JPWO2019189458A1 - Latent curing catalyst for epoxy resin and epoxy resin composition using this - Google Patents

Abstract

To provide a latent curing catalyst for an epoxy resin, which has a small particle size, is excellent in miscibility with an epoxy resin, has high storage stability in a composition with an epoxy resin, and is also excellent in curability. .. A core containing a phosphorus-based curing catalyst and a vinyl-based polymer, a polymer of a monomer component containing a first vinyl-based monomer and a first crosslinkable vinyl-based monomer, or a weight of the first vinyl-based monomer. A polymer of a monomer component composed of a coalesced primary vinyl resin, an inner shell layer covering the core, and a secondary vinyl-based monomer and a second crosslinkable vinyl-based monomer, or An epoxy composed of a second vinyl resin which is a polymer of a second crosslinkable vinyl-based monomer and having an average particle size of 0.01 to 50 μm including an outer shell layer covering the inner shell layer. Latent curing polymer for resins.

Description

The present invention relates to a latent curing catalyst used by blending with an epoxy resin, and an epoxy resin composition comprising the potential curing catalyst.

The epoxy resin is a compound having two or more highly reactive epoxy groups in the molecule, and is a curable resin that forms a crosslinked network by the reaction of the epoxy groups. Epoxy resins are usually mixed with a curing agent such as acid anhydride or polyamine and a curing catalyst (also referred to as a curing accelerator) such as phosphine, tertiary amine, or imidazole to prepare an epoxy resin composition, which is then heated. To proceed with curing. Such an epoxy resin composition is widely used in various applications, and is particularly attracting attention as a sealing material in semiconductor devices and electronic components.

In general, the curing catalyst easily starts curing when it comes into contact with the epoxy resin, so that the epoxy resin composition is widely stored as a two-component composition in which the main agent and the auxiliary agent are separated. However, in the two-component type, it is necessary to weigh the required amounts of the main agent and the auxiliary agent immediately before use and then mix the two agents, which is complicated in terms of work. Further, if a one-component composition is prepared to avoid complications, it is necessary to suppress the progress of the curing reaction by storing in freezing or refrigerating, which is disadvantageous in terms of cost. In addition, in the process of returning to room temperature from the freezing or refrigerating state before use, curing will proceed if it is left at room temperature for a long time, and when it is used for sealing, the fluidity will decrease due to the increase in viscosity. There was a problem that the filling property was poor.

Therefore, it does not thicken while it is returned to room temperature from the stored state in freezing or refrigerating, and then used for sealing purposes (for example, 24 hours in storage at room temperature after thawing), and it can be stored without freezing or refrigerating. Methods for realizing a possible one-component epoxy resin composition are being studied. As one of such methods, a method of microencapsulating a curing catalyst has been proposed (see, for example, Patent Documents 1 to 5), and such an encapsulated curing catalyst may be commercially available.

Japanese Unexamined Patent Publication No. 8-73566 Japanese Unexamined Patent Publication No. 2012-136650 Japanese Unexamined Patent Publication No. 2016-35056 Japanese Unexamined Patent Publication No. 2016-35057 Japanese Unexamined Patent Publication No. 2016-153475

Since the encapsulation curing catalyst suppresses the progress of the curing reaction even when it is in contact with the epoxy resin, it can be stored in a mixed state. However, commercially available encapsulation curing catalysts are coarse particles having a particle size of about 50 μm, and are state-of-the-art semiconductor devices having extremely narrow bump / bump gaps, chip / chip gaps, chip / substrate gaps, and the like. In the case of encapsulant applications in electronic components and electronic components, there is a problem that it is not suitable for use due to poor penetration into such gaps.

In addition, since a state-of-the-art smartphone needs to process a huge amount of information (signal), it is a fan-out wafer level package (FO-) which is a semiconductor device that is small and has a large number of I / O terminals corresponding to it. WLP) has been applied. In FO-WLP, in order to increase the number of I / O terminals, a rewiring layer is formed not only on the lower surface of the semiconductor chip but also on the lower surface of the encapsulant protruding from the lower surface to form bumps (I / O terminals). It has a structure to arrange. The smoothness of the lower surface of the chip and the lower surface of the encapsulant, which are the covering surfaces, is important for forming a thin rewiring layer. There was a problem that the unevenness derived from the capsule was formed and the rewiring layer could not be formed. Therefore, it is desired to develop a semiconductor device having such an extremely narrow gap and an encapsulation curing catalyst having a smaller particle size that can cope with the formation of a rewiring layer of FO-WLP.

However, if the particle size of the encapsulation curing catalyst is simply reduced, the miscibility with the epoxy resin may be deteriorated, or the storage stability, which is the original purpose, may be lowered. Further, if the storage stability of the encapsulation curing catalyst is increased, the reactivity with the epoxy resin may be lowered, that is, there is a problem that good curability of the epoxy resin composition cannot be achieved.

Although the encapsulated curing catalyst is excellent in compatibility with the epoxy resin, the curing reaction does not proceed at a temperature lower than the predetermined curing temperature, and while exhibiting high storage stability, it is heated to the predetermined curing temperature. It is required that the curing reaction proceeds rapidly.

In view of the above situation, the present invention has an epoxy resin having a small particle size, excellent compatibility with an epoxy resin, high storage stability in a composition with an epoxy resin, and excellent curability. It is an object of the present invention to provide a latent curing catalyst for use and an epoxy resin composition containing the same.

The first invention is a polymer of a core containing a phosphorus-based curing catalyst and a vinyl-based polymer, a polymer of a monomer component containing a first vinyl-based monomer and a first crosslinkable vinyl-based monomer, or a first. A single amount composed of a first vinyl resin which is a polymer of a vinyl-based monomer and containing an inner shell layer covering the core, and a second vinyl-based monomer and a second crosslinkable vinyl-based monomer. It is composed of a second vinyl resin which is a polymer of a body component or a polymer of a second crosslinkable vinyl-based monomer, and is composed of particles including an outer shell layer which coats the inner shell layer, and the particles are averaged. The particle size is 0.01 to 50 μm, and the weight ratio of the second crosslinkable vinyl polymer in the second vinyl resin is higher than the weight ratio of the first crosslinkable vinyl polymer in the first vinyl resin. Also large, related to latent curing polymers for epoxy resins.

Preferably, the first crosslinkable vinyl-based monomer and the second crosslinkable vinyl-based monomer have a (meth) acrylic group. Preferably, the vinyl-based polymer contained in the core is a vinyl-based polymer having a crosslinked structure. Preferably, the weight ratio of the second crosslinkable vinyl-based monomer in the second vinyl resin is 50 to 100% by weight. Preferably, the amount of the second vinyl resin with respect to 100 parts by weight of the first vinyl resin is 5 to 50 parts by weight.

The second invention is a method for producing a latent curing catalyst for an epoxy resin, in which a monomer component containing a vinyl-based monomer is polymerized by emulsion polymerization in the presence of a phosphorus-based curing catalyst to form a core. In the step of forming the core, a monomer component containing a first vinyl-based monomer and a first crosslinkable vinyl-based monomer or a first vinyl-based monomer is obtained by emulsion polymerization in the presence of the core. A step of polymerizing to form an inner shell layer that coats the core, and in the presence of the inner shell layer that coats the core, by emulsion polymerization, a second vinyl-based monomer and a second crosslinkable vinyl-based monomer The present invention relates to a method comprising a step of polymerizing a monomer component containing and or a second crosslinkable vinyl-based monomer to form an outer shell layer covering the inner shell layer. Preferably, the emulsion polymerization in the step of forming the outer shell layer is carried out in the presence of a monomer-soluble radical polymerization initiator.

The third invention relates to an epoxy resin composition containing an epoxy resin and a latent curing catalyst for an epoxy resin according to the first invention.

The fourth invention is a cured product obtained by curing the epoxy resin composition according to the third invention. Preferably, the size of the convex or concave portion on the surface of the cured product is 10 μm or less.

The fifth invention relates to a semiconductor device containing a cured product according to the fourth invention as a sealing material. The semiconductor device may have a gap of 100 μm or less, and the encapsulant may penetrate into the gap. Further, a rewiring layer may be formed on the surface of the sealing material.

According to the present invention, the particle size is small, the mixture with the epoxy resin is excellent, the composition with the epoxy resin has high storage stability, and the curability is also excellent. An epoxy resin composition containing a catalyst and the curing catalyst, which has extremely good penetration into a sandwiching gap and excellent fluidity, and a surface smoothness obtained by heating the epoxy resin composition. It is possible to provide a cured product having excellent properties.

When the epoxy resin composition of the present invention is a liquid composition, the viscosity immediately after the composition is produced is low, the viscosity is unlikely to increase even after a lapse of time from the production, and the epoxy resin of the present invention is produced. When the composition is in the form of a solid sheet, the melt viscosity immediately after the composition is prepared is low, and the melt viscosity is unlikely to increase even after a lapse of time from the preparation. However, even when a large amount of an inorganic filler or the like is blended, there is an advantage that the fluidity is good and the penetration into an extremely narrow gap is good.

It is a drawing which shows the SEM observation image of the surface of a cured product (Example 1). It is a drawing which shows the SEM observation image of the surface of a cured product (Comparative Example 3).

Embodiments of the present invention will be described in detail below.
The latent curing catalyst for an epoxy resin of the present invention is in the form of particles having a layer structure consisting of at least three layers, that is, a core, an inner shell layer covering the core, and an outer shell layer covering the inner shell layer. Is. Then, the core contains a phosphorus-based curing catalyst, which functions as a curing catalyst for the epoxy resin. The outer shell layer and the inner shell layer may be directly laminated, and it is not necessary that the curing catalyst is arranged between the two layers as in Patent Document 2.

The resin contained in the core, the inner shell layer, and the outer shell layer are all vinyl-based. Since the curing temperature of a general epoxy resin exceeds the glass transition temperature (Tg) of a vinyl resin, the vinyl resin is changed to a rubber state at the curing temperature, and the substance permeability of the capsule is significantly improved. Therefore, the epoxy resin can flow into the capsule to dissolve the phosphorus-based curing catalyst and wash it out, or the phosphorus-based curing catalyst itself spontaneously permeates the capsule and is released into the epoxy resin. .. Further, when the stress load on the capsule is increased due to the above phenomenon or the capsule is thermally decomposed by heating, the capsule is disintegrated and the release rate of the phosphorus-based curing catalyst is remarkably increased. Further, since the vinyl resin itself does not inhibit the curing reaction of the epoxy resin, the epoxy resin exhibits good curability at the curing temperature. On the other hand, at the storage temperature, since the vinyl resin is in a glass state, the substance permeability of the capsule is low, and the invasion of the epoxy resin into the capsule is suppressed. Further, in the latent curing catalyst of the present invention, in addition to the above, since the outer shell layer is composed of a highly crosslinked vinyl resin, the preventive property of the epoxy resin from entering the capsule is remarkably high. Therefore, while exhibiting high storage stability below a predetermined temperature, it can exhibit high curability when heated to a predetermined temperature.

Further, since the outer shell layer of the latent curing catalyst of the present invention is composed of a highly crosslinked vinyl resin, only a weak cohesive force due to an intermolecular force acts between the particles of the latent curing catalyst (long from the particle surface). Since there are no graft chains, etc., aggregation due to entanglement is unlikely to occur). Therefore, in the blending of the particles and the epoxy resin, the agglutination of the particles is disengaged and the particles are easily miscible with the epoxy resin. In particular, when the outer shell layer has a functional group such as an ester group, the miscibility is further improved by the interaction between the ester group on the particle surface and the epoxy resin. Therefore, the latent curing catalyst of the present invention is highly miscible with the epoxy resin, and can exhibit high storage stability when heated to a predetermined temperature while exhibiting high storage stability below a predetermined temperature.

(core)
The phosphorus-based curing catalyst contained in the core is not particularly limited as long as it is a curing catalyst containing phosphorus among the curing catalysts that can be used as a curing catalyst for the epoxy resin. It is preferably an organic phosphine compound, specifically, alkylphosphine such as ethylphosphine, propylphosphine, butylphosphine and first phosphine such as phenylphosphine; dialkyl such as dimethylphosphine, diethylphosphine, dipropylphosphine and diamilphosphine. Second phosphine such as phosphine, diphenylphosphine, methylphenylphosphine, ethylphenylphosphine; trialkylphosphine such as trimethylphosphine, triethylphosphine, tributylphosphine, trioctylphosphine, tricyclohexylphosphine, triphenylphosphine, alkyldiphenylphosphine, dialkylphenyl Triphenylphosphine, tribenzylphosphine, triphenylphosphine (tri-o-triphenylphosphine, tri-p-trilphosphine, tri-m-trilphosphine), tri-p-styrylphosphine, tris (2,6-dimethoxyphenyl) phosphine, Third phosphine such as tri-4-methylphenylphosphine, tri-4-methoxyphenylphosphine, tri-2-cyanoethylphosphine; phosphinealcan compounds such as bis (diphenylphosphine) methane, 1,2-bis (diphenylphosphine). Examples include fino) ethane, 1,4- (diphenylphosphine) butane; triphenylphosphine-triphenylborane, tetraphenylphosphonium, tetraphenylborate and the like. Of these, third phosphine is more preferred, and triphenylphosphine is particularly preferred.

The core contains a vinyl-based polymer as well as a phosphorus-based curing catalyst. By including the vinyl polymer in the core, the phosphorus-based curing catalyst can be enclosed in the core, and the storage stability of the latent curing catalyst can be enhanced without lowering the curability. In addition, the containment enables the subsequent formation of an inner shell layer. From this viewpoint, the content of the vinyl polymer in the core is preferably 50 to 500 parts by weight, more preferably 100 to 300 parts by weight, based on 100 parts by weight of the phosphorus-based curing catalyst. In the case of a curing catalyst having low solvent solubility such as try-p-tolylphosphine, the content of the vinyl polymer in the core may be 50 to 5000 parts by weight with respect to 100 parts by weight of the phosphorus-based curing catalyst, and 100 parts by weight. It may be ~ 4000 parts by weight.

When the content of the vinyl-based polymer in the core is low, the phosphorus-based curing catalyst cannot be completely dissolved in the vinyl-based monomer at the stage of adjusting the core component before the polymerization reaction to form the core, resulting in a coarse phosphorus-based polymer. The curing catalyst may remain, and it may be difficult to contain the phosphorus-based curing catalyst in a minute core. For example, at the stage of adjusting the core component before the polymerization reaction for forming the core, the catalyst may not be completely dissolved in the vinyl-based monomer, and a coarse catalyst may remain. In this case, it becomes impossible to form a minute core. On the contrary, when the content of the vinyl polymer in the core is increased, the particle size of the latent curing catalyst is increased, or the content of the phosphorus-based curing catalyst in the latent catalyst particles is decreased, so that the curability is lowered. There is an inconvenience to do.

Before the polymerization reaction for forming the core, the phosphorus-based curing catalyst is preferably in a state of being dissolved in the vinyl-based monomer, but the phosphorus-based curing catalyst and the vinyl-based polymer are formed by the polymerization of the vinyl-based monomer. However, there are cases where polymerization reaction-induced phase separation occurs. In the present invention, the distribution state of the phosphorus-based curing catalyst is not particularly limited inside the core. For example, the core may be one in which a vinyl-based polymer and a phosphorus-based curing catalyst are compatible with each other to form a single phase. Alternatively, it may have a double structure in which the phosphorus-based curing catalyst is unevenly distributed in the center of the core and the vinyl-based polymer surrounds the phosphorus-based curing catalyst. Further, in the continuous phase made of the vinyl polymer, the discontinuous phase formed by the aggregation of the phosphorus-based curing catalyst may be dispersed to form a so-called sea-island structure. Further, the vinyl-based polymer and the phosphorus-based curing catalyst may be in a state of forming a co-continuous structure. Before the polymerization reaction for forming the core, even if the phosphorus-based curing catalyst is dissolved in the vinyl-based monomer, the phosphorus-based curing catalyst and the vinyl-based polymer are separated by the polymerization of the vinyl-based monomer. In some cases, polymerization reaction-induced phase separation may occur.

In the present invention, the vinyl-based polymer in the core is not particularly limited as long as it is a polymer obtained by polymerizing a monomer component containing a radically polymerizable vinyl-based monomer. Examples of the vinyl-based monomer that can be used include (meth) acrylic-based monomer, olefin-based monomer, and styrene-based monomer (for example, metachlorostyrene, parachlorostyrene, parafluorostyrene, paramethoxystyrene, and meta. Tershallive butoxystyrene, paratarsial butoxystyrene, paravinylbenzoic acid, paramethyl-α-methylstyrene, 1-ethynyl-4-fluorobenzene), vinyl ester-based monomer (formula: C = C- (C = O)) -OR), maleic acid-based monomer (including maleic anhydride-based monomer), maleimide-based monomer (for example, phenylmethane maleimide), vinyl alcohol ester-based monomer (formula: C = C) -O- (C = O) -R) (for example, vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate, vinyl benzoate) and the like can be mentioned. Only one type of these monomers may be used, or two or more types may be used in combination. The vinyl-based monomer referred to in the present application is a monomer having one radically polymerizable vinyl group in one molecule.

Of these monomers, (meth) acrylic monomers are preferred. Examples of the (meth) acrylic monomer include methyl (meth) acrylic acid, ethyl (meth) acrylic acid, -n-propyl (meth) acrylic acid, isopropyl (meth) acrylic acid, and- (meth) acrylic acid. n-butyl, isobutyl (meth) acrylate, -tert-butyl (meth) acrylate, -n-pentyl (meth) acrylate, -n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth) ) N-Heptyl acrylate, -n-octyl acrylate, -2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, ( (Meta) acrylic acid alkyl ester having an alkyl group having 1 to 18 carbon atoms such as stearyl acrylate; phenyl (meth) acrylate, toluyl (meth) acrylate, benzyl (meth) acrylate, (meth) -2-methoxyethyl acrylate, -3-methoxybutyl (meth) acrylate, -2-hydroxyethyl (meth) acrylate, -2-hydroxypropyl (meth) acrylate, 2-aminoethyl (meth) acrylate , 2- (Dimethylamino) ethyl (meth) acrylic acid, γ- (methacryloyloxypropyl) trimethoxysilane, ethylene oxide adduct of (meth) acrylic acid, trifluoromethylmethyl (meth) acrylic acid, (meth) acrylic 2-Trifluoromethylethyl acid, 2-perfluoroethyl ethyl (meth) acrylate, 2-perfluoroethyl-2-perfluorobutyl ethyl (meth) acrylate, 2-perfluoroethyl (meth) acrylate, ( Perfluoromethyl (meth) acrylate, diperfluoromethylmethyl (meth) acrylate, 2-perfluoromethyl-2-perfluoroethylmethyl (meth) acrylate, 2-perfluorohexylethyl (meth) acrylate, ( Examples thereof include 2-perfluorodecylethyl (meth) acrylate and 2-perfluorohexadecylethyl (meth) acrylate. Only one kind of these (meth) acrylic monomers may be used, or two or more kinds may be used in combination. The vinyl-based polymer contained in the core is not obtained by polymerizing allyl glycidyl ether or glycidyl (meth) acrylate, and may not have a glycidyl group.

The vinyl-based polymer contained in the core may be a vinyl-based polymer having no crosslinked structure, but is preferably a vinyl-based polymer having a crosslinked structure (hereinafter, also referred to as a crosslinked vinyl-based polymer). .. The crosslinked structure is preferably low density (has a loose crosslinked structure). Since the vinyl polymer in the core has a crosslinked structure, it is possible to more reliably contain the phosphorus-based curing catalyst in the core, further enhance the storage stability of the latent curing catalyst, and crosslink. By lowering the density of the structure, it becomes easy to release the phosphorus-based curing catalyst at the curing temperature.

In order to introduce a crosslinked structure into a vinyl polymer, the vinyl polymer may be produced by polymerizing the vinyl monomer and the crosslinkable vinyl monomer. The crosslinkable vinyl-based monomer referred to in the present application is a crosslinkable vinyl-based monomer having two or more radically polymerizable vinyl groups in one molecule and capable of radical polymerization together with the vinyl-based monomer. Specific examples of such a crosslinkable vinyl-based monomer include the same specific examples as those of the first crosslinkable vinyl-based monomer described later. As the crosslinkable vinyl-based monomer used in the core, the same monomer as the first crosslinkable vinyl-based monomer may be used, or a different monomer may be used. For the same reason as the first crosslinkable vinyl monomer described later, the crosslinkable vinyl monomer used in the core is preferably a monomer having one or more (meth) acrylic groups in one molecule. , Specifically, allyl acrylate, allyl methacrylate, or di-, tri-, or tetra- (meth) acrylic acid esters of polyhydric alcohols or polyhydric phenols are more preferred, allyl acrylate, or methacrylic acid. Allyl acid acid is particularly preferred.

However, if the content of the crosslinkable vinyl monomer in the crosslinked vinyl polymer in the core is high and the degree of crosslinking is high, it becomes difficult to contain the phosphorus-based curing catalyst in the core, or the epoxy resin is used even at the curing temperature. It becomes difficult to release the phosphorus-based curing catalyst inside, and the curability may decrease. From this point of view, the amount of the crosslinkable vinyl monomer used in the core is preferably small, and specifically, the crosslinkable vinyl monomer in the crosslinkable vinyl polymer forming the core. The weight ratio (the weight ratio of the crosslinkable vinyl monomer to the total crosslinked vinyl polymer) is preferably 0.01 to 10% by weight, more preferably 0.5 to 5% by weight.

(Inner shell layer)
The inner shell layer is a resin layer that covers the core and is formed of a first vinyl resin. The first vinyl resin is a polymer of a monomer component containing a first vinyl-based monomer and a first crosslinkable vinyl-based monomer, or a polymer of the first vinyl-based monomer. is there. That is, the first vinyl resin is a polymer in which the first vinyl-based monomer is an essential monomer, and even if it is polymerized together with the first crosslinkable vinyl-based monomer which is an arbitrary monomer. Good. Of these, a polymer of a first vinyl-based monomer and a first crosslinkable vinyl-based monomer is preferable. The first vinyl resin may be a vinyl resin having no acidic group.

In this way, by providing the inner shell layer between the core and the outer shell layer described later, it is possible to increase the degree of cross-linking of the outer shell layer, thereby exhibiting high curability and a latent curing catalyst. Can enhance the storage stability of.

The first vinyl-based monomer is not particularly limited as long as it is a monomer having one radically polymerizable vinyl group in one molecule, and specifically, a (meth) acrylic-based monomer or an olefin-based monomer. Styrenes, styrene-based monomers (eg, metachlorostyrene, parachlorostyrene, parafluorostyrene, paramethoxystyrene, metatarsial butoxystyrene, paratersial butoxystyrene, paravinylbenzoic acid, paramethyl-α-methylstyrene) , 1-ethynyl-4-fluorobenzene), vinyl ester-based monomer (formula: C = C- (C = O) -OR), maleic acid-based monomer (maleic anhydride-based monomer) Includes), maleimide-based monomers (eg, phenylmethanemaleimide), vinyl alcohol ester-based monomers (formula: C = CO- (C = O) -R) (eg, vinyl acetate, vinyl formate, propion) (Vinyl styrene, vinyl butyrate, vinyl benzoate) and the like can be mentioned. Only one type of these monomers may be used, or two or more types may be used in combination. Of these monomers, (meth) acrylic monomers are preferred. As the (meth) acrylic monomer, those described above (specific examples are described in the places where (core) is described in detail) can be used. Only one kind of these (meth) acrylic monomers may be used, or two or more kinds may be used in combination. The first vinyl resin is not formed by polymerizing allyl glycidyl ether or glycidyl (meth) acrylate, and may not have a glycidyl group.

As the first crosslinkable vinyl-based monomer, a crosslinkable vinyl-based monomer having two or more radically polymerizable vinyl groups in one molecule and capable of radical polymerization with the first vinyl-based monomer is used. Can be used. Examples of such first crosslinkable vinyl monomer include allyl acrylate and allyl methacrylate; aromatic polyfunctional vinyl monomers such as divinylbenzene, divinyltoluene and trivinylbenzene; ethylene glycol di (meth). Acrylate, diethylene glycol (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butane Didioldi (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonane dioldi (meth) acrylate, 1,10-decanediol di (meth) Acrylate, glycerin di (meth) acrylate, 2-hydroxy-3-acryloyloxypropyl (meth) acrylate, dimethylol-tricyclodecandi (meth) acrylate, ethylene oxide adduct di (meth) acrylate of bisphenol A, trimethylol Propanetri (meth) acrylate, 3-methyl-1,5-pentanediol di (meth) acrylate, 2-butyl-2-ethyl-1,3-propanediol di (meth) acrylate, dimethylol-tricyclodecandi ( Di (meth) acrylate, neopentyl glycol di (meth) acrylate of hydroxypivalate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, bisphenol A di (meth) acrylate and other polyhydric alcohols or polyhydric phenols. -, Tri-, or tetra- (meth) acrylic acid ester; di or triallyl compounds such as diallyl phthalate, diallyl sebacate, triallyl triazine, triallyl cyanurate, triallyl isocyanurate; methylenebis (meth) acrylamide; 4, 4'-Diphenylmethane bismaleimide, m-phenylene bismaleimide, bisphenol A diphenyl ether bismaleimide, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3- Examples thereof include bismaleimide-based compounds such as phenylene bismaleimide and 1,6'-bismaleimide- (2,2,4-trimethyl) hexane. These may be used alone or in combination of two or more.

Among these, 1 or 2 or more (meth) acrylic groups per molecule because the polymerizability with the first vinyl-based monomer is good and the first vinyl resin exhibits good capsule characteristics. A monomer having is preferable, and specifically, allyl acrylate, allyl methacrylate, or a di-, tri-, or tetra- (meth) acrylic acid ester of a polyhydric alcohol or a polyhydric phenol is more preferable. In addition, good capsule characteristics mean that the capsule shows low substance permeability in the glass state at the time of storage, while the capsule becomes rubber state at the curing temperature of the epoxy resin and shows high substance permeability, and the disintegration property of the capsule becomes good. Say that.

Further, among the monomers having one or more (meth) acrylic groups in one molecule, the double bond having high polymerizability with the (meth) acrylic monomer and the polymerizable property are relatively low. For the monomer having a double bond, a linear polymer having the latter double bond as a graft chain was formed by the polymerization reaction of the former double bond and the (meth) acrylic monomer. Later, the latter double bond tends to contribute to the formation of crosslinks, and the degree of crosslinks can be achieved according to the compounding design. From this point of view, allyl acrylate or allyl methacrylate is particularly preferable among the monomers having one or more (meth) acrylic groups in one molecule. By introducing a double bond into the polymer in this way, side reactions that do not contribute to cross-linking (such as cyclization due to intramolecular reaction) can be suppressed, and the degree of cross-linking as designed for formulation can be achieved.

In the first vinyl resin forming the inner shell layer, the weight ratio of the first crosslinkable vinyl-based monomer in the first vinyl resin (the weight occupied by the first crosslinkable vinyl-based monomer in the entire first vinyl resin). The ratio) is preferably 10 to 60% by weight, more preferably 15 to 40% by weight, still more preferably 20 to 30% by weight. Further, the weight ratio of the first crosslinkable vinyl-based monomer in the first vinyl resin is preferably larger than the weight ratio of the crosslinkable vinyl-based monomer in the vinyl-based polymer forming the core. ..

(Outer shell layer)
The outer shell layer is a resin layer that covers the inner shell layer, and is formed of a second vinyl resin. The second vinyl resin is a polymer of a monomer component containing a second vinyl-based monomer and a second crosslinkable vinyl-based monomer, or is a weight of the second crosslinkable vinyl-based monomer. It is a coalescence. That is, the second vinyl resin is a polymer having a second crosslinkable vinyl-based monomer as an essential monomer, and the second vinyl-based monomer is a second crosslinkable vinyl-based monomer as an arbitrary monomer. It may or may not be polymerized (copolymerized) together with the monomer. The second vinyl resin may be a vinyl resin having no acidic group.

Since the second vinyl resin that forms the outer shell layer in this way has a crosslinked structure, it is possible to prevent the phosphorus-based curing catalyst of the core from leaking to the outside of the particles, and the epoxy resin permeates the inside of the particles. Can be suppressed. Thereby, the storage stability of the latent curing catalyst can be enhanced.

The second vinyl-based monomer is particularly as long as it has one radically polymerizable vinyl group in one molecule and is capable of radical polymerization with the second crosslinkable vinyl-based monomer. Not limited, specifically, (meth) acrylic monomer, olefin monomer, styrene-based monomer (for example, metachlorostyrene, parachlorostyrene, parafluorostyrene, paramethoxystyrene, metatasha). Reeve Toxystyrene, Paratercious Revetoxystyrene, Paravinylbenzoic acid, Paramethyl-α-Methylstyrene, 1-ethynyl-4-fluorobenzene), Vinyl ester-based monomer (Formula: C = C- (C = O)- OR), maleic acid-based monomer (including maleic anhydride-based monomer), maleimide-based monomer (for example, phenylmethanemaleimide), vinyl alcohol ester-based monomer (formula: C = C-). O- (C = O) -R) (for example, vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate, vinyl benzoate) and the like can be mentioned. Only one type of these monomers may be used, or two or more types may be used in combination. Of these monomers, (meth) acrylic monomers are preferred. As the (meth) acrylic monomer, those described above can be used. Only one kind of these (meth) acrylic monomers may be used, or two or more kinds may be used in combination. The second vinyl resin is not formed by polymerizing allyl glycidyl ether or glycidyl (meth) acrylate, and may not have a glycidyl group.

As the second crosslinkable vinyl-based monomer, a monomer having two or more radically polymerizable vinyl groups in one molecule can be used. Specific examples of the second crosslinkable vinyl-based monomer include the same monomer as the first crosslinkable vinyl-based monomer described above, and the same monomer as the first crosslinkable vinyl-based monomer. Or different monomers may be used. For the same reason as the first crosslinkable vinyl-based monomer described above, the second crosslinkable vinyl-based monomer is preferably a monomer having one or more (meth) acrylic groups in one molecule, and acrylic. Allyl acetate, allyl methacrylate, or di-, tri-, or tetra- (meth) acrylic acid esters of polyhydric alcohols or polyhydric phenols are more preferred, and allyl acrylate or allyl methacrylate is particularly preferred.

In the second vinyl resin forming the outer shell layer, the weight ratio of the second crosslinkable vinyl monomer in the second vinyl resin (the weight occupied by the second crosslinkable vinyl monomer in the entire second vinyl resin). The ratio) is preferably 60 to 100% by weight, more preferably 80 to 100% by weight, still more preferably 90 to 99.9% by weight.

Further, the weight ratio of the second crosslinkable vinyl-based monomer in the second vinyl resin is preferably larger than the weight ratio of the first crosslinkable vinyl-based monomer in the first vinyl resin. As described above, the inner shell layer uses a large amount of crosslinkable vinyl-based monomer in the outer shell layer, and the amount of the crosslinkable vinyl-based monomer used is relatively small or does not use the crosslinkable vinyl-based monomer inside. By providing, it is possible to form a shell layer with a high degree of cross-linking on the outermost side of the particles, which suppresses the leakage of the phosphorus-based curing catalyst and the penetration of the epoxy resin as described above, and the latent curing catalyst. Can enhance the storage stability of.

Particularly preferably in the present invention, the degree of cross-linking is increased in the order of the core, the inner shell layer, and the outer shell layer, that is, the cross-linkable vinyl-based single amount in the vinyl-based polymer forming the core. Crosslinkable vinyl-based in the order of body weight ratio, weight ratio of the first crosslinkable vinyl-based monomer in the first vinyl resin, and weight ratio of the second crosslinkable vinyl-based monomer in the second vinyl resin. The structure is such that the weight ratio of the monomer is large. As a result, it is possible to form an outer shell layer having a sufficiently high degree of cross-linking while reliably enclosing the phosphorus-based curing catalyst in the core, and it is possible to easily release the phosphorus-based curing catalyst into the epoxy resin at the curing temperature. it can.

The weight ratio of the core described above, the first vinyl resin forming the inner shell layer, and the second vinyl resin forming the outer shell layer is not particularly limited, but the degree of cross-linking is determined from the viewpoint of suppressing a decrease in curability. The tall outer shell layer is preferably a thin film rather than the inner shell layer. From this viewpoint, the amount of the second vinyl resin with respect to 100 parts by weight of the first vinyl resin is preferably 5 to 50 parts by weight, more preferably 10 to 30 parts by weight.

In the latent curing catalyst according to the embodiment of the present invention, the center of the particles is in the order of a low crosslinked or uncrosslinked core containing a phosphorus-based curing catalyst, a thick inner shell layer with a medium crosslinked density, and a thin outer shell layer with a high crosslinked density. It is preferable that a plurality of shell layers are formed outward from the core. It is preferable that the structure is provided with a gradation of the crosslink density as described above, the inner shell layer is thick, and the outer shell layer is thin. With such a structure, it is possible to improve both excellent stability during storage and excellent curability during curing.

That is, during storage, the phosphorus-based curing catalyst leaks out of the capsule due to the thin outer shell layer (thin hard wall) with high cross-linking density and the thick inner shell layer (thick wall) with moderate cross-linking density, and the epoxy resin is encapsulated. Although it suppresses invasion into the inside, at the curing temperature of epoxy resin, the hard, brittle and thin outer shell layer collapses due to thermal shock such as pressure difference between the inside and outside of the capsule, thermal expansion difference, and stress increase due to mass transfer. It's easy to do. When the outer shell layer collapses, it is induced and the collapse is chained to the inner shell layer and the core. That is, the crack propagates and the entire particle collapses. Further, even if the inner shell layer does not collapse, the inner shell layer having a medium cross-linking density exhibits physical properties in which the cross-linked chains move flexibly (rubber state) and the phosphorus-based curing catalyst is easily released.

The greatest feature of the latent curing catalyst according to the embodiment is that the outer shell layer has a high crosslink density and is thin. Since the motility of the crosslinked chains due to the viaduct density is extremely low, the outer shell layer with the viaduct density is difficult for substances to permeate and exhibits extremely high stability during storage. On the other hand, at the curing temperature of the epoxy resin, the outer shell layer is thin and very brittle, so that it easily disintegrates due to a thermal shock, thereby exhibiting good curability.

As described above, the fact that the outer shell layer has a high cross-linking density and is thin greatly contributes to both storage stability and curability. In addition, the inner shell layer plays a role of enhancing the function of the outer shell layer. That is, since the inner shell layer is relatively thick with a medium crosslink density, even if the epoxy resin permeates the thin outer shell layer during storage, the inner shell layer is a phosphorus-based core containing the epoxy resin. It can suppress the arrival of the curing catalyst, and this structure enhances the stability during storage. Further, since the inner shell layer has a medium crosslink density, the effect of suppressing the collapse of the outer shell layer at the time of curing is low, and the curability is not deteriorated. However, if the inner shell layer has a viaduct density, there is a high possibility that the collapse of the outer shell layer during curing will be suppressed.

(Particle size)
The latent curing catalyst of the present invention is in the form of particles, and its average particle size (D ₅₀ (cumulative volume 50%)) is 0.01 to 50 μm. It is preferably 0.05 to 5 μm, more preferably 0.1 to 3 μm, still more preferably 0.3 to 2 μm, and particularly preferably 0.3 to 1 μm. Since the average particle size is small as described above, the latent curing catalyst of the present invention has invasion into extremely narrow gaps and the like, and is used for semiconductor devices and electronic components having such narrow gaps and the like. It can be suitably used in the sealing material to be used.

(Manufacturing method)
The latent curing catalyst for epoxy resin of the present invention can be produced by carrying out the following steps. First, in the presence of a phosphorus-based curing catalyst, a monomer component containing a vinyl-based monomer and, in some cases, a crosslinkable vinyl-based monomer is polymerized by emulsion polymerization to form a core. Next, in the presence of the core, a monomer component containing a first vinyl-based monomer and, in some cases, a first crosslinkable vinyl-based monomer is polymerized by emulsion polymerization to coat the core. Form a shell layer. Further, in the presence of the inner shell layer covering the core, a monomer component containing a second crosslinkable vinyl-based monomer and, in some cases, a second vinyl-based monomer is polymerized by emulsion polymerization. The outer shell layer that covers the inner shell layer is formed.

Each emulsion polymerization can follow a conventional method. To explain a specific example, first, in order to form core particles, a polymerization initiator and an emulsifier are mixed with water and stirred to form micelles. Separately, the phosphorus-based curing catalyst and the monomer component of the core are uniformly mixed, then added to the micelle, both are mixed, water is added as necessary, and then stirred to form an emulsion. The particle size of the oil droplets in the emulsion can be appropriately adjusted by selecting the number of rotations of stirring, selecting the type of emulsifier, adjusting the amount of addition, and the like. Then, the temperature is raised in an inert atmosphere to allow the heat polymerization reaction to proceed at a predetermined temperature to obtain an emulsion of core particles. The reaction temperature is not particularly limited, but is preferably about 60 to 100 ° C., and the reaction time is preferably about 1 to 10 hours.

As the polymerization initiator that can be used in emulsion polymerization, a radical polymerization initiator such as a thermal radical polymerization initiator or a photoradical polymerization initiator that can be generally used in emulsion polymerization can be used. For example, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrate. , 2,2'-azobis (2-methylpropion amidine) dihydrochloride, 2,2'-azobis- [N- (2-carboxyethyl) -2-methylpropion amidine], 2,2'-azobis [2- (2-Imidazolin-2-yl) Propane], 2,2'-azobis- [2-methyl-N- (2-hydroxyethyl) propionamide, 4,4'-azobis (4-cyanovaleric acid), etc. Water-soluble azo compound, 2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis (N-butyl-2-methylpropionamide), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), dimethyl 2,2'-azobis (2-methylpro) Pionate), azo compounds such as oil-soluble azo compounds such as 1,1'-azobis (cyclohexane-1-carbonitrile), dimethyl 1,1'-azobis (1-cyclohexanecarboxylate); potassium persulfate, excess Persulfy-based compounds such as sodium sulfate and ammonium persulfate; organic peroxides (hydroperoxides) such as diisopropylbenzene hydroperoxide, p-menthan hydroperoxide, cumen hydroperoxide, and t-butyl hydroperoxide; Organic peroxides such as benzobis oxide (diacyl peroxide); examples thereof include the persulfate-based compound or a redox-based initiator in ^{which Fe 2+} or Cu ^{+ ions are added to the organic peroxide.}

Among these polymerization initiators, a polymerization initiator that is easily dissolved in water is preferable, and examples thereof include water-soluble azo compounds and persulfates. The 10-hour half-life temperature of the thermal polymerization initiator is generally preferably between 40 and 90 ° C. If it is lower than this, decomposition proceeds during preparation at room temperature, and if it is higher than this, a long time is required for the polymerization reaction. .. Many of the above organic peroxides have a 10-hour half-life temperature exceeding the above range, and the radical generation rate at a general emulsion polymerization temperature is slow. Therefore, a low-valent metal ion (Fe ²⁺ , Cu ^+, etc.) is added thereto, and a Fenton reaction (redox reaction) is performed to improve the radical generation rate in the temperature range. Therefore, the redox-based initiator of the organic peroxide is preferable because it can be used in a general emulsion polymerization temperature range.

One of these polymerization initiators may be used alone, or two or more thereof may be used in combination. In the case of the combined use of two or more kinds, only the water-soluble radical polymerization initiator may be used, any combination of the water-soluble radical polymerization initiator and the oil-soluble radical polymerization initiator may be used, or only the oil-soluble radical polymerization initiator may be used. The amount of the polymerization initiator used can be appropriately set, and may be, for example, 0.01 to 1.00 parts by weight with respect to 100 parts by weight of the monomer component. When a water-soluble radical polymerization initiator and another polymerization initiator (for example, an oil-soluble radical polymerization initiator) are used in combination, for example, the total amount of the polymer is 0.01 to 100 parts by weight of the monomer component. It may be 2.00 parts by weight.

Examples of emulsifiers that can be used in emulsification polymerization include alkali metal salts and ammonium salts of higher fatty acids such as disproportionate logonic acid, oleic acid and stearic acid, alkali metal salts and ammonium salts of sulfonic acids such as dodecylbenzene sulfonic acid, and anions. Examples thereof include system emulsifiers and nonionic emulsifiers. The anionic emulsifier is not particularly limited, and is, for example, polyoxyethylene alkyl ether sulfate ester salt (for example, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, etc.), alkyl. Examples thereof include diphenyl ether disulfonate (sodium alkyl diphenyl ether disulfonate, sodium alkyl diphenyl ether disulfonate, etc.), reactive anionic surfactant (polyoxyalkylene alkenyl ether ammonium sulfate, etc.) and the like. Further, the nonionic emulsifier is not particularly limited, and polyoxyethylene alkyl ether (for example, polyoxyethylene alkyl ether, etc.), polyoxyalkylene alkyl ether (for example, polyoxyalkylene alkyl ether, etc.), reactive nonionic surfactant, etc. Activators (polyoxyalkylene alkenyl ethers, etc.) and the like can be mentioned.

Among the emulsifiers, ammonium salt-type anion-based emulsifiers and nonionic emulsifiers that do not contain metal ions are preferable in order to reduce metal ions in the obtained polymer. Specifically, as the ammonium salt-type anionic emulsifier, ammonium lauryl sulfate and ammonium di- (2-ethylhexyl) sulfosuccinate are preferable in order to achieve the stability of emulsion polymerization, and as the nonionic emulsifier, the stability of emulsion polymerization. Therefore, polyoxyethylene monotetradecyl ether and polyoxyethylene distyrene phenyl ether are preferable. Moreover, from the viewpoint of being easily available industrially, a sodium salt type anionic emulsifier is preferable. As the sodium salt type anionic emulsifier, sodium di- (2-ethylhexyl) sulfosuccinate is preferable. The amount of the emulsifier used can be appropriately set, and may be, for example, 0.01 to 10.00 parts by weight with respect to 100 parts by weight of the monomer component.

Next, in order to form the inner shell layer, first, the polymerization initiator and the emulsifier are mixed with water and stirred to form micelles. Separately, after uniformly mixing the monomer components of the inner shell layer, they are added to the micelles, and both are mixed and stirred to form an emulsion for the inner shell layer. Next, after the emulsion of the core particles was brought to a predetermined temperature in an inert atmosphere, the emulsion for the inner shell layer was added dropwise thereto, and the heat polymerization reaction proceeded at a predetermined temperature while mixing and stirring them. To obtain an emulsion of single-shelled particles. The reaction temperature, reaction time, etc. can be appropriately adjusted with reference to the above-mentioned ranges.

Then, in order to form the outer shell layer, first, the emulsifier and water are mixed, or the emulsifier, the polymerization initiator and water are mixed and stirred to form micelles. Separately, the monomer component of the outer shell layer is uniformly mixed, or the monomer component of the outer shell layer and the polymerization initiator are uniformly mixed, then added to the micelle, and both are mixed and stirred to stir the outer shell. Form a layered emulsion. Next, after the emulsion of the single shelled particles was brought to a predetermined temperature in an inert atmosphere, the emulsion for the outer shell layer was added dropwise thereto, and the mixture was mixed and stirred while being heated and polymerized at a predetermined temperature. To obtain an emulsion of double-shelled particles. The reaction temperature, reaction time, etc. can be appropriately adjusted with reference to the above-mentioned ranges.

In the case of emulsion polymerization to form the outer shell layer, the polymerization initiator is used by being pre-dissolved only in the monomer component added to the micelles, or is pre-dissolved in water before the micelle formation and then. , It is preferable to dissolve the monomer component added to the micelle in advance before use. In the former case, it is preferable to use a monomer-soluble radical polymerization initiator as the polymerization initiator, and in the latter case, a water-soluble radical polymerization initiator is used as the polymerization initiator when it is dissolved in water, and It is preferable to use a monomer-soluble radical polymerization initiator when dissolving the monomer component. That is, in the polymerization of the outer shell, in the former case, the radical polymerization initiation reaction occurs in the monomer component, but in the latter case, the radical polymerization initiation reaction occurs both in the monomer component and in the aqueous phase. The monomer-soluble radical polymerization initiator here refers to a radical polymerization initiator having a weight of 0.50 parts by weight or more that uniformly dissolves at 25 ° C. with respect to 100 parts by weight of allyl methacrylate (AMA). Generally, many oil-soluble radical polymerization initiators are applicable. Further, the polymerization initiator may be used by being dissolved in water before the micelle formation in advance, and in this case, it is preferable to use a water-soluble radical polymerization initiator as the polymerization initiator. In the above case, a radical polymerization initiation reaction occurs in the aqueous phase.

Examples of the monomer-soluble radical polymerization initiator include the oil-soluble radical polymerization initiator described above, and examples thereof include 2,2'-azobisisobutyronitrile and 2,2'-azobis (2,4-dimethylvalero). Nitrile), 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis (N-butyl-2-methylpropionamide), 2,2'-azobis (4-methoxy-2,4) -Dimethylvaleronitrile), dimethyl 2,2'-azobis (2-methylpropionate), 1,1'-azobis (cyclohexane-1-carbonitrile), dimethyl 1,1'-azobis (1-cyclohexanecarboxylate) ) And other oil-soluble azo compounds; organic peroxides (diacyl peroxides) such as benzoyl peroxide and the like can be mentioned. As described above, it is preferable to use the monomer-soluble radical polymerization initiator to promote the progress of the cross-linking reaction by the second cross-linking vinyl-based monomer in the outer shell layer and to increase the degree of cross-linking of the outer shell layer. .. Further, the combined use of the monomer-soluble radical polymerization initiator and the water-soluble radical polymerization initiator is also preferable for increasing the degree of cross-linking of the outer shell layer. On the other hand, it is preferable to use a water-soluble radical polymerization initiator in the emulsion polymerization that forms the core and the inner shell layer.

After all the polymerization reactions are completed, the latent curing catalyst of the present invention can be obtained by a spray drying method, a freeze drying method, or a coagulation method. Alternatively, the latent curing catalyst of the present invention can also be obtained by separating the particles from the emulsion by centrifugation or filtration, washing with water if necessary, and drying by a conventional method. Of these, it is preferable to use the spray drying method because the obtained powder has excellent dispersibility in the epoxy resin.

Unless otherwise specified, the water described in the present specification uses ion-exchanged water, but is not limited thereto.

(Epoxy resin composition)

The epoxy resin composition of the present invention contains at least an epoxy resin and the latent curing catalyst described above. The epoxy resin composition refers to a product in a state before curing, and may be a liquid product or a gel-like molded product having a certain shape. The shape of such a molded product is not particularly limited and can be appropriately designed according to the intended use, and examples thereof include a sheet shape, a film shape, and a tablet shape.

The epoxy resin that can be used in the present invention is not particularly limited as long as it is a compound having two or more epoxy groups in the molecule, and generally known ones can be used. Specifically, biphenyl type epoxy resin, tetramethylbiphenyl type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, triphenylmethane type epoxy resin, tetraphenylethane type epoxy resin, dicyclopentadienephenol addition reaction type. Epoxy resin, phenol aralkyl type epoxy resin, naphthol novolak type epoxy resin, naphthol aralkyl type epoxy resin, naphthol phenol co-shrink novolak type epoxy resin, naphthol cresol co-shrink novolak type epoxy resin, aromatic hydrocarbon formaldehyde resin modified phenol resin type epoxy Resin, biphenyl novolac type epoxy resin, ethylphenol novolac type epoxy resin, butylphenol novolac type epoxy resin, octylphenol novolac type epoxy resin, xylylene skeleton-containing phenol novolac type epoxy resin, fluorene skeleton-containing phenol novolac type epoxy resin, 4,4'- Biphenylphenol type epoxy resin, tetramethyl-4,4'-biphenol type epoxy resin, dimethyl-4,4'-biphenylphenol type epoxy resin, 1- (4-hydroxyphenyl) -2- [4- (1,1) -Bis (4-hydroxyphenyl) ethyl) phenyl] propane type epoxy resin, 2,2'-methylenebis (4-methyl-6-tert-butylphenol) type epoxy resin, 4,4'-butylidenebis (3-methyl-6) -Tert-butylphenol) type epoxy resin, trishydroxyphenylmethane type epoxy resin, resorcinol type epoxy resin, hydroquinone type epoxy resin, pyrogallol type epoxy resin, diisopropylidene type epoxy resin, 1,1-di-4-hydroxyphenylfluorene Type epoxy resin, phenolized polybutadiene type epoxy resin, 3,4-epoxycyclohexylmethyl-3', 4'-cyclohexylcarboxylate type epoxy resin, 1,4-butanediol type epoxy resin, 1,6-hexanediol type epoxy Resin, polyethylene glycol type epoxy resin, polypropylene glycol type epoxy resin, pentaerythritol type epoxy resin, xylylene glycol derivative type epoxy resin, isocyanul ring type epoxy resin, hydantin ring type epoxy resin, hexahydrophthalic acid diglycidyl ester type epoxy resin , Tetrahydrophthal Diglycidyl acid acid ester type epoxy resin, aniline type epoxy resin, toluidine type epoxy resin, p-phenylenediamine type epoxy resin, m-phenylenediamine type epoxy resin, diaminodiphenylmethane derivative type epoxy resin, diaminomethylbenzene derivative type epoxy resin, Examples thereof include brominated phenol novolac type epoxy resin and brominated cresol novolac type epoxy resin. Only one type of epoxy resin may be used, or two or more types may be used in combination. The epoxy resin may be selected according to desired properties and properties (liquid or solid) and is not particularly limited. For example, among the above specific examples, a bis (hydroxyphenyl) alkane-based epoxy resin and a naphthalene-based epoxy are used. Resin is preferred.

The amount of the latent curing catalyst of the present invention used for the epoxy resin is not particularly limited, and can be appropriately determined according to a desired curing rate and physical characteristics of the cured product. Specifically, the latent curing catalyst of the present invention is preferably 0.05 to 50 parts by weight, more preferably 0.1 to 40 parts by weight, still more preferably 0.5 parts by weight, based on 100 parts by weight of the epoxy resin. It is ~ 30 parts by weight, particularly preferably 1.0 to 20 parts by weight. Further, the phosphorus-based curing catalyst contained in the latent curing catalyst of the present invention is preferably 0.01 to 20 parts by weight, more preferably 0.05 to 15 parts by weight, still more preferably 100 parts by weight, based on 100 parts by weight of the epoxy resin. Can also be blended so as to be 0.1 to 10 parts by weight.

The epoxy resin composition of the present invention can further contain an epoxy resin curing agent. Such a curing agent is not particularly limited, and a commonly known curing agent to be blended with an epoxy resin can be used. Specifically, for example, of 2-ethyl-4-methylimidazole, diaminodiphenylmethane, diethylenetriamine, triethylenetetramine, diaminodiphenylsulfone, isophoronediamine, imidazole, boron trifluoride-amine complex, guanidine derivative, dicyandiamide, linolenic acid. Polyaldehyde resin synthesized with dimer and ethylenediamine, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride , Methylhexahydrophthalic anhydride, phenol novolac resin, cresol novolac resin, aromatic hydrocarbon formaldehyde resin modified phenol resin, dicyclopentadienephenol addition type resin, phenol aralkyl resin, polyvalent hydroxy compound and polymorphic compound synthesized from formaldehyde Valical phenol novolac resin, naphthol aralkyl resin, trimethylolmethane resin, tetraphenylol ethane resin, naphthol novolac resin, naphthol phenol co-shrink novolac resin, naphthol cresol co-shrink novolak resin, biphenyl-modified phenol resin, biphenyl-modified naphthol resin, aminotriazine Examples thereof include a modified phenol resin and an alkoxy group-containing aromatic ring-modified novolac resin. Only one type of curing agent may be used, or two or more types may be used in combination. The curing agent may be selected according to desired properties and properties (liquid or solid), and is not particularly limited. For example, among the above specific examples, acid anhydrides from the viewpoint of heat resistance and chemical resistance. Amine-based curing agent is preferable, an amine-based curing agent is preferable from the viewpoint of low-temperature curing and high adhesiveness, and a phenol-based curing agent is preferable from the viewpoint of low outgassing property, moisture resistance, heat cycle resistance, etc. at the time of curing. It is preferably used.

The amount of the curing agent used for the epoxy resin is not particularly limited, and may be a general amount, and can be appropriately determined according to a desired curing rate and physical properties of the cured product. Specifically, the curing agent is preferably 1 to 300 parts by weight, more preferably 5 to 200 parts by weight, based on 100 parts by weight of the epoxy resin.

Further, a known additive in the epoxy resin composition can be appropriately added to the epoxy resin composition of the present invention. Examples of such additives include fillers such as carbon black, adhesive-imparting agents, solvents, reactive diluents, antioxidants, light stabilizers, ultraviolet absorbers, defoamers, leveling agents, pigments and the like. Can be mentioned.

The filler is not particularly limited, and a known filler can be used, and examples thereof include a filler composed of an inorganic oxide, an inorganic salt, glass, a nitride, a metal powder, or the like. Examples of the inorganic oxide include titanium oxide, silicon oxide, aluminum oxide, beryllium oxide, zirconium oxide and the like. Examples of the inorganic salt include calcium carbonate, barium sulfate, zirconium silicate, calcium silicate, magnesium silicate and the like. Examples of the nitride include boron nitride, aluminum nitride, gallium nitride, indium nitride, silicon nitride and the like. Examples of the metal powder include silver powder, copper powder, silver-plated copper powder, tin-plated copper powder, nickel powder, aluminum powder and the like. Only one type of filler may be used, or two or more types may be used in combination.

Examples of the adhesiveness-imparting agent include a coupling agent, a phenol resin, an organic polyisocyanate, and the like. Only one kind of adhesiveness-imparting agent may be used, or two or more kinds may be used in combination.

Examples of the coupling agent include various coupling agents such as silane-based, aluminum-based, zirco-aluminate-based, and titanium-based coupling agents, and partially hydrolyzed condensates thereof. Among these coupling agents, a silane-based coupling agent and a partially hydrolyzed condensate thereof are preferable because they have a high adhesiveness-imparting effect. The partially hydrolyzed condensate of the coupling agent may be a partially hydrolyzed condensate of the same type of coupling agent, or may be a partially hydrolyzed condensate of two or more kinds of coupling agents.

Examples of the silane coupling agent include 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, and N- (2-). Aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, etc. Examples thereof include compounds containing the alkoxysilyl group of.

The solvent is not particularly limited, and for example, N-methylpyrrolidone; N, N-dimethylformamide; dimethylsulfoxide; ketones such as methylethylketone, cyclohexanone, cyclopentanone; aromatic hydrocarbons such as toluene, xylene, tetramethylbenzene, etc. Classes; glycol ethers such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, diethylene glycol monoethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monoethyl ether; ethyl acetate, Esters such as butyl acetate, cellosolve acetate, diethylene glycol monoethyl ether acetate and esterified products of the above glycol ethers; alcohols such as ethanol, propanol, methanol, ethylene glycol and propylene glycol; aliphatic hydrocarbons such as octane and decane. ; Petroleum-based solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha can be mentioned. Only one type of solvent may be used, or two or more types may be used in combination.

The reactive diluent is not particularly limited, and for example, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, p-sec-butyl phenyl glycidyl ether, tert-butyl phenyl glycidyl ether, o-phenylphenol glycidyl ether, etc. Ethylene Glycol Diglycidyl Ether, Polyethylene Glycol Diglycidyl Ether, Polypropylene Glycol Diglycidyl Ether, Butanediol Diglycidyl Ether, 1,6-Hexanediol Diglycidyl Ether, Trimethylol Propanetriglycidyl Ether, 4-Vinyl Cyclohexene Monooxide, Vinyl Cyclohexene Dioxide, methylated vinylcyclohexene dioxide, (3,4-epoxycyclohexyl) methyl-3,4-epoxycyclohexylcarboxylate, bis- (3,4-epoxycyclohexyl) adipate, bis- (3,4-epoxycyclohexyl) Examples thereof include methylene) adipate, bis- (2,3-epoxycyclopentyl) ether, (2,3-epoxy-6-methylcyclohexylmethyl) adipate, and dicyclopentadiendioxide. Only one type of reactive diluent may be used, or two or more types may be used in combination.

Since the latent curing catalyst for epoxy resin of the present invention itself can have an action of gelling an epoxy resin composition, it can act as a sheeting agent. Therefore, the epoxy resin composition of the present invention can be made into a sheet-like molded product without adding a sheeting agent as an additional component. However, when the epoxy resin composition of the present invention is a molded product such as a sheet, a sheeting agent such as a thermoplastic resin powder may be separately added to the epoxy resin composition. The thermoplastic resin powder can absorb and swell the epoxy resin or other components to form a gel, or can be compatible with the epoxy resin or other components to form a gel. ..

Examples of the thermoplastic resin constituting such a powder include polyvinyl chloride, polyethylene, polypropylene, polystyrene, and synthetic rubber (polybutadiene, butadiene-styrene copolymer, polyisoprene, polychloroprene, ethylene-propylene copolymer). , Polyvinyl acetate, poly (meth) acrylic acid ester, polyacrylic acid amide, polyoxymethylene, polyphenylene oxide, polyester, polyamide, polycarbonate, cellulose resin, polyacrylonitrile, thermoplastic polyimide, polyvinyl alcohol, polyvinylpyrrolidone, etc. Be done. These may be used alone or in combination of two or more. Of these, polymethacrylic acid esters such as polymethylmethacrylate are preferable from the viewpoint of sheetability.

Further, when the epoxy resin composition of the present invention is a molded product such as a sheet, a photopolymerizable compound and a radical generator acting as a sheeting agent can be blended with the epoxy resin composition. In this case, first, a mixture of the epoxy resin composition and other components, a photopolymerizable compound and a radical generator is prepared, the obtained mixture is made into a sheet, and then irradiated with light to be photopolymerizable. A polymerized compound is used as a gel-like curable sheet.

Examples of the photopolymerizable compound include compounds containing one or more (meth) acryloyl groups in the molecule, specifically, (meth) acrylic acid, alkyl alcohols, alkylene diols, polyhydric alcohols, and the like. , And the compounds described in [0009] to [0012] of JP-A-11-12543.

The radical generator is a compound that generates radicals when irradiated with active rays such as ultraviolet rays and electron beams, and various conventionally used compounds can be used, for example, 2-hydroxy-2-methyl-. 1-Phenylpropane-1-one, benzoin, acetophenone and the like can be used.

The epoxy resin composition of the present invention can be obtained by mixing the epoxy resin with the latent curing catalyst of the present invention, as well as a curing agent and other additives. The method for mixing these is not particularly limited, and a conventionally known method can be used. For example, a method of stirring using a stirrer, a method of kneading using a three-roll mill, a ball mill, or the like is used. Can be done.

When the epoxy resin composition of the present invention is formed into a sheet-like molded product, each component may be mixed as described above and then molded by a usual method such as heat molding. Further, the epoxy resin composition liquefied by heating as necessary is used as a coating product whose film thickness is controlled by a roll coater or the like, and is used at 60 to 150 ° C. for 0.5 to 30 minutes, and further at 80 to 120 ° C. for 1 It can also be made into a sheet by drying for 10 minutes.

A cured product can be obtained by curing the epoxy resin composition. The curing method may be a condition for curing a general epoxy resin composition, and is not particularly limited. For example, a heating device is used to heat the epoxy resin composition at 100 ° C. for 1 hour and then at 180 ° C. for 4 hours. The method of doing this can be mentioned. However, the specific curing conditions can be appropriately determined depending on the use of the epoxy resin composition. The heating device is not particularly limited, and for example, a blower constant temperature dryer, a constant temperature constant temperature dryer, or the like can be used.

Further, the surface shape of the cured product of the present invention preferably has a convex or concave size of 10 μm or less on the surface. The surface shape is as follows: after depositing gold on the surface of the cured product, using a scanning electron microscope (SEM) JSM-6390LV manufactured by JEOL Ltd., the acceleration voltage is 15 kV, the observation angle is 45 °, and the magnification is 400 times (observation area: 300 μm ×). It can be confirmed by SEM observation at 200 μm) or 2000 times (observation area: 60 μm × 40 μm). The size of the convex portion or the concave portion can be determined from the SEM observation image. The SEM observation image can particularly evaluate the size of the uneven region in an arbitrary direction in the plane. The arbitrary direction in the plane is an arbitrary direction in the SEM photographic plane.

The surface shape can be observed using the stylus type surface shape measuring device DEKTAK 150 under the conditions of scanning speed: 1,000 μm / 60 s, scanning distance: 1.0 mm, measuring points: 5 points, and measured values: steps. .. The stylus type surface shape measuring instrument can evaluate the size of unevenness especially in the direction perpendicular to the surface. The plane vertical direction is the direction perpendicular to the photographic plane at an arbitrary position on the SEM photographic plane.

(Use)
The use of the epoxy resin composition of the present invention is not particularly limited, but it can be suitably used as a sealing material or an adhesive. Among them, the latent curing catalyst of the present invention has a small particle size and can penetrate into an extremely narrow gap, etc., and therefore, particularly as a sealing material used for a semiconductor device or an electronic component having such a narrow gap. It can be preferably used. Examples of the gap include a gap between a substrate and a chip, a gap between chips, and a gap between solder bumps and solder bumps. The width of the gap may be 100 μm or less, 50 μm or less, or 30 μm or less.

Further, since the surface of the cured product formed from the epoxy resin composition containing the latent curing catalyst of the present invention is smooth without unevenness, it is suitable for applications requiring smoothness. For example, as a specific application as a sealing material, since a rewiring layer can be formed on the lower surface of the sealing material, a sealing material for FO-WLP and a circuit such as an antenna on the upper surface of the sealing material. Since it can be formed, it can be used as a sealing material for an antenna-on-package (AoP) in which an antenna and a semiconductor device are integrated, or metal plating can be performed on the entire surface or a part of the sealing, so that the semiconductor device can be formed. It can be suitably used as a sealing material for electromagnetic wave shielding applications.

An example of such an encapsulant is a semiconductor encapsulant used when encapsulating a wafer level chip size package, which is a large area semiconductor package, by an overmold molding method. The encapsulant is an overmolding material that encapsulates terminals, element electrodes, and a semiconductor bare chip arranged on a semiconductor wafer substrate. Examples of the overmold molding include transfer molding and compression molding. Of these, compression molding is preferable. Overmolding is preferably carried out at 50-200 ° C, more preferably 100-175 ° C for 1-15 minutes. If necessary, post-cure can be performed at 100 to 200 ° C. for 30 minutes to 24 hours. By such heating, the epoxy resin composition is cured to form an overmolding material. The liquid epoxy resin composition of the present invention can be preferably used as such a sealing material.

Further, as another example of the sealing material, it is an elastic surface wave device in which an elastic surface wave chip is mounted on a substrate on which a wiring pattern is formed, and the electrode surface of the surface acoustic wave chip and the wiring pattern are connected by bumps. However, the electrode surface and the wiring pattern are not in direct contact with each other, and in an elastic surface wave device having a hollow structure between the substrate and the chip, a seal for sealing the surface acoustic wave chip is performed. A stop material can be mentioned. As such a sealing material, the epoxy resin composition of the present invention, which is a molded product having a certain shape, can be preferably used.

When sealing a surface acoustic wave chip using the epoxy resin composition, for example, a sheet-shaped epoxy resin composition is arranged so as to cover the surface acoustic wave chip, and then heat pressing is performed. As a result, the epoxy resin composition can be cured to form a protective layer for the chip while maintaining the hollow structure. The conditions of such a heat press can be appropriately determined. For example, the pressure is 100 Pa to 10 MPa, preferably 0.01 to 2 MPa, the temperature is 250 ° C. or lower, preferably 60 to 180 ° C., and the time is 5 seconds to. It may be 3 hours, preferably 1 to 15 minutes.

In the above, the specific applications of the encapsulant in which the epoxy resin composition of the present invention can be preferably used have been described in detail. In these applications, it is required that the sealing material penetrates into an extremely narrow gap and cures, so the significance of applying the epoxy resin composition of the present invention is extremely great. However, the use of the epoxy resin composition of the present invention is not limited to these.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

The present invention will be described in detail with reference to the following examples, but the present invention is not limited to these examples.

[Example 1]
<Synthesis of core particles>
[Preparation of emulsion consisting of core components]
(material)
(1) Emulsifier Nonionic surfactant Polyoxyethylene distyrene phenyl ether (trade name "Emargen A-90" manufactured by Kao Corporation)
Anionic surfactant di- (2-ethylhexyl) sodium sulfosuccinate (trade name "Ricasurf P-10" manufactured by New Japan Chemical Co., Ltd.)
(2) Radical polymerization initiator Water-soluble radical polymerization initiator 2,2'-azobis- [N- (2-carboxyethyl) -2-methylpropion amidine] (trade name "VA-057" manufactured by Wako Pure Chemical Industries, Ltd. 10-hour half-life temperature 57 ° C)
(3) Acrylic Monomer Methyl Methacrylate (Product Name "Acrylic Ester M" manufactured by Mitsubishi Chemical Corporation)
Allyl methacrylate (trade name "AMA" manufactured by Mitsubishi Gas Chemical Company)
(4) Water Ion-exchanged water (Deionized Water: DW)
(5) Catalysis for inclusion Triphenylphosphine (trade name "TPP" manufactured by Hokuko Chemical Industry Co., Ltd.)

(Preparation method of emulsion)
The emulsifier and the radical polymerization initiator were dissolved in ion-exchanged water and stirred at a rotation speed of 1500 rpm for 15 minutes at high speed to prepare micelles. After uniformly dissolving the encapsulating catalyst and the acrylic monomer, the mixture was added to the micelles and mixed, water was further added, and the mixture was stirred at a rotation speed of 2000 rpm for 20 minutes at high speed to prepare an emulsion. The blending amount of each component is as shown in Table 1.

[Synthesis of core particles by heating emulsion]
The emulsion was heated at 75 ° C. for 2 hours in a nitrogen atmosphere to synthesize core particles by radical polymerization (emulsion polymerization).

<Synthesis of single-shelled particles>
[Preparation of emulsion consisting of inner layer shell component]
(material)
Using the raw materials (1) emulsifier, (2) radical polymerization initiator, (3) acrylic monomer, and (4) water used in the "preparation of an emulsion composed of core components" in the "synthesis of core particles", (3) In addition to the above, the following acrylic monomers were additionally used.
n-Butyl acrylate (trade name "Butyl acrylate" manufactured by Mitsubishi Chemical Corporation)

(Preparation method of emulsion)
The emulsifier and the radical polymerization initiator were dissolved in ion-exchanged water and stirred at a rotation speed of 1500 rpm for 15 minutes at high speed to prepare micelles. After the acrylic monomer was uniformly mixed, in addition to the micelles, an emulsion composed of an inner layer shell component was prepared by stirring at a high speed of 20 minutes at a rotation speed of 2000 rpm. The blending amount of each component is as shown in Table 1.

[Synthesis of single-shelled particles by dropping an emulsion consisting of inner shell components]
The emulsion of the "core particles" was heated to 75 ° C. in a nitrogen atmosphere. Then, the "emulsion solution composed of the inner layer shell component" was added dropwise to form an inner shell layer by radical polymerization (emulsion polymerization) at 75 ° C. for 1 hour to synthesize single shelled particles.

<Synthesis of double-shelled particles>
[Preparation of emulsion consisting of outer layer shell component]
(material)
In addition to the raw materials (1) emulsifier and (4) water used in the "preparation of emulsion consisting of core components" in the "synthesis of core particles", (2) radical polymerization initiator and (3) acrylic monomer Used the following.
(2) Radical polymerization initiator Fat-soluble radical polymerization initiator dimethyl 2,2'-azobis (2-methylpropionate) (trade name "V-601" manufactured by Wako Pure Chemical Industries, Ltd., 10-hour half-life temperature 66 ° C.)
(3) Acrylic monomer allyl methacrylate (trade name "AMA" manufactured by Mitsubishi Gas Chemical Company) is used alone.

(Preparation method of emulsion)
The emulsifier was dissolved in ion-exchanged water and stirred at a rotation speed of 1500 rpm for 5 minutes at high speed to prepare micelles. After dissolving the radical polymerization initiator in the acrylic monomer, it was added to the micelles and stirred at a high speed for 25 minutes at a rotation speed of 2000 rpm to prepare an emulsion composed of an outer layer shell component. The blending amount of each component is as shown in Table 1.

[Synthesis of double-shelled particles by dropping an emulsion consisting of outer layer shell components]
The emulsion of the "single shelled particles" was heated to 75 ° C. in a nitrogen atmosphere. Then, the "emulsion solution composed of the outer layer shell component" was added dropwise to form an outer shell layer by radical polymerization (emulsion polymerization) at 75 ° C. for 1 hour to synthesize double-shelled particles.

[Dry]
After the synthesis, the emulsion was spray-dried to obtain the double-shelled particles of Example 1.

[Example 2]
In the "synthesis of double-shelled particles" described in Example 1, in addition to allyl methacrylate (trade name "AMA" manufactured by Mitsubishi Gas Chemical Company, Inc.), as "(3) acrylic monomer" which is the "raw material of the outer layer shell". , Methyl methacrylate (trade name "acrylic ester M" manufactured by Mitsubishi Chemical Company, Inc.) was added, but the double-shelled particles were synthesized and dried according to the procedure of Example 1. The blending amount of each component is as shown in Table 1.

[Examples 3 and 4]
In the "preparation of an emulsion composed of core components" described in Example 1, a predetermined amount (listed in Table 1) of the "(5) encapsulation catalyst" which is the "raw material of the core components" is added to the curing catalyst trip-p-. The double-shelled particles were synthesized and dried according to the procedure of Example 2 except that the particles were replaced with trillphosphine (trade name "TPTP" manufactured by Hokuko Chemical Co., Ltd.). The blending amount of each component is as shown in Table 1.

[Example 5]
In the "synthesis of double-shelled particles" described in Example 1, as the "(2) radical polymerization initiator" which is the "raw material of the outer layer shell", the water-soluble radical polymerization initiator 2,2'-azobis [2- (2-Imidazolin-2-yl) Propane] Disulfate dihydrate (trade name "VA-046B" manufactured by Wako Pure Chemical Industries, Ltd., 10-hour half-life temperature 46 ° C.), and oil-soluble radical polymerization initiator dimethyl 1,1 Using'-azobis (1-cyclohexanecarboxylate) (trade name "VE-073" manufactured by Wako Pure Chemical Industries, Ltd., 10-hour half-life temperature 73 ° C.); as "(3) acrylic monomer", allyl methacrylate (Mitsubishi Gas Chemicals) In addition to the company's product name "AMA"), a small amount of methyl methacrylate (Mitsubishi Chemical's product name "acrylic ester M") was added; "Synthesis of heavy shelled particles" was modified as follows; except that, double shelled particles were synthesized and dried according to the procedure of Example 1. The blending amount of each component is as shown in Table 1.

[Synthesis of double-shelled particles by dropping an emulsion consisting of outer layer shell components]
The emulsion of the "single shelled particles" was heated to 65 ° C. in a nitrogen atmosphere. Then, the above-mentioned "emulsifying solution composed of outer layer shell component" is dropped, and radical polymerization (emulsion polymerization) is carried out at 65 ° C. for 1 hour, then the temperature is raised to 90 ° C. and radical polymerization (emulsification) is carried out at 90 ° C. for 1 h. The outer shell layer was formed by polymerization) to synthesize double-shelled particles.

[Comparative Example 1]
The emulsion of the "single-shelled particles" obtained during the preparation of the double-shelled particles of Example 1 was dried by spray drying to obtain the single-shelled particles of Comparative Example 1. Comparative Example 1 is a different lot from Example 1.

[Comparative Example 2]
The emulsion of the "core particles" obtained during the preparation of the double-shelled particles of Example 1 was dried by spray drying to obtain the core particles of Comparative Example 2. Comparative Example 2 is a different lot from Example 1 and Comparative Example 1.

[Comparative Example 3]
A commercially available coarse particle catalyst (EP-CAT-T manufactured by Nippon Kayaku) was used.

<Particle evaluation method>
[Particle size: particle size distribution]
Volume-based particle size distribution curve and cumulative volume curve in ion-exchanged water containing particles of Examples 1 to 5 or Comparative Examples 1 to 3 using BlueRaytrac, a laser diffraction / scattering particle size distribution measuring device manufactured by Microtrac. _{Was measured, and the particle size D 50,} which is integrated from the small particle size side and has a cumulative volume of 50%, was determined.

[Thermal stability of the shell]
Example using a differential thermogravimetric simultaneous measuring device (TG / DTA) Exstar TG / DTA7200 manufactured by SII Nanotechnology (currently Hitachi High-Tech) at a heating rate of 10 ° C./min in a nitrogen atmosphere. The particles of 1 to 5 or Comparative Examples 1 and 3 were measured. After the weight loss due to the thermal decomposition of the inclusion catalyst (in the case of TPP and TPTP, the weight loss occurs from about 150 ° C. and continues to less than 300 ° C.), the weight loss due to the acrylic resin can be confirmed at around 300 ° C. The temperature at which the weight loss rate due to the acrylic resin reached 2% / min (100 ng / min when the sample was 5.00 mg) was defined as the thermal decomposition temperature of the shell.

[Reaction rate evaluation]
Using a Fourier transform infrared spectrophotometer (FT-IR) Nicolet iS50 and / and iS5 manufactured by Thermo Fisher Scientific, the particles of Examples 1 to 5 or Comparative Examples 1 and 3 were subjected to the ATR method under the condition of ^{wave number resolution of 4 cm -1.} And measured. Evaluation and the peak of 1650 cm ^-1, the height ratio of the peak around 2950 cm ^-1 derived from C-H, which is an internal standard (n (C = C) / n (C-H)) derived from the C = C did.

<Epoxy resin composition evaluation>
[Storing stability evaluation Shell permeability]
Particles of Examples 1 to 5 or Comparative Example 3 having the same weight as the liquid alicyclic epoxy resin (trade name: Celoxide 2021P (epoxy equivalent: 138 g / eq) manufactured by Daicel Co., Ltd.) were added and dispersed by a roll mill (ball mill). Using a stress-controlled rheometer AR G2 manufactured by TA Instruments, the viscosity was measured while heating at a heating rate of 10 ° C./min between 20 and 100 ° C. After the viscosity decreased with increasing temperature, the viscosity increased with the penetration of the epoxy resin into the particles was observed. Examples 1, 3 and 5 are dispersion using a roll mill, and Examples 2, 4 and Comparative Example 3 are dispersion using a ball mill.

The temperature at the start of the viscosity increase (temperature at the minimum viscosity) was evaluated. In addition, the viscosity (minimum viscosity) at the start of the viscosity increase was evaluated. The viscosity at 25 ° C. obtained in the above measurement was evaluated as the initial viscosity. The above results are shown in Table 2.

[Evaluation of surface unevenness]
-Evaluation of unevenness in any direction (plane direction) in the plane 100 parts by weight of liquid alicyclic epoxy resin (trade name SELOXIDE 2021P (epoxy equivalent 138 g / eq) manufactured by Daicel Co., Ltd.), methyltetrahydrophthalic anhydride (Hitachi Kasei Co., Ltd.) 100 parts by weight of acid anhydride equivalent 164 g / eq) and 100 parts by weight of particles of Examples 1 to 5 or Comparative Examples 1 to 3 were added and dispersed by a roll mill (ball mill) to prepare a resin composition. Each resin composition was heated at 100 ° C. for 1 hour and then at 180 ° C. for 4 hours using a heating device to obtain a cured product.

The surface shape of each of the obtained cured products was observed and evaluated as follows. After depositing gold on the surface of the cured product, using a scanning electron microscope (SEM) JSM-6390LV manufactured by JEOL Ltd., the acceleration voltage is 15 kV, the observation angle is 45 °, and the magnification is 400 times (observation area: 300 μm × 200 μm). Confirmed by SEM observation.

The case where the size of the convex portion or the concave portion was 10 μm or less was designated as A, and the case where the size exceeded 10 μm was designated as C. The results are shown in Table 2. Further, FIG. 1 shows an SEM observation image of the surface of the cured product of the resin composition to which the particles of Example 1 are added, and FIG. 2 shows an SEM observation image of the surface of the cured product of the resin composition to which the particles of Comparative Example 3 are added. ..

-Evaluation of unevenness in the direction perpendicular to the plane Further, for the cured product of the resin composition to which the particles of Example 1 were added, a stylus type surface shape measuring instrument DEKTAK 150 was used to scan at a scanning speed of 1,000 μm / 60 s. Observation was performed under the conditions of distance: 1.0 mm, measurement points: 5 points, and measurement values: steps.

As a result, the maximum value of the step at each of the five measurement points was as follows. First location: 0.41 μm, second location: 0.46 μm, third location: 0.87, fourth location: 0.74 μm, and fifth location: 0.55 μm. Therefore, it was found that the unevenness of the surface of the cured product of the resin composition to which the particles of Example 1 were added in the direction perpendicular to the plane was 10 μm or less.

[Evaluation of narrow gap invasion]
Similar to the above "evaluation of surface unevenness", each resin composition to which the particles of Examples 1 to 5 or Comparative Examples 1 to 3 are added is mounted on a glass substrate on which a dummy chip with bumps (bump height: 50 μm) is mounted. Was placed on a 90 ° C. hot plate, the resin composition was applied with a dispenser, and the permeability after 5 minutes was evaluated.

The resin composition under the chip that could penetrate without voids was designated as A, the one that could penetrate but had voids and the like was designated as B, and the one that could not penetrate was designated as C. The results are shown in Table 2.

Claims (13)

Core containing phosphorus-based curing catalyst and vinyl-based polymer,
The core is composed of a polymer of a monomer component containing a first vinyl-based monomer and a first crosslinkable vinyl-based monomer or a first vinyl resin which is a polymer of the first vinyl-based monomer. It is a polymer of a monomer component containing a second vinyl-based monomer and a second crosslinkable vinyl-based monomer, or a polymer of a second crosslinkable vinyl-based monomer. An outer shell layer composed of a second vinyl resin and covering the inner shell layer,
Consists of particles containing
The particles have an average particle size of 0.01 to 50 μm and have an average particle size of 0.01 to 50 μm.
A latent curing catalyst for epoxy resins in which the weight ratio of the second crosslinkable vinyl-based monomer in the second vinyl resin is larger than the weight ratio of the first crosslinkable vinyl-based monomer in the first vinyl resin. The latent curing catalyst for an epoxy resin according to claim 1, wherein the first crosslinkable vinyl-based monomer and the second crosslinkable vinyl-based monomer have a (meth) acrylic group. The latent curing catalyst for an epoxy resin according to claim 1 or 2, wherein the vinyl polymer contained in the core is a vinyl polymer having a crosslinked structure. The latent curing catalyst for an epoxy resin according to any one of claims 1 to 3, wherein the weight ratio of the second crosslinkable vinyl-based monomer in the second vinyl resin is 50 to 100% by weight. The latent curing catalyst for an epoxy resin according to any one of claims 1 to 4, wherein the amount of the second vinyl resin with respect to 100 parts by weight of the first vinyl resin is 5 to 50 parts by weight. The method for producing a latent curing catalyst for an epoxy resin according to any one of claims 1 to 5.
A step of polymerizing a monomer component containing a vinyl-based monomer by emulsion polymerization in the presence of a phosphorus-based curing catalyst to form a core.
In the presence of the core, a monomer component containing a first vinyl-based monomer and a first crosslinkable vinyl-based monomer or a first vinyl-based monomer is polymerized by emulsion polymerization to obtain the above. The process of forming the inner shell layer that covers the core,
In the presence of the inner shell layer that coats the core, a monomer component containing a second vinyl-based monomer and a second crosslinkable vinyl-based monomer or a second crosslinkable vinyl-based single component is subjected to emulsion polymerization. A step of polymerizing a dimer to form an outer shell layer that coats the inner shell layer.
How to include. The method according to claim 6, wherein the emulsion polymerization in the step of forming the outer shell layer is carried out in the presence of a monomer-soluble radical polymerization initiator. An epoxy resin composition containing an epoxy resin and a latent curing catalyst for an epoxy resin according to any one of claims 1 to 5. A cured product obtained by curing the epoxy resin composition according to claim 8. The cured product according to claim 9, wherein the size of the convex or concave portion on the surface is 10 μm or less. A semiconductor device containing the cured product according to claim 9 or 10 as a sealing material. The semiconductor device according to claim 11, wherein the semiconductor device has a gap of 100 μm or less, and the encapsulant penetrates into the gap. The semiconductor device according to claim 11 or 12, wherein a rewiring layer is formed on the surface of the sealing material.

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