JP7191936B2 - Latent curing catalyst for epoxy resin, and epoxy resin composition using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a latent curing catalyst used by blending in an epoxy resin, and an epoxy resin composition blended with the same.

An epoxy resin is a compound having two or more highly reactive epoxy groups in its molecule, and is a curable resin that forms a crosslinked network by reaction of the epoxy groups. Epoxy resins are usually mixed with curing agents such as acid anhydrides and polyamines, and curing catalysts (also called curing accelerators) such as phosphine, tertiary amines and imidazole to form epoxy resin compositions, which are then heated. to proceed with curing. Such epoxy resin compositions are widely used in various applications, and have attracted particular attention as sealing materials for semiconductor devices and electronic parts.

In general, curing catalysts readily initiate curing when they come into contact with epoxy resins. Therefore, epoxy resin compositions are widely stored as two-component compositions in which the main and secondary agents are separated. However, in the case of the two-liquid type, it is necessary to measure the required amount of each of the main agent and the secondary agent immediately before use, and then mix the two agents, which is complicated in terms of work. In addition, if a one-liquid type composition is used to avoid complexity, it is necessary to suppress the progress of the curing reaction by freezing or refrigerating, which is disadvantageous in terms of cost. In addition, in the process of returning to room temperature from a frozen or refrigerated storage state before use, if the product is left at room temperature for a long time, curing progresses. However, there was a problem that the filling property was poor.

Therefore, it does not increase in viscosity during the time it is returned to room temperature from a frozen or refrigerated storage state and then used for sealing (for example, 24 hours in room temperature storage after thawing), and can be stored without freezing or refrigeration. Methods have been explored to achieve a possible one-component epoxy resin composition. As one of such methods, a method of microencapsulating a curing catalyst has been proposed (see, for example, Patent Documents 1 to 5), and some such encapsulated curing catalysts are commercially available.

JP-A-8-73566 JP 2012-136650 A JP 2016-35056 A JP 2016-35057 A JP 2016-153475 A

Since the progress of the curing reaction of the encapsulated curing catalyst is suppressed even when it is in contact with the epoxy resin, the two can be stored in a mixed state. However, commercially available encapsulated curing catalysts are coarse particles with a particle size of about 50 μm, and are used in state-of-the-art semiconductor devices with extremely narrow gaps such as bump-to-bump, chip-to-chip, and chip-to-substrate gaps. In the case of sealing material applications in electronic parts and electronic parts, there is a problem that it is not suitable for use due to poor penetrability into such gaps.

In addition, since state-of-the-art smartphones need to process a huge amount of information (signals), fan-out wafer level packages (FO-), which are compact semiconductor devices equipped with a large number of I/O terminals corresponding to this, have been developed. WLP) has been applied. In the FO-WLP, in order to increase the number of I/O terminals, a rewiring layer is formed not only on the bottom surface of the semiconductor chip, but also on the bottom surface of the encapsulating material that protrudes outward from the rewiring layer to form bumps (I/O terminals). It has a structure to be placed. In order to form a thin rewiring layer, the smoothness of the bottom surface of the chip and the bottom surface of the sealing material, which are the coating surfaces, is important. There was a problem that the recesses and protrusions derived from the capsule were formed and the rewiring layer could not be formed. Therefore, it is desired to develop an encapsulated curing catalyst with a smaller particle size that can be applied to semiconductor devices with such an extremely narrow gap and formation of rewiring layers of FO-WLP.

However, when the particle diameter of the encapsulated curing catalyst is simply reduced, miscibility with the epoxy resin is deteriorated, and storage stability, which is the original purpose, is sometimes deteriorated. In addition, if the storage stability of the encapsulated curing catalyst is enhanced, the reactivity with the epoxy resin may be lowered, ie, there is also the problem that good curability of the epoxy resin composition cannot be achieved.

Although the encapsulated curing catalyst has excellent miscibility with the epoxy resin, the curing reaction does not proceed at a temperature lower than the predetermined curing temperature, and while it exhibits high storage stability, it can be heated up to the predetermined curing temperature. It is required that the curing reaction proceeds rapidly.

In view of the above-mentioned current situation, the present invention provides an epoxy resin having a small particle size, excellent miscibility with epoxy resins, high storage stability in a composition with epoxy resins, and excellent curability. It is an object of the present invention to provide a latent curing catalyst for use in a wide variety of applications, and an epoxy resin composition containing the same.

A first aspect of the present invention is a core comprising a phosphorus-based curing catalyst and a vinyl-based polymer, a polymer of monomer components including a first vinyl-based monomer and a first cross-linkable vinyl-based monomer, or a first An inner shell layer composed of a first vinyl resin that is a polymer of vinyl monomers and covering the core, and a monomer containing a second vinyl monomer and a second crosslinkable vinyl monomer. an outer shell layer that is composed of a second vinyl resin that is a polymer of a body component or a polymer of a second cross-linkable vinyl-based monomer, and that covers the inner shell layer; The particle size is 0.01 to 50 μm, and the weight ratio of the second crosslinkable vinyl monomer in the second vinyl resin is higher than the weight ratio of the first crosslinkable vinyl monomer in the first vinyl resin. also relates to latent curing catalysts 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 polymer contained in the core is a vinyl 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 is 5-50 parts by weight per 100 parts by weight of the first vinyl resin.

A second aspect of the present invention is a method for producing a latent curing catalyst for epoxy resins, wherein a monomer component containing a vinyl monomer is polymerized by emulsion polymerization in the presence of a phosphorus curing catalyst to form a core forming a monomer component containing a first vinyl-based monomer and a first cross-linkable vinyl-based monomer, or a first vinyl-based monomer, by emulsion polymerization in the presence of the core polymerizing to form an inner shell layer covering the core; in the presence of the inner shell layer covering the core, a second vinyl-based monomer and a second cross-linkable vinyl-based monomer by emulsion polymerization; or polymerizing 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 the latent curing catalyst for 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 protrusions or recesses on the surface of the cured product is 10 μm or less.

The fifth invention relates to a semiconductor device containing the 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 sealing material may enter the gap. Further, a rewiring layer may be formed on the surface of the sealing material.

According to the present invention, a latent curing agent for epoxy resins has a small particle size, excellent miscibility with epoxy resins, high storage stability in a composition with epoxy resins, and excellent curability. An epoxy resin composition containing a catalyst and said curing catalyst, which has excellent penetrability into narrow gaps and excellent fluidity, and surface smoothness obtained by heating said 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 preparation of the composition is low, and the viscosity does not easily increase even after a long period of time has passed since preparation. When the composition is in the form of a solid sheet, the melt viscosity immediately after preparation of the composition is low, and the melt viscosity does not easily increase even after the passage of time from preparation. Also, even when a large amount of inorganic filler or the like is blended, there is also the advantage that the fluidity is good and the penetrability into extremely narrow gaps is good.

It is drawing which shows the SEM observation image of the hardened|cured material surface (Example 1). It is drawing which shows the SEM observation image of the hardened|cured material surface (comparative example 3).

Embodiments of the present invention are described in detail below.
The latent curing catalyst for epoxy resins of the present invention is in the form of particles having a layer structure consisting of at least three layers: a core, an inner shell layer covering the core, and an outer shell layer covering the inner shell layer. is. The core contains a phosphorus-based curing catalyst, thereby functioning as a curing catalyst for epoxy resin. The outer shell layer and the inner shell layer may be directly laminated, and there is no need to place a curing catalyst between the layers as in Patent Document 2.

The resins contained in the core, inner shell layer, and outer shell layer are all vinyl-based. Since the curing temperature of general epoxy resins exceeds the glass transition temperature (Tg) of vinyl resins, vinyl resins have changed to a rubbery state at said curing temperatures, and the mass permeability of capsules is greatly improved. Therefore, the epoxy resin flows into the capsule, and the phosphorus-based curing catalyst can be dissolved and washed out, or the phosphorus-based curing catalyst itself can spontaneously permeate the capsule and be released into the epoxy resin. . Furthermore, if the stress load on the capsule increases due to the phenomenon described above, or if the capsule thermally decomposes due to heating, the capsule collapses and the release rate of the phosphorus-based curing catalyst remarkably increases. Further, since the vinyl resin itself does not inhibit the curing reaction of the epoxy resin, the epoxy resin exhibits good curability at the above curing temperature. On the other hand, at the storage temperature, the vinyl resin is in a vitreous state, and the substance permeability of the capsule is low, which suppresses the penetration of the epoxy resin into the capsule. Furthermore, 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 penetration of the epoxy resin into the capsules is remarkably prevented. Therefore, it is possible to exhibit high curability when heated to a predetermined temperature while exhibiting high storage stability below a predetermined temperature.

In addition, 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 intermolecular forces acts between the particles of the latent curing catalyst (a long Since there are no graft chains or the like, aggregation due to entanglement is less likely to occur). Therefore, when the particles are blended with the epoxy resin, the aggregation of the particles is broken and the particles are easily mixed 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 has high miscibility with epoxy resins, and can exhibit high curability 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 contains phosphorus among curing catalysts that can be used as curing catalysts for epoxy resins. Preferred are organic phosphine compounds, specifically alkylphosphines such as ethylphosphine, propylphosphine and butylphosphine, and primary phosphines such as phenylphosphine; secondary phosphines such as phosphine, diphenylphosphine, methylphenylphosphine and ethylphenylphosphine; phosphine, tribenzylphosphine, tritolylphosphine (tri-o-tolylphosphine, tri-p-tolylphosphine, tri-m-tolylphosphine), tri-p-styrylphosphine, tris(2,6-dimethoxyphenyl)phosphine, Tertiary phosphines such as tri-4-methylphenylphosphine, tri-4-methoxyphenylphosphine, tri-2-cyanoethylphosphine; phosphinoalkane compounds such as bis(diphenylphosphino)methane, 1,2-bis(diphenylphosphine); phino)ethane, 1,4-(diphenylphosphino)butane and the like; triphenylphosphine-triphenylborane, tetraphenylphosphonium/tetraphenylborate and the like. Among these, tertiary phosphines are more preferred, and triphenylphosphine is particularly preferred.

The core contains a phosphorus-based curing catalyst as well as a vinyl-based polymer. By including the vinyl-based 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 deteriorating the curability. The containment also allows subsequent formation of the inner shell layer. From this point of view, 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, per 100 parts by weight of the phosphorus curing catalyst. In the case of a curing catalyst with low solvent solubility such as tri-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 curing catalyst. It may be up to 4000 parts by weight.

When the content of the vinyl-based polymer in the core is low, the phosphorus-based curing catalyst cannot completely dissolve in the vinyl-based monomer during the preparation of the core components prior to the polymerization reaction to form the core, resulting in coarse phosphorus-based curing catalysts. The curing catalyst may remain, and it may be difficult to enclose the phosphorus-based curing catalyst in minute cores. For example, at the stage of preparation of the core component prior to the polymerization reaction for forming the core, the catalyst may not completely dissolve in the vinyl-based monomer and a coarse catalyst may remain. In this case, minute cores cannot be formed. Conversely, when the content of the vinyl-based polymer in the core increases, the particle size of the latent curing catalyst increases, or the content of the phosphorus-based curing catalyst in the latent catalyst particles decreases, resulting in decreased curability. There is an inconvenience to do.

Before the polymerization reaction for forming the core, the phosphorus-based curing catalyst is preferably dissolved in the vinyl-based monomer. However, polymerization reaction-induced phase separation may occur. In the present invention, the distribution state of the phosphorus-based curing catalyst inside the core is not particularly limited. For example, the core may be composed of a vinyl polymer and a phosphorus curing catalyst that 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 it. In addition, a so-called sea-island structure may be formed in which a discontinuous phase formed by agglomeration of the phosphorus-based curing catalyst is dispersed in the continuous phase composed of the vinyl-based polymer. Also, the vinyl polymer and the phosphorus curing catalyst may be in a co-continuous structure. Even if the phosphorus-based curing catalyst is dissolved in the vinyl-based monomer before the polymerization reaction for forming the core, the polymerization of the vinyl-based monomer causes the phosphorus-based curing catalyst and the vinyl-based polymer to 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. Usable vinyl monomers include (meth)acrylic monomers, olefin monomers, styrene monomers (e.g., metachlorostyrene, parachlorostyrene, parafluorostyrene, paramethoxystyrene, meta tertiary-butoxystyrene, para-tertiary-butoxystyrene, paravinylbenzoic acid, paramethyl-α-methylstyrene, 1-ethynyl-4-fluorobenzene), vinyl ester monomers (formula: C=C-(C=O) —OR), maleic acid-based monomers (including maleic anhydride-based monomers), maleimide-based monomers (e.g., phenylmethane maleimide), vinyl alcohol ester-based monomers (formula: C=C -O-(C=O)-R) (eg, vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate, vinyl benzoate) and the like. 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 per molecule.

Among these monomers, (meth)acrylic monomers are preferred. Examples of (meth)acrylic monomers include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, (meth)acrylate- 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 (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, ( (Meth)acrylic acid alkyl esters having an alkyl group having 1 to 18 carbon atoms, such as stearyl methacrylate; phenyl (meth)acrylate, toluyl (meth)acrylate, benzyl (meth)acrylate, (meth)acrylate 2-methoxyethyl acrylate, 3-methoxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-aminoethyl (meth)acrylate , 2-(dimethylamino)ethyl (meth)acrylate, γ-(methacryloyloxypropyl)trimethoxysilane, ethylene oxide adduct of (meth)acrylic acid, trifluoromethylmethyl (meth)acrylate, (meth)acrylic 2-trifluoromethylethyl acid, 2-perfluoroethylethyl (meth)acrylate, 2-perfluoroethyl-2-perfluorobutylethyl (meth)acrylate, 2-perfluoroethyl (meth)acrylate, ( meth) perfluoromethyl acrylate, diperfluoromethyl methyl (meth) acrylate, 2-perfluoromethyl-2-perfluoroethyl methyl (meth) acrylate, 2-perfluorohexylethyl (meth) acrylate, ( 2-perfluorodecylethyl meth)acrylate, 2-perfluorohexadecylethyl (meth)acrylate, and the like. These (meth)acrylic monomers may be used alone or in combination of two or more. The vinyl-based polymer contained in the core may not have a glycidyl group, instead of polymerizing allyl glycidyl ether or glycidyl (meth)acrylate.

The vinyl polymer contained in the core may be a vinyl polymer having no crosslinked structure, but is preferably a vinyl polymer having a crosslinked structure (hereinafter also referred to as a crosslinked vinyl polymer). . The crosslinked structure preferably has a low density (has a loose crosslinked structure). When the vinyl-based polymer in the core has a crosslinked structure, the phosphorus-based curing catalyst can be more reliably enclosed in the core, and the storage stability of the latent curing catalyst can be further enhanced. The low density structure facilitates the release of the phosphorus curing catalyst at the curing temperature.

In order to introduce a crosslinked structure into the vinyl polymer, the vinyl polymer may be produced by polymerizing the vinyl monomer and the crosslinkable vinyl monomer. The crosslinkable vinyl-based monomer as used in the present application is a crosslinkable vinyl-based monomer having two or more radically polymerizable vinyl groups in one molecule and capable of being radically polymerized together with the vinyl-based monomer. Specific examples of such a crosslinkable vinyl-based monomer include the same specific examples as 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 per molecule. Specifically, allyl acrylate, allyl methacrylate, or di-, tri-, or tetra-(meth)acrylic acid esters of polyhydric alcohols or polyhydric phenols are more preferred, and allyl acrylate or methacryl Allyl acid is particularly preferred.

However, when the content of the cross-linkable vinyl monomer in the cross-linked vinyl polymer in the core increases and the degree of cross-linking increases, it becomes difficult to enclose the phosphorus-based curing catalyst in the core, and even at the curing temperature, epoxy resin It becomes difficult to release the phosphorus-based curing catalyst inside, and the curability may be lowered. From this point of view, the amount of the crosslinkable vinyl monomer used in the core is preferably small. The weight ratio (the weight ratio of the crosslinkable vinyl monomer in the whole 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 made 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 cross-linkable vinyl-based monomer, or a polymer of the first vinyl-based monomer. be. That is, the first vinyl resin is a polymer containing the first vinyl-based monomer as an essential monomer, and may be polymerized together with the first cross-linkable vinyl-based monomer, which is an optional monomer. good. Among these, a polymer of a first vinyl-based monomer and a first cross-linkable vinyl-based monomer is preferred. The first vinyl resin may be a vinyl resin having no acidic groups.

Thus, by providing the inner shell layer between the core and the later-described outer shell layer, it is possible to increase the degree of cross-linking of the outer shell layer, thereby exhibiting high curability while maintaining a latent curing catalyst. can improve 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 per molecule. Monomers, styrenic monomers (e.g., metachlorostyrene, parachlorostyrene, parafluorostyrene, paramethoxystyrene, meta-tertiary-butoxystyrene, para-tertiary-butoxystyrene, paravinylbenzoic acid, paramethyl-α-methylstyrene , 1-ethynyl-4-fluorobenzene), vinyl ester-based monomers (formula: C=C-(C=O)-OR), maleic acid-based monomers (maleic anhydride-based monomers ), maleimide-based monomers (e.g., phenylmethane maleimide), vinyl alcohol ester-based monomers (formula: C=C-O-(C=O)-R) (e.g., vinyl acetate, vinyl formate, propion vinyl acid, vinyl butyrate, vinyl benzoate) and the like. Only one type of these monomers may be used, or two or more types may be used in combination. Among these monomers, (meth)acrylic monomers are preferred. As the (meth)acrylic monomer, those mentioned above (specific examples are described in the section where the (core) is described in detail) can be used. These (meth)acrylic monomers may be used alone or in combination of two or more. In addition, the first vinyl resin may not have a glycidyl group, instead of polymerizing allyl glycidyl ether or glycidyl (meth)acrylate.

As the first cross-linkable vinyl-based monomer, a cross-linkable vinyl-based monomer that has two or more radically polymerizable vinyl groups in one molecule and is capable of radical polymerization with the first vinyl-based monomer. Available. Examples of such first crosslinkable vinyl monomers include allyl acrylate, 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 Diol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate Acrylate, glycerin di(meth)acrylate, 2-hydroxy-3-acryloyloxypropyl(meth)acrylate, dimethylol-tricyclodecane di(meth)acrylate, ethylene oxide adduct of bisphenol A di(meth)acrylate, trimethylol Propane tri(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 2-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, dimethylol-tricyclodecanedi ( Polyhydric alcohols such as meth)acrylates, neopentyl glycol hydroxypivalate di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, bisphenol A di(meth)acrylate, or polyhydric phenol di(meth)acrylates -, tri-, or tetra-(meth)acrylic acid esters; di- or triallyl compounds such as diallyl phthalate, diallyl sebacate, triallyltriazine, triallyl cyanurate, and triallyl isocyanurate; methylenebis(meth)acrylamide; 4′-diphenylmethanebismaleimide, m-phenylenebismaleimide, bisphenol A diphenyletherbismaleimide, 3,3′-dimethyl-5,5′-diethyl-4,4′-diphenylmethanebismaleimide, 4-methyl-1,3- Examples include bismaleimide 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, the polymerizability with the first vinyl-based monomer is good, and the first vinyl resin exhibits good capsule properties, so one or two or more (meth)acrylic groups per molecule Specifically, allyl acrylate, allyl methacrylate, or di-, tri-, or tetra-(meth)acrylic acid esters of polyhydric alcohols or polyhydric phenols are more preferred. Good capsule properties mean that the capsule is in a glass state during storage and exhibits low substance permeability, while at the curing temperature of the epoxy resin, the capsule becomes a rubber state and exhibits high substance permeability, and the disintegration property of the capsule is good. Say things.

Furthermore, among the monomers having one or more (meth)acrylic groups in one molecule, the double bonds having high polymerizability with (meth)acrylic monomers and the polymerizability are relatively low. A monomer having double bonds forms a linear polymer having the latter double bond as a graft chain through the polymerization reaction of the former double bond and the (meth)acrylic monomer. After that, the latter double bond easily contributes to the formation of crosslinks, and the degree of crosslinkage can be achieved as designed. From this point of view, among the monomers having one or more (meth)acrylic groups in one molecule, allyl acrylate or allyl methacrylate is particularly preferable. By introducing double bonds into the polymer in this manner, side reactions that do not contribute to cross-linking (such as cyclization due to intramolecular reactions) can be suppressed, and the degree of cross-linking as designed can be achieved.

In the first vinyl resin forming the inner shell layer, the weight ratio of the first cross-linkable vinyl-based monomer in the first vinyl resin (the weight of the first cross-linkable vinyl-based monomer in the entire first vinyl resin ratio) is preferably 10 to 60% by weight, more preferably 15 to 40% by weight, even more preferably 20 to 30% by weight. Also, the weight ratio of the first crosslinkable vinyl monomer in the first vinyl resin is preferably greater than the weight ratio of the crosslinkable vinyl monomer in the vinyl polymer forming the core. .

(outer shell layer)
The outer shell layer is a resin layer covering the inner shell layer and is made of a second vinyl resin. The second vinyl resin is a polymer of monomer components containing a second vinyl monomer and a second crosslinkable vinyl monomer, or a polymer of the second crosslinkable vinyl monomer. It is a coalescence. That is, the second vinyl resin is a polymer in which the second cross-linkable vinyl monomer is an essential monomer, and the second vinyl monomer is an optional second cross-linkable vinyl monomer. It may be polymerized (copolymerized) together with the monomer, or may not be polymerized (copolymerized). The second vinyl resin may be a vinyl resin having no acidic groups.

Since the second vinyl resin forming the outer shell layer has a crosslinked structure, it is possible to prevent leakage of the phosphorus-based curing catalyst in the core to the outside of the particles, and also to allow the epoxy resin to permeate the inside of the particles. can be suppressed. Thereby, the storage stability of the latent curing catalyst can be enhanced.

As the second vinyl-based monomer, a monomer having one radically polymerizable vinyl group per molecule and capable of undergoing radical polymerization with the second cross-linkable vinyl-based monomer is particularly preferred. Specifically, (meth)acrylic monomers, olefinic monomers, styrenic monomers (e.g., metachlorostyrene, parachlorostyrene, parafluorostyrene, paramethoxystyrene, metatarsia Le-butoxystyrene, para-tertiary-butoxystyrene, para-vinylbenzoic acid, para-methyl-α-methylstyrene, 1-ethynyl-4-fluorobenzene), vinyl ester monomers (formula: C=C-(C=O)- OR), maleic acid-based monomers (including maleic anhydride-based monomers), maleimide-based monomers (e.g., phenylmethane maleimide), vinyl alcohol ester-based monomers (formula: C=C- O-(C=O)-R) (eg, vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate, vinyl benzoate) and the like. Only one type of these monomers may be used, or two or more types may be used in combination. Among these monomers, (meth)acrylic monomers are preferred. As the (meth)acrylic monomer, those mentioned above can be used. These (meth)acrylic monomers may be used alone or in combination of two or more. In addition, the second vinyl resin may not have a glycidyl group, instead of polymerizing allyl glycidyl ether or glycidyl (meth)acrylate.

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 cross-linkable vinyl-based monomer include the same monomers as the first cross-linkable vinyl-based monomer described above, and the same monomer as the first cross-linkable vinyl-based monomer. may be used, or different monomers may be used. For the same reason as the first cross-linkable vinyl-based monomer described above, the second cross-linkable vinyl-based monomer is preferably a monomer having one or more (meth)acrylic groups per molecule. Allyl acid, 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 cross-linkable vinyl-based monomer in the second vinyl resin (the weight of the second cross-linkable vinyl-based monomer in the entire second vinyl resin ratio) is preferably 60 to 100% by weight, more preferably 80 to 100% by weight, and even more preferably 90 to 99.9% by weight.

Furthermore, the weight ratio of the second cross-linkable vinyl monomer in the second vinyl resin is preferably greater than the weight ratio of the first cross-linkable vinyl monomer in the first vinyl resin. In this way, the outer shell layer uses a large amount of the crosslinkable vinyl-based monomer, and the inner shell layer uses a relatively small amount of the crosslinkable vinyl-based monomer or does not use the crosslinkable vinyl-based monomer. By providing a shell layer with a high degree of cross-linking, it is possible to form a shell layer on the outermost side of the particle, thereby suppressing the leakage of the phosphorus curing catalyst and the penetration of the epoxy resin as described above, and the latent curing catalyst can improve the storage stability of

In the present invention, it is particularly preferable to configure the core, the inner shell layer, and the outer shell layer so that the degree of cross-linking increases in this order. In the order of the weight ratio of the body, the weight ratio of the first cross-linkable vinyl monomer in the first vinyl resin, and the weight ratio of the second cross-linkable vinyl monomer in the second vinyl resin, It is to constitute so that the weight ratio of the monomer is large. This makes it possible to form an outer shell layer with a sufficiently high degree of cross-linking while reliably enclosing the phosphorus-based curing catalyst in the core, and facilitate the release of the phosphorus-based catalyst into the epoxy resin at the curing temperature. can.

The weight ratio of the core, the first vinyl resin that forms the inner shell layer, and the second vinyl resin that forms the outer shell layer is not particularly limited. The tall outer shell layer is preferably thinner than the inner shell layer. From this point of view, the amount of the second vinyl resin 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 embodiments of the present invention, the center of the particle is in the order of a low cross-linking density or uncrosslinked core containing a phosphorus-based curing catalyst, a thick inner shell layer with a medium cross-linking density, and a thin outer shell layer with a high cross-linking density. It is preferred that a plurality of shell layers be constructed outwardly from a core that is . A structure having a gradation of cross-linking density in this manner and having a thick inner shell layer and a thin outer shell layer is preferable. Such a structure can improve both excellent stability during storage and excellent curability during curing.

That is, during storage, the thin outer shell layer (thin hard wall) with a high cross-linking density and the thick inner shell layer (thick wall) with a moderate cross-linking density prevent the phosphorous-based curing catalyst from leaking out of the capsule and the epoxy resin from the capsule. At the curing temperature of the epoxy resin, the hard, brittle and thin outer shell layer collapses due to thermal shock such as pressure difference inside and outside the capsule, thermal expansion difference, and stress increase due to mass transfer. It's easy to do. When the outer shell layer collapses, it induces a chain of collapses to the inner shell layer and the core. In other words, the crack propagates and the whole particle collapses. In addition, even if the inner shell layer does not collapse, the inner shell layer, which has an intermediate 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 mobility of the crosslinked chains due to the high crosslink density is extremely low, the outer shell layer with the high crosslink density is less permeable to substances and exhibits very 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, and is prone to collapse due to thermal shock, thereby exhibiting good curability.

Thus, the fact that the outer shell layer has a high crosslink density and is thin greatly contributes to achieving both storage stability and curability. Also, the inner shell layer serves to enhance the function of the outer shell layer. That is, the inner shell layer has a moderate crosslink density and is relatively thick, so even if the epoxy resin permeates the thin outer shell layer during storage, the inner shell layer will still be a phosphorus-based epoxy resin core containing epoxy resin. Reaching the curing catalyst can be suppressed, and this structure enhances the stability during storage. In addition, since the inner shell layer has a moderate crosslink density, the effect of suppressing the collapse of the outer shell layer during curing is low, and curability is not lowered. However, if the inner shell layer has a high cross-linking density, there is a high possibility of suppressing the collapse of the outer shell layer during curing.

(Particle size)
The latent curing catalyst of the present invention is particulate and has an average particle diameter (D ₅₀ (cumulative volume 50%)) of 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. Due to such a small average particle size, the latent curing catalyst of the present invention has the ability to penetrate extremely narrow gaps, etc., and is used for semiconductor devices and electronic components having such narrow gaps. It can be suitably used in a sealing material to be used.

(Manufacturing method)
The latent curing catalyst for epoxy resins 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 optionally a crosslinkable vinyl-based monomer is polymerized by emulsion polymerization to form a core. Next, in the presence of the core, by emulsion polymerization, a monomer component containing a first vinyl-based monomer and optionally a first cross-linkable vinyl-based monomer is polymerized to coat the inner side of the core. Form a shell layer. Further, in the presence of the inner shell layer covering the core, by emulsion polymerization, a monomer component containing a second crosslinkable vinyl-based monomer and optionally a second vinyl-based monomer is polymerized, forming an outer shell layer covering the inner shell layer;

Each emulsion polymerization can follow a conventional method. To describe 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, after uniformly mixing the phosphorus-based curing catalyst and the monomer component of the core, it is added to the micelles, the two are mixed, water is added as necessary, and then stirred to form an emulsion. The particle size of the oil droplets in the emulsified liquid can be appropriately adjusted by selecting the rotational speed of stirring, the type of emulsifier, adjusting the amount added, and the like. Thereafter, the temperature is raised under an inert atmosphere to allow the thermal polymerization reaction to proceed at a predetermined temperature, thereby obtaining an emulsion of core particles. Although the reaction temperature is not particularly limited, it is preferably about 60 to 100° C., and the reaction time is preferably about 1 to 10 hours.

As a polymerization initiator that can be used in emulsion polymerization, a radical polymerization initiator that can be generally used in emulsion polymerization, such as a thermal radical polymerization initiator and a photoradical polymerization initiator, 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-methylpropionamidine) dihydrochloride, 2,2′-azobis-[N-(2-carboxyethyl)-2-methylpropionamidine], 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. and water-soluble azo compounds, 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-methylpropionamide) Pionate), 1,1'-azobis (cyclohexane-1-carbonitrile), dimethyl 1,1'-azobis (1-cyclohexanecarboxylate) oil-soluble azo compounds such as azo compounds; potassium persulfate, peroxide Persulfate compounds such as sodium sulfate and ammonium persulfate; organic peroxides such as diisopropylbenzene hydroperoxide, p-menthane hydroperoxide, cumene hydroperoxide, and t-butyl hydroperoxide; organic peroxides (diacyl peroxides) such as benzoyl oxide; and redox initiators obtained by adding Fe ²⁺ or Cu ⁺ ions to the above persulfate compounds or organic peroxides.

Among these polymerization initiators, water-soluble polymerization initiators are 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 will proceed during charging at room temperature, and if it is higher than this, the polymerization reaction will take a long time. . Many of the above organic peroxides have a 10-hour half-life temperature exceeding the above range, and the rate of radical generation at the general emulsion polymerization temperature is slow. Therefore, low-valence metal ions (Fe ²⁺ , Cu ⁺ , etc.) are added to this to improve the radical generation rate in the above temperature range by the Fenton reaction (redox reaction). Therefore, the organic peroxide redox initiator 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. When two or more are used in combination, 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 the oil-soluble radical polymerization initiator alone may be used. The amount of the polymerization initiator to be used can be appropriately set, and may be, for example, 0.01 to 1.00 parts by weight per 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 0.01 per 100 parts by weight of the monomer component. It may be 2.00 parts by weight.

Emulsifiers that can be used in emulsion polymerization include alkali metal salts and ammonium salts of higher fatty acids such as disproportionated rosin acid, oleic acid, and stearic acid, alkali metal salts and ammonium salts of sulfonic acids such as dodecylbenzenesulfonic acid, and anions. system emulsifiers and nonionic emulsifiers. The anionic emulsifier is not particularly limited, and examples thereof include polyoxyethylene alkyl ether sulfate salts (e.g., sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, etc.), alkyl Examples include diphenyl ether disulfonates (sodium alkyldiphenyl ether disulfonate, sodium alkyl diphenyl ether disulfonate, etc.), reactive anionic surfactants (polyoxyalkylene alkenyl ether ammonium sulfate, etc.), and the like. In addition, the nonionic emulsifier is not particularly limited, and polyoxyethylene alkyl ether (e.g., polyoxyethylene alkyl ether, etc.), polyoxyalkylene alkyl ether (e.g., polyoxyalkylene alkyl ether, etc.), reactive nonionic interface activators (polyoxyalkylene alkenyl ethers, etc.) and the like.

Among emulsifiers, ammonium salt-type anionic emulsifiers and nonionic emulsifiers containing no metal ions are preferred in order to reduce metal ions in the resulting polymer. Specifically, as the ammonium salt type anionic emulsifier, ammonium lauryl sulfate and di-(2-ethylhexyl) ammonium sulfosuccinate are preferable in order to achieve stability of emulsion polymerization, and as the nonionic emulsifier, stability of emulsion polymerization is preferable. polyoxyethylene monotetradecyl ether and polyoxyethylene distyrenated phenyl ether are preferred. Moreover, from the viewpoint of industrial availability, a sodium salt type anionic emulsifier is preferable. As the sodium salt type anionic emulsifier, di-(2-ethylhexyl)sodium sulfosuccinate is preferred. The amount of the emulsifier to be used can be appropriately set, and may be, for example, 0.01 to 10.00 parts by weight per 100 parts by weight of the monomer component.

Next, in order to form the inner shell layer, first, a polymerization initiator and an 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 the two are mixed and stirred to form an emulsion for the inner shell layer. Next, after the core particle emulsion is brought to a predetermined temperature in an inert atmosphere, the inner shell layer emulsion is added dropwise to the core particle emulsion, which is then mixed and stirred to allow the thermal polymerization reaction to proceed at the predetermined temperature. to obtain an emulsion of single-shelled particles. The reaction temperature, reaction time, and the like can be appropriately adjusted with reference to the ranges described above.

In order to form the outer shell layer, first, an emulsifier and water are mixed, or an emulsifier, a 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 the two are mixed and stirred to form the outer shell. Form a layer emulsion. Next, after the emulsion of the single-shelled particles is brought to a predetermined temperature in an inert atmosphere, the emulsion for the outer shell layer is added dropwise thereto, and the mixture is mixed and stirred while undergoing a thermal polymerization reaction at a predetermined temperature. to obtain an emulsion of double-shelled particles. The reaction temperature, reaction time, and the like can be appropriately adjusted with reference to the ranges described above.

In the emulsion polymerization for forming the outer shell layer, the polymerization initiator is dissolved in advance only in the monomer component to be added to the micelle before use, or dissolved in water before forming the micelle, and then It is preferable to dissolve in advance in the monomer components to be added to the micelles. 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 dissolved in water, and When dissolved with the monomer component, it is preferable to use a monomer-soluble radical polymerization initiator. That is, in the polymerization of the outer shell, the radical polymerization initiation reaction occurs in the monomer component in the former case, whereas the radical polymerization initiation reaction occurs in both the monomer component and the aqueous phase in the latter case. The term "monomer-soluble radical polymerization initiator" as used herein refers to a radical polymerization initiator that uniformly dissolves at 25° C. in an amount of 0.50 parts by weight or more with respect to 100 parts by weight of allyl methacrylate (AMA). In general, many oil-soluble radical polymerization initiators are suitable. Moreover, the polymerization initiator may be dissolved in advance only in water before the micelle is formed, 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 within the aqueous phase.

Examples of monomer-soluble radical polymerization initiators include the above-mentioned oil-soluble radical polymerization initiators. 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; Thus, the use of a monomer-soluble radical polymerization initiator is preferable for promoting the progress of the cross-linking reaction by the second cross-linkable vinyl-based monomer in the outer shell layer and increasing the degree of cross-linking of the outer shell layer. . In addition, the combined use of a monomer-soluble radical polymerization initiator and a 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 for forming the core and inner shell layers.

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 emulsified liquid by centrifugation or filtration, washing with water if necessary, and drying by a conventional method. Among these methods, it is preferable to use the spray drying method because the resulting powder has excellent dispersibility in the epoxy resin.

Unless otherwise specified, the water described herein is ion-exchanged water, but is not limited to this.

(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 is in a state before curing, and may be in a liquid state, or may be a gel-like molded article having a certain shape. The shape of such a molded article is not particularly limited, and can be appropriately designed according to the application. Examples thereof include sheet-like, film-like, and tablet-like shapes.

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 novolak type epoxy resin, triphenylmethane type epoxy resin, tetraphenylethane type epoxy resin, dicyclopentadiene phenol addition reaction type Epoxy resin, phenol aralkyl type epoxy resin, naphthol novolak type epoxy resin, naphthol aralkyl type epoxy resin, naphthol phenol co-condensation novolac type epoxy resin, naphthol cresol co-condensation novolak type epoxy resin, aromatic hydrocarbon formaldehyde resin modified phenol resin type epoxy Resins, biphenyl novolac type epoxy resins, ethylphenol novolac type epoxy resins, butylphenol novolak type epoxy resins, octylphenol novolak type epoxy resins, xylylene skeleton-containing phenol novolak type epoxy resins, fluorene skeleton-containing phenol novolac type epoxy resins, 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'-cyclohexyl carboxylate 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, isocyanuric ring type epoxy resin, hydantoin ring type epoxy resin, hexahydrophthalic acid diglycidyl ester type epoxy resin , tetrahydrophthalate diglycidyl 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, Brominated phenol novolac type epoxy resins, brominated cresol novolac type epoxy resins, and the like can be mentioned. 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 the desired properties and properties (liquid or solid), and is not particularly limited. Resins are preferred.

The amount of the latent curing catalyst of the present invention to be used relative to the epoxy resin is not particularly limited, and can be appropriately determined according to the desired curing speed and physical properties 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 part by weight, based on 100 parts by weight of the epoxy resin. to 30 parts by weight, particularly preferably 1.0 to 20 parts by weight. In addition, 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, and still more preferably 100 parts by weight of the epoxy resin. can 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 those commonly known as curing agents to be mixed with epoxy resins can be used. Specifically, for example, 2-ethyl-4-methylimidazole, diaminodiphenylmethane, diethylenetriamine, triethylenetetramine, diaminodiphenylsulfone, isophoronediamine, imidazole, boron trifluoride-amine complex, guanidine derivative, dicyandiamide, linolenic Polyamide resins synthesized from dimers and ethylenediamine, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride , methylhexahydrophthalic anhydride, phenolic novolac resin, cresol novolac resin, aromatic hydrocarbon-formaldehyde resin-modified phenolic resin, dicyclopentadiene phenol addition type resin, phenol aralkyl resin, poly(polyethylene) synthesized from polyhydric hydroxy compound and formaldehyde. Hydric phenol novolak resin, naphthol aralkyl resin, trimethylolmethane resin, tetraphenylolethane resin, naphthol novolac resin, naphthol phenol co-condensed novolac resin, naphthol cresol co-condensed novolac resin, biphenyl-modified phenol resin, biphenyl-modified naphthol resin, aminotriazine Modified phenol resins, alkoxy group-containing aromatic ring-modified novolak resins, and the like can be mentioned. Only one curing agent may be used, or two or more curing agents may be used in combination. The curing agent may be selected according to the desired properties and properties (liquid or solid) and is not particularly limited. For example, from the viewpoint of heat resistance and chemical resistance, acid anhydride Amine-based curing agents are preferable from the viewpoint of low-temperature curability and high adhesion, and phenol-based curing agents are preferable from the viewpoints of low outgassing during curing, moisture resistance, and heat cycle resistance. It is preferably used.

The amount of the curing agent to be used relative to the epoxy resin is not particularly limited, and may be a general amount, and can be appropriately determined according to the desired curing speed and the 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, per 100 parts by weight of the epoxy resin.

The epoxy resin composition of the present invention may further contain known additives for epoxy resin compositions as appropriate. Examples of such additives include fillers such as carbon black, adhesion imparting agents, solvents, reactive diluents, antioxidants, light stabilizers, ultraviolet absorbers, antifoaming agents, leveling agents, pigments, and the like. is mentioned.

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

Adhesion imparting agents include, for example, coupling agents, phenolic resins, organic polyisocyanates, and the like. Only one type of adhesion imparting agent may be used, or two or more types 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, and partially hydrolyzed condensates thereof. Among these coupling agents, silane-based coupling agents and partial hydrolysis condensates thereof are preferred because of their high adhesion-imparting effect. The partially hydrolyzed condensate of the coupling agent may be a partially hydrolyzed condensate of the same type of coupling agent or a partially hydrolyzed condensate of two or more coupling agents.

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

The solvent is not particularly limited, and examples thereof include N-methylpyrrolidone; N,N-dimethylformamide; dimethylsulfoxide; ketones such as methylethylketone, cyclohexanone and cyclopentanone; aromatic hydrocarbons such as toluene, xylene and tetramethylbenzene. 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, and triethylene glycol monoethyl ether; ethyl acetate, Esters such as butyl acetate, cellosolve acetate, diethylene glycol monoethyl ether acetate and esters of the above glycol ethers; Alcohols such as ethanol, propanol, methanol, ethylene glycol and propylene glycol; Aliphatic hydrocarbons such as octane and decane petroleum solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha and solvent naphtha; 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 examples include allyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, p-sec-butylphenyl glycidyl ether, tert-butylphenyl glycidyl ether, o-phenylphenol glycidyl ether, Ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, 4-vinylcyclohexene monoxide, vinylcyclohexene Dioxide, methylated vinylcyclohexene dioxide, (3,4-epoxycyclohexyl)methyl-3,4-epoxycyclohexylcarboxylate, bis-(3,4-epoxycyclohexyl)adipate, bis-(3,4-epoxycyclohexyl) methylene)adipate, bis-(2,3-epoxycyclopentyl)ether, (2,3-epoxy-6-methylcyclohexylmethyl)adipate, dicyclopentadiene dioxide and the like. Only one type of reactive diluent may be used, or two or more types may be used in combination.

The latent curing catalyst for epoxy resins of the present invention can act as a sheeting agent because it itself can have the effect of gelling the epoxy resin composition. Therefore, the epoxy resin composition of the present invention can be molded into a sheet or the like without blending a sheeting agent as an additional component. However, when the epoxy resin composition of the present invention is a molded article 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 absorbs and swells the epoxy resin or other components to make the composition gel, or is compatible with the epoxy resin or other components to make the composition gel. .

Thermoplastic resins constituting such powders include, for example, polyvinyl chloride, polyethylene, polypropylene, polystyrene, 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. Among these, polymethacrylic acid esters such as polymethyl methacrylate are preferable from the standpoint of sheet forming properties.

Moreover, when the epoxy resin composition of the present invention is a molded article such as a sheet, a photopolymerizable compound and a radical generator acting as a sheeting agent may be added to the epoxy resin composition. In this case, first, a mixture of an epoxy resin composition and other components, a photopolymerizable compound, and a radical generator is prepared, and the obtained mixture is formed into a sheet, and then irradiated with light to form a photopolymerizable compound. 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 alcohol, alkylenediol, polyhydric alcohol, and the like. and compounds described in [0009] to [0012] of JP-A-11-12543.

The radical generator is a compound that generates radicals upon irradiation with actinic rays such as ultraviolet rays and electron beams, and various conventionally used ones can be used. 1-Phenylpropan-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, the latent curing catalyst of the present invention, a curing agent and other additives. The method of mixing these is not particularly limited, and conventionally known methods can be used. can be done.

When the epoxy resin composition of the present invention is formed into a sheet-like molded article, the components may be mixed as described above and then molded by a conventional method such as heat molding. In addition, if necessary, the epoxy resin composition liquefied by heating is coated with a film thickness controlled by a roll coater or the like, and is heated at 60 to 150° C. for 0.5 to 30 minutes, and further at 80 to 120° C. for 1 hour. It can also be made into a sheet form by drying for ~10 minutes.

A cured product can be obtained by curing the epoxy resin composition. The curing method may be the conditions for curing a general epoxy resin composition, and is not particularly limited. For example, using a heating device, heat at 100° C. for 1 hour and then at 180° C. for 4 hours. and the like. However, specific curing conditions can be appropriately determined depending on the application 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.

The surface shape of the cured product of the present invention is preferably such that the size of the projections or recesses on the surface is 10 μm or less. After depositing gold on the surface of the cured product, the surface shape was measured using a scanning electron microscope (SEM) JSM-6390LV manufactured by JEOL Ltd., an acceleration voltage of 15 kV, an observation angle of 45 °, and a magnification of 400 times (observation area: 300 μm × 200 μm) or 2000 times (observation area: 60 μm×40 μm). The size of the convex portion or concave portion can be obtained from the SEM observation image. The SEM observation image can be used to evaluate the size of the uneven area in any direction in the plane. An arbitrary direction within a plane is an arbitrary direction within the plane of the SEM photograph.

The surface profile can be observed using a stylus surface profiler DEKTAK 150 under the following conditions: scanning speed: 1,000 μm/60 s, scanning distance: 1.0 mm, measurement points: 5 points, and measured value: steps. . A stylus-type surface profiler can evaluate the size of unevenness in a direction perpendicular to a surface, in particular. The direction perpendicular to the plane means the direction perpendicular to the photographic plane at any position on the SEM photographic plane.

(Application)
Although the use of the epoxy resin composition of the present invention is not particularly limited, 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 extremely narrow gaps, so it is particularly suitable as a sealing material for semiconductor devices or electronic parts having such narrow gaps. It can be used preferably. Gaps include, for example, substrate-to-chip gaps, chip-to-chip gaps, and solder bump-to-solder bump gaps. The width of the gap may be 100 μm or less, 50 μm or less, or 30 μm or less.

In addition, 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, the specific application as a sealing material is a sealing material for FO-WLP applications because it is possible to form a rewiring layer on the bottom surface of the sealing material, and circuits such as antennas on the top surface of the sealing material. Since it can be formed, it is possible to use a sealing material for Antenna-on-Package (AoP) in which an antenna and a semiconductor device are integrated, or metal plating on the entire surface or a part of the sealing, so that a semiconductor device can be suitably used as a sealing material for electromagnetic wave shielding applications.

An example of such a sealing material is a semiconductor sealing material used when sealing a wafer level chip size package, which is a large-area semiconductor package, by an overmolding method. The sealing material serves as an overmolding material for sealing the terminals, element electrodes, and semiconductor bare chips arranged on the semiconductor wafer substrate. Examples of overmold molding include transfer molding and compression molding. Among them, compression molding is preferred. Overmolding is preferably carried out at 50-200° C., more preferably 100-175° C., for 1-15 minutes. If necessary, post curing at 100 to 200° C. for 30 minutes to 24 hours can be performed. Such heating cures the epoxy resin composition to form an overmold material. As such a sealing material, the liquid epoxy resin composition of the present invention can be suitably used.

Another example of the sealing material is a surface acoustic wave device in which a surface acoustic wave chip is mounted on a substrate on which a wiring pattern is formed. However, in a surface acoustic wave device having a hollow structure between the substrate and the chip, the electrode surface and the wiring pattern are not in direct contact. A fixing material is mentioned. As such a sealing material, the epoxy resin composition of the present invention, which is a molded article having a certain shape, can be preferably used.

When the epoxy resin composition is used to seal the surface acoustic wave chip, for example, a sheet-like epoxy resin composition is placed so as to cover the surface acoustic wave chip and then heat-pressed. As a result, the epoxy resin composition can be cured to form a protective layer of the chip while maintaining the hollow structure. Such heat press conditions can be determined as appropriate. For example, the pressure is 100 Pa to 10 MPa, preferably 0.01 to 2 MPa, the temperature is 250 ° C. or less, preferably 60 to 180 ° C., and the time is 5 seconds to 5 seconds. It may be 3 hours, preferably 1 to 15 minutes.

The specific sealing material applications for which the epoxy resin composition of the present invention can be suitably used have been described above. In these uses, it is required that the encapsulant penetrates into an extremely narrow gap and cures, so the application of the epoxy resin composition of the present invention is of great significance. However, the uses of the epoxy resin composition of the present invention are not limited to these.

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

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

[Example 1]
<Synthesis of core particles>
[Preparation of Emulsion Consisting of Core Components]
(material)
(1) Emulsifier Nonionic surfactant polyoxyethylene distyrenated phenyl ether (trade name “Emulgen A-90” manufactured by Kao Corporation)
Anionic surfactant di-(2-ethylhexyl) sodium sulfosuccinate (trade name “Likasurf P-10” manufactured by Shin Nippon Rika Co., Ltd.)
(2) Radical polymerization initiator Water-soluble radical polymerization initiator 2,2′-azobis-[N-(2-carboxyethyl)-2-methylpropionamidine] (trade name “VA-057” manufactured by Wako Pure Chemical Industries, Ltd.) , 10 hour half-life temperature 57°C)
(3) Acrylic monomer methyl methacrylate (trade name “Acrylic Ester M” manufactured by Mitsubishi Chemical Corporation)
Allyl methacrylate (trade name “AMA” manufactured by Mitsubishi Gas Chemical Company, Inc.)
(4) Deionized Water (DW)
(5) Encapsulation catalyst curing catalyst triphenylphosphine (trade name “TPP” manufactured by Hokko Chemical Co., Ltd.)

(Method for preparing emulsion)
An emulsifier and a radical polymerization initiator were dissolved in ion-exchanged water, and stirred at a rotational speed of 1500 rpm for 15 minutes at high speed to prepare micelles. After uniformly dissolving the encapsulated catalyst and the acrylic monomer, they were added to and mixed with the micelles, water was added, and high-speed stirring was performed at a rotational speed of 2000 rpm for 20 minutes 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 "preparation of emulsion comprising core components" in "synthesis of core particles", (3) In addition to the above, the following acrylic monomers were used.
n-butyl acrylate (manufactured by Mitsubishi Chemical Corporation, trade name “butyl acrylate”)

(Method for preparing emulsion)
An emulsifier and a radical polymerization initiator were dissolved in ion-exchanged water, and stirred at a rotational speed of 1500 rpm for 15 minutes at high speed to prepare micelles. After uniformly mixing the acrylic monomers, the mixture was added to the micelles and stirred at a high speed of 2000 rpm for 20 minutes to prepare an emulsion comprising the inner layer shell component. The blending amount of each component is as shown in Table 1.

[Synthesis of Single Shelled Particles by Dropping Emulsion Consisting of Inner Shell Components]
The "core particle" emulsion was heated to 75°C under a nitrogen atmosphere. After that, the above-mentioned "emulsion liquid composed of the inner layer shell component" was added dropwise, and the inner shell layer was formed 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 "Preparation of emulsion comprising core components" in "Synthesis of core particles", (2) radical polymerization initiator and (3) acrylic monomer used:
(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, 10-hour half-life temperature 66 ° C.)
(3) Single use of acrylic monomer allyl methacrylate (trade name “AMA” manufactured by Mitsubishi Gas Chemical Company, Inc.)

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

[Synthesis of Double Shelled Particles by Dropping Emulsion Consisting of Outer Layer Shell Components]
The emulsion of the "single-shelled particles" was heated to 75°C under a nitrogen atmosphere. After that, the "emulsion liquid comprising the outer layer shell component" was added dropwise, and the outer shell layer was formed by radical polymerization (emulsion polymerization) at 75°C for 1 hour to synthesize double-shelled particles.

[Dry]
After synthesis, the emulsion was dried by spray drying 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 (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name "AMA") as "(3) acrylic monomer" which is the "raw material of the outer layer shell" A double-shelled particle was synthesized and dried according to the procedure of Example 1, except that a small amount of methyl methacrylate (manufactured by Mitsubishi Chemical Co., Ltd., trade name "Acrylic Ester M") was added. The blending amount of each component is as shown in Table 1.

[Examples 3 and 4]
In the "preparation of the emulsion comprising the core component" described in Example 1, "(5) encapsulating catalyst", which is the "raw material of the core component", was added to a predetermined amount (described in Table 1) of the curing catalyst tri-p- Double-shelled particles were synthesized and dried according to the procedure of Example 2, except that tolylphosphine (manufactured by Hokko Chemical Co., Ltd., trade name “TPTP”) was used. 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, 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 an oil-soluble radical polymerization initiator dimethyl 1,1 '-azobis (1-cyclohexane carboxylate) (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 Chemical In addition to adding a small amount of methyl methacrylate (manufactured by Mitsubishi Chemical Corporation under the trade name of "Acrylic Ester M") in addition to the product name "AMA" manufactured by Mitsubishi Chemical Corporation); Double-shelled particles were synthesized and dried according to the procedure of Example 1, except that "Synthesis of Heavy-Shelled Particles" was modified as follows. The blending amount of each component is as shown in Table 1.

[Synthesis of Double Shelled Particles by Dropping Emulsion Consisting of Outer Layer Shell Components]
The emulsion of the "single-shelled particles" was heated to 65°C under a nitrogen atmosphere. After that, the "emulsified liquid comprising the outer layer shell component" was added dropwise, and radical polymerization (emulsion polymerization) was performed at 65°C for 1 hour. polymerization) to form an outer shell layer 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 single-shelled particles of Comparative Example 1. Comparative Example 1 is a different lot from Example 1.

[Comparative Example 2]
The emulsified liquid 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 Co., Ltd.) was used.

<Evaluation method of particles>
[Particle size: Particle size distribution]
Using Microtrac's laser diffraction/scattering particle size distribution measuring device BlueRaytrac, in ion-exchanged water containing the particles of Examples 1 to 5 or Comparative Examples 1 to 3, the particle size distribution curve on a volume basis and the cumulative volume curve was measured, and the particle diameter D50 at which the cumulative volume was ₅₀ % was obtained by accumulating from the small particle diameter side.

[Shell Thermal Stability]
Using a simultaneous differential thermogravimetric analyzer (TG/DTA) Exstar TG/DTA7200 manufactured by SII Nanotechnology Co., Ltd. (currently Hitachi High-Tech Co., Ltd.), in a nitrogen atmosphere, at a temperature increase rate of 10 ° C./min, Examples Particles of 1 to 5 or Comparative Examples 1 and 3 were measured. After weight loss due to thermal decomposition of the encapsulated catalyst (in the case of TPP and TPTP, weight loss occurs from about 150°C and continues until below 300°C), weight loss due to the acrylic resin can be confirmed around 300°C. The temperature at which the rate of weight loss due to the acrylic resin became 2%/min (100 ng/min when the sample was 5.00 mg) was defined as the thermal decomposition temperature of the shell.

[Response rate evaluation]
Using a Fourier transform infrared spectrophotometer (FT-IR) Nicolet iS50 or / and iS5 manufactured by ThermoFisher Scientific, the particles of Examples 1 to 5 or Comparative Examples 1 and 3 were subjected to the ATR method under the condition of a wavenumber resolution of 4 cm ^-1 . measured by Evaluate the height ratio (n (C=C)/n (C-H)) between the peak at 1650 cm ^-1 derived from C=C and the peak around 2950 cm ^-1 derived from the internal standard C-H. did.

<Evaluation of epoxy resin composition>
[Storage stability evaluation shell permeability]
Liquid alicyclic epoxy resin (manufactured by Daicel under the trade name Celoxide 2021P (epoxy equivalent: 138 g/eq)) and the same weight of the particles of Examples 1 to 5 or Comparative Example 3 were added and dispersed in a roll mill (ball mill). Using a stress-controlled rheometer AR G2 manufactured by TA Instruments Co., Ltd., the viscosity was measured while heating between 20 and 100° C. at a heating rate of 10° C./min. After a decrease in viscosity with increasing temperature, an increase in viscosity was observed due to penetration of the epoxy resin into the particles. Examples 1, 3 and 5 are dispersions by a roll mill, and Examples 2, 4 and Comparative Example 3 are dispersions by a ball mill.

The temperature at the onset of viscosity increase (temperature at 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 by the above measurement was evaluated as the initial viscosity. Table 2 shows the above results.

[Evaluation of surface unevenness]
・ Evaluation of unevenness in an arbitrary direction (planar direction) in a plane Liquid alicyclic epoxy resin (trade name Celoxide 2021P (epoxy equivalent: 138 g / eq) manufactured by Daicel) 100 parts by weight, methyltetrahydrophthalic anhydride (Hitachi Chemical Co., Ltd. 100 parts by weight of the acid anhydride equivalent of 164 g/eq) and 100 parts by weight of the 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. Using a heating device, each resin composition was heated at 100° C. for 1 hour and then at 180° C. for 4 hours to obtain a cured product.

The surface shape of each cured product obtained 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., an acceleration voltage of 15 kV, an observation angle of 45 °, and a magnification of 400 times (observation area: 300 μm × 200 μm). It was confirmed by SEM observation.

When the size of the protrusion or recess was 10 µm or less, A was rated, and when the size exceeded 10 µm, C was rated. Table 2 shows the results. 1 shows an SEM observation image of the surface of the cured resin composition to which the particles of Example 1 are added, and FIG. 2 shows an SEM observation image of the cured surface of the resin composition to which the particles of Comparative Example 3 are added. .

・ Evaluation of unevenness in the direction perpendicular to the surface Further, the cured product of the resin composition to which the particles of Example 1 were added was scanned using a stylus surface profiler DEKTAK 150 at a scanning speed of 1,000 μm / 60 s. Observation was made under the conditions of distance: 1.0 mm, measurement points: 5 points, and measured value: steps.

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

[Narrow gap penetration evaluation]
Each resin composition to which the particles of Examples 1 to 5 or Comparative Examples 1 to 3 were added was mounted on a glass substrate with a dummy chip with bumps (bump height: 50 μm) in the same manner as in the above “evaluation of surface unevenness”. was placed on a 90° C. hot plate, the resin composition was applied with a dispenser, and the penetrability was evaluated after 5 minutes.

The case where the resin composition penetrated under the chip without voids was rated as A, the case where the resin composition penetrated but had voids or the like was rated as B, and the case where the resin composition did not penetrate was rated as C. Table 2 shows the results.

Claims (14)

a core comprising a phosphorus-based curing catalyst and a vinyl-based polymer;
The core is composed of a polymer of monomer components containing a first vinyl-based monomer and a first cross-linkable vinyl-based monomer or a first vinyl resin that is a polymer of the first vinyl-based monomer. and a polymer of a monomer component containing a second vinyl-based monomer and a second cross-linkable vinyl-based monomer or a polymer of the second cross-linkable vinyl-based monomer. an outer shell layer made 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,
A latent curing catalyst for epoxy resins, wherein the weight ratio of the second crosslinkable vinyl monomer in the second vinyl resin is greater than the weight ratio of the first crosslinkable vinyl monomer in the first vinyl resin. The latent curing catalyst for epoxy resins according to claim 1, wherein the first cross-linkable vinyl-based monomer and the second cross-linkable vinyl-based monomer have a (meth)acrylic group. 3. The latent curing catalyst for epoxy resin according to claim 1, wherein said vinyl polymer contained in said core is a vinyl polymer having a crosslinked structure. The latent curing catalyst for epoxy resins 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 epoxy resin according to any one of claims 1 to 4, wherein the amount of the second vinyl resin is 5 to 50 parts by weight with respect to 100 parts by weight of the first vinyl resin. A method for producing the latent curing catalyst for epoxy resin according to any one of claims 1 to 5,
a step of polymerizing a monomer component containing a vinyl monomer by emulsion polymerization in the presence of a phosphorus curing catalyst to form a core;
In the presence of the core, the monomer component containing the first vinyl monomer and the first crosslinkable vinyl monomer or the first vinyl monomer is polymerized by emulsion polymerization to obtain the forming an inner shell layer covering the core;
In the presence of the inner shell layer covering the core, a monomer component containing a second vinyl-based monomer and a second cross-linkable vinyl-based monomer, or a second cross-linkable vinyl-based monomer is obtained by emulsion polymerization. polymerizing a polymer to form an outer shell layer covering the inner shell layer;
method including. 7. The method of 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 comprising an epoxy resin and the latent curing catalyst for 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 . 10. The cured product according to claim 9, wherein the size of the protrusions or recesses on the surface is 10 [mu]m or less. A semiconductor device comprising the cured product according to claim 9 or 10 as a sealing material. 12. The semiconductor device according to claim 11, wherein said semiconductor device has a gap of 100 [mu]m or less, and said encapsulant penetrates said gap. 13. The semiconductor device according to claim 11, wherein a rewiring layer is formed on the surface of said sealing material. The vinyl polymer contained in the core is a polymer obtained by polymerizing a monomer component containing a (meth)acrylic monomer,
The first vinyl-based monomer and the second vinyl-based monomer comprise a (meth)acrylic monomer,
The latent curing catalyst for epoxy resins according to any one of claims 1 to 5, wherein the first crosslinkable vinyl-based monomer and the second crosslinkable vinyl-based monomer have a (meth)acrylic group.

Images