JP7268256B1 - Epoxy resin, curable resin composition, and cured product thereof - Google Patents

Abstract

The present invention provides epoxy resins and curable resin compositions whose cured products are excellent in heat resistance, flame retardancy and tracking resistance. An epoxy resin represented by the following formula (1). [Formula 1] TIFF0007268256000010.tif86160 (In formula (1), n is the average number of repetitions, and 1<n<20.)

Description

TECHNICAL FIELD The present invention relates to an epoxy resin having a specific structure, a curable resin composition, and a cured product thereof.

Epoxy resin is excellent in electrical properties (dielectric constant/dielectric loss tangent, insulating properties), mechanical properties, adhesive properties, and thermal properties (heat resistance, etc.). It is widely used in the fields of electrical and electronic materials, structural materials, adhesives, and paints.

In recent years, in the electrical and electronic fields, performance improvements such as flame retardancy, moisture resistance, adhesion, and dielectric properties of resin compositions, high purity, low viscosity for high filling of fillers (inorganic or organic fillers) There is a demand for further improvement in various properties such as improved reactivity in order to shorten the molding cycle (Patent Document 1). In addition, as structural materials, lightweight materials with excellent mechanical properties are required for use in aerospace materials, leisure and sports equipment, and the like. Especially in the field of semiconductor encapsulation, substrates (substrates themselves or their peripheral materials) have become more complicated with thinning, stacking, systematization, and three-dimensionalization in accordance with the transition of semiconductors. Required properties such as heat resistance and high fluidity are required.

Furthermore, with the development of automatic driving technology and the expansion of the electric vehicle market, various power supply boards and inverter boards are required to have tracking resistance (CTI resistance: Comparative Tracking Index resistance), which has not been required for FR-4 boards. It has become so.

Generally, it is known that an epoxy resin having a structure that easily carbonizes has poor tracking resistance, while an epoxy resin that has a structure that easily carbonizes is known to have high flame retardancy.

An aromatic cross-linking unit is sometimes introduced for the purpose of improving the heat resistance of the resin composition, but in this case, since the main skeleton is aromatic, it is easily carbonized, and the tracking resistance deteriorates. Further, when the heat resistance is improved by increasing the molecular weight, the thermal decomposition temperature rises due to the increase in the molecular weight, and the tracking resistance deteriorates. In other words, there is a trade-off relationship between heat resistance and tracking resistance (Non-Patent Document 1).

Against this background, there is a demand for the development of materials that exhibit high heat resistance as well as flame retardancy and tracking resistance.

In particular, in applications such as photovoltaic power generation, wind power generation, and EV, tracking resistance is considered important, and a comparative tracking index (CTI) exceeding 600 is required.

JP 2015-147854 A Development of Highly Reliable, Environmentally Responsive Multilayer Materials (by Sumitomo Bakelite Co., Ltd., Research Department, Circuit Materials Research Laboratory)

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an epoxy resin and a curable resin composition whose cured product is excellent in heat resistance, flame retardancy and tracking resistance.

The present inventors have completed the present invention as a result of intensive research to solve the above problems. That is, the present invention relates to the following [1] to [6]. In the present application, "(numerical value 1) to (numerical value 2)" indicate that upper and lower limits are included.
[1]
An epoxy resin represented by the following formula (1).

(In formula (1), n is the average number of repetitions, and 1<n<20.)
[2]
An epoxy resin represented by the following formula (2).

(In formula (2), n is the average number of repetitions, and 1<n<20.)
[3]
The epoxy resin according to the preceding item [1] or [2], which has a weight average molecular weight of 400 to 3000 as determined by gel permeation chromatography (GPC).
[4]
A curable resin composition containing the epoxy resin according to any one of [1] to [3] above.
[5]
The curable resin composition according to [4] above, further comprising a curing accelerator.
[6]
A cured product obtained by curing the curable resin composition according to [4] or [5] above.

TECHNICAL FIELD The present invention relates to an epoxy resin having a specific structure, a curable resin composition, and a cured product thereof, and the cured product has tracking resistance, heat resistance, and flame retardancy.
Therefore, the present invention can be applied to insulating materials for electric and electronic parts (such as highly reliable semiconductor sealing materials), laminated boards (printed wiring boards, build-up boards, etc.), various composite materials such as CFRP, adhesives, paints, etc. Useful.

1 shows a GPC chart of Synthesis Example 1. FIG. 2 shows a GPC chart of Synthesis Example 2. FIG. 1 shows a GPC chart of Synthesis Example 3. FIG. 4 shows a GPC chart of Synthesis Example 4. FIG. 1 shows a GPC chart of bisphenol A novolak resin. 1 shows a GPC chart of Synthesis Example 5. FIG.

The present invention will be described in detail below.

The epoxy resin of the present invention is represented by the following formula (1).

(In formula (1), n is the average number of repetitions, and 1<n<20.)

The compound represented by the formula (1) has excellent tracking resistance, heat resistance, and flame retardancy by adopting a molecular design that introduces a large number of isopropylidene structures that are difficult to carbonize while maintaining the density of the aromatic ring. .

In the formula (1), the value of n can be calculated from the number average molecular weight determined by gel permeation chromatography (GPC, detector: RI) or from the area ratio of each separated peak. More preferably, the value of n is 1<n<15, and most preferably 1<n<10.

The weight average molecular weight by GPC measurement is preferably 400-4500, more preferably 500-4000, still more preferably 1000-3000. When the weight average molecular weight is less than 400, it is difficult to obtain the effect of improving heat resistance by increasing the molecular weight. In addition, when the weight average molecular weight is more than 4500, purification by water washing etc. becomes difficult, and when used as a semiconductor encapsulant etc., the viscosity is too high to ensure fluidity and it is difficult to fill between wirings. In addition, it becomes difficult to ensure the fluidity of the prepreg in substrate applications, and the embedding of wiring is impaired.

The epoxy resin represented by the above formula (1) is usually in the form of a semi-solid to solid resin at room temperature, and its softening point is preferably 100° C. or lower, more preferably 90° C. or lower. If the softening point is higher than 100° C., the viscosity is high and the fiber impregnation property is lowered during prepreg production. The epoxy equivalent is preferably 200-1000 g/eq, more preferably 280-800 g/eq, particularly preferably 290-700 g/eq, and most preferably 295-600 g/eq. Also, the ICI viscosity at 150° C. is preferably 0.01 to 1.2 Pa·s, more preferably 0.01 to 1.0 Pa·s, still more preferably 0.01 to 0.01 Pa·s. 8 Pa·s. If it is said range, when it is set as a sealing material composition, the fluidity|liquidity suitable as a sealing material can be ensured.

An example of a preferable structure of the epoxy resin represented by the formula (1) is an epoxy resin represented by the following formula (2).

(In formula (2), n is the average number of repetitions, and 1<n<20.)

A preferred range of n in the formula (2) is the same as in the formula (1).

The epoxy resin represented by the formula (2) has low crystallinity, and can reduce the solvent solubility and the risk of crystal precipitation in the solvent.

Although the method for producing the epoxy resin of the present invention is not particularly limited, it can be obtained, for example, by adding or ring-closing a phenol resin represented by the following formula (3) and epihalohydrin in the presence of a solvent and a catalyst. The amount of epihalohydrin to be used is generally 1.0 to 20.0 mol, preferably 1.5 to 10.0 mol, per 1 mol of phenolic hydroxyl group of the phenolic resin.

(In formula (3), n is the average number of repetitions, and 1<n<20.)

A preferred range of n in the formula (3) is the same as in the formula (1).

The phenol resin represented by the formula (3) preferably has a weight average molecular weight of 400 to 4,500, more preferably 500 to 4,000, and still more preferably 1,000 to 3,000 as measured by GPC. A preferable range of hydroxyl equivalent is 100 to 300 g/eq, more preferably 120 to 250 g/eq, and still more preferably 120 to 230 g/eq. The preferred range of melt viscosity (ICI viscosity) at 150° C. is 0.01 to 3.0 Pa·s, more preferably 0.02 to 2.0 Pa·s, and still more preferably 0.02 to 1.5 Pa·s. is. A preferred softening point range is 40 to 180°C, more preferably 50 to 150°C, and even more preferably 60 to 140°C. When the softening point is less than 40°C, it is difficult to obtain the effect of improving the heat resistance by increasing the molecular weight. In addition, when the softening point is higher than 180°C, it becomes difficult to purify by washing with water. In addition, it becomes difficult to secure the fluidity of the prepreg in the substrate application, and the embedding property of the wiring is impaired.

Examples of alkali metal hydroxides that can be used in the epoxidation reaction include sodium hydroxide and potassium hydroxide. The alkali metal hydroxide may be solid or its aqueous solution may be used. When an aqueous solution is used, an aqueous solution of the alkali metal hydroxide is continuously added to the reaction system, and water and epihalohydrin are continuously distilled off under reduced pressure or normal pressure, and the water is removed by liquid separation. Alternatively, epihalohydrin may be continuously returned to the reaction system. The amount of the alkali metal hydroxide to be used is generally 0.9 to 2.5 mol, preferably 0.95 to 1.5 mol, per 1 mol of the phenolic hydroxyl group of the phenolic resin. If the amount of alkali metal hydroxide used is too small, the reaction will not proceed sufficiently. On the other hand, excessive use of alkali metal hydroxide exceeding 2.5 mol per 1 mol of phenolic hydroxyl groups in the phenolic resin leads to unnecessary waste by-production.

A quaternary ammonium salt such as tetramethylammonium chloride, tetramethylammonium bromide or trimethylbenzylammonium chloride may be added as a catalyst to promote the above reaction. The amount of the quaternary ammonium salt to be used is usually 0.1 to 15 g, preferably 0.2 to 10 g, per 1 mol of the phenolic hydroxyl group of the phenolic resin. If the amount used is too small, a sufficient reaction acceleration effect cannot be obtained, and if the amount used is too large, the amount of quaternary ammonium salt remaining in the epoxy resin increases, which may cause deterioration in electrical reliability.

During the epoxidation reaction, it is preferable to add an alcohol such as methanol, ethanol and isopropyl alcohol, and an aprotic polar solvent such as dimethylsulfone, dimethylsulfoxide, tetrahydrofuran and dioxane to proceed with the reaction. When alcohols are used, the amount used is generally 2-50% by weight, preferably 4-20% by weight, based on the amount of epihalohydrin used. When an aprotic polar solvent is used, its amount is generally 5-100% by weight, preferably 10-80% by weight, based on the amount of epihalohydrin used. The reaction temperature is usually 30-90°C, preferably 35-80°C. The reaction time is usually 0.5 to 100 hours, preferably 1 to 30 hours.
After completion of the reaction, epihalohydrin, solvent and the like are removed from the reaction product under heating and reduced pressure after washing with water or without washing with water. In order to further reduce the hydrolyzable halogen content of the epoxy resin, the recovered epoxy resin is dissolved in a solvent such as toluene or methyl isobutyl ketone, and an aqueous solution of an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide is added. can also be used to ensure ring closure. In this case, the alkali metal hydroxide is used in an amount of usually 0.01 to 0.3 mol, preferably 0.05 to 0.2 mol, per 1 mol of the phenolic hydroxyl group of the phenolic resin used for glycidylation. The reaction temperature is generally 50-120° C., and the reaction time is generally 0.5-24 hours. After completion of the reaction, the salt produced is removed by filtration, washing with water, etc., and the solvent is distilled off under heating and reduced pressure to obtain the epoxy resin of the present invention.

Here, a method for producing the phenolic resin represented by the formula (3) will be described. The method for producing the phenol resin represented by the formula (3) is not particularly limited. α,α',α'-tetramethylbenzenedifluoride, α,α,α',α'-tetramethylbenzenedichloride, α,α,α',α'-tetramethylbenzenedibromide, α,α,α A desired phenol resin can be obtained by reacting a halogen compound such as ',α'-tetramethylbenzene diiodide) in a solvent under an acid catalyst. In this case, it is preferable to use a material substituted at the meta position as the material. Specifically, in addition to α,α,α',α'-tetramethyl-1,3-benzenedimethanol and 1,3-diisopropenylbenzene, α,α,α',α'-tetramethyl- 1,3-benzenedifluoride, α,α,α',α'-tetramethyl-1,3-benzenedichloride, α,α,α',α'-tetramethyl-1,3-benzenedibromide, α , α,α',α'-tetramethyl-1,3-benzenediaiodide. By using a raw material having a substitution position at the meta position, the crystallinity of the raw material and the compound after synthesis can be reduced, and the solvent solubility and the risk of crystal precipitation in the solvent can be reduced. In addition to hydrochloric acid, phosphoric acid, sulfuric acid, formic acid, p-toluenesulfonic acid, and methanesulfonic acid as acid catalysts during synthesis, Lewis acids such as aluminum chloride and zinc chloride, activated clay, acid clay, white carbon, zeolite, A solid acid such as silica alumina, an acidic ion exchange resin, or the like can be used. These may be used alone or in combination of two or more. The amount of the catalyst used is the reaction substrate bisphenol A and α,α,α',α'-tetramethylbenzenedimethanol (or diisopropenylbenzene, or α,α,α',α'-tetramethylbenzene Difluoride, α,α,α',α'-tetramethylbenzene dichloride, α,α,α',α'-tetramethylbenzene dibromide, α,α,α',α'-tetramethylbenzene diiodide 0.01 to 10% by weight, preferably 0.1 to 5% by weight, based on the total weight of the halogen compounds such as If the amount of catalyst used is too large, bisphenol A may decompose, and if it is too small, the progress of the reaction may be slowed down. Examples of solvents to be used include aromatic solvents such as toluene and xylene, aliphatic solvents such as cyclohexane and n-hexane, ethers such as diethyl ether and diisopropyl ether, ester solvents such as ethyl acetate and butyl acetate, and methyl isobutyl. Water-insoluble solvents such as ketone-based solvents such as ketones and cyclopentanone are included, but are not limited to these, and two or more kinds may be used in combination. An aprotic polar solvent can also be used in combination with the water-insoluble solvent. Examples thereof include dimethylsulfone, dimethylsulfoxide, dimethylformamide, dimethylacetamide, 1,3-dimethyl-2-imidazolidinone, N-methylpyrrolidone and the like, and two or more of them may be used in combination. When an aprotic polar solvent is used, it is preferable to use one having a boiling point higher than that of the water-insoluble solvent used in combination. The reaction temperature is preferably 80 to 150°C, more preferably 90 to 140°C, even more preferably 100 to 130°C. If the reaction temperature is too high, bisphenol A may decompose, and if the reaction temperature is too low, the reaction may not proceed sufficiently. Since water is by-produced when an alcohol-based raw material is used, it is removed from the system while being azeotropically distilled with the solvent when the temperature is raised. After completion of the reaction, the acidic catalyst is neutralized with an alkaline aqueous solution or the like, and a non-water-soluble organic solvent is added to the oil layer, and washing is repeated until the wastewater becomes neutral, and then the solvent is removed under heating and reduced pressure. When activated clay or ion exchange resin is used, the reaction solution is filtered to remove the catalyst after completion of the reaction.

An example of a preferable structure of the phenol resin represented by the formula (3) is a phenol resin represented by the following formula (4).

(In formula (4), n is the average number of repetitions, and 1<n<20.)

A preferred range of n in the formula (4) is the same as in the formula (1).

The curable resin composition of the present invention is described below.
In the curable resin composition of the present invention, the epoxy resin represented by formula (1) can be used alone or in combination with other epoxy resins. When used in combination, the ratio of the epoxy resin represented by the formula (1) to the total epoxy resin is preferably 10 to 98% by weight, more preferably 20 to 95% by weight, and still more preferably 30 to 95% by weight. % by weight. By setting the amount to be added to 10% by weight or more, tracking resistance can be improved, and high heat resistance and flame retardancy can be exhibited.

Specific examples of other epoxy resins that can be used in combination with the epoxy resin of the present invention include bisphenols (bisphenol A, bisphenol F, bisphenol S, biphenol, bisphenol AD, etc.) or phenols (phenol, alkyl-substituted phenol, aromatic-substituted Phenol, naphthol, alkyl-substituted naphthol, dihydroxybenzene, alkyl-substituted dihydroxybenzene, dihydroxynaphthalene, etc.) and various aldehydes (formaldehyde, acetaldehyde, alkylaldehyde, benzaldehyde, alkyl-substituted benzaldehyde, hydroxybenzaldehyde, naphthaldehyde, glutaraldehyde, phthalaldehyde, croton aldehyde, cinnamaldehyde, etc.); the above phenols and various diene compounds (dicyclopentadiene, terpenes, vinylcyclohexene, norbornadiene, vinylnorbornene, tetrahydroindene, divinylbenzene, divinylbiphenyl, diisopropenylbiphenyl, butadiene , isoprene, etc.); polycondensates of the phenols and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone, benzophenone, etc.); the phenols and aromatic dimethanols (benzenedimethanol, biphenyl dimethanol, etc.); polycondensation products of the above phenols and aromatic dichloromethyls (α,α'-dichloroxylene, bischloromethylbiphenyl, etc.); the above phenols and aromatic bisalkoxymethyls (bismethoxymethylbenzene, bismethoxymethylbiphenyl, bisphenoxymethylbiphenyl, etc.) polycondensates; polycondensates of the above bisphenols and various aldehydes or glycidyl ether-based epoxy resins obtained by glycidylating alcohols, alicyclic Epoxy resins, glycidyl amine-based epoxy resins, glycidyl ester-based epoxy resins, and the like can be mentioned, but the epoxy resins are not limited to these as long as they are commonly used epoxy resins. These may be used independently and may use 2 or more types.

Curing agents that can be used in the curable resin composition of the present invention include amine-based curing agents, acid anhydride-based curing agents, amide-based curing agents, and phenol-based curing agents. Specific examples of usable curing agents include o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 4,4′-diaminodiphenylsulfone, 3,4′-diaminodiphenylsulfone, 3,3′-diamino Diphenylsulfone, 2,2'-diaminodiphenylsulfone, diethyltoluenediamine, dimethylthiotoluenediamine, diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-diethyl-4,4' -diaminodiphenylmethane, 4,4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane, 4,4'-diamino-3,3',5,5'-tetramethyldiphenylmethane, 4,4 '-diamino-3,3',5,5'-tetraethyldiphenylmethane, 4,4'-diamino-3,3',5,5'-tetraisopropyldiphenylmethane, 4,4'-methylenebis(N-methylaniline) , bis(aminophenyl)fluorene, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 2,2′-bis[4-(4-aminophenoxy)phenyl]propane, bis[4-(4- aminophenoxy)phenyl]sulfone, 1,3′-bis(4-aminophenoxy)benzene, 1,4′-bis(4-aminophenoxy)benzene, 1,4′-bis(4-aminophenoxy)biphenyl, 4 ,4'-(1,3-phenylenediisopropylidene)bisaniline, 4,4'-(1,4-phenylenediisopropylidene)bisaniline, naphthalenediamine, benzidine, dimethylbenzidine, International Publication No. 2017/170551 synthesis example 1 and aromatic amine compounds described in Synthesis Example 2, 1,3-bis(aminomethyl)cyclohexane, isophoronediamine, 4,4'-methylenebis(cyclohexylamine), norbornanediamine, ethylenediamine, propane Aliphatic amines such as diamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, dimerdiamine, and triethylenetetramine are included, but are not limited thereto, and can be suitably used depending on the properties desired to be imparted to the composition. can. It is preferable to use an aromatic amine in order to secure a pot life, and it is preferable to use an aliphatic amine in order to impart quick curing. By using an amine-based compound containing a bifunctional component as a main component as a curing agent, a highly linear network can be constructed during the curing reaction, and particularly excellent toughness can be expressed. Also, amide compounds such as polyamide resin synthesized from dicyandiamide, dimer of linolenic acid and ethylenediamine; phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydro Acid anhydride compounds such as phthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride; bisphenols (bisphenol A, bisphenol F, bisphenol S, biphenol, bisphenol AD, etc.) or phenols ( Phenol, alkyl-substituted phenol, aromatic-substituted phenol, naphthol, alkyl-substituted naphthol, dihydroxybenzene, alkyl-substituted dihydroxybenzene, dihydroxynaphthalene, etc.) and various aldehydes (formaldehyde, acetaldehyde, alkylaldehyde, benzaldehyde, alkyl-substituted benzaldehyde, hydroxybenzaldehyde, naphtho aldehyde, glutaraldehyde, phthalaldehyde, crotonaldehyde, cinnamaldehyde, etc.), or the above phenols and various diene compounds (dicyclopentadiene, terpenes, vinylcyclohexene, norbornadiene, vinylnorbornene, tetrahydroindene, divinylbenzene , divinylbiphenyl, diisopropenylbiphenyl, butadiene, isoprene, etc.), or polycondensates of the above phenols and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone, benzophenone, etc.), or the above phenols and aromatic dimethanols (benzenedimethanol, biphenyldimethanol, etc.), or polycondensates of the phenols and aromatic dichloromethyls (α,α'-dichloroxylene, bischloromethylbiphenyl, etc.) Condensates, or polycondensates of the phenols and aromatic bisalkoxymethyls (bismethoxymethylbenzene, bismethoxymethylbiphenyl, bisphenoxymethylbiphenyl, etc.), or polycondensates of the bisphenols and various aldehydes, and Phenolic compounds such as modified products thereof; imidazole, trifluoroborane-amine complexes, guanidine derivatives, etc., but not limited to these.

The amount of the curing agent used in the curable resin composition of the present invention is preferably 0.5 to 1.5 equivalents, particularly preferably 0.6 to 1.2 equivalents, per equivalent of the epoxy group of the epoxy resin. Good cured physical properties can be obtained by setting the equivalent weight to 0.5 to 1.5.

When performing a curing reaction using the curing agent, a curing accelerator may be used in combination. Curing accelerators that can be used include, for example, imidazoles such as 2-methylimidazole, 2-ethylimidazole, 2-phenylimidazole, 2-ethyl-4-methylimidazole, 2-(dimethylaminomethyl)phenol, triethylenediamine, Tertiary amines such as triethanolamine, 1,8-diazabicyclo(5,4,0)undecene-7, triphenylphosphine, tri(toluyl)phosphine, tetraphenylphosphonium bromide, tetraphenylphosphonium tetraphenylborate, etc. Phosphines and phosphonium compounds, organic phosphines such as tributylphosphine, metal compounds such as tin octylate, tetraphenylphosphonium/tetraphenylborate, tetrasubstituted phosphonium/tetrasubstituted borate such as tetraphenylphosphonium/ethyltriphenylborate, 2- Tetraphenylboron salts such as ethyl-4-methylimidazole/tetraphenylborate, N-methylmorpholine/tetraphenylborate, carboxylic acid compounds such as benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, naphthoic acid, salicylic acid, etc. mentioned. A carboxylic acid compound such as salicylic acid is preferred from the viewpoint of promoting the curing reaction between the amine compound and the epoxy resin. The curing accelerator is used in an amount of 0.01 to 15 parts by weight based on 100 parts by weight of the epoxy resin.

Furthermore, an inorganic filler can be added to the curable resin composition of the present invention, if necessary. Inorganic fillers include powders of crystalline silica, fused silica, alumina, zircon, calcium silicate, calcium carbonate, silicon carbide, silicon nitride, boron nitride, zirconia, fosterite, steatite, spinel, titania, talc, etc. Beads formed by spheroidizing are included, but are not limited to these. These may be used independently and may use 2 or more types. The amount of these inorganic fillers used varies depending on the application. From the aspect of the curable resin composition, it is preferably used in a proportion of 20% by weight or more, more preferably 30% by weight or more, and in particular 70 to 95% by weight in order to improve the coefficient of linear expansion with the lead frame % is more preferable.

The curable resin composition of the present invention may contain a mold release agent to improve release from the mold during molding. As the mold release agent, any of those conventionally known can be used. system waxes and the like. These may be used alone or in combination of two or more. The blending amount of these release agents is preferably 0.5 to 3% by weight based on the total organic components. If the amount is too small, the release from the mold will be poor, and if the amount is too large, adhesion to the lead frame or the like will be poor.

A coupling agent can be added to the curable resin composition of the present invention in order to increase the adhesion between the inorganic filler and the resin component. Any known coupling agent can be used, for example vinylalkoxysilane, epoxyalkoxysilane, styrylalkoxysilane, methacryloxyalkoxysilane, acryloxyalkoxysilane, aminoalkoxysilane, mercaptoalkoxysilane, isocyanatoalkoxy. Examples include various alkoxysilane compounds such as silane, alkoxytitanium compounds, and aluminum chelates. These may be used alone or in combination of two or more. The coupling agent may be added by first treating the surface of the inorganic filler with the coupling agent and then kneading it with the resin, or by mixing the coupling agent with the resin and then kneading the inorganic filler. .

Further, the curable resin composition of the present invention may contain known additives as required. Specific examples of additives that can be used include polybutadiene and its modified products, modified acrylonitrile copolymers, polyphenylene ethers, polystyrene, polyethylene, polyimide, fluororesins, maleimide compounds, cyanate ester compounds, silicone gels, and silicone oils. and coloring agents such as carbon black, phthalocyanine blue and phthalocyanine green.

The curable resin composition of the present invention is obtained by uniformly mixing the above components. The curable resin composition of the present invention can be easily cured by the same method as conventionally known methods. For example, an epoxy resin and a curing agent, and if necessary, a curing accelerator, an inorganic filler, a release agent, a silane coupling agent, and an additive are mixed until uniform using an extruder, a kneader, a roll, etc. The curable resin composition of the present invention is obtained by thorough mixing, which is molded by a melt casting method, a transfer molding method, an injection molding method, a compression molding method, or the like. A cured product can be obtained by heating for a period of time.

Moreover, the curable resin composition of the present invention may contain a solvent, if necessary. A curable resin composition (varnish) containing a solvent is obtained by impregnating a fibrous substance (base material) such as glass fiber, carbon fiber, polyester fiber, polyamide fiber, alumina fiber, paper, etc., followed by heating and drying to obtain a prepreg, which is hot-pressed. By molding, a cured product of the curable resin composition of the present invention can be obtained. The solvent content of this curable resin composition is usually 10 to 70% by weight, preferably about 15 to 70% by weight. Examples of the solvent include amide solvents such as γ-butyrolactones, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide and N,N-dimethylimidazolidinone; sulfones such as tetramethylenesulfone; Ether solvents such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether monoacetate, propylene glycol monobutyl ether, preferably lower (1 to 3 carbon atoms) alkylene glycol mono- or di-lower (1 carbon atom) 3) Alkyl ethers; ketone-based solvents such as methyl ethyl ketone and methyl isobutyl ketone, more preferably two alkyl groups may be the same or different. Di-lower (C 1-3) alkyl ketones; aromatic solvents such as toluene and xylene; These may be used alone or as a mixed solvent of two or more.

Also, a sheet-like adhesive (also referred to simply as a sheet) can be obtained by coating the release film with the epoxy resin varnish, removing the solvent under heating, and performing B-stage. This sheet-like adhesive can be used as an interlayer insulating layer in multilayer substrates and the like.

The cured product obtained by the present invention can be used for various purposes. More specifically, general applications where thermosetting resins such as epoxy resins are used include adhesives, paints, coating agents, molding materials (including sheets, films, FRP, etc.), insulating materials (printed circuit boards, wire coating, etc.), sealing agents, additives to other resins, and the like.

Adhesives include adhesives for civil engineering, construction, automobiles, general office and medical use, as well as adhesives for electronic materials. Among them, adhesives for electronic materials include interlayer adhesives for multilayer substrates such as build-up substrates, die bonding agents, adhesives for semiconductors such as underfill, underfill for BGA reinforcement, anisotropic conductive films ( ACF), mounting adhesives such as anisotropic conductive paste (ACP), and the like.

Potting, dipping, transfer mold sealing for capacitors, transistors, diodes, light-emitting diodes, ICs, LSIs, etc., potting sealing for COBs, COFs, TABs of ICs, LSIs, flip chips, etc. and sealing (including reinforcing underfill) when mounting IC packages such as QFP, BGA, and CSP.

EXAMPLES Next, the present invention will be described in more detail with reference to examples. In the following, all parts are parts by weight unless otherwise specified. However, the present invention is not limited to these examples. In the examples, the epoxy equivalent was measured according to JIS K-7236, and the softening point was measured according to JIS K-7234. The softening point was measured using a softening point measuring instrument FP90 manufactured by METTLER TOLEDO. The hydroxyl equivalent is determined by acetylating a sample in a pyridine solution using acetic anhydride, decomposing the remaining acid anhydride with water after the acetylation is completed, and then using a 0.5 N KOH ethanol solution to potentiometrically titrate. The amount of free acetic acid was measured by titration with , and the hydroxyl equivalent was determined from the results.

・GPC (gel permeation chromatography) analysis column: SHODEX GPC KF-601 (2 columns), KF-602, KF-602.5, KF-603
Flow rate: 0.5 ml/min.
Column temperature: 40°C
Solvent used: THF (tetrahydrofuran)
Detector: RI (differential refraction detector)

[Synthesis Example 1]
250 parts of toluene, 142.7 parts of bisphenol A, 97.1 parts of α,α,α',α'-tetramethylbenzenedimethanol and 2.5 parts of p-toluenesulfonic acid were added, heated to 125°C and reacted for 6 hours. let me The organic layer was washed with water until the waste liquid became neutral and then concentrated to obtain 192 parts of a phenolic resin (P1) as a brown solid resin. The number average molecular weight Mn was 1279, the weight average molecular weight Mw was 1774, the hydroxyl equivalent was 203.8 g/eq, the ICI viscosity (150°C) was 0.82 Pa·s, and the softening point was 98.0°C. A GPC chart is shown in FIG.

[Synthesis Example 2]
While purging a flask equipped with a thermometer, a cooling tube, a fractionating tube, and a stirrer, 180 parts of the phenolic resin (P1) obtained in Synthesis Example 1, 326.7 parts of epichlorohydrin, and 163.3 parts of dimethyl sulfoxide were added. , and 3.6 parts of water were added, and the internal temperature was raised to 50°C. After adding 37.8 parts of sodium hydroxide in portions over 1.5 hours, the mixture was reacted at 55°C for 2 hours and at 70°C for 1 hour. Unreacted epichlorohydrin and the solvent were distilled off under heating and reduced pressure. 500 parts of MIBK was added, and the organic layer was washed once with 500 parts of water. The organic layer was returned to the reaction vessel, 11.9 parts of a 30 wt % sodium hydroxide aqueous solution was added, and the mixture was reacted at 75° C. for 1 hour. After standing to cool, the organic layer was washed four times with 100 parts of water, and the solvent was distilled off under heating and reduced pressure to obtain 201 parts of the target compound (E1) as a pale yellow solid resin. The number average molecular weight Mn was 1253, the weight average molecular weight Mw was 1947, the epoxy equivalent was 298.6 g/eq, the ICI viscosity (150°C) was 0.44 Pa·s, and the softening point was 80.9°C. A GPC chart is shown in FIG.

[Synthesis Example 3]
200 parts of toluene, 235.3 parts of phenol, 388.5 parts of α,α,α',α'-tetramethylbenzenedimethanol and 7.6 parts of p-toluenesulfonic acid were added, heated to 125°C and reacted for 5 hours. let me 200 parts of toluene was added, and the organic layer was washed with water until the waste liquid became neutral and then concentrated to obtain 475 parts of a phenolic resin (P2) as a pale yellow solid resin. The number average molecular weight Mn was 822, the weight average molecular weight Mw was 1181, and the hydroxyl group equivalent was 254.0 g/eq. A GPC chart is shown in FIG.

[Synthesis Example 4]
While purging a flask equipped with a thermometer, a cooling tube, a fractionating tube, and a stirrer, 400 parts of the phenolic resin (P2) obtained in Synthesis Example 3, 582.7 parts of epichlorohydrin, and 291.4 parts of dimethyl sulfoxide were added. , and 6.4 parts of water were added, and the internal temperature was raised to 50°C. After adding 67.3 parts of sodium hydroxide in portions over 1.5 hours, the mixture was reacted at 55°C for 2 hours and at 70°C for 1 hour. Unreacted epichlorohydrin and the solvent were distilled off under heating and reduced pressure. 900 parts of MIBK was added, and the organic layer was washed once with 400 parts of water. The organic layer was returned to the reaction vessel, 21.1 parts of a 30 wt % sodium hydroxide aqueous solution was added, and the mixture was reacted at 75° C. for 1 hour. After standing to cool, the organic layer was washed 6 times with 100 parts of water, and the solvent was distilled off under heating and reduced pressure to obtain 455 parts of the objective compound (E2) as a pale yellow solid resin. The number average molecular weight Mn was 827, the weight average molecular weight Mw was 1352, the epoxy equivalent was 334.0 g/eq, the ICI viscosity (150°C) was 0.17 Pa·s, and the softening point was 69.7°C. A GPC chart is shown in FIG.

[Synthesis Example 5]
Bisphenol A novolak resin (synthesized with reference to Comparative Example 1 described in JP 2014-198755 A and formaldehyde while purging with nitrogen in a flask equipped with a thermometer, a condenser tube, a fractionating tube, and a stirrer. Condensate of, hydroxyl equivalent: 118 g / eq, ICI viscosity (150 ° C.) detection limit (6.8 Pa s or more), softening point 120.6 ° C., number average molecular weight Mn: 1907, weight average molecular weight Mw: 4533 , a GPC chart is shown in FIG. 5), 415 parts of epichlorohydrin, 157 parts of dimethylsulfoxide and 28.2 parts of water were added, and the internal temperature was raised to 35°C. After adding 36.1 parts of sodium hydroxide portionwise over 3 hours, the mixture was reacted at 35°C for 2 hours and at 70°C for 0.5 hours. Unreacted epichlorohydrin and the solvent were distilled off under heating and reduced pressure. 440 parts of MIBK was added, and the organic layer was washed once with 170 parts of water. The organic layer was returned to the reaction vessel, 8 parts of methanol, 22.6 parts of water, and 22.6 parts of 30 wt % sodium hydroxide aqueous solution were added and reacted at 75° C. for 1 hour. After standing to cool, the organic layer was washed four times with 100 parts of water, and the solvent was distilled off under heating and reduced pressure to obtain 147.5 parts of the target compound (E3) as a pale yellow solid resin. It had a number average molecular weight Mn of 2233, a weight average molecular weight Mw of 39351, an epoxy equivalent of 199.0 g/eq, an ICI viscosity (150°C) of 1.22 Pa·s, and a softening point of 81.6°C. A GPC chart is shown in FIG.

[Example 1, Comparative Examples 1 and 2]
For each of the epoxy resin (E1) obtained in Synthesis Example 2, the epoxy resin (E2) obtained in Synthesis Example 4, and the epoxy resin (E3) obtained in Synthesis Example 5, a biphenylaralkyl-type phenolic resin was used as a curing agent. (GPH-65 manufactured by Nippon Kayaku Co., Ltd.), triphenylphosphine (TPP, manufactured by Tokyo Kasei Co., Ltd.) as a catalyst, and silica gel (fused silica MSR-2212, manufactured by Tatsumori) as an inorganic filler in the proportions shown in Table 1. and uniformly mixed and kneaded using a mixing roll to obtain a curable resin composition.
This curable resin composition was pulverized and then tableted with a tablet machine. The tableted curable resin composition was subjected to transfer molding (175° C. for 60 to 15 minutes) and further cured under the conditions of 160° C.×2 hours+180° C.×6 hours after demolding to obtain test pieces for evaluation.

The test pieces for evaluation were measured under the following conditions, and the results are shown in Table 1.

<Heat resistance test (Tg)>
A dynamic viscoelasticity tester was used to measure the glass transition temperature (the temperature at which tan δ reaches its maximum value).
・ Dynamic viscoelasticity measuring instrument: DMA-2980 manufactured by TA-instruments
・Temperature increase rate: 2°C/min ・Frequency: 10Hz

<Tracking resistance test (CTI)>
Applicable standard IEC-Pub. 60112-2003 (4th edition) and JIS-C2134-2007
Target test voltage 400V to 600V
Test liquid 0.1% aqueous solution of ammonium chloride Number of drops 50 drops or until the test piece breaks Test room temperature and humidity 21°C to 23°C 40 to 45%RH
Test equipment YST-112 type tracking resistance tester manufactured by Yamayo Testing Machine Co., Ltd. Test sample shape Diameter 50 mm Thickness 3 mm
1 point measurement per sheet

<Flame Retardancy Test>
The test piece is held vertically in a clamp, the burner flame is adjusted to a 19 mm blue flame, and a 9.5 mm flame is applied to the center of the lower end of the test piece for 10 seconds. After contacting the flame, remove the burner and measure the duration of combustion. Immediately after the flame is extinguished, the flame is applied for 10 seconds, the burner is removed, and the duration of combustion is measured. Table 1 shows the total burning time for 10 samples.

The number following n in parentheses in the tracking resistance test represents the number of samples. In the 500 V test of Comparative Example 2, the test piece broke at 13 drops in the first time, and the test piece did not break at 50 drops in the second time.

From the results in Table 1, it was confirmed that Example 1 had high heat resistance, high tracking resistance, and high flame retardancy.

The epoxy resin of the present invention is used as an insulating material for electrical and electronic parts (such as a highly reliable semiconductor sealing material), a laminate (such as a printed wiring board, a BGA substrate, and a build-up substrate), and an adhesive (such as a conductive adhesive). It is useful for various composite materials such as CFRP and coatings, and is particularly useful for insulating materials for electrical and electronic parts that require tracking resistance (such as highly reliable semiconductor encapsulation materials) and laminates (printed wiring boards, BGA substrates, build-up substrates, etc.).

Claims (7)

An epoxy resin represented by the following formula (1).

(In formula (1), n is the average number of repetitions, and 1<n<20.) An epoxy resin represented by the following formula (2).

(In formula (2), n is the average number of repetitions, and 1<n<20.) 3. The epoxy resin according to claim 1, which has a weight average molecular weight of 1,000 to 3,000 as determined by gel permeation chromatography (GPC). A curable resin composition containing the epoxy resin according to claim 1 or 2 . 5. The curable resin composition according to claim 4, further comprising a curing accelerator. A cured product obtained by curing the curable resin composition according to claim 4 . A cured product obtained by curing the curable resin composition according to claim 5 .

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