when the thermosetting adhesive of the present invention is used for connection of electrical parts such as a wiring board and a semiconductor element, it is preferable to disperse conductive particles having a particle size on the order of several μm. As for metal particles, those in which the surface of the resin core is coated with a metal plating layer, those whose surfaces are further coated with an insulating thin film, and the like are blended in an amount of 1 wt% to 10 wt% of the entire adhesive. It is preferable. As a result, the adhesive can be used as an anisotropic conductive adhesive paste or an anisotropic conductive film.

  The adhesive can be produced by uniformly mixing and stirring the latent curing agent produced according to the present invention, the thermosetting resin, and other additives added as necessary according to a conventional method. it can.

  Since the adhesive obtained in this manner has a latent hardener, it is excellent in storage stability despite being a one-component type. In addition, the latent curing agent does not dissolve at room temperature, but dissolves at a low temperature when heated, so that the adhesive cures in a short time under low temperature conditions.

Electron micrograph of resin particles (5000 times) Graph showing particle size distribution of resin particles Electron micrograph of the latent curing agent (5000 times) DSC curve of adhesive to which latent curing agent is added and adhesive to which curing agent component is added as it is DSC curve of adhesive with varying imidazole concentration DSC curve of adhesive with different resin particle size DSC curve of adhesives with varying amounts of raw material solvent DSC curve of adhesive with different temperature when impregnating hardener component

Claims (7)

Reacting the first resin component to form resin particles composed of the second resin component as a reaction product;
A latent curing agent for contacting the resin particles with a solution of a curing agent component that reacts with the first resin component and does not react with the second resin component, and impregnates the curing agent component inside the resin particles. A manufacturing method comprising :
Using isocyanate as the first resin component,
As the curing agent component, one or more compounds of imidazole, polyamine, tertiary amine, or phenol are used,
A method for producing a latent curing agent, wherein a part of the isocyanate is hydrolyzed to produce an amine, and the amine is reacted with another isocyanate to produce a polyurea resin that is the second resin component .   The resin particles are formed by dispersing a raw material liquid in which the first resin component is dissolved in a raw material solvent in a dispersion solvent to form droplets of the raw material liquid, and the dispersion solvent in which the droplets are formed The manufacturing method of the latent hardening | curing agent of Claim 1 with which said 1st resin component is made to react by heating. The raw material solvent method for producing the latent curing agent according to any one of claims 1 or claim 2 which is ethyl acetate. The manufacturing method of the latent hardening | curing agent of any one of Claim 1 thru | or 3 which uses the said raw material liquid which has 40 weight part or more of the said raw material solvent with respect to 11 weight part of said 1st resin components. Method for producing a latent curing agent according to any one of claims 1 to 4, adding an alcohol to the solution of contacting the resin particles. The manufacturing method of the latent hardening | curing agent of Claim 5 which makes the density | concentration of the said hardening | curing agent component contacted with the said resin particle 30 to 40 weight%. The formation of the resin particles, method for producing a latent curing agent according to any one of claims 1 to 6 to an average particle diameter of the resin particles than 2 [mu] m.