JP7473144B2 - Curable resin composition for electronic materials - Google Patents

Description

The present invention relates to a curable resin composition for electronic materials.

In order to prevent the spread of fire in the event of a fire, flame retardancy has been promoted in automobile parts, home appliances, electronic materials, sporting goods, building materials, and other materials.

In recent years, there has been remarkable progress in the field of electronics, particularly in the miniaturization, weight reduction, and high density of electronic devices. This has resulted in an increasing demand for electronic materials, including printed wiring boards and light-emitting diodes (LEDs), to be thinner, multi-layered, and more precise. There is also a demand for such electronic materials to be flame-retardant.

Patent Document 1 discloses a flame-retardant resin composition containing (A) a polymeric compound, (B) ammonium polyphosphate, (C) aluminum hydroxide and/or magnesium hydroxide, (D) a polyhydric alcohol, (E) a compound having a melamine skeleton, and (F) hollow ceramic beads and/or expanded graphite.

JP 2021-14513 A

However, the flame-retardant resin composition of Patent Document 1 has a problem in that it has a high viscosity, making it difficult to apply to electronic materials.

The present invention provides a curable resin composition for electronic materials that has excellent coatability, can be easily applied to electronic materials, and can impart flame retardancy to or improve the flame retardancy of electronic materials.

The curable resin composition for electronic materials of the present invention is characterized by containing a curable resin, feldspars, and a phosphorus-based compound.

[Hardening resin]
The curable resin may be a one-component curable resin or a two-component curable resin. The one-component curable resin includes a polymer that is cured by introducing a crosslinking structure by moisture, light irradiation, or heat. The two-component curable resin includes a polymer that is cured by mixing a base agent and a curing agent and introducing a crosslinking structure.

[One-component curable resin]
Examples of the one-component curable resin include a polymer having a hydrolyzable silyl group, a hydrolysis-crosslinkable silicone-based polymer, a polymer having a hydrolyzable isocyanate group, and a photocrosslinkable polymer, and it is preferable that the one-component curable resin contains a polymer having a hydrolyzable silyl group.

In the presence of water, the hydrolyzable groups of the hydrolyzable silyl groups in the polymers are hydrolyzed to generate silanol groups (≡SiOH). The silanol groups then undergo dehydration condensation to form a crosslinked structure. In the presence of water, the hydrolyzable isocyanate groups in the hydrolyzable silicone polymers and polymers having hydrolyzable isocyanate groups generate urea bonds (-NHCONH-) while generating carbon dioxide, forming a crosslinked structure.

A hydrolyzable silyl group is a group in which 1 to 3 hydrolyzable groups are bonded to a silicon atom. The hydrolyzable groups of the hydrolyzable silyl group are not particularly limited, and examples thereof include a hydrogen atom, a halogen atom, an alkoxy group, an acyloxy group, a ketoximate group, an amino group, an amide group, an acid amide group, an aminooxy group, a mercapto group, an alkenyloxy group, and an oxime group.

Among these, alkoxysilyl groups are preferred as hydrolyzable silyl groups because the hydrolysis reaction is mild. Examples of alkoxysilyl groups include trialkoxysilyl groups such as trimethoxysilyl, triethoxysilyl, triisopropoxysilyl, and triphenoxysilyl groups; dialkoxysilyl groups such as propyldimethoxysilyl, methyldimethoxysilyl, and methyldiethoxysilyl groups; and monoalkoxysilyl groups such as dimethylmethoxysilyl and dimethylethoxysilyl groups.

A hydrolyzable isocyanate group is an isocyanate group that can form a urea bond (-NHCONH-) by hydrolysis.

[Polymer having hydrolyzable silyl group]
The polymer having a hydrolyzable silyl group is not particularly limited, and examples thereof include polyalkylene oxide having a hydrolyzable silyl group, acrylic polymer having a hydrolyzable silyl group, urethane polymer having a hydrolyzable silyl group, polyolefin polymer having a hydrolyzable silyl group, etc. The polymer having a hydrolyzable silyl group preferably contains a polyalkylene oxide having a hydrolyzable silyl group. The polymer having a hydrolyzable silyl group may be used alone or in combination of two or more kinds.

The content of the polymer having a hydrolyzable silyl group in the curable resin is preferably 50% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, more preferably 80% by mass or more, more preferably 90% by mass or more, and more preferably 100% by mass.

[Polyalkylene oxide having hydrolyzable silyl group]
In the polyalkylene oxide having a hydrolyzable silyl group, the hydrolyzable silyl group is preferably an alkoxysilyl group, more preferably a dialkoxysilyl group, more preferably a dimethoxysilyl group, and more preferably a propyldimethoxysilyl group.

The polyalkylene oxide having a hydrolyzable silyl group preferably has an average of 1 to 4 hydrolyzable silyl groups per molecule. When the number of hydrolyzable silyl groups in the polyalkylene oxide having a hydrolyzable silyl group is within the above range, the flame retardancy of the cured product of the curable resin composition for electronic materials is improved. The polyalkylene oxide having a hydrolyzable silyl group preferably has a hydrolyzable silyl group at at least one of the two ends of its main chain.

The average number of hydrolyzable silyl groups per molecule in a polyalkylene oxide having hydrolyzable silyl groups can be calculated based on the concentration of hydrolyzable silyl groups in the polyalkylene oxide determined by ^1H -NMR and the number average molecular weight of the polyalkylene oxide determined by GPC.

Preferred examples of the polyalkylene oxide constituting the polyalkylene oxide having a hydrolyzable silyl group include polymers whose main chain contains a repeating unit represented by the general formula: -(R-O) _m- (wherein R represents an alkylene group having 1 to 14 carbon atoms, and m is the number of repeating units and is a positive integer). The main chain skeleton of the polyalkylene oxide may be composed of only one type of repeating unit, or may be composed of two or more types of repeating units.

In the present invention, an alkylene group is a divalent atomic group resulting from the removal of two hydrogen atoms bonded to two different carbon atoms in an aliphatic saturated hydrocarbon, and includes both linear and branched atomic groups.

Examples of the alkylene group include an ethylene group, a propylene group [--CH(CH ₃ )--CH ₂ --], a trimethylene group [--CH ₂ --CH ₂ --CH ₂ --], a butylene group, an amylene group [--(CH ₂ ) ₅ --], and a hexylene group.

Examples of the main chain skeleton of the polyalkylene oxide include polyethylene oxide, polypropylene oxide, polybutylene oxide, polytetramethylene oxide, polyethylene oxide-polypropylene oxide copolymer, and polypropylene oxide-polybutylene oxide copolymer. Of these, polypropylene oxide is preferred. Polypropylene oxide reduces the viscosity of the curable resin composition for electronic materials, improving the coatability, and allows the curable resin composition for electronic materials to be coated accurately in narrow coating areas.

The number average molecular weight of the polyalkylene oxide having a hydrolyzable silyl group is preferably 3000 or more, more preferably 10000 or more. The number average molecular weight of the polyalkylene oxide having a hydrolyzable silyl group is preferably 50000 or less, more preferably 40000 or less, and more preferably 30000 or less. When the number average molecular weight of the polyalkylene oxide is 3000 or more, the polyalkylene oxide does not easily thermally decompose into low molecular weight substances, so the cured product of the curable resin composition for electronic materials has excellent flame retardancy. When the number average molecular weight of the polyalkylene oxide is 50000 or less, the coating property of the curable resin composition for electronic materials for electronic materials is improved, and it can be accurately coated on the desired location of a small electronic material.

In the present invention, the number average molecular weight of a polyalkylene oxide having a hydrolyzable silyl group means the value converted into polystyrene measured by GPC (gel permeation chromatography).

The number average molecular weight of the polyalkylene oxide having a hydrolyzable silyl group can be measured, for example, using the following measuring device and under the following measuring conditions.
Measuring device: TOSOH product name "HLC-8121GPC/HT"
Measurement conditions Column: TSKgelGMHHR-H(20)HT x 3
TSKguardcolumn-HHR(30)HT x 1
Mobile phase: o-DCB 1.0 mL/min
Sample concentration: 1 mg/mL
Detector: Bryce type refractometer
Standard material: Polystyrene (TOSOH, molecular weight: 500-8420000)
Elution conditions: 145°C
SEC temperature: 145° C.

Polyalkylene oxides having hydrolyzable silyl groups can be commercially available. For example, polyalkylene oxides having hydrolyzable silyl groups include those manufactured by Kaneka Corporation under the trade names "MS Polymer S-203", "MS Polymer S-303", "MS Polymer S-303H", "Silyl Polymer SAT-200", "Silyl Polymer SAT-350" and "Silyl Polymer SAT-400". Polyalkylene oxides having hydrolyzable silyl groups include those manufactured by Asahi Glass Company under the trade names "Exestar ESS-3620", "Exestar ESS-2420", "Exestar ESS2410" and "Exestar ESS3430".

A polyalkylene oxide having a polypropylene oxide main chain and a (methoxymethyl)dimethoxysilyl group at the end of the polypropylene oxide is commercially available from Kaneka Corporation under the product name "HS-2."

A polyalkylene oxide having a polypropylene oxide main chain and an isopropyldimethoxymethylsilyl group at the end of the polypropylene oxide is commercially available from Kaneka Corporation under the product name "SAX720."

[Acrylic polymer having hydrolyzable silyl group]
As the hydrolyzable silyl group contained in the acrylic polymer having a hydrolyzable silyl group, an alkoxysilyl group is preferable, a trialkoxysilyl group is more preferable, and a trimethoxysilyl group is particularly preferable, because the hydrolysis reaction is mild.

In an acrylic polymer having a hydrolyzable silyl group, the average number of hydrolyzable silyl groups in one molecule is preferably 1 or more, more preferably 2 or more. In an acrylic polymer having a hydrolyzable silyl group, the average number of hydrolyzable silyl groups in one molecule is preferably 4 or less, more preferably 2.5 or less. When the number of hydrolyzable silyl groups is 1 or more, the flame retardancy of the cured product of the curable resin composition for electronic materials is improved. When the number of hydrolyzable silyl groups is 4 or less, the viscosity of the curable resin composition for electronic materials is reduced to improve the coating property, and the curable resin composition for electronic materials can be accurately coated on a narrow coating area, and when the curable resin composition for electronic materials is coated on the coating area, the curable resin composition for electronic materials flows smoothly at the coating area and has excellent leveling properties. It is preferable that the acrylic polymer having a hydrolyzable silyl group has a hydrolyzable silyl group on at least one of both ends of its main chain.

The acrylic polymer having a hydrolyzable silyl group may be used in combination with an acrylic polymer not having a hydrolyzable silyl group. In this case, the number of hydrolyzable silyl groups per molecule in the total of both is preferably 0.3 or more, more preferably 0.5 or more. When the number of hydrolyzable silyl groups is 0.3 or more, the curability of the curable resin composition for electronic materials is improved. On the other hand, the number of hydrolyzable silyl groups per molecule in the total of both is preferably 2.0 or less, more preferably 1.8 or less. When the number of hydrolyzable silyl groups is 2.0 or less, the viscosity of the curable resin composition for electronic materials is reduced to improve the coatability, and the curable resin composition for electronic materials can be applied to a narrow coating area with good accuracy, and when the curable resin composition for electronic materials is applied to the coating area, the curable resin composition for electronic materials flows smoothly at the coating area and has excellent leveling properties.

There are no particular limitations on the method for introducing hydrolyzable silyl groups into acrylic polymers. For example, an example would be a method in which an unsaturated group is introduced into a copolymer of monomers that make up the main chain skeleton, and then a hydrosilane having a hydrolyzable silyl group is allowed to react with the copolymer to hydrosilylate it.

The average number of hydrolyzable silyl groups per molecule in the acrylic polymer having hydrolyzable silyl groups is calculated based on the concentration of hydrolyzable silyl groups in the acrylic polymer having hydrolyzable silyl groups determined by ^1H -NMR and the number average molecular weight of the acrylic polymer having hydrolyzable silyl groups determined by GPC.

The main chain skeleton of the acrylic polymer having a hydrolyzable silyl group is preferably a copolymer of a monomer containing methyl (meth)acrylate and butyl (meth)acrylate, more preferably a copolymer of a monomer containing methyl methacrylate and butyl acrylate, and even more preferably a copolymer of a monomer containing methyl methacrylate and n-butyl acrylate. The acrylic polymer having a hydrolyzable silyl group, the main chain skeleton of which is the above-mentioned copolymer, improves the flame retardancy of the cured product of the curable resin composition for electronic materials. Note that (meth)acrylate means methacrylate and/or acrylate.

In the acrylic polymer having a hydrolyzable silyl group, the content of the methyl (meth)acrylate component is preferably 3% by mass or more, more preferably 5% by mass or more. In the acrylic polymer having a hydrolyzable silyl group, the content of the methyl (meth)acrylate component is preferably 70% by mass or less, more preferably 50% by mass or less. By having a content of the methyl (meth)acrylate component of 3% by mass or more, the viscosity of the curable resin composition for electronic materials is reduced to improve the coatability, and the curable resin composition for electronic materials can be precisely coated on a narrow coating area, and when the curable resin composition for electronic materials is coated on the coating area, the curable resin composition for electronic materials flows smoothly at the coating area and has excellent leveling properties. By having a content of the methyl (meth)acrylate component of 70% by mass or less, the viscosity of the curable resin composition for electronic materials is reduced to improve the coatability, and the curable resin composition for electronic materials can be precisely coated on a narrow coating area.

In the acrylic polymer having a hydrolyzable silyl group, the content of the butyl (meth)acrylate component is preferably 30 to 97% by mass, more preferably 50 to 95% by mass. When the content of the butyl (meth)acrylate component is 30% by mass or more, the viscosity of the curable resin composition for electronic materials is reduced, improving the coatability, and the curable resin composition for electronic materials can be applied with high precision to narrow application areas.

In acrylic polymers having hydrolyzable silyl groups, the monomers used in the polymer constituting the main chain may include, in addition to methyl acrylate, methyl methacrylate, butyl acrylate, and butyl methacrylate, further monomers. Examples of other monomers include styrene derivatives such as styrene, indene, α-methylstyrene, p-methylstyrene, p-chlorostyrene, p-chloromethylstyrene, p-methoxystyrene, p-tert-butoxystyrene, and divinylbenzene; compounds having a vinyl ester group such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl benzoate, and vinyl cinnamate; maleic anhydride, N-vinylpyrrolidone, N-vinylmorpholine, methacrylonitrile, acrylonitrile, acrylamide, methacrylamide, N-cyclohexylmaleimide, N-phenylmaleimide, N-laurylmaleimide, N-benzylmaleimide, n-propyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, tert-amyl vinyl ether, cyclohexyl vinyl ether, 2-ethylhexyl vinyl ether, dodecyl vinyl ether, octadecyl vinyl ether, 2-chloroethyl vinyl ether, ethylene glycol butyl vinyl ether, trimethylol ...tert-butyl vinyl ether, tert-amyl vinyl ether, tert-butyl vinyl ether, tert-butyl vinyl ether, tert-butyl vinyl ether, tert-butyl vinyl ether, tert-butyl vinyl ether, tert-butyl vinyl ether, tert-butyl vinyl ether, tert-butyl vinyl ether, tert-butyl vinyl ether, tert-butyl vinyl ether, tert-butyl vinyl ether, tert-butyl vinyl ether, tert- Examples of the vinyloxy group-containing compounds include ethylene glycol methyl vinyl ether, (4-vinyloxy)butyl benzoate, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, tetraethylene glycol divinyl ether, butane-1,4-diol-divinyl ether, hexane-1,6-diol-divinyl ether, cyclohexane-1,4-dimethanol-divinyl ether, di(4-vinyloxy)butyl isophthalate, di(4-vinyloxy)butyl glutarate, di(4-vinyloxy)butyl succinate, trimethylolpropane trivinyl ether, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, 6-hydroxyhexyl vinyl ether, cyclohexane-1,4-dimethanol monovinyl ether, diethylene glycol monovinyl ether, 3-aminopropyl vinyl ether, 2-(N,N-diethylamino)ethyl vinyl ether, urethane vinyl ether, and polyester vinyl ether. These monomers may be used alone or in combination of two or more.

The polymerization method for the acrylic polymer having a hydrolyzable silyl group is not particularly limited, and any known method can be used, such as free radical polymerization, anionic polymerization, cationic polymerization, UV radical polymerization, living anionic polymerization, living cationic polymerization, and living radical polymerization.

The weight-average molecular weight of the acrylic polymer having a hydrolyzable silyl group is preferably 1000 to 50000, more preferably 2000 to 30000, and particularly preferably 3000 to 15000. According to an acrylic polymer having a hydrolyzable silyl group whose weight-average molecular weight is within the above range, the viscosity of the curable resin composition for electronic materials is reduced to improve the coatability, and the curable resin composition for electronic materials can be applied with high precision to a narrow coating area. In addition, when the curable resin composition for electronic materials is applied to the coating area, the curable resin composition for electronic materials flows smoothly at the coating area, and has excellent leveling properties.

[Urethane polymer having hydrolyzable silyl group]
The urethane polymer refers to a polymer having a main chain formed by repeating urethane bonds (-NHCOO-). The urethane polymer having a hydrolyzable silyl group has a plurality of hydrolyzable silyl groups in the main chain of the urethane polymer. The urethane polymer having a hydrolyzable silyl group preferably has hydrolyzable silyl groups at both ends of the main chain of the urethane polymer.

[Polyolefin polymer having hydrolyzable silyl group]
Examples of the polyolefin polymer include polyethylene polymers and polypropylene polymers. The polyolefin polymer having a hydrolyzable silyl group has a plurality of hydrolyzable silyl groups in the main chain of the polyolefin polymer. The polyolefin polymer having a hydrolyzable silyl group preferably has hydrolyzable silyl groups at both ends of the main chain of the polyolefin polymer.

[Hydrolysis-crosslinkable silicone polymer]
A silicone polymer is a polymer having a molecular chain (main chain) formed by repeating siloxane bonds (-Si-O-). The main chain of the silicone polymer is preferably linear. A hydrolysis-crosslinkable silicone polymer has a hydrolyzable group bonded to a part of the silicon atoms constituting the main chain of the silicone polymer.

When the curable resin contains a hydrolysis-crosslinkable silicone polymer, the cured product of the curable resin composition for electronic materials expands quickly in the early stages of combustion, reducing the spread of fire caused by the burning of the electronic materials and imparting excellent flame retardancy to the electronic materials.

The hydrolyzable group is not particularly limited, and examples thereof include a hydrogen atom, a halogen atom, an alkoxy group, an acyloxy group, a ketoximate group, an amino group, an amide group, an acid amide group, an aminooxy group, a mercapto group, and an alkenyloxy group, with an alkoxy group being preferred.

Examples of alkoxy groups include methoxy groups, ethoxy groups, propoxy groups, and butoxy groups, with methoxy groups and ethoxy groups being preferred.

In the presence of moisture or a crosslinking agent, and if necessary using a catalyst, etc., hydrolysis-crosslinkable silicone polymers undergo a condensation reaction at the hydrolyzable groups to form a crosslinked structure. When the hydrolysis-crosslinkable silicone polymer has alkoxy groups as hydrolyzable groups, some of the alkoxy groups are hydrolyzed to form hydroxyl groups, and these hydroxyl groups and alkoxy groups undergo a dealcoholization condensation reaction to form a crosslinked structure.

The content of the hydrolyzable group in the hydrolysis crosslinkable silicone polymer is preferably 5% by mass or more, more preferably 10% by mass or more. The content of the hydrolyzable group in the hydrolysis crosslinkable silicone polymer is preferably 50% by mass or less, more preferably 40% by mass or less, and more preferably 35% by mass or less. When the content of the hydrolyzable group is 5% by mass or more, the hardness of the combustion residue of the cured product of the curable resin composition for electronic materials is improved, and the curable resin composition for electronic materials is stably present at the application site of the electronic material, and excellent flame retardancy can be imparted to the electronic material. When the content of the hydrolyzable group is 50 ^% by mass or less, the expansion property of the cured product of the curable resin composition for electronic materials is improved, and the flame retardancy of the curable resin composition for electronic materials can be improved. The content of the hydrolyzable group in the hydrolysis crosslinkable silicone polymer can be calculated based on the concentration of the hydrolyzable group in the hydrolysis crosslinkable silicone polymer determined by 1 H-NMR and the number average molecular weight of the hydrolysis crosslinkable silicone polymer determined by GPC method.

The content of the hydrolyzable group in the hydrolysis crosslinkable silicone polymer is preferably 5 mol% or more, more preferably 10 mol% or more. The content of the hydrolyzable group in the hydrolysis crosslinkable silicone polymer is preferably 50 mol% or less, more preferably 40 mol% or less, more preferably 35 mol% or less. When the content of the hydrolyzable group is 5 mol% or more, the hardness of the combustion residue of the cured product of the curable resin composition for electronic materials is improved, and the curable resin composition for electronic materials is stably present at the application site of the electronic material, and excellent flame retardancy can be imparted to the electronic material. When the content of the hydrolyzable group is 50 ^mol % or less, the expansion property of the cured product of the curable resin composition for electronic materials is improved, and the flame retardancy of the curable resin composition for electronic materials can be improved. The content of the hydrolyzable group in the hydrolysis crosslinkable silicone polymer can be calculated based on the concentration of the hydrolyzable group in the hydrolysis crosslinkable silicone polymer determined by 1 H-NMR and the number average molecular weight of the hydrolysis crosslinkable silicone polymer determined by GPC.

It is preferable that a methyl group or a phenyl group is bonded to some of the silicon atoms in the hydrolysis crosslinkable silicone polymer. It is preferable that the hydrolysis crosslinkable silicone polymer has silicon atoms to which a methyl group or a phenyl group is bonded. When a methyl group or a phenyl group is bonded to some of the silicon atoms in the hydrolysis crosslinkable silicone polymer, the flame retardancy of the curable resin composition for electronic materials can be improved.

It is preferable that methyl groups and phenyl groups are bonded to some of the silicon atoms in the hydrolyzable silicone polymer. In other words, it is preferable that the hydrolyzable silicone polymer has silicon atoms to which methyl groups and phenyl groups are bonded. When methyl groups and phenyl groups are bonded to some of the silicon atoms in the hydrolyzable crosslinkable silicone polymer, the flame retardancy of the curable resin composition for electronic materials can be improved.

In the hydrolyzable silicone polymer, the content of the phenyl group is preferably 10 mol% or more, more preferably 20 mol% or more, more preferably 25 mol% or more, and more preferably 30 mol% or more. In the hydrolyzable silicone polymer, the content of the phenyl group is preferably 80 mol% or less, more preferably 70 mol% or less, more preferably 60 mol% or less, more preferably 50 mol% or less, more preferably 40 mol% or less, and more preferably 35 mol% or less. When the content of the phenyl group is 10 mol% or more, the flame retardancy of the curable resin composition for electronic materials can be improved. When the content of the phenyl group is 80 mol% or less, the viscosity of the curable resin composition for electronic materials is reduced, and the coatability of the curable resin composition for electronic materials is improved.

The phenyl group content (mol %) is represented by the following formula:
Phenyl group content (mol %) = 100 x number of phenyl groups / number of bonds of silicon atoms. Note that "the number of phenyl groups" refers to the total number of phenyl groups bonded to silicon atoms constituting a linear molecular chain (main chain) (polysiloxane) formed by repeating siloxane bonds (-Si-O-). "The number of bonds of silicon atoms" refers to the total number of bonds remaining after excluding the bonds used to constitute the main chain from the four bonds possessed by silicon atoms constituting the main chain. For silicon atoms at both ends of the main chain, the bonds used to constitute the main chain refer only to the bonds bonded to oxygen.

In the hydrolyzable silicone polymer, the content of methyl groups is preferably 10 mol% or more, more preferably 20 mol% or more, more preferably 30 mol% or more, more preferably 40 mol% or more, more preferably 50 mol% or more, and more preferably 55 mol% or more. In the hydrolyzable silicone polymer, the content of methyl groups is preferably 98 mol% or less, more preferably 96 mol% or less, more preferably 95 mol% or less, more preferably 90 mol% or less, more preferably 80 mol% or less, and more preferably 70 mol% or less. When the content of methyl groups is 10 mol% or more, the viscosity of the curable resin composition for electronic materials is reduced, and the coatability of the curable resin composition for electronic materials is improved. When the content of methyl groups is 98 mol% or less, the flame retardancy of the curable resin composition for electronic materials is improved.

The methyl group content (mol %) is represented by the following formula:
Methyl group content (mol %) = 100 x number of methyl groups / number of bonds of silicon atoms. Note that the "number of methyl groups" refers to the total number of methyl groups bonded to silicon atoms constituting a linear molecular chain (main chain) (polysiloxane) formed by repeating siloxane bonds (-Si-O-). The "number of bonds of silicon atoms" refers to the total number of bonds remaining after excluding the bonds used to constitute the main chain from the four bonds possessed by silicon atoms constituting the main chain. For silicon atoms at both ends of the main chain, the bonds used to constitute the main chain refer only to the bonds bonded to oxygen.

In the hydrolyzable silicone polymer, the phenyl group content and the methyl group content are values measured according to the following method.
The methyl group concentration and phenyl group concentration in the hydrolysis-crosslinkable silicone polymer are calculated from the signal intensity ratio determined from Si-NMR by MNR measurement.
For example, the measurement can be performed using the following measurement device and under the following measurement conditions.
Measurement device: AVANCE 400 (manufactured by Bruker Biospin)
Probe: Prodigy (BBO)
Rotation speed: 20Hz
Measurement pulse: Single pulse
Solvent: deuterated chloroform Concentration: 29Si about 5 wt/vol%
Temperature: 24.85°C (298K)
Number of scans: 360 Chemical shift reference: TMS 0.0 ppm

In the hydrolyzable silicone polymer, the total content of phenyl groups and methyl groups is preferably 50 mol% or more, more preferably 60 mol% or more, and more preferably 70 mol% or more. In the hydrolyzable silicone polymer, the total content of phenyl groups and methyl groups is preferably 99 mol% or less, more preferably 96 mol% or less, and more preferably 95 mol% or less. When the total content of phenyl groups and methyl groups is 50 mol% or more, the flame retardancy of the curable resin composition for electronic materials can be improved. When the total content of phenyl groups and methyl groups is 99 mol% or less, the curing reaction of the curable resin composition for electronic materials proceeds smoothly, so that the obtained cured product has excellent hardness.

The viscosity of the hydrolysis crosslinkable silicone polymer at 25°C is preferably 5 Pa·s or more, more preferably 10 mPa·s or more, and more preferably 13 Pa·s or more. The viscosity of the hydrolysis crosslinkable silicone polymer at 25°C is preferably 1000 Pa·s or less, more preferably 500 Pa·s or less. When the viscosity at 25°C is 5 Pa·s or more, the viscosity of the cured product of the curable resin composition for electronic materials is improved, and the curable resin composition for electronic materials does not separate during the curing process and maintains a uniformly mixed state, resulting in improved flame retardancy of the cured product of the curable resin composition for electronic materials. When the viscosity at 25°C is 1000 Pa·s or less, the coating property of the curable resin composition for electronic materials is improved. The viscosity of the hydrolysis crosslinkable silicone polymer at 25°C refers to a value measured using a B-type viscosity watch under conditions of 20°C and 60 rpm in accordance with JIS Z8803.

The content of hydrolytically crosslinkable silicone polymer in the curable resin is preferably 50% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, more preferably 80% by mass or more, more preferably 90% by mass or more, and more preferably 100% by mass.

[Polymer having hydrolyzable isocyanate group]
Examples of the polymer having a hydrolyzable isocyanate group include a urethane-based polymer having a hydrolyzable isocyanate group. The urethane-based polymer refers to a polymer having a main chain formed by repeating urethane bonds (-NHCOO-). The urethane-based polymer having a hydrolyzable isocyanate group has a plurality of hydrolyzable isocyanate groups in the main chain of the urethane-based polymer. The urethane-based polymer having a hydrolyzable isocyanate group preferably has hydrolyzable isocyanate groups at both ends of the main chain of the urethane-based polymer. The urethane-based polymer includes a polyether-based urethane-based polymer made from a polyether polyol as a raw material, and a polyester-based urethane-based polymer made from a polyester polyol as a raw material, but may be any of these.

The content of the polymer having a hydrolyzable isocyanate group in the curable resin is preferably 50% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, more preferably 80% by mass or more, more preferably 90% by mass or more, and more preferably 100% by mass.

[Photocrosslinkable polymer]
A photocrosslinkable polymer has photocrosslinkable groups in its molecules, and when irradiated with light such as ultraviolet light, a chemical bond is formed between the molecules, forming a crosslinked structure and curing.

The photocrosslinkable group may be one that forms a chemical bond by irradiation with light. The photocrosslinkable group is not particularly limited, and examples thereof include thiol, glycidyl, oxetanyl, vinyl, (meth)acryloyl, benzophenone, benzoin, and thioxanthone groups. Benzophenone, benzoin, and thioxanthone groups are preferred, and benzophenone groups are more preferred. (Meth)acryloyl means methacryloyl or acryloyl.

The main chain structure of the photocrosslinkable polymer is not particularly limited, and examples thereof include polyolefin polymers, acrylic polymers, epoxy polymers, and cyanoacrylate polymers. Examples of methods for introducing photocrosslinkable groups into the main chain include a method of polymerizing a monomer composition containing a photocrosslinkable group-containing monomer.

The photocrosslinkable group-containing monomer is not particularly limited, and examples thereof include glycidyl (meth)acrylate, 4-hydroxybutyl acrylate glycidyl ether, 4-(meth)acryloyloxybenzophenone, 4-[2-((meth)acryloyloxy)ethoxy]benzophenone, 4-(meth)acryloyloxy-4'-methoxybenzophenone, 4-(meth)acryloyloxyethoxy-4'-methoxybenzophenone, 4-(meth)acryloyloxy-4'-bromobenzophenone, and 4-(meth)acryloyloxyethoxy-4'-bromobenzophenone, with 4-(meth)acryloyloxybenzophenone and 4-[2-((meth)acryloyloxy)ethoxy]benzophenone being preferred. The ultraviolet crosslinkable group-containing monomer (D) may be used alone or in combination of two or more. In addition, (meth)acryloyloxy means methacryloyloxy or acryloyloxy.

The content of the photocrosslinkable polymer in the curable resin is preferably 50% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, more preferably 80% by mass or more, more preferably 90% by mass or more, and more preferably 100% by mass.

[Two-component curing resin]
The two-component curable resin is not particularly limited, and examples thereof include isocyanate-based polymers and glycidyl-based polymers.

Isocyanate-based polymers are two-part curable resins consisting of a base agent containing polyisocyanate and a curing agent containing polyol. By mixing the base agent and the curing agent and reacting the polyisocyanate with the polyol, urethane bonds are formed, crosslinking occurs, and the resin hardens.

Examples of polyisocyanates include araliphatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, etc. Examples of araliphatic diisocyanates include diphenylmethane diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, 1,3-bis(1-isocyanato-1-methylethyl)benzene, 1,4-bis(1-isocyanato-1-methylethyl)benzene, ω,ω'-diisocyanato-1,4-diethylbenzene, and urethane prepolymers having isocyanate groups at both ends.

Examples of aliphatic diisocyanates include hexamethylene diisocyanate, tetramethylene diisocyanate, 2-methyl-pentane-1,5-diisocyanate, 3-methyl-pentane-1,5-diisocyanate, lysine diisocyanate, and trioxyethylene diisocyanate.

Examples of alicyclic diisocyanates include isophorone diisocyanate, cyclohexyl diisocyanate, hydrogenated diphenylmethane diisocyanate, norbornane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, and hydrogenated tetramethylxylene diisocyanate.

Examples of polyols include polyurethane polyols, polyester polyols, polyether polyols, acrylic polyols, polyolefin polyols, castor oil-based polyols, etc.

Glycidyl polymers are two-part curable resins consisting of a base agent containing an epoxy polymer and a curing agent. Epoxy polymers are not particularly limited, and examples include bisphenol A type epoxy polymers obtained by reacting bisphenol A with epichlorohydrin, bisphenol F type epoxy polymers obtained by reacting bisphenol F with epichlorohydrin, and hydrogenated versions of these, glycidyl ester type epoxy polymers, novolac type epoxy polymers, urethane modified epoxy polymers, nitrogen-containing epoxy polymers such as triglycidyl isocyanurate, and rubber modified epoxy polymers containing polybutadiene or NBR.

The curing agent is not particularly limited, but examples thereof include amine-based curing agents, acid anhydride-based curing agents, polyamide-based curing agents, imidazole-based curing agents, and polymercapran-based curing agents.

Examples of amine-based curing agents include aliphatic polyamines such as polyoxypropylenetriamine, diethylenetriamine, and triethylenetetramine, and aromatic polyamines such as metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, and 2,4,6-tris(dimethylaminomethyl)phenol.

Examples of acid anhydride curing agents include tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, pyromellitic anhydride, HET anhydride, dodecenyl succinic anhydride, etc. Examples of polyamide curing agents include dimer acid, etc.

The content of the two-component curable resin in the curable resin is preferably 50% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, more preferably 80% by mass or more, more preferably 90% by mass or more, and more preferably 100% by mass.

[Feldspars]
The curable resin composition for electronic materials contains feldspars. Since the curable resin composition for electronic materials contains feldspars, the cured product of the curable resin composition for electronic materials has excellent flame retardancy. The feldspars are a concept including feldspar and feldspathic spar, and preferably contain feldspathic spar. The feldspars may be used alone or in combination of two or more kinds.

Examples of feldspars include alkali feldspars such as orthoclase, sanidine, microcline, and anorthoclase; plagioclases such as albite, oligoclase, andesite, albite, anorthite, and anorthite.

Examples of feldspars include nephelines such as kalsilite and cancrinite, nepheline syenite, leucite, sodalite, hauyne, lazurite, nosean, and melilite, with nepheline syenite being preferred. Nepheline syenite is sometimes referred to as syenite.

The average particle size of the feldspars is preferably 0.1 μm or more, more preferably 1 μm or more, more preferably 2 μm or more, and more preferably 3 μm or more. The average particle size of the feldspars is preferably 50 μm or less, more preferably 25 μm or less, and more preferably 15 μm or less. When the average particle size of the feldspars is 0.1 μm or more, the cohesive force of the curable resin composition for electronic materials before curing is improved, and the curable resin composition for electronic materials can be accurately applied to a narrow coating area. When the average particle size of the feldspars is 50 μm or less, the feldspars can be uniformly dispersed in the curable resin composition for electronic materials, and the cured product of the curable resin composition for electronic materials can be given excellent mechanical strength, and the electronic material can be given excellent flame retardancy stably over a long period of time. The average particle size of the feldspars refers to a value measured by image analysis using a transmission electron microscope. Specifically, 100x magnified photographs of feldspars are taken using a transmission electron microscope, 50 random feldspars are selected, the diameters of each feldspar are measured, and the arithmetic mean of the diameters of each feldspar is taken as the average particle size of the feldspars. The diameter of the feldspars refers to the diameter of the smallest circle that can surround the feldspars.

The content of feldspars in the curable resin composition for electronic materials is preferably 1 part by mass or more, more preferably 30 parts by mass or more, more preferably 50 parts by mass or more, and more preferably 80 parts by mass or more, per 100 parts by mass of the curable resin. The content of feldspars in the curable resin composition for electronic materials is preferably 800 parts by mass or less, more preferably 600 parts by mass or less, more preferably 450 parts by mass or less, more preferably 300 parts by mass or less, more preferably 200 parts by mass or less, more preferably 150 parts by mass or less, more preferably 100 parts by mass or less, and more preferably 80 parts by mass or less, per 100 parts by mass of the curable resin. When the content of feldspars is 1 part by mass or more, the hardness of the combustion residue in the cured product of the curable resin composition for electronic materials is improved, and the electronic material is stably present at the coating location, and excellent flame retardancy can be imparted to the electronic material. When the content of the feldspar is 800 parts by mass or less, the viscosity of the curable resin composition for electronic materials is reduced to improve the coatability, and the curable resin composition for electronic materials can be coated with high precision in a narrow coating area.

[Phosphorus compounds]
The curable resin composition for electronic materials contains a phosphorus-based compound. By containing a phosphorus-based compound in the curable resin composition for electronic materials, a cured product of the curable resin composition for electronic materials expands in the event of a fire, thereby protecting the electronic materials and imparting excellent flame retardancy to the electronic materials.

The phosphorus-based compound may contain a phosphorus atom in the molecule. There are no particular limitations on the phosphorus-based compound. The phosphorus-based compound is preferably ammonium polyphosphate or a poorly water-soluble phosphorus-based compound, and more preferably ammonium polyphosphate. The phosphorus-based compound may be used alone or in combination of two or more kinds.

The content of ammonium polyphosphate in the phosphorus-based compound is preferably 50% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, more preferably 80% by mass or more, more preferably 90% by mass or more, and more preferably 100% by mass.

The content of poorly water-soluble phosphorus-based compounds in the phosphorus-based compounds is preferably 50% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, more preferably 80% by mass or more, more preferably 90% by mass or more, and more preferably 100% by mass.

The poorly water-soluble phosphorus compound is not particularly limited, and examples thereof include poorly water-soluble inorganic phosphorus compounds such as aluminum phosphite, aluminum monophosphate, aluminum diphosphate, aluminum triphosphate, aluminum metaphosphate, and condensed aluminum phosphate, and poorly water-soluble organic phosphorus compounds such as melam polyphosphate, melamine polyphosphate, and melem polyphosphate. It is preferable to contain a poorly water-soluble inorganic phosphorus compound, more preferably to contain aluminum phosphite or ammonium monophosphate, and more preferably to contain aluminum phosphite. The poorly water-soluble phosphorus compound may be used alone or in combination of two or more kinds.

The term "poorly water-soluble phosphorus compound" refers to a phosphorus compound having a saturated concentration (solubility) of 0.03 g/100 g-H ₂ O or less in a saturated solution obtained by dissolving the phosphorus compound in 100 g of water at 25° C. Specifically, an excess amount of the phosphorus compound is supplied to 1000 g of water at 25° C. to the extent that a slight precipitate is generated, and the solution is prepared by stirring and dissolving. The solution is suction filtered through a filter paper of type 5C conforming to JIS P3801 to remove the insoluble matter in the solution, thereby preparing a saturated solution. The saturated solution is heated to 100° C. to evaporate the water of the saturated solution to obtain a precipitate of the phosphorus compound. The mass of this precipitate is measured, and the value of 1/10 of the mass of this precipitate is taken as the solubility (g/100 g-H ₂ O). Note that, in the process of removing the insoluble matter, a part of the water is absorbed by the filter paper, but since the amount is extremely small compared to 1000 g of water, the mass of the water absorbed by the filter paper does not affect the value of the solubility and can be ignored.

The content of the phosphorus-based compound in the curable resin composition for electronic materials is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, more preferably 70 parts by mass or more, more preferably 80 parts by mass or more, more preferably 90 parts by mass or more, more preferably 100 parts by mass or more, and more preferably 110 parts by mass or more, per 100 parts by mass of the curable resin. The content of the phosphorus-based compound in the curable resin composition for electronic materials is preferably 200 parts by mass or less, more preferably 180 parts by mass or less, more preferably 160 parts by mass or less, and more preferably 140 parts by mass or less, per 100 parts by mass of the curable resin. When the content of the phosphorus-based compound is 50 parts by mass or more, the cured product of the curable resin composition for electronic materials expands more effectively in the event of a fire, more reliably protecting the electronic material, and imparting even better flame retardancy to the electronic material. When the content of the phosphorus-based compound is 200 parts by mass or less, the hardness of the combustion residue of the cured product of the curable resin composition for electronic materials is improved, and the combustion residue is stably present at the coated portion of the electronic material where the curable resin composition for electronic materials is applied, thereby imparting excellent flame retardancy to the electronic material.

In the curable resin composition for electronic materials, the ratio of the content of feldspars to the content of phosphorus-based compounds (mass of feldspars/mass of phosphorus-based compounds) is preferably 0.05 or more, more preferably 0.08 or more. In the curable resin composition for electronic materials, the ratio of the content of feldspars to the content of phosphorus-based compounds (mass of feldspars/mass of phosphorus-based compounds) is preferably 1.00 or less, more preferably 0.90 or less. When the ratio of the content of feldspars to the content of phosphorus-based compounds is 0.05 or more, the hardness of the combustion residue of the cured product of the curable resin composition for electronic materials is improved, the electronic materials can be more reliably protected in the event of a fire, and the flame retardancy of the electronic materials can be improved. When the ratio of the content of feldspars to the content of phosphorus-based compounds is 1.00 or less, the cured product of the curable resin composition for electronic materials expands more effectively in the event of a fire, protecting the electronic materials and imparting flame retardancy to the electronic materials.

[Titanium oxide]
The curable resin composition for electronic materials preferably contains titanium oxide. When the curable resin composition for electronic materials contains titanium oxide, the hardness of the combustion residue of the cured product of the curable resin composition for electronic materials is further improved by the reaction between the titanium oxide and the phosphorus-based compound, so that the electronic materials can be more reliably protected in the event of a fire and the flame retardancy of the electronic materials can be improved.

The average particle diameter of titanium oxide is preferably 0.005 μm or more, more preferably 0.01 μm or more, and more preferably 0.02 μm or more. The average particle diameter of titanium oxide is preferably 10 μm or less, more preferably 8 μm or less, and more preferably 5 μm or less. When the average particle diameter of titanium oxide is 0.05 μm or more, the viscosity of the curable resin composition for electronic materials is reduced from increasing rapidly, and the coating property of the curable resin composition for electronic materials is improved. When the average particle diameter of titanium oxide is 10 μm or less, the dispersibility of titanium oxide in the curable resin composition for electronic materials is improved, and the hardness of the combustion residue in the cured product of the curable resin composition for electronic materials is improved. Therefore, it is stable in the coating area of the electronic material and can impart excellent flame retardancy to the electronic material. The average particle diameter of titanium oxide refers to the particle diameter D50 at which the cumulative frequency from the small particle diameter side in the volume-based particle size distribution measured by the laser diffraction method is 50 mass%.

The content of titanium oxide in the curable resin composition for electronic materials is preferably 1 part by mass or more, more preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and more preferably 8 parts by mass or more, per 100 parts by mass of the curable resin. The content of titanium oxide in the curable resin composition for electronic materials is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, more preferably 16 parts by mass or less, more preferably 14 parts by mass or less, and more preferably 12 parts by mass or less, per 100 parts by mass of the curable resin. When the content of titanium oxide is 1 part by mass or more, the hardness of the combustion residue of the cured product of the curable resin composition for electronic materials is further improved by the reaction between titanium oxide and the phosphorus-based compound, and the curable resin composition for electronic materials is stably present at the application location of the curable resin composition for electronic materials in the electronic material in the event of a fire, and excellent flame retardancy can be imparted to the electronic material. When the content of titanium oxide is 20 parts by mass or less, the viscosity of the curable resin composition for electronic materials is reduced to improve the application property, and the curable resin composition for electronic materials can be applied to a narrow application location with good precision.

[Glass frit]
The curable resin composition for electronic materials preferably contains glass frit. The glass frit acts as a binder for binding the combustion residue of the curable resin and feldspars in the combustion residue of the cured product of the curable resin composition for electronic materials, and the combustion residue has excellent hardness. Therefore, the combustion residue of the cured product of the curable resin composition for electronic materials is stably present at the application site of the curable resin composition for electronic materials in the electronic material, and can impart excellent flame retardancy to the electronic material.

Examples of the glass constituting the glass frit include phosphate glass, borate glass, bismuth oxide glass, silicate glass, and sodium oxide glass, with phosphate glass and borate glass being preferred, and phosphate glass being more preferred. These glass frits can be obtained by adjusting _B2O3 , _P2O5 , ZnO, _SiO2 , _Bi2O3 , _Al2O3 , BaO, CaO, MgO, MnO2, _ZrO2 , _{TiO2 , CeO2} , _SrO , _V2O5 , _SnO2 , _{Li2O , Na2O} , _K2O , CuO, _{Fe2O3 ,} and _the like in _a predetermined _component ratio.

The content of the glass frit in the curable resin composition for electronic materials is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, and more preferably 40 parts by mass or more, relative to 100 parts by mass of the curable resin. The content of the glass frit in the curable resin composition for electronic materials is preferably 200 parts by mass or less, more preferably 100 parts by mass or less, and more preferably 80 parts by mass or less, relative to 100 parts by mass of the curable resin. When the content of the glass frit is 5 parts by mass or more, the combustion residue of the cured product of the curable resin composition for electronic materials has excellent hardness and is stably present at the application location of the curable resin composition for electronic materials in the electronic material, and excellent flame retardancy can be imparted to the electronic material. When the content of the glass frit is 200 parts by mass or less, the viscosity of the curable resin composition for electronic materials is reduced to improve the application property, and the curable resin composition for electronic materials can be applied to a narrow application location with good precision.

[Calcium carbonate]
The curable resin composition for electronic materials may contain calcium carbonate. Examples of calcium carbonate include heavy calcium carbonate, precipitated calcium carbonate, colloidal calcium carbonate, and light calcium carbonate, and colloidal calcium carbonate is preferred.

Heavy calcium carbonate can be obtained, for example, by grinding natural calcium carbonate such as natural chalk, marble, or limestone into a fine powder.

Precipitated calcium carbonate can be produced, for example, using limestone as a raw material through a chemical reaction.

The average particle diameter of the primary particles of calcium carbonate is preferably 0.01 μm or more, more preferably 0.03 μm or more, more preferably 0.05 μm or more, and more preferably 0.06 μm or more. The average particle diameter of the primary particles of calcium carbonate is preferably 5.0 μm or less, more preferably 2.5 μm or less, more preferably 1.0 μm or less, and more preferably 0.5 μm or less. When the average particle diameter of the primary particles of calcium carbonate is 0.01 μm or more, the viscosity of the curable resin composition for electronic materials is reduced to improve the coatability, and the curable resin composition for electronic materials can be precisely coated on a narrow coating area. When the average particle diameter of the primary particles of calcium carbonate is 5.0 μm or less, the hardness of the combustion residue in the cured product of the curable resin composition for electronic materials is improved, and it is stably present in the coating area of the electronic material, and excellent flame retardancy can be imparted to the electronic material.

The average particle size of the primary particles of calcium carbonate refers to a value calculated based on the following formula using the specific surface area per gram of calcium carbonate. The specific surface area per gram of calcium carbonate can be measured using, for example, a powder specific surface area measuring device commercially available from Shimadzu Corporation under the product name "SS-100 Model."
Average particle size of calcium carbonate (μm) = 6 x 10,000 / (specific gravity x specific surface area)

The content of calcium carbonate in the curable resin composition for electronic materials is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and more preferably 30 parts by mass or more, per 100 parts by mass of the curable resin. The content of calcium carbonate in the curable resin composition for electronic materials is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and more preferably 60 parts by mass or less, per 100 parts by mass of the curable resin. When the content of calcium carbonate is 10 parts by mass or more, the hardness of the combustion residue in the cured product of the curable resin composition for electronic materials is improved, and it is stably present at the coated portion of the electronic material, and excellent flame retardancy can be imparted to the electronic material. When the content of calcium carbonate is 100 parts by mass or less, the coatability of the curable resin composition for electronic materials is stable and preferable.

[Silanol condensation catalyst]
The curable resin composition for electronic materials may contain a silanol condensation catalyst. The silanol condensation catalyst is a catalyst for promoting curing by a condensation reaction of a curable resin when the curable resin is a polymer having a hydrolyzable silyl group or a hydrolysis-crosslinkable silicone polymer.

Examples of silanol condensation catalysts include organotin compounds such as dibutyltin diacetylacetonate, 1,1,3,3-tetrabutyl-1,3-dilauryloxycarbonyl-distannoxane, dibutyltin dilaurate, dibutyltin oxide, dibutyltin diacetate, dibutyltin phthalate, bis(dibutyltin laurate) oxide, dibutyltin bis(acetylacetonate), dibutyltin bis(monoester maleate), tin octoate, dibutyltin octoate, dioctyltin oxide, dibutyltin bis(triethoxysilicate), bis(dibutyltin bistriethoxysilicate) oxide, and dibutyltin oxybisethoxysilicate; organotin compounds such as tetra-n-butoxytitanate and tetraisopropoxytitanate; and organotin compounds are preferred. These silanol condensation catalysts may be used alone or in combination of two or more.

As a silanol condensation catalyst, 1,1,3,3-tetrabutyl-1,3-dilauryloxycarbonyl-distannoxane is preferred. Such a silanol condensation catalyst makes it easy to adjust the curing speed of the curable resin composition for electronic materials.

The content of the silanol condensation catalyst in the curable resin composition for electronic materials is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, and more preferably 0.3 parts by mass or more, relative to 100 parts by mass of the curable resin. The content of the silanol condensation catalyst in the curable resin composition for electronic materials is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, more preferably 6 parts by mass or less, and more preferably 5 parts by mass or less, relative to 100 parts by mass of the curable resin. When the content of the silanol condensation catalyst in the curable resin composition for electronic materials is 0.1 parts by mass or more, the curing speed of the curable resin composition for electronic materials can be increased, and the time required for curing the curable resin composition for electronic materials can be shortened. When the content of the silanol condensation catalyst in the curable resin composition for electronic materials is 10 parts by mass or less, the curable resin composition for electronic materials has an appropriate curing speed, and the storage stability and handling of the curable resin composition for electronic materials can be improved.

[Dehydrating agent]
The curable resin composition for electronic materials preferably further contains a dehydrating agent, which can suppress curing of the curable resin composition for electronic materials due to moisture contained in the air or the like during storage of the curable resin composition for electronic materials.

Examples of dehydrating agents include silane compounds such as vinyltrimethoxysilane, dimethyldimethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, phenyltrimethoxysilane, and diphenyldimethoxysilane; and ester compounds such as methyl orthoformate, ethyl orthoformate, methyl orthoacetate, and ethyl orthoacetate. These dehydrating agents may be used alone or in combination of two or more. Of these, vinyltrimethoxysilane is preferred.

The content of the dehydrating agent in the curable resin composition for electronic materials is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, per 100 parts by mass of the curable resin. The content of the dehydrating agent in the curable resin composition for electronic materials is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, per 100 parts by mass of the curable resin. When the content of the dehydrating agent in the curable resin composition for electronic materials is 0.5 parts by mass or more, the effect obtained by the dehydrating agent is sufficiently obtained. In addition, when the content of the dehydrating agent in the curable resin composition for electronic materials is 20 parts by mass or less, the curable resin composition for electronic materials has excellent curability.

[Other Additives]
The curable resin composition for electronic materials may contain other additives such as a thixotropic agent, an antioxidant, an ultraviolet absorber, a pigment, a dye, an antisettling agent, an aminosilane coupling agent, a thixotropic agent, a plasticizer, and a solvent, within the range that does not impair the physical properties of the composition. Among these, the thixotropic agent, the ultraviolet absorber, and the antioxidant are preferable.

It is preferable that the curable resin composition for electronic materials contains a black pigment (e.g., carbon black, etc.) as a pigment. By making the cured product of the curable resin composition for electronic materials black, it is possible to reduce light reflection and improve the optical properties of the cured product.

The curable resin composition for electronic materials preferably contains an aminosilane coupling agent. By using an aminosilane coupling agent, the rubber elasticity and adhesiveness of the cured product of the curable resin composition for electronic materials can be improved. The aminosilane coupling agent means a compound containing a silicon atom to which an alkoxy group is bonded and a functional group containing a nitrogen atom in one molecule.

Specific examples of aminosilane coupling agents include 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N,N'-bis-[3-(trimethoxysilyl)propyl]ethylenediamine, N,N'-bis-[3-(triethoxysilyl)propyl]ethylenediamine, N,N'-bis-[3-(methyldimethoxysilyl)propyl]ethylenediamine, N,N'-bis-[3-(trimethoxysilyl)propyl]hexamethylenediamine, and N,N'-bis-[3-(triethoxysilyl)propyl]hexamethylenediamine. These aminosilane coupling agents may be used alone or in combination of two or more.

Among these, preferred aminosilane coupling agents include 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropyltriethoxysilane, with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane being more preferred.

The content of the aminosilane coupling agent in the curable resin composition for electronic materials is preferably 1 to 10 parts by mass, and more preferably 1 to 5 parts by mass, per 100 parts by mass of the curable resin. When the content of the aminosilane coupling agent is within the above range, the rubber elasticity and adhesion of the cured product of the curable resin composition for electronic materials can be improved.

The thixotropic agent may be any agent capable of imparting thixotropy to the curable resin composition for electronic materials. Preferred examples of thixotropic agents include hydrogenated castor oil, fatty acid bisamide, and fumed silica.

The content of the thixotropic agent in the curable resin composition for electronic materials is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, per 100 parts by mass of the curable resin. The content of the thixotropic agent in the curable resin composition for electronic materials is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, per 100 parts by mass of the curable resin. When the content of the thixotropic agent in the curable resin composition for electronic materials is 0.1 parts by mass or more, the curable resin composition for electronic materials can be effectively imparted with thixotropy. In addition, when the content of the thixotropic agent in the curable resin composition for electronic materials is 200 parts by mass or less, the curable resin composition for electronic materials has an appropriate viscosity, and the handleability of the curable resin composition for electronic materials is improved.

Examples of ultraviolet absorbers include benzotriazole-based ultraviolet absorbers and benzophenone-based ultraviolet absorbers, with benzotriazole-based ultraviolet absorbers being preferred. The content of the ultraviolet absorber in the curable resin composition for electronic materials is preferably 0.1 parts by mass or more per 100 parts by mass of the curable resin. The content of the ultraviolet absorber in the curable resin composition for electronic materials is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, per 100 parts by mass of the curable resin.

Examples of antioxidants include hindered phenol-based antioxidants, monophenol-based antioxidants, bisphenol-based antioxidants, and polyphenol-based antioxidants, and hindered phenol-based antioxidants are preferred. The content of the antioxidant in the curable resin composition for electronic materials is preferably 0.1 parts by mass or more, and more preferably 0.3 parts by mass or more, per 100 parts by mass of the curable resin. The content of the antioxidant in the curable resin composition for electronic materials is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of the curable resin.

[Light stabilizer]
The curable resin composition for electronic materials preferably contains a hindered amine-based light stabilizer. The hindered amine-based light stabilizer can provide a curable resin composition for electronic materials that can maintain excellent rubber elasticity for a long period of time after curing.

Examples of hindered amine light stabilizers include a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidylsebacate, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, dibutylamine/1,3,5-triazine/N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N-(2,2,6,6 poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl)imino}], and a polycondensate of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol.

Preferred examples of the hindered amine light stabilizer include NOR-type hindered amine light stabilizers. The NOR-type hindered amine light stabilizer can provide a curable resin composition for electronic materials in which the decrease in rubber elasticity over time after curing is suppressed.

NOR-type hindered amine light stabilizers have a NOR structure in which an alkyl group (R) is bonded to a nitrogen atom (N) contained in a piperidine ring skeleton via an oxygen atom (O). The number of carbon atoms in the alkyl group in the NOR structure is preferably 1 to 20, more preferably 1 to 18, and particularly preferably 18. Examples of the alkyl group include linear alkyl groups, branched alkyl groups, and cyclic alkyl groups (saturated alicyclic hydrocarbon groups).

Examples of linear alkyl groups include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, and n-decyl groups. Examples of branched alkyl groups include isopropyl, isobutyl, sec-butyl, and tert-butyl. Examples of cyclic alkyl groups (saturated alicyclic hydrocarbon groups) include cyclopentyl, cyclohexyl, and cyclooctyl groups. In addition, the hydrogen atoms constituting the alkyl groups may be substituted with halogen atoms (e.g., fluorine, chlorine, and bromine atoms) or hydroxyl groups.

Examples of NOR type hindered amine light stabilizers include the hindered amine light stabilizers represented by the following formula (I):

When using a NOR-type hindered amine light stabilizer, it is preferable to use the NOR-type hindered amine light stabilizer in combination with a benzotriazole-based UV absorber or a triazine-based UV absorber. This makes it possible to provide a curable resin composition for electronic materials in which the decrease in rubber elasticity over time after curing is more significantly suppressed.

The content of the hindered amine-based light stabilizer in the curable resin composition for electronic materials is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, per 100 parts by mass of the curable resin. The content of the hindered amine-based light stabilizer in the curable resin composition for electronic materials is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, per 100 parts by mass of the curable resin.

[Curable resin composition for electronic materials]
The curable resin composition for electronic materials can be produced by mixing a curable resin, a feldspar, a phosphorus-based compound, and additives added as necessary. The curable resin composition for electronic materials may be in the form of a suspension or emulsion by being suspended or emulsified in an aqueous solvent. The curable resin composition for electronic materials may be in the form of a solution by being dissolved in a solvent. Examples of the aqueous solvent include alcohols such as ethyl alcohol, methyl alcohol, and isopropyl alcohol, and water. Examples of the solvent include xylene, toluene, and acetone.

By using feldspars and phosphorus-based compounds in combination, the curable resin composition for electronic materials has excellent flame retardancy when cured.

Furthermore, since the viscosity of the curable resin composition for electronic materials is kept low, it has excellent coatability and can be precisely coated on the narrow areas of electronic materials that are becoming increasingly smaller. Therefore, the curable resin composition for electronic materials can be precisely coated on the specified areas of electronic materials without affecting the performance of the electronic materials, and can impart excellent flame retardancy or improve the flame retardancy of the electronic materials and/or electronic devices that contain the electronic materials.

In particular, when the curable resin composition for electronic materials contains a hydrolysis-crosslinkable silicone polymer, feldspars, and a phosphorus-based compound, the hydrolysis-crosslinkable silicone polymer expands quickly in the early stages of combustion during a fire, further reducing the spread of fire caused by the burning of the electronic material. Furthermore, the curable resin composition for electronic materials is provided with even better expandability, and the combustion residue of the cured product of the curable resin composition for electronic materials can be provided with even better hardness. Thus, the curable resin composition for electronic materials can provide even better flame retardancy or further improve the flame retardancy of electronic materials and/or electronic devices containing electronic materials.

In addition, electronic devices are not limited to, but examples include car navigation systems, mobile phones, smartphones, game consoles, digital cameras, televisions, DVD players, electronic dictionaries, calculators, hard disk recorders, personal computers, video cameras, printers, liquid crystal displays, plasma displays, radios, and electronic musical instruments.

Electronic devices are becoming smaller and lighter, and the electronic materials that make up the devices are also becoming smaller. Examples of such electronic materials include, but are not limited to, printed wiring boards, light-emitting diodes (LEDs), light-emitting diode mounting boards, flexible copper-clad laminates, bonding sheets, touch panels, and sensor substrates.

The method for applying the curable resin composition for electronic materials to a specified application location of the electronic material is not particularly limited, and examples include a coating method using a brush and a coating method using a known coating tool.

The viscosity of the curable resin composition for electronic materials is preferably 500 mPa·s or more, more preferably 1000 mPa·s or more, and more preferably 3000 mPa·s or more. The viscosity of the curable resin composition for electronic materials is preferably 200,000 mPa·s or less, more preferably 100,000 mPa·s or less, and more preferably 50,000 mPa·s or less. The viscosity of the curable resin composition for electronic materials is a value measured using a BH type viscometer under conditions of 23°C, 10 rpm, and rotor No. 5.

The curable resin composition for electronic materials applied to the electronic material produces a cured product by curing the curable resin. The curing of the curable resin may be carried out in a known manner (e.g., by supplying moisture, irradiating light such as ultraviolet light, heating, etc.) depending on the type of curable resin.

The cured product of the curable resin composition for electronic materials expands when burned due to the heat of a fire, producing a combustion residue with excellent hardness. This combustion residue remains stably disposed at the applied area even in the event of a fire, demonstrating excellent flame retardancy.

The curable resin composition for electronic materials of the present invention has excellent coatability due to its low viscosity, and can be applied accurately and easily to desired locations on electronic materials without impairing the functionality of the electronic materials.

The cured product produced by curing the curable resin composition for electronic materials expands due to heat from a fire or the like and produces a combustion residue with high hardness. The combustion residue of the cured product expands to cover the electronic material or an electronic device containing the electronic material, thereby protecting the electronic material and the like from a fire and inhibiting the spread of the fire.

Furthermore, the combustion residue of the cured product of the curable resin composition for electronic materials has excellent hardness, and therefore remains stable at the location where the curable resin composition for electronic materials is applied, thereby imparting excellent flame retardancy to the electronic material or improving the flame retardancy of the electronic material.

The present invention will be explained in more detail below using examples, but the present invention is not limited to these.

The following raw materials were used in the production of the curable resin compositions for electronic materials in the examples and comparative examples.

[Hardening resin]
Polyalkylene oxide having a hydrolyzable silyl group (polyalkylene oxide having a main chain skeleton made of polypropylene oxide and a dimethoxysilyl group at the end of the main chain, number average molecular weight: 38,000, manufactured by Kaneka Corporation, product name "Exestar S303H")
Hydrolytically crosslinkable silicone polymer 1 (manufactured by Momentive Performance Materials Japan, LLC, product name "XR31-B2230", hydrolyzable group: alkoxy group, alkoxy group content: 5 mol%, phenyl group content: 30 mol%, methyl group content: 65 mol%, viscosity at 25°C: 16 Pa·s, for silicon atoms constituting a linear main chain, each bond not used to constitute the main chain is bonded to a methyl group, a phenyl group, or an alkoxy group, and some silicon atoms are bonded to methyl groups and phenyl groups)
Hydrolytically crosslinkable silicone polymer 2 (manufactured by Momentive Performance Materials Japan, product name "XR31-B2733", hydrolyzable group: alkoxy group, alkoxy group content: 5 mol%, methyl group content: 95 mol%, viscosity at 25°C: 250 Pa·s, for silicon atoms constituting a linear main chain, each bond not used to form the main chain is bonded to a methyl group or an alkoxy group.)

[Feldspars]
Feldspar (nepheline syenite, average particle size: 5 μm, product name "Nesper" manufactured by Shiraishi Calcium Co., Ltd.)

[Phosphorus compounds]
Ammonium polyphosphate (Clariant product name "AP462")
・Aluminum phosphite

[Titanium oxide]
Titanium oxide (manufactured by Ishihara Sangyo Kaisha, product name "CR-90", average particle size: 0.25 μm)

[Carbon black]
・Carbon black (manufactured by Ishihara Sangyo Kaisha, product name "SG-103")

[Calcium carbonate]
Colloidal calcium carbonate (manufactured by Shiraishi Calcium Co., Ltd., product name "CCR", average particle size of primary particles: 0.08 μm)

[Glass frit]
Glass frit (phosphate glass, " _VY0144 " manufactured by Nippon Frit Co., Ltd., main components: _P2O5 , _AI2O3 and _R2O , _where R is an alkali metal atom, softening point: 404°C)

Silanol condensation catalyst (dibutyltin diacetylacetonate, product name "U220H" manufactured by Nitto Kasei Co., Ltd.)
Dehydrating agent (vinyltrimethoxysilane, product name "KBM1003" manufactured by Shin-Etsu Chemical Co., Ltd.)
Aminosilane coupling agent (N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, product name KBM-603, manufactured by Shin-Etsu Chemical Co., Ltd.)

(Examples 1 to 10, Comparative Examples 1 to 3)
The curable resin, feldspar, phosphorus-based compound, titanium oxide, carbon black, colloidal calcium carbonate, glass frit, silanol condensation catalyst, dehydrating agent and aminosilane coupling agent were mixed in the amounts shown in Table 1 using a planetary mixer under a vacuum atmosphere for 60 minutes until the mixture became uniform, thereby obtaining a curable resin composition for electronic materials.

The flame retardancy, post-combustion hardness, coatability, expansion ratio, and viscosity of the obtained curable resin composition for electronic materials were measured as described below, and the results are shown in Table 1.

(Flame retardance)
A test sheet with a thickness of 1.5 mm was prepared using the curable resin composition for electronic materials and aged for 7 days at 23° C. The test sheet was cut into a flat rectangular shape with a length of 15 mm, a width of 130 mm, and a thickness of 1.5 mm to prepare five test pieces.

The test was conducted based on the UL94V-0 standard. Specifically, one lateral end of the test specimen was held by a clamp and the test specimen was hung vertically. Next, the other lateral end (lower end) of the vertically hung test specimen was exposed to a flame for 3 seconds using a burner, and after the burner was temporarily removed from the test specimen, the other lateral end of the test specimen was exposed to a flame for 3 seconds using a burner to measure flame retardancy. Evaluation was conducted based on the following criteria.
A: For each test piece, the afterflame time after two flame contacts was within 10 seconds, and the total afterflame time for the five test pieces was within 50 seconds. Furthermore, no test piece continued to glow for 30 seconds or more after the second flame contact.
B: For each test piece, the afterflame time after two flame contacts was within 10 seconds, and the total afterflame time of the five test pieces exceeded 50 seconds. Furthermore, no test piece continued to glow for 30 seconds or more after the second flame contact.
C: For each test piece, the afterflame time after two flame contacts was within 10 seconds, and the total afterflame time of five test pieces exceeded 50 seconds. Furthermore, there was a test piece that continued to glow for 30 seconds or more after the second flame contact.
D: All test pieces were burned down to the clamp, etc. None of A to C were applicable.

(Post-combustion hardness)
The curable resin composition for electronic materials was cured for one week in an atmosphere of 23°C and 50% relative humidity to produce a cured product. 100 g of the cured product of the curable composition was prepared as a test piece. The test piece was fed into a combustion furnace. The test piece was burned in the combustion furnace at 600°C for 30 minutes. The combustion residue obtained by burning the test piece was immediately left in an atmosphere of 23°C for one hour after the end of the combustion. Next, the rubber elasticity of the combustion residue was measured by Shore A using an A-type durometer at a measurement temperature of 23°C in accordance with JIS K6253. Evaluation was performed based on the following criteria.
A: The rubber hardness was 30 or more.
B: The rubber hardness was 20 or more and less than 30.
C: The rubber hardness was 10 or more and less than 20.
D: The rubber hardness was less than 10 or was too brittle to be measured with an A-type durometer.

(Coatability)
The curable resin composition for electronic materials was filled into a volumetric syringe and attached to an air dispenser (Performus X100, manufactured by Nordson Corporation) to measure the coatability. Substrates on which coating grooves with widths of 0.5 mm, 1.0 mm, and 2.0 mm were formed were prepared. The coating grooves with widths of 0.5 mm, 1.0 mm, and 2.0 mm were referred to as "coating grooves 1 to 3" in order.

The curable resin composition for electronic materials was applied to each of the coating grooves having widths of 0.5 mm, 1.0 mm, and 2.0 mm by operating an air dispenser under conditions of 23° C. and an air pressure of 0.6 MPa. Evaluation was performed based on the following criteria.
A: All of coating grooves 1 to 3 were neatly coated. B: Coating grooves 2 and 3 were neatly coated, but coating groove 1 was not neatly coated.
C: Coating groove 3 was coated neatly, but coating grooves 1 and 2 were not coated neatly.
D: None of coating grooves 1 to 3 could be neatly coated.

(Expansion ratio)
A test piece was prepared by curing the curable resin composition for electronic materials. The test piece was a flat square sheet (length: 2 cm, width: 2 cm, thickness: 2 mm). The test piece was placed in an electric furnace previously kept at 600°C, and the test piece was heated and burned for 10 minutes, and the combustion residue of the test piece was taken out of the electric furnace. The expansion ratio was calculated based on the following formula.
Expansion ratio (%) = 100 x volume of combustion residue / volume of test piece before combustion

(viscosity)
The viscosity of the curable resin composition for electronic materials was measured using a BH type viscometer under conditions of 23° C., 10 rpm, and rotor No. 5.

The combustion residue of the cured product produced by curing the curable resin composition for electronic materials of the present invention expands and covers the electronic materials or electronic devices containing the electronic materials, thereby protecting the electronic materials, etc. from fire and inhibiting the spread of fire.

CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority based on Japanese Patent Application No. 2022-050856, filed on March 25, 2022, the disclosure of which is incorporated herein by reference in its entirety.

Claims (8)

A curable resin composition for electronic materials, comprising: a curable resin; at least one of feldspar and feldsparoid as a feldspar; and a phosphorus-based compound, the phosphorus-based compound containing ammonium polyphosphate. A curable resin composition for electronic materials, comprising: a curable resin; at least one of feldspar and feldsparoid as a feldspar; and a phosphorus-based compound, and further comprising titanium oxide. A curable resin composition for electronic materials, comprising: a curable resin; at least one of feldspar and feldsparoid as a feldspar; and a phosphorus-based compound, and further comprising a glass frit. A curable resin composition for electronic materials, comprising: a curable resin; at least one of feldspar and feldsparoid as a feldspar; and a phosphorus-based compound, wherein the curable resin contains a polyalkylene oxide having a hydrolyzable silyl group. A curable resin composition for electronic materials, comprising: a curable resin; at least one of feldspar and feldsparoid as a feldspar; and a phosphorus-based compound, wherein the curable resin contains a hydrolysis-crosslinkable silicone-based polymer. The curable resin composition for electronic materials according to claim 5, characterized in that the hydrolysis-crosslinkable silicone polymer contains silicon atoms to which methyl groups or phenyl groups are bonded. The curable resin composition for electronic materials according to claim 5, characterized in that the hydrolytically crosslinkable silicone polymer contains silicon atoms to which methyl groups and phenyl groups are bonded. The curable resin composition for electronic materials according to any one of claims 1 to 7, characterized in that the ratio of the content of the feldspars to the content of the phosphorus-based compound (mass of feldspars/mass of phosphorus-based compound) is 0.05 to 1.00.