JP7360249B2 - Polymer-coated inorganic filler, and resin compositions containing it, dry films, cured products, electronic components - Google Patents

Description

The present invention relates to a polymer-coated inorganic filler in which the surface of inorganic particles is coated with a polymer, and a resin composition, dry film, cured product, and electronic component containing the same.

Electronic materials such as solder resists and encapsulants are filled with inorganic particles to improve the required thermal dimensional stability and dielectric properties. In this case, inorganic particles have poor wettability with the resin, which is the main component of the solder resist and sealing material, due to the difference in polarity, and it is difficult to uniformly disperse the inorganic particles in the resin composition, making it difficult to achieve the desired performance. Therefore, studies have been conducted to improve dispersibility by chemically modifying the surface of inorganic particles.

Patent Document 1 proposes a method of improving the dispersibility by preparing a polymer containing a silane coupling agent in advance and bonding it to the surface of the inorganic particle to introduce the polymer onto the surface of the inorganic particle.

Patent Document 2 discloses that a silane coupling agent is used to introduce a monomer that is a raw material for a polymer onto the surface of an inorganic particle, and living radical polymerization is performed in the monomer, thereby introducing the polymer onto the surface of the inorganic particle and dispersing it. Methods have been proposed to improve sex.

Patent Document 3 proposes a method in which a monomer serving as a raw material for a polymer and a RAFT agent are bonded to the surface of an inorganic particle, the polymer is grown, and the dispersibility is improved.

International Publication No. 2008/101581 Japanese Patent Application Publication No. 2005-120365 Japanese Patent Application Publication No. 2016-180121

According to the method described in Patent Document 1, the dispersibility is improved. However, it is necessary to prepare a polymer containing a silane coupling agent in advance, which may be time consuming and costly.

The method described in Patent Document 2 also improves the dispersibility. However, since it is necessary to introduce a monomer that serves as a starting point for polymerization onto the particle surface in advance, and the reaction proceeds in situ, it is difficult to increase the conversion rate of the monomer, and therefore, there is a risk that a large amount of monomer must be blended. This could be time consuming and costly.

The dispersibility is also improved by the method described in Patent Document 3. However, RAFT agents are expensive, and RAFT polymerization requires time and effort in production, such as in an oxygen-free atmosphere, which can be laborious and costly.

Therefore, the object of the present invention is to provide a polymer-coated inorganic filler that has excellent dispersibility in a resin or an organic solvent, is inexpensive, has high manufacturing efficiency, and can easily introduce various functional groups, and a cured filler containing the same. The purpose of the Company is to provide synthetic resin compositions, dry films, cured products, and electronic components.

The present inventors, while making intensive studies to achieve the above object, coated inorganic particles with a specific coating polymer, and further introduced various functional groups into the side chains of the coating polymer via urethane bonds. The present inventors have discovered that such inorganic particles are inexpensive, have high production efficiency, and can be easily imparted with various properties and functions, leading to the completion of the present invention.

That is, the present invention
A polymer-coated inorganic filler in which the surface of inorganic particles is coated with a coating polymer,
The coating polymer is a polymer or copolymer obtained by polymerizing a radically polymerizable monomer,
The present invention provides a polymer-coated inorganic filler characterized in that the coating polymer has an organic functional group in a side chain via a urethane bond.

In the polymer-coated inorganic filler of the present invention, the inorganic particles are treated in a treatment solution containing inorganic particles, an organic solvent, a radical polymerizable monomer serving as a raw material for the coating polymer, and a radical polymerization initiator. It is a copolymer that is copolymerized using a radically polymerizable monomer adsorbed on part or all of the surface of the
The polymer-coated inorganic filler may be characterized in that at least one of the radically polymerizable monomers and the soluble organic solvent have the following relationship.
(SP value of radically polymerizable monomer) - (SP value of organic solvent) ≧0.5

The polymer-coated inorganic filler of the present invention may be a polymer-coated inorganic filler characterized in that the radically polymerizable monomer includes a (meth)acrylic monomer containing a hydroxyl group.

Furthermore, the present invention provides a curable resin composition containing the polymer-coated inorganic filler.

Further, the present invention provides a dry film characterized in that the curable resin composition has a resin layer formed by coating and drying the curable resin composition on a base material.

The present invention also provides a cured product, characterized in that the curable resin composition or the resin layer is cured.

The present invention also provides an electronic component comprising the cured product.

According to the present invention, a polymer-coated inorganic filler that is inexpensive, has high manufacturing efficiency, and can easily be provided with various properties and functions, and a curable resin composition, dry film, and cured product containing the same are provided. , polymer coated inorganic filler can provide electronic components.

In addition, when isomers exist in the described compound, all possible isomers can be used in the present invention unless otherwise specified.

In the present invention, the term (meth)acrylate refers to methacrylate, acrylate, or a mixture of methacrylate and acrylate.

Furthermore, in the present invention, inorganic particles mean inorganic particles whose surfaces have not been subjected to any modification treatment such as a coupling agent, unless otherwise specified.

In the present invention, the SP value of the radically polymerizable monomer and organic solvent used can be calculated by the Fedors method.

<<<Polymer coated inorganic filler>>>
In the polymer-coated inorganic filler according to the present invention, the surfaces of inorganic particles are coated with a coating polymer. Here, the expression that the surface of the inorganic particle is "coated" with the coating polymer means that part or all of the surface of the inorganic particle is coated with the coating polymer, and Fourier transform infrared spectroscopy (FT-IR) It is possible to analyze the presence or absence of coating and the amount of coating by thermogravimetric analysis (TG/DTA). From the viewpoint of dispersibility in a resin or an organic solvent, the polymer-coated inorganic particles are preferably coated with a polymer in an amount of 1.5% by mass or more based on the inorganic particles.

The coating polymer according to the present invention is a polymer or copolymer obtained by polymerizing a radically polymerizable monomer.

The coating polymer according to the present invention has an organic functional group in the side chain via a urethane bond.

The coating polymer is treated with the radically polymerizable monomer in a treatment solution containing inorganic particles, an organic solvent, a radically polymerizable monomer that is a raw material for the polymer, and a radical polymerization initiator that polymerizes the radically polymerizable monomer. is adsorbed onto the surface of the inorganic particles and is formed by polymerization on the surfaces of the inorganic particles. Here, a polymer is a product obtained by polymerizing radically polymerizable monomers, and the degree of polymerization as a polymer is determined by the type and amount of each component of the radically polymerizable monomer, organic solvent, radical polymerization initiator, and inorganic particles, and the reaction It can be adjusted by temperature, reaction time, stirring treatment, etc.

Further, the SP value of the radically polymerizable monomer according to the present invention and the SP value of the organic solvent have the following relationship.
(SP value of radically polymerizable monomer) - (SP value of organic solvent) ≧0.5

When such a relationship exists, the compatibility between the radically polymerizable monomer and the organic solvent deteriorates, and as a result, the radically polymerizable monomer is more efficiently adsorbed onto the surface of inorganic particles, which is generally more hydrophilic than the organic solvent. I think it will happen.

Further, the polymer may be a polymer of a single radically polymerizable monomer or a copolymer of multiple types of radically polymerizable monomers. In the case of forming a copolymer, a plurality of radically polymerizable monomers are contained in the solution. The copolymer is not particularly limited, and may be a random copolymer, a block copolymer, a graft copolymer, a block-graft copolymer, or the like.

<Inorganic particles>
The inorganic particles used in the present invention refer to inorganic particles whose surfaces are not modified, but if they have lower hydrophilicity than an organic solvent, it is preferable to perform a hydrophilic treatment.

Generally, inorganic particles whose surfaces are not modified are not particularly limited as long as their surfaces have sufficiently high polarity and are more hydrophilic than the organic solvent used in combination. Examples of such inorganic particles include silica, crystalline silica, Neuburg silica, aluminum oxide, aluminum hydroxide, boron nitride, aluminum nitride, glass powder, talc, clay, magnesium carbonate, calcium carbonate, natural mica, synthetic Using inorganic particles such as mica, barium sulfate, barium titanate, iron oxide, non-fibrous glass, hydrotalcite, mineral wool, aluminum silicate, calcium silicate, calcium zirconate, zinc oxide, solder particles, silver powder, copper powder, etc. be able to. Among these, in electronic materials such as solder resists and sealants, it is preferable to use silica, which has excellent thermal dimensional stability and dielectric properties, and aluminum oxide, boron nitride, and the like, which have excellent thermal conductivity. Further, as the silica and aluminum oxide, from the viewpoint of improving the filling properties into the composition, spherical silica, calcium zirconate, and spherical aluminum oxide are more preferable.

The average particle size of the inorganic particles is not particularly limited, but can be, for example, 10 nm to 20,000 nm, preferably 20 nm to 10,000 nm, more preferably 50 nm to 5,000 nm. The average particle diameter of the inorganic particles can be the value of D50 measured by laser diffraction method. An example of a measuring device using a laser diffraction method is Microtrac MT3300EXII manufactured by Microtrac Bell.

<Coating polymer>
The coating polymer according to the present invention is a polymer or copolymer obtained by polymerizing a radically polymerizable monomer.

The coating polymer according to the present invention has an organic functional group in the side chain via a urethane bond.

As a method for obtaining a coating polymer which is a polymer or copolymer having an organic functional group via a urethane bond in the side chain of the coating polymer according to the present invention, after polymerizing a radically polymerizable monomer containing a hydroxyl group, Examples include a method of reacting with a compound having an isocyanate group to obtain a coated polymer having an organic functional group via a urethane bond.

<<<Method for producing polymer-coated inorganic filler>>>
The method for producing the polymer-coated inorganic filler of the present invention will be described in detail below.
＜＜Raw materials＞＞
<Organic solvent>
The organic solvent used in the present invention is not particularly limited as long as it satisfies the numerical relationship of the SP value of the present invention. Organic solvents usually exhibit hydrophobicity and have an SP value in the range of 7.0 to 12.0. For example, those with an SP value of 7.2 to 10.0 are preferable, and those with an SP value of 7.0 to 12.0 are preferable. Those with an SP value of 5 to 9.5 are more preferred, and those with an SP value of 8.0 to 9.2 are even more preferred.

Specifically, as organic solvents, toluene (SP value 9.14), methyl ethyl ketone (SP value 9.9), PMA (SP value 9.25), ethyl acetate (SP value 9.1), carbitol acetate ( Examples include SP value 9.98), cyclohexanone (SP value 8.56), acetone (SP value 10.0), and 1-propanol (SP value 11.84). These can be used alone or in combination. Among these, toluene and ethyl acetate are preferred because they do not interfere with the radical polymerization reaction.

Further, the SP value when a plurality of organic solvents are mixed and used can be calculated according to the following formula. The following formula is a calculation formula when two organic solvents are mixed.
δsm=Xs1×δs1+(1-Xs1)×δs2
In the formula, δsm means the SP value of the mixed solvent, δs1 means the SP value of organic solvent 1, δs2 means the SP value of organic solvent 2, and Xs1 means the molar fraction of organic solvent 1.

The amount of the organic solvent blended in the treatment solution is preferably 100 parts by mass to 500 parts by mass, when the blended amount of the inorganic particles is 100 parts by mass. When the amount of the organic solvent is within this range, the organic solvent in which the radically polymerizable monomer is dissolved will spread over the surface of the inorganic particles, allowing efficient coating.

<Radical polymerizable monomer>
The radically polymerizable monomer used in the present invention is a monomer having a radically polymerizable reactive group, and is not particularly limited as long as it satisfies the numerical relationship of the SP value in the present invention. By satisfying this numerical relationship of SP values, the radically polymerizable monomer becomes more hydrophilic than the organic solvent that is blended with it, and its compatibility becomes lower, allowing it to be efficiently adsorbed onto the hydrophilic inorganic particles. . As such radically polymerizable monomers, for example, those having an SP value of 9.0 to 15.0 can be used, and those having an SP value of 9.5 to 13.5 are preferable.

Here, the radically polymerizable reactive group is not particularly limited and may include, for example, a vinyl group, an allyl group, an alkenyl group, an alkylene group, etc., and the radically polymerizable monomer has at least one type of such polymerizable reactive group. It is fine as long as it includes.

Moreover, this radically polymerizable monomer has a hydroxyl group in its structure. Therefore, hydroxyl groups exist on the surface of inorganic particles coated with a polymer or copolymer obtained by polymerizing a radically polymerizable monomer, and they can be easily modified by reacting with a compound having an isocyanate group. , various functional groups can be introduced, and it becomes possible to easily impart various properties and functions depending on the use of the polymer-coated inorganic filler.

As such radically polymerizable monomers (SP value), (meth)acrylic monomers containing hydroxyl groups are preferable, such as acrylic acid, 2-hydroxyethyl acrylate (SP value 12.45), and 4-hydroxybutyl acrylate (SP value). value 11.64), 2-hydroxypropyl acrylate (SP value 11.83), 2-hydroxyethyl methacrylate (SP value 10.80), 4-hydroxybutyl methacrylate (SP value 10.59), 2-hydroxypropyl methacrylate (SP value 10.80). These can be used alone or in combination. In addition, when a plurality of polymers are used in combination, the polymer that coats the inorganic particles becomes a copolymer.

Further, a radically polymerizable monomer containing a cyclic ether group such as an epoxy group, a glycidyl group, an oxirane group, or an oxetane group can be used in combination with a radically polymerizable monomer having a hydroxyl group in its structure. When such a radically polymerizable monomer is used, a cyclic ether group will be present in the polymer that coats the inorganic particles. Therefore, the resulting polymer-coated inorganic filler can react with a resin containing active hydrogen such as a hydroxyl group that reacts with a cyclic ether group. Therefore, it becomes possible to impart various properties and functions to the cured product.

Such radically polymerizable monomers (SP value) include acrylic acid, 2-hydroxyethyl acrylate (SP value 12.45), 4-hydroxybutyl acrylate (SP value 11.64), and 2-hydroxypropyl acrylate (SP value). value 11.83), tetrahydrofurfuryl acrylate (SP value 9.99), 4-hydroxybutyl acrylate glycidyl ether (SP value 9.99), 2-hydroxyethyl methacrylate (SP value 10.80), 4-hydroxybutyl Examples include methacrylate (SP value 10.59), 2-hydroxypropyl methacrylate (SP value 10.80), and glycidyl methacrylate (SP value 10.21). These can be used alone or in combination. In addition, when a plurality of polymers are used in combination, the polymer that coats the inorganic particles becomes a copolymer.

Note that when a plurality of monomers are used as a mixture, it is sufficient that at least one type of radically polymerizable monomer satisfying the following formula is included. If one or more radically polymerizable monomers that satisfy the following formula are contained, the radically polymerizable monomer that satisfies the following formula will be preferentially adsorbed to the surface of the inorganic particle even if other monomers do not satisfy the following formula. Then, a polymer is formed starting from the adsorbed monomer and can coat the inorganic particles.
(SP value of radically polymerizable monomer) - (SP value of organic solvent) ≧0.5

The amount of the radically polymerizable monomer in the treatment solution is 0.5 parts by mass to 15 parts by mass, preferably 1 part to 10 parts by mass, when the amount of inorganic particles is 100 parts by mass. More preferably 1.5 parts by mass to 7.5 parts by mass. When the amount of the monomer is within this range, the surfaces of the inorganic particles can be coated.

<Radical polymerization initiator>
The radical polymerization initiator used in the present invention is not particularly limited as long as it does not impede the effects of the present invention, and a photo radical polymerization initiator, a thermal radical polymerization initiator, etc. can be used. The radical polymerization initiator generates active species (also referred to as free radicals) by heat or ultraviolet rays, causes the radically polymerizable monomer to undergo a polymerization reaction, and can easily form a polymer. Radical polymerization initiators can be used alone or in combination of two or more.

Thermal radical polymerization initiators are not particularly limited, but include, for example, azo polymerization initiators (for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2 , 2'-azobis(2-methylpropionate) dimethyl, 4,4'-azobis-4-cyanovalerianic acid, azobisisovaleronitrile, 2,2'-azobis(2-amidinopropane) dihydrochloride, 2, 2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis(2-methylpropionamidine) disulfate, 2,2'-azobis(N , N'-dimethyleneisobutyramidine) dihydrochloride, etc.); peroxide polymerization initiators (for example, dibenzoyl peroxide, t-butyl permaleate, lauroyl peroxide, etc.); redox polymerization initiators, etc. .

Examples of the photoradical polymerization initiator include, but are not particularly limited to, benzoin ether photopolymerization initiators, acetophenone photopolymerization initiators, α-ketol photopolymerization initiators, aromatic sulfonyl chloride photopolymerization initiators, and photopolymerization initiators. Active oxime photoinitiator, benzoin photoinitiator, benzyl photoinitiator, benzophenone photoinitiator, ketal photoinitiator, thioxanthone photoinitiator, acylphosphine oxide photoinitiator Initiators and the like can be mentioned.

Specifically, benzoin ether photopolymerization initiators include, for example, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and 2,2-dimethoxy-1,2-diphenylethane. Examples include 1-one [trade name: Omnirad 651, manufactured by IGM Resins], anisoin, and the like. Examples of the acetophenone photopolymerization initiator include 1-hydroxycyclohexylphenylketone [trade name: Omnirad 184, manufactured by IGM Resins], 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 1-[4-( 2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one [trade name: Omnirad2959, manufactured by IGM Resins], 2-hydroxy-2-methyl-1-phenyl-propane- Examples include 1-one [trade name: Omnirad 1173, manufactured by IGM Resins], methoxyacetophenone, and the like. Examples of the α-ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1-[4-(2-hydroxyethyl)-phenyl]-2-hydroxy-2-methylpropane-1- Ong et al. Examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalenesulfonyl chloride. Examples of the photoactive oxime photopolymerization initiator include 1-phenyl-1,2-propanedione-2-(O-ethoxycarbonyl)-oxime.

Furthermore, the benzoin-based photopolymerization initiator includes, for example, benzoin. Benzyl photoinitiators include, for example, benzyl. Examples of the benzophenone photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α-hydroxycyclohexylphenyl ketone. Ketal-based photopolymerization initiators include, for example, benzyl dimethyl ketal. Examples of thioxanthone-based photopolymerization initiators include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone, These include 2,4-diisopropylthioxanthone, dodecylthioxanthone, and the like.

Examples of acylphosphine-based photopolymerization initiators include bis(2,6-dimethoxybenzoyl)phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)(2,4,4-trimethylpentyl)phosphine oxide, bis( 2,6-dimethoxybenzoyl)-n-butylphosphine oxide, bis(2,6-dimethoxybenzoyl)-(2-methylpropan-1-yl)phosphine oxide, bis(2,6-dimethoxybenzoyl)-(1- Methylpropan-1-yl)phosphine oxide, bis(2,6-dimethoxybenzoyl)-t-butylphosphine oxide, bis(2,6-dimethoxybenzoyl)cyclohexylphosphine oxide, bis(2,6-dimethoxybenzoyl)octylphosphine oxide, bis(2-methoxybenzoyl)(2-methylpropan-1-yl)phosphine oxide, bis(2-methoxybenzoyl)(1-methylpropan-1-yl)phosphine oxide, bis(2,6-diethoxy) benzoyl)(2-methylpropan-1-yl)phosphine oxide, bis(2,6-diethoxybenzoyl)(1-methylpropan-1-yl)phosphine oxide, bis(2,6-dibutoxybenzoyl)(2 -methylpropan-1-yl)phosphine oxide, bis(2,4-dimethoxybenzoyl)(2-methylpropan-1-yl)phosphine oxide, bis(2,4,6-trimethylbenzoyl)(2,4-dimethoxybenzoyl)(2-methylpropan-1-yl)phosphine oxide, pentoxyphenyl)phosphine oxide, bis(2,6-dimethoxybenzoyl)benzylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2-phenylpropylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2-phenyl Ethylphosphine oxide, bis(2,6-dimethoxybenzoyl)benzylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2-phenylpropylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2-phenylethylphosphine oxide , 2,6-dimethoxybenzoylbenzylbutylphosphine oxide, 2,6-dimethoxybenzoylbenzyloctylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,5-diisopropylphenylphosphine oxide, bis(2,4, 6-trimethylbenzoyl)-2-methylphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-4-methylphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,5-diethylphenyl Phosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,3,5,6-tetramethylphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,4-di-n-butoxy Phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis(2,4,6-trimethylbenzoyl)isobutylphosphine oxide, 2,6-dimethythoxybenzoyl-2,4,6-trimethylbenzoyl-n-butylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,4,6-trimethylbenzoyl) )-2,4-dibutoxyphenylphosphine oxide, 1,10-bis[bis(2,4,6-trimethylbenzoyl)phosphine oxide]decane, tri(2-methylbenzoyl)phosphine oxide, and the like.

The amount of the radical polymerization initiator in the treatment solution is preferably 0.1 parts by weight to 6 parts by weight, when the amount of the radically polymerizable monomer is 100 parts by weight. When the amount of the polymerization initiator is within this range, the inhibitory effect of the photopolymerization initiator on absorbing ultraviolet rays is suppressed, and by obtaining a sufficient molecular length of the polymer, the polymer is peeled off from the surface of the inorganic particles. The surface of the inorganic particles can be coated efficiently.

<Isocyanate compound>
The isocyanate compound used in the present invention reacts with the hydroxyl groups present on the surface of the inorganic particles coated with the polymer or copolymer obtained by polymerizing the radically polymerizable monomer. The isocyanate compound is not particularly limited as long as it does not impede the effects of the present invention, and any compound having an isocyanate group at the terminal of an organic compound may be used. Furthermore, if it contains a reactive functional group (organic functional group) at another end, the polymer-coated inorganic filler can be easily further modified using these functional groups. There is no particular problem with such organic functional groups as long as they have reactivity, but examples include vinyl groups, allyl groups, (meth)acrylic groups, isocyanate groups, epoxy groups, glycidyl groups, oxirane groups, oxetane groups, etc. can be mentioned. When an isocyanate compound containing a cyclic ether group such as an epoxy group, a glycidyl group, an oxirane group, or an oxetane group is used, the cyclic ether group will be present in the polymer coating the inorganic particles. Therefore, the obtained polymer-coated inorganic filler can be easily modified with a monomer containing active hydrogen such as a hydroxyl group or an amino group that reacts with a cyclic ether group. Therefore, it is possible to easily impart various properties and functions depending on the use of the polymer-coated inorganic filler.

Examples of the isocyanate compound include benzyl isocyanate, cyclohexyl isocyanate, butyl isocyanate, 2-phenylethyl isocyanate, 2-isocyanatoethyl (meth)acrylate, 2-isocyanatopropyl (meth)acrylate, and 3-isocyanatopropyl (meth)acrylate. Acrylate, 2-isocyanato-1-methylethyl (meth)acrylate, 2-isocyanato-1,1-dimethylethyl (meth)acrylate, 4-isocyanatocyclohexyl (meth)acrylate, methacryloyl isocyanate, 3-isocyanatopropyltrimethoxy Examples include silane.

The blending amount of the isocyanate compound is determined by the ratio of the isocyanate group equivalent contained in the isocyanate compound to the hydroxyl group equivalent of a polymer or copolymer obtained by polymerizing or copolymerizing a radically polymerizable monomer containing a hydroxyl group (the above hydroxyl group equivalent/isocyanate group equivalent). The equivalent weight is not particularly limited, but can be, for example, 0.1 to 10, preferably 0.5 to 2, and more preferably 0.7 to 1.4.

Further, a catalyst can be used when reacting the isocyanate compound with the hydroxyl groups present on the surface of the inorganic particles coated with the polymer or copolymer obtained by polymerizing the radically polymerizable monomer. Specific examples include strong bases such as triethylamine, diazabicycloundecene and 1,4-diazabicyclo[2.2.2]octane, and tin catalysts such as dibutyltin dilaurate.

<<Preferred example of method for producing polymer-coated inorganic filler>>
A preferred example of the method for producing a polymer-coated inorganic filler of the present invention is that inorganic particles are contained in a treatment solution containing an organic solvent, a radically polymerizable monomer that is a raw material for the coating polymer, and a radical polymerization initiator that polymerizes the monomer. One feature is that it includes a step of adsorbing the radically polymerizable monomer onto the surface of the inorganic particles by immersing the inorganic particles and preferably stirring.

Particularly, in this step, the greatest feature is that at least one of the radically polymerizable monomers and the organic solvent have the following relationship in terms of SP value.
(SP value of radically polymerizable monomer) - (SP value of organic solvent) ≧0.5
When such a relationship exists, the compatibility between the radically polymerizable monomer and the organic solvent deteriorates, and as a result, the radically polymerizable monomer is more efficiently adsorbed onto the surface of inorganic particles, which is generally more hydrophilic than the organic solvent. I think it will happen.

Here, in the present invention, the stirring method (including conditions) is not particularly limited, and any known method can be used. In particular, adjusting the stirring temperature (temperature of the treatment solution) is effective in efficiently carrying out the polymerization reaction in that it is possible to adjust the adsorption efficiency of the radically polymerizable monomer onto the surface of the inorganic particles.

In the present invention, the above numerical relationship of the SP value is based on the affinity (wettability) between the organic solvent and the radically polymerizable monomer in the treatment solution for coating the surface of the inorganic particle with an organic polymer by polymerizing the radically polymerizable monomer. A small difference in SP value between the components indicates a high affinity between the components. Furthermore, since the SP value of water is larger than that of organic solvents and radically polymerizable monomers (SP value of water: 23.4), a high SP value also indicates high hydrophilicity.

Therefore, in the treatment solution of the present invention, in order to efficiently adsorb the radically polymerizable monomer on the surface of the inorganic particles, the radically polymerizable monomer is It is important to improve the affinity between the radical polymerizable monomer and the inorganic particles, and in terms of the SP value, the SP value of the radical polymerizable monomer is large and the SP value of the radical polymerizable monomer is large, and the SP value of the radical polymerizable monomer is large, and It is necessary that the difference in values be 0.5 or more.

According to this numerical relationship of SP values, in a treatment solution containing a mixture of a radically polymerizable monomer, a radical polymerization initiator, an organic solvent, and inorganic particles to coat the surface of the inorganic particles, a radically polymerizable monomer is coated on the surface of the inorganic particles. Monomers are efficiently adsorbed, and problems such as separation of radically polymerizable monomers and organic solvents and aggregation of inorganic particles do not occur. Furthermore, as will be described later, when a radically polymerizable monomer is polymerized using a radical polymerization initiator mixed in the above treatment solution, the radically polymerizable monomer adsorbed on the surface of the inorganic particles is preferentially polymerized. It is presumed that a film made of a good organic polymer can be efficiently formed on the surface.

Further, the method for producing a polymer-coated inorganic filler of the present invention includes a step of polymerizing the radically polymerizable monomer adsorbed to the inorganic particles in the above step to a radical polymerization initiator, preferably by applying heat or ultraviolet rays. One feature is that it includes. Thereby, the polymer-coated inorganic filler of the present invention can be obtained by forming an organic polymer film on the surface of the inorganic particles, and further mixing and reacting with a compound having an isocyanate group.

The polymer-coated inorganic filler thus obtained may be taken out of the treatment solution and used in a dried state, or it may be used in a state where it is dispersed in the treatment solution. When used in a dry state, the polymer-coated inorganic filler is separated by filtration or the like using a known method. After separation, the polymer-coated inorganic filler can be washed with an organic solvent or the like to remove unreacted monomers and polymers that are not bonded to the surfaces of the inorganic particles, and then dried by heating to a predetermined temperature. The drying method can be performed using a known method such as a drying oven.

As described above, the polymer-coated inorganic filler of the present invention can be produced by an inexpensive radical polymerization reaction and an addition reaction between a hydroxyl group and an isocyanate, and has high production efficiency.

<<<Curable resin composition>>>
The polymer-coated inorganic filler of the present invention can be included in a curable resin composition containing a curable resin, a curing agent, a curing catalyst, and the like. The polymer-coated inorganic filler of the present invention exhibits excellent dispersibility in a curable resin composition. In addition, depending on the use of the curable resin composition and its cured product, various functional groups can be included in the radically polymerizable monomers and isocyanate compounds to be blended, so that the curable resin composition and its cured product can be easily prepared. In addition, it is possible to have various properties and functions such as excellent adhesiveness, chemical resistance and heat resistance, low thermal expansion, high elongation at break (high toughness), low curing shrinkage, and low dielectric loss tangent.

The method for producing the curable resin composition of the present invention is not particularly limited, and known methods can be used. For example, the curable resin composition of the present invention can be obtained by blending the polymer-coated inorganic filler of the present invention with a curable resin, a curing agent, a curing catalyst, etc., and stirring the mixture with a homogenizer or the like.

<<<Dry film>>>
The dry film according to the present invention is a resin layer obtained by applying or impregnating the above-mentioned curable composition onto a base material and drying the same.

Here, examples of the base material include metal foil such as copper foil, films such as polyimide film, polyester film, and polyethylene naphthalate (PEN) film, glass cloth, and fibers such as aramid fiber.

The dry film can be obtained, for example, by applying a curable composition onto a polyethylene terephthalate film, drying it, and laminating a polypropylene film as necessary.

<<<Cured product>>>
The cured product is obtained by curing the above-mentioned curable composition (including the resin layer included in the dry film).

The method for obtaining a cured product from a curable composition is not particularly limited, and can be changed as appropriate depending on the composition of the curable composition. As an example, after carrying out the step of coating the curable composition on the substrate as described above (e.g., coating with an applicator, etc.), a drying step of drying the curable composition is carried out as necessary. Then, a thermosetting step may be performed in which the curable resin and the curing agent are thermally crosslinked by heating (for example, heating using an inert gas oven, hot plate, vacuum oven, vacuum press machine, etc.). Note that the conditions for implementing each step (for example, coating thickness, drying temperature and time, heating temperature and time, etc.) may be changed as appropriate depending on the composition, use, etc. of the curable composition.

<<<Electronic parts>>>
Such cured products have excellent adhesion, chemical resistance, heat resistance, low thermal expansion, high elongation at break (high toughness), low curing shrinkage, and low dielectric loss tangent, so they are used for electronic parts, etc. Available for use. In particular, it is used in printed wiring boards as an interlayer insulating film or a solder resist dry film.

<<<Applications of polymer-coated inorganic fillers>>>
The polymer-coated inorganic filler of the present invention can be used as a filler to be filled into a resin. In particular, by filling resin layers made of curable resin compositions such as encapsulants used in wiring boards and electronic components, and curable resin compositions constituting dry films, these curable resin compositions and dry The thermal dimensional stability and dielectric properties of a cured product obtained by curing the resin layer of the film can be improved.

(Example 1)
・Raw material inorganic particles 1: Silica particles, average particle size 500 μm (SQ-C6 manufactured by Admatex Co., Ltd.), 15 g
Organic solvent: Toluene (manufactured by Fuji Film Wako Pure Chemical Industries, SP value 9.14), 36 g
Radically polymerizable monomer 1:2-hydroxyethyl acrylate containing hydroxyl group, SP value 12.45, 0.3g
Radical polymerization initiator: Azo polymerization initiator (Fuji Film Wako Pure Chemical Industries, Ltd. V65), 54 mg
Isocyanate compound: benzyl isocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.), 3.9 g
・Manufacturing method The above raw materials toluene, 2-hydroxyethyl acrylate, and azo polymerization initiator are weighed into a container and stirred to prepare a treatment solution, and then the separately weighed raw materials silica particles are immersed in the treatment solution. The reaction was carried out at 60° C. for 20 hours under a nitrogen atmosphere. Next, the above-mentioned raw material ibenzyl isocyanate, which had been weighed separately, was added, and the mixture was reacted at 65° C. for 7 hours with stirring. Thereafter, the reactants were removed by filtration and washed with propylene glycol monomethyl ether acetate (manufactured by Sankyo Chemical Co., Ltd.) to completely remove remaining monomers, isocyanate compounds, and polymers that did not cover the inorganic particle surfaces. , in a drying oven at 80° C. for 5 hours to obtain the polymer-coated inorganic filler of Example 1. Furthermore, by FT-IR measurement of the polymer-coated inorganic filler, a peak derived from carbonyl group and a peak derived from urethane bond were confirmed, and it was confirmed that the inorganic particles were coated with 2-hydroxyethyl polymer and further reacted with benzyl isocyanate. I confirmed that there is.

( Examples 2-4, Reference Examples 5-6 )
Polymer-coated inorganic fillers of Examples 2 to 4 and Reference Examples 5 to 6 were obtained in the same manner as in Example 1, except that the isocyanate compound of Example 1 was changed to the isocyanate compound listed in Table 1.

( Examples 7-10, Reference Examples 11-12 )
Example 7 was carried out in the same manner as in Example 1, except that the hydroxyl group-containing radically polymerizable monomer and isocyanate compound of Example 1 were changed to the hydroxyl group-containing radically polymerizable monomer and isocyanate compound listed in Tables 1 and 2. Polymer-coated inorganic fillers of ~10 and Reference Examples 11-12 were obtained.

( Examples 13-16, Reference Examples 17-18 )
The polymer-coated inorganic fillers of Examples 13 to 16 and Reference Examples 17 to 18 were produced in the same manner as in Example 1, except that the inorganic particles and isocyanate compounds of Example 1 were changed to the inorganic particles and isocyanate compounds listed in Table 2. I got it.

(Comparative Examples 1 to 3)
In Comparative Examples 1 to 3, polymer-coated inorganic fillers of Comparative Examples 1 to 3 were obtained in the same manner as in Examples 1, 7, and 13 except that the formulations shown in Table 2 were not added and no isocyanate compound was added.

(Dispersibility evaluation)
The evaluation criteria were as follows. 1 mg of surface-coated particles was weighed into a 5 mL vial, and 5 mL of the solvent listed in Table 1 was added. After performing ultrasonic treatment for 30 minutes, it was left to stand and the dispersion stability was evaluated. The evaluation criteria were as follows.
○: Good dispersibility, no precipitation observed after standing for 1 hour.
△: Precipitation occurred 30 minutes after standing.
×: Precipitation occurred within 10 minutes after standing.
The results are shown in Table 1.

・Inorganic particles SiO ₂ : Admatex SQ-C6
CaZrO ₃ : CZ-03 manufactured by Sakai Chemical Industry Co., Ltd.
・Organic solvent Toluene: Manufactured by Fuji Film Wako Pure Chemical Industries, Ltd. ・Radical polymerizable monomer having a hydroxyl group 2-hydroxyethyl acrylate: Manufactured by Tokyo Kasei Kogyo Co., Ltd. 4-Hydroxybutyl acrylate: Manufactured by Tokyo Kasei Kogyo Co., Ltd. Polymerization initiator V-65 : Fujifilm Wako Pure Chemical Industries, Ltd. 2,2'-azobis2,4-dimethylvaleronitrile isocyanate compound Benzyl isocyanate: Tokyo Chemical Industry Co., Ltd. 2-phenylethyl isocyanate: Tokyo Chemical Industry Co., Ltd. cyclohexyl isocyanate: Tokyo Chemical Industry Co., Ltd. Butyl isocyanate: manufactured by Tokyo Chemical Industry Co., Ltd. 2-isocyanatoethyl acrylate: manufactured by Tokyo Chemical Industry Co., Ltd. 2-isocyanatoethyl methacrylate: manufactured by Tokyo Chemical Industry Co., Ltd. Dispersibility test CA: Carbitol acetate, manufactured by Tokyo Chemical Industry Co., Ltd. PMA : Propylene glycol monomethyl ether acetate, manufactured by Tokyo Kasei Kogyo Co., Ltd. Acetone: Manufactured by Tokyo Kasei Kogyo Co., Ltd.

(Evaluation of cured product)
<Preparation of curable resin composition>
- Raw material filler 1: Polymer-coated inorganic filler of Example 1 Filler 2: Polymer-coated inorganic filler of Example 2 Filler 3: Polymer-coated inorganic filler of Example 3 Filler 4: Polymer-coated inorganic filler of Example 4 Filler 5: Implementation Polymer coated inorganic filler of Example 7 Filler 6: Polymer coated inorganic filler of Example 8 Filler 7: Polymer coated inorganic filler of Example 9 Filler 8: Polymer coated inorganic filler of Example 10 Filler 9: Polymer coated inorganic of Example 13 Filler Filler 10: Polymer-coated inorganic filler of Example 16 Filler 11: Polymer-coated inorganic filler of Comparative Example 1 Filler 12: Polymer-coated inorganic filler of Comparative Example 2 Filler 13: Polymer-coated inorganic filler of Comparative Example 3 Epoxy resin: JER828 ( Bisphenol A type epoxy, epoxy equivalent: 190) Mitsubishi Chemical Curing agent: KAYAHARD AA Nippon Kayaku Co., Ltd. Curing catalyst 1: 2E4MZ (2-ethyl-4-methylimidazole) Shikoku Kasei Kogyo Co., Ltd. Preparation solvent: cyclohexanone

・Preparation method of curable resin composition The curable resin compositions of Examples A to N and Comparative Examples A to F were prepared by mixing and stirring each component according to the descriptions in Tables 3 and 4 below. Each curable resin composition was prepared by kneading using this roll mill. The numerical values in Tables 3 and 4 indicate parts by mass.

<Thermal expansion coefficient>
The compositions of each example and comparative example were applied to a copper foil with a thickness of 18 μm using an applicator so that the film thickness after curing was 55 μm, and dried at 80 ° C. for 20 minutes in a hot air circulation drying oven. After that, it was cured by heating at 180° C. for 30 minutes in a hot air circulation type drying oven, and was peeled off from the copper foil to obtain a film sample consisting of a cured product of each composition. The obtained film sample was cut into a size of 3 mm width x 30 mm length, and was used as a test piece for measuring the coefficient of thermal expansion.

This test piece was heated at 5°C/min from 20 to 250°C in a nitrogen atmosphere using TMA (Thermomechanical Analysis) Q400 manufactured by TA Instruments in tensile mode with a chuck distance of 16 mm and a load of 30 mN. The temperature was then lowered from 250 to 20°C at a rate of 5°C/min, and the coefficient of thermal expansion (ppm/K) was measured. The results are shown in Tables 3 and 4.

<Tensile elongation at break and stress at break>
For the compositions of Examples A to N and Comparative Examples A to F, film samples made of cured products of each composition prepared in the thermal expansion coefficient evaluation were cut into 5 mm x 10 cm and tested for tensile elongation at break and strength measurement. A piece was made. Regarding this test piece, the tensile stress at break [MPa] and tensile elongation at break (maximum strain) [%] were measured at a tensile rate of 10 mm/min using a small tabletop testing machine EZ-SX manufactured by Shimadzu Corporation. The results are shown in Tables 3 and 4 below.

(Evaluation results)
It can be seen from the evaluation results that the polymer-coated inorganic filler of the present invention can be manufactured at low cost and by a method with high production efficiency, and has excellent dispersibility in organic solvents.

Claims (7)

A polymer-coated inorganic filler in which the surface of inorganic particles whose surface is not modified is coated with a coating polymer,
The coating polymer is a polymer or copolymer obtained by polymerizing a radically polymerizable monomer,
The coating polymer has an organic functional group in a side chain via a urethane bond,
A polymer-coated inorganic filler, wherein the organic functional group is at least one selected from a benzyl group, a cyclohexyl group, a butyl group, and a 2- phenylethyl group. The coating polymer is a polymer or copolymer that is polymerized in a treatment solution containing the inorganic particles, an organic solvent, a radically polymerizable monomer serving as a raw material for the coating polymer, and a radical polymerization initiator. ,
The polymer-coated inorganic filler according to claim 1, wherein at least one kind of the radically polymerizable monomer and the organic solvent have the following relationship.
(SP value of radically polymerizable monomer) - (SP value of organic solvent) ≧0.5 The polymer-coated inorganic filler according to claim 1 or 2, wherein the radically polymerizable monomer includes a (meth)acrylic monomer containing a hydroxyl group. A curable resin composition comprising the polymer-coated inorganic filler according to any one of claims 1 to 3. A dry film comprising a resin layer formed by applying and drying the curable resin composition according to claim 4 on a base material. A cured product obtained by curing the curable resin composition according to claim 4 or the resin layer according to claim 5 . An electronic component comprising the cured product according to claim 6.