KR20240021736A - Epoxy resin, curable resin composition and cured product thereof - Google Patents

Abstract

The present invention provides an epoxy resin and curable resin composition whose cured product has excellent heat resistance and tracking resistance. An epoxy resin represented by the following formula (1), where the value obtained by dividing the epoxy equivalent (g/eq.) by the softening point (°C) is 2.0 or more and less than 2.2.
[Formula 1]

(In formula (1), multiple R exists independently and represents a methyl group or a hydrogen atom. n is the average value of the number of repetitions and is a real number from 1 to 10.)

Description

Epoxy resin, curable resin composition and cured product thereof

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

Epoxy resin has excellent electrical properties (dielectric constant, dielectric loss tangent, insulation), mechanical properties, adhesiveness, and thermal properties (heat resistance, etc.), so it is used in the electrical and electronic fields such as molded products, laminates, IC sealing materials, structural materials, and adhesives. It is widely used in fields such as paints.

Recently, 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 filler (inorganic or organic filler), and improved reactivity to shorten the molding cycle are achieved. Further improvement of various characteristics such as these is required (Patent Document 1). In addition, as structural materials, materials that are lightweight and have excellent mechanical properties are required in aerospace materials, leisure/sports equipment applications, etc.

In the field of semiconductor encapsulation, substrates (the substrate itself or its surrounding materials) become more complex with thinning, stacking, systemization, and three-dimensionalization in accordance with the evolution of the semiconductor, and required characteristics such as extremely high level heat resistance and high fluidity are required. It is required. In particular, with the expansion of plastic packages into automotive applications, requirements for improved heat resistance are becoming more stringent. Specifically, extremely high heat resistance has been required due to the increase in the driving temperature of semiconductors, and with the recent movement toward high-wide gap semiconductors, it is also necessary to respond to driving temperatures of 175°C and even 200°C or higher. For these driving temperatures, the surrounding members are required to have sufficient heat resistance (glass transition temperature (Tg), especially Tg in thermomechanical properties (TMA)). Specifically, a temperature that is approximately 10% higher than the operating temperature is required (in the case of 200°C, a Tg of 220°C or higher, for example, 225°C is required), and the demand is increasing every year (Non-patent Document 1).

In addition, in recent years, in demand for electric vehicles, etc., the demand for high-voltage power devices has rapidly increased, and anti-tracking characteristics have become important. In addition, anti-tracking characteristics are considered important in applications such as solar power generation, wind power generation, and EV, and in particularly strict applications, a comparative tracking index (CTI) exceeding 600 is required.

Patent Document 1: Japanese Patent Publication No. 2019-001841

Non-patent Document 1: Fuji Electric Press 2016 vol. 89No. 4 pages 247-250

In general, an aromatic crosslinking 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 prone to carbonization and the tracking resistance deteriorates. In addition, when heat resistance is improved by increasing the molecular weight, the thermal decomposition temperature increases as the molecular weight increases, and the tracking resistance decreases. In other words, since heat resistance and tracking characteristics have a trade-off relationship, it is very difficult to clear the tracking characteristics while maintaining heat resistance. Furthermore, when a resin containing a polyaromatic compound is blended to provide properties such as flame retardancy, the tracking resistance tends to deteriorate, and it is difficult to achieve both high tracking resistance and flame retardancy.

Generally, a performance level category (PLC) is set according to the value of CTI. Since the size (creep distance) of the device design can be reduced by the PLC belonging to a smaller class, it is preferable that the PLC is 3 or less, and it is especially preferable that the PLC is 1 or less.

Additionally, PLC and CTI have the following relationship.

PLC1: CTI600 or more, PLC2: CTI400 or more but less than 600, PLC3: 250 or more but less than 400, PLC4: 100 or more but less than 175, PLC5: less than 100.

The present invention was made in consideration of this situation, and its purpose is to provide an epoxy resin and curable resin composition whose cured product has excellent heat resistance and tracking resistance properties.

As a result of intensive research to solve the above problems, the present inventors have completed the present invention. That is, the present invention relates to the following [1] to [3]. In addition, in this application, “(numerical value 1) to (numerical value 2)” indicates that the upper and lower limits are included.

[One]

An epoxy resin represented by the following formula (1), where the value obtained by dividing the epoxy equivalent (g/eq.) by the softening point (°C) is 2.0 or more and less than 2.2.

(In formula (1), multiple R exists independently and represents a methyl group or a hydrogen atom. n is the average value of the number of repetitions and is a real number from 1 to 10.)

[2]

A curable resin composition containing the epoxy resin according to the preceding paragraph [1].

[3]

The curable resin composition according to the preceding paragraph [2], wherein the content of the inorganic filler is 74% by weight or more and 95% by weight or less in the total amount of the curable resin composition.

[4]

A cured product obtained by curing the curable resin composition according to the preceding item [2] or [3].

The present invention relates to an epoxy resin, a curable resin composition, and a cured product thereof having a specific structure, and the cured product has excellent heat resistance and tracking resistance properties.

Therefore, the present invention is useful for insulating materials for electrical and electronic components (high-reliability semiconductor encapsulation materials, etc.), laminated boards (printed wiring boards, build-up boards, etc.), various composite materials including CFRP, adhesives, paints, etc.

Figure 1 shows the GPC chart of Synthesis Example 1.
Figure 2 shows the GPC chart of Synthesis Example 2.
Figure 3 shows the GPC chart of Synthesis Example 3.
Figure 4 shows the GPC chart of Example 1.
Figure 5 shows the GPC chart of Example 2.
Figure 6 shows the GPC chart of Example 3.
Figure 7 shows the GPC chart of Comparative Synthesis Example 1.
Figure 8 shows the GPC chart of Comparative Synthesis Example 2.
Figure 9 shows the GPC chart of FAE-2500.
Figure 10 shows TMA charts of Examples 4 and 5 and Comparative Examples 1 and 2.
Figure 11 shows the GPC chart of Synthesis Example 4.
Figure 12 shows the GPC chart of Example 7.
Figure 13 shows the CTI measurement results of Examples 10 to 13 and Comparative Examples 5 to 8.

The epoxy resin of the present invention is represented by the following formula (1), and the epoxy equivalent (g/eq.) divided by the softening point (°C) is 2.0 or more and less than 2.2.

(In formula (1), multiple R exists independently and represents a methyl group or a hydrogen atom. n is the average value of the number of repetitions and is a real number from 1 to 10.)

In the formula (1), n can be calculated from the number average molecular weight determined by gel permeation chromatography (GPC, detector: UV 254 nm) or the area ratio of each separated peak. It is more preferable that n is a real number of 1 to 5, and it is especially preferable that it is a real number of 2 to 4.

n=1 in the above formula (1) is preferably less than 50 area%, and more preferably less than 45 area%. In addition, the lower limit is 25 area%. If it is less than 25 area%, the fluidity of the resin is poor, and when used as a sealing material, productivity deteriorates. The melt viscosity of the resin serves as an index of fluidity, and in viscosity measurement by the corn plate method at 150°C (ICI melt viscosity), the viscosity is preferably 2 Pa·s or less. Additionally, if the viscosity is too low, there is a possibility that voids may occur during molding to trap air, etc., and there may be blocking during mixing (or modification) of liquid resin, etc., so it is preferably 0.4 Pa·s or more. Furthermore, considering the balance between heat resistance and thermal decomposition characteristics, it is more preferable that it is 0.45 Pa·s or more, and it is especially preferable that it is 0.5 Pa·s or more.

In addition, the compound of formula (1) with n = 1 or less is preferably contained in a ratio of 0.5 to 10 area%, more preferably 0.5 to 5 area%, and particularly preferably 0.5 to 2.5 area%. . Since compounds with less than n = 1 are compounds with a structure less than trifunctional or epoxy resins of tertiary butylmethylphenol, if the amount of compounds with less than n = 1 exceeds 10 area%, a decrease in heat resistance is suggested. However, there are concerns about bad odor during handling or adverse effects on the human body. On the other hand, if the compound with n = 1 is less than 0.5 area%, the network becomes too dense, so the weight loss due to thermal decomposition increases, which adversely affects the thermal decomposition characteristics (it is assumed to have a negative effect on the further tracking characteristics). I'm concerned.

The epoxy resin of the present invention is usually in a solid dendritic state at room temperature, and its softening point is preferably 90°C or higher, and more preferably 95°C or higher. Additionally, the upper limit is 150°C. If the softening point is higher than 150°C, the solvent is likely to remain when the resin is taken out, and voids are likely to form during curing. In addition, there are also significant production challenges, such as the possibility of foaming during solvent distillation. On the other hand, when the softening point is 90°C or lower, heat resistance and thermal decomposition resistance are adversely affected. Additionally, the epoxy equivalent is preferably 200 to 300 g/eq., and more preferably 205 to 250 g/eq. If the epoxy equivalent weight is less than 200 g/eq., there is a possibility of deterioration of properties due to the residual epichlorohydrin or epoxide impurities remaining in large quantities. Additionally, if it exceeds 300 g/eq., a decrease in heat resistance becomes an issue.

In the present invention, the epoxy equivalent was measured by a method according to JIS K-7236. The softening point was measured using a softening point measuring instrument FP90 from METLER TOLEDO.

The epoxy resin of the present invention preferably has a high softening point and a large number of functional groups per unit molecular weight. The softening point tends to increase as the molecular weight increases. This means that the softening point refers to the fluidity of the resin when heated, and the larger the molecular weight, the more difficult it is for the molecules to move, that is, the softening point rises. On the other hand, it is generally known that heat resistance improves as the softening point increases, but the increase in heat resistance is effectively due to the improvement in the number of functional groups per unit weight, and the epoxy equivalent becomes a value related to the number of functional groups.

When the softening point is low and the epoxy equivalent is large, it suggests that there are few functional groups per molecule. Conversely, when the softening point is high and the epoxy equivalent is small, it can be seen that there are many functional groups per molecule. Therefore, compounds with a high softening point and a low epoxy equivalent weight are preferable.

In the present invention, the value obtained by dividing the epoxy equivalent (g/eq.) by the softening point (°C) is taken as parameter A, and it is preferable that parameter A is 2.0 or more and less than 2.2. If the parameter A is less than 2.0, the epoxy equivalent is too small, so some impurities may be present. Conversely, if it is 2.2 or more, it means that the epoxy equivalent is large and the softening point is low compared to the epoxy equivalent, and heat resistance and thermal decomposition characteristics are low. cannot be compatible.

Here, thermal decomposition characteristics are considered to be a parameter that affects anti-tracking characteristics, and in a trunking test, the lower the thermal decomposition temperature, the more difficult it is to establish conduction between electrodes, so it is thought that it can withstand high voltages. Normally, when the molecular weight is increased, the thermal decomposition temperature tends to increase, but in the present invention, there is no significant difference in the thermal decomposition temperature even when the molecular weight is increased, and it is believed that high tracking resistance can be maintained.

The production method of the epoxy resin of the present invention is not particularly limited, but can be obtained, for example, by subjecting a phenol resin and epihalohydrin represented by the following formula (2) to an addition or ring closure reaction in the presence of a solvent and a catalyst.

(In formula (2), multiple R exists independently and represents a methyl group or a hydrogen atom. n is the average value of the number of repetitions and is a real number from 1 to 10.)

In the formula (2), n can be calculated from the number average molecular weight determined by gel permeation chromatography (GPC, detector: UV 254 nm) or the area ratio of each separated peak. As for n, it is more preferable that it is 1-5, and it is especially preferable that it is 1-3.

The hydroxyl equivalent weight of the phenol resin of the above formula (2) is preferably 140 to 180 g/eq., and more preferably 140 to 165 g/eq. Additionally, the amount of the n=1 compound is preferably 30 to 60 area%, more preferably 40 to 60 area%. In addition, it is preferable that the total of n=2 or more compounds is 25 to 40 area%.

Here, a method for producing the phenol resin represented by the above formula (2) will be described.

The production method of the phenol resin represented by the above formula (2) is not particularly limited, but specifically, alkylphenol (3-methyl-6-t-butylphenol and 4-methyl-2-t-butylphenol) and p-hyde Roxybenzaldehyde is polycondensed under acidic conditions and novolakized. It is preferable to react alkylphenol (3-methyl6-t-butylphenol and 4-methyl-2-t-butylphenol) and p-hydroxybenzaldehyde at a ratio of 3:2 to 2:1. The ratio of 3-methyl-6-t-butylphenol to 4-methyl-2-t-butylphenol is preferably 90% by weight or more of the alkylphenol is 3-methyl6-t-butylphenol, and this ratio is phenol It is adjusted according to the amount of alkyl phenol mixed during production of the resin. Specifically, alkyl phenol as a raw material is added according to the target alkyl phenol introduction ratio.

The hydroxyl equivalent weight of the obtained phenol resin is preferably 140 to 170 g/eq., more preferably 145 to 165 g/eq. Particularly preferably, it is 150 to 160 g/eq.

Acidic catalysts used when synthesizing the phenol resin represented by the above formula (2) include hydrochloric acid, phosphoric acid, sulfuric acid, formic acid, zinc chloride, ferric chloride, aluminum chloride, p-toluenesulfonic acid, methanesulfonic acid, activated clay, and ion exchange resin. etc. can be mentioned. These may be used alone or in combination of two or more types. The amount of catalyst used is 0.1 to 50% by weight, preferably 1 to 30% by weight, based on the phenolic hydroxyl group used. If it is too much, waste increases, and if it is too small, the progress of the reaction is slowed.

The reaction may be performed using an organic solvent as needed, or may be performed without a solvent. However, since the reaction can proceed more efficiently by azeotropically dehydrating the water to be purified during the reaction, it is preferable to use a solvent that can form an azeotrope with water. In the present invention, the use of hydrocarbon-based organic solvents such as toluene and xylene is particularly preferable.

After that, a process such as water washing or neutralization is performed, and the resin can be taken out after solvent distillation, or by a method such as reprecipitation or recrystallization. Since the softening point of the phenol resin represented by the above formula (2) is very high, it is preferable to extract it by methods such as reprecipitation or recrystallization. For example, methods such as precipitation by replacing the solvent with a poor solvent can be applied. there is.

The phenol resin represented by the above formula (2) is a crystal or solid resin, and the ratio of n=1 in GPC at that time is preferably less than 60%. In particular, it is less than 55 area%, and even less than 50 area%. The total amount of remaining raw material monomer is preferably 5 area% or less, and each peak is preferably less than 1.5 area%. This monomer amount affects the residual amount of low molecular weight epoxy resin, and this amount affects heat resistance, etc.

Next, the manufacturing method of the epoxy resin of the present invention is explained.

As described above, the method for producing the epoxy resin of the present invention is not particularly limited, but for example, it can be obtained by adding or ring-closing a phenol resin represented by the above formula (2) and epihalohydrin in the presence of a solvent and a catalyst. You can.

The amount of epihalohydrin used is usually 1.0 to 20.0 mol, preferably 1.5 to 10.0 mol, per mole of phenolic hydroxyl group of the phenol resin.

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 using an aqueous solution, the aqueous solution of the alkali metal hydroxide is continuously added to the reaction system, water and epihalohydrin are continuously distilled out under reduced pressure or normal pressure, and water is further separated to remove epihalohydrin. A method of continuously returning lohydrin to the reaction system may be used. The amount of alkali metal hydroxide used is usually 0.9 to 2.5 mol, preferably 0.95 to 1.5 mol, per mole of phenolic hydroxyl group of the phenol resin. If the amount of alkali metal hydroxide used is small, the reaction does not proceed sufficiently. On the other hand, excessive use of alkali metal hydroxide in excess of 2.5 moles per mole of phenolic hydroxyl group of the phenolic resin causes unnecessary by-products.

In order to promote the above reaction, quaternary ammonium salts such as tetramethylammonium chloride, tetramethylammonium bromide, and trimethylbenzylammonium chloride may be added as a catalyst. The amount of quaternary ammonium salt used is usually 0.1 to 15 g, preferably 0.2 to 10 g, per mole of phenolic hydroxyl group of the phenol resin. If the amount used is too small, a sufficient reaction promotion 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 of electrical reliability.

During the epoxidation reaction, it is preferable for the reaction to proceed by adding alcohols such as methanol, ethanol, and isopropyl alcohol, and aprotic polar solvents such as dimethyl sulfone, dimethyl sulfoxide, tetrahydrofuran, and dioxane. When alcohols are used, the amount used is usually 2 to 50% by weight, preferably 4 to 20% by weight, relative to the amount of epihalohydrin used. Additionally, when an aprotic polar solvent is used, it is usually 5 to 100% by weight, preferably 10 to 80% by weight, based on the amount of epihalohydrin used. The reaction temperature is usually 30 to 90°C, preferably 35 to 80°C. The reaction time is usually 0.5 to 100 hours, preferably 1 to 30 hours.

After completion of the reaction, the epihalohydrin, solvent, etc. are removed under heat and reduced pressure, with or without washing the reactant with water. Additionally, in order to make an epoxy resin with less hydrolyzable halogen, 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 for reaction to ensure ring closure. You can also do it. In this case, the amount of alkali metal hydroxide used is usually 0.01 to 0.3 mol, preferably 0.05 to 0.2 mol, per mole of phenolic hydroxyl group of the phenol resin used for glycidylation. The reaction temperature is usually 50 to 120°C and the reaction time is usually 0.5 to 24 hours. After completion of the reaction, the produced salt is removed by filtration, washing with water, etc., and the solvent is further distilled off under heating and reduced pressure to obtain the epoxy resin of the present invention.

Hereinafter, the curable resin composition of the present invention is explained.

The epoxy resin used in the curable resin composition of the present invention may be an epoxy resin represented by the above formula (1), which may be used alone, or may be used in combination with another epoxy resin. When used together, the proportion of the epoxy resin represented by the above formula (1) to the total epoxy resin is preferably 10 to 98% by weight, more preferably 30 to 95% by weight, and still more preferably 60 to 95% by weight. %am. By setting the addition amount of the epoxy resin represented by the above formula (1) to 10% or more, the elastic modulus can be improved and low water absorption can be achieved.

Specific examples of other epoxy resins that can be used in combination with the epoxy resin represented by the formula (1) 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, polycondensates with naphthaldehyde, glutaraldehyde, phthalaldehyde, crotonaldehyde, cinnamaldehyde, etc.); The above phenols and various diene compounds (dicyclopentadiene, terpenes, vinylcyclohexene, norbornadiene, vinylnorbornene, tetrahydroindene, divinylbenzene, divinylbiphenyl, disopropenylbiphenyl, butadiene, isoprene, etc.); polycondensates of the above phenols and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone, benzophenone, etc.); Polycondensates of the above-mentioned phenols and aromatic dimethanols (benzenedimethanol, biphenyldimethanol, etc.); polycondensates of the above phenols and aromatic dichloromethyls (α,α'-dichloroxyrene, bischloromethylbiphenyl, etc.); Polycondensates of the above-mentioned phenols and aromatic bisalkoxymethyls (bismethoxymethylbenzene, bismethoxymethylbiphenyl, bisphenoxymethylbiphenyl, etc.); Examples include glycidyl ether-based epoxy resins, alicyclic epoxy resins, glycidylamine-based epoxy resins, and glycidyl ester-based epoxy resins obtained by glycidylating polycondensates of the above-mentioned bisphenols and various aldehydes or alcohols. However, it is not limited to commonly used epoxy resins. These may be used individually, or two or more types may be used.

Examples of 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 curing agents that can be used include o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 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-phenylenedisopropylidene)bisaniline, 4,4'-(1,4-phenylenedisopropylidene)bisaniline, naphthalenediamine, benzidine, dimethylbenzidine, International Publication No. 2017/ No. 170551 Aromatic amine compounds such as those described in Synthesis Example 1 and Synthesis Example 2, 1,3-bis(aminomethyl)cyclohexane, isophorone diamine, 4,4'-methylenebis(cyclohexylamine), nor Aliphatic amines such as bornanediamine, ethylenediamine, propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, dimerdiamine, triethylenetetramine, etc. are included, but are not limited to these and the properties desired to be imparted to the composition. It can be used appropriately. In order to ensure pot life, it is preferable to use an aromatic amine, and when it is desired to provide immediate curing, it is preferable to use an aliphatic amine. By using an amine-based compound containing a bifunctional component as a main component as a curing agent, a network with high linearity can be constructed during the curing reaction, and particularly excellent toughness can be exhibited. In addition, amide-based compounds such as dicyandiamide, polyamide resin synthesized from a dimer of linolenic acid and ethylenediamine; acid anhydride compounds such as phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnagic 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, naphthaldehyde, glutaraldehyde, phthalaldehyde, crotonaldehyde, cinnamaldehyde, etc.) Compounds, or the above phenols and various diene compounds (dicyclopentadiene, terpenes, vinylcyclohexene, norbornadiene, vinylnorbornene, tetrahydroindene, divinylbenzene, divinylbiphenyl, disopropenyl Biphenyl, 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 dimethanol (benzene) Dimethanol, biphenyl dimethanol, etc.), or polycondensates of the above phenols and aromatic dichloromethyls (α,α'-dichloroxyrene, bischloromethylbiphenyl, etc.), or polycondensates of the above phenols and aromatic bis. Phenolic products such as polycondensates with alkoxymethyls (bismethoxymethylbenzene, bismethoxymethylbiphenyl, bisphenoxymethylbiphenyl, etc.), polycondensates of the above-mentioned bisphenols with various aldehydes, and modified products thereof. compound; Examples include, but are not limited to, imidazole, trifluoroboran-amine complex, and guanidine derivative.

In the curable resin composition of the present invention, the amount of the curing agent used is preferably 0.5 to 1.5 equivalents, and particularly preferably 0.6 to 1.2 equivalents, based on 1 equivalent of the epoxy group of the epoxy resin. Good cured properties can be obtained by adjusting the weight to 0.5 to 1.5 equivalents.

When performing a curing reaction using the above curing agent, there is no problem in using a curing accelerator together. Curing accelerators that can be used include, for example, imidazoles such as 2-methylimidazole, 2-ethylimidazole, 2-phenylimidazole, and 2-ethyl-4-methylimidazole, and 2-(dimethyl Aminomethyl)phenol, triethylenediamine, triethanolamine, tertiary amines such as 1,8-diazabicyclo(5,4,0)undecen-7, triphenylphosphine, diphenylphosphine, and tributylphos Organic phosphines such as pin, metal compounds such as tin octylate, tetra-substituted phosphonium and tetra-substituted borates such as tetraphenylphosphonium, tetraphenyl borate, tetraphenylphosphonium, ethyltriphenyl borate, 2-ethyl-4- Tetraphenyl boron salts such as methylimidazole, tetraphenyl borate, N-methylmorpholine, and tetraphenyl borate, and carboxylic acid compounds such as benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, naphthoic acid, and salicylic acid. there is. From the viewpoint of promoting the curing reaction between the amine compound and the epoxy resin, carboxylic acid compounds such as salicylic acid are preferable. 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, inorganic fillers can be added to the curable resin composition of the present invention as needed. Inorganic fillers include powders such as crystalline silica, fused silica, alumina, zircon, calcium silicate, calcium carbonate, silicon carbide, silicon nitride, boron nitride, zirconia, forsterite, steatite, spinel, titania, and talc, or spherical beads thereof. These may be mentioned, but are not limited to these. These may be used individually, or two or more types may be used. The amount of these inorganic fillers used varies depending on the application, but for example, when used as a sealant for semiconductors, they should be used in 20 weight of the curable resin composition in terms of heat resistance, moisture resistance, mechanical properties, flame retardancy, etc. of the cured product of the curable resin composition. It is preferable to use it in a proportion of % or more, more preferably 30% by weight or more, and especially to improve the linear expansion rate with the lead frame, it is more preferable to use it in a proportion of 70 to 95% by weight.

In addition, in the present invention, the content of inorganic filler becomes important, especially in improving anti-tracking performance. When anti-tracking performance is taken into consideration, the preferred content of the inorganic filler in the total amount of the curable resin composition of the present invention is 74% by weight or more and 95% by weight or less, and particularly preferably 78% by weight or more and 95% by weight or less. In the case of the epoxy resin structure of the present invention, if it is 74% by weight or more, it can be seen that the tracking resistance is greatly improved, and if it is less than 74% by weight, for example, if it is less than 70% by weight, the tracking performance is less superior to other epoxy resins. .

A mold release agent may be added to the curable resin composition of the present invention to improve mold release during molding. Any known release agent can be used. For example, ester waxes such as carnava wax and montan wax, fatty acids such as stearic acid and partyminic acid and metal salts thereof, oxidized polyethylene, non-oxidized polyethylene, etc. Polyolefin-based wax, etc. can be mentioned. These may be used individually or two or more types may be used together. The mixing amount of these release agents is preferably 0.5 to 3% by weight based on the total organic components. If it is too less than this, release from the mold will deteriorate, and if it is too much, adhesion to the lead frame, etc. will deteriorate.

A coupling agent may be added to the curable resin composition of the present invention to increase the adhesion between the inorganic filler and the resin component. Any conventionally known coupling agent can be used, for example, vinyl alkoxysilane, epokyalkoxysilane, styrylalkoxysilane, methacryloxyalkoxysilane, acryloxyalkoxysilane, aminoalkoxysilane, mercaptoalkoxysilane. , various alkoxysilane compounds such as isocyanate alkoxy silane, alkoxy titanium compounds, and aluminum chelates. These may be used individually or in combination of two or more types. The method of adding the coupling agent may be performed by previously 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.

Furthermore, known additives can be blended into the curable resin composition of the present invention as needed. Specific examples of additives that can be used include polybutadiene and its modifications, acrylonitrile copolymer modifications, polyphenylene ether, polystyrene, polyethylene, polyimide, fluororesin, maleimide compounds, cyanate ester compounds, and silicone. Gels, silicone oils, and colorants such as carbon black, phthalocyanine blue, and phthalocyanine green can be mentioned.

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 converted into a cured product by the same method as a conventionally known method. For example, the curability of the present invention can be improved by sufficiently mixing the epoxy resin, the curing agent, and, if necessary, the curing accelerator, inorganic filler, mold release agent, silane coupling agent, and additives using an extruder, kneader, roll, etc., as needed, until uniform. A cured product can be obtained by obtaining a resin composition, molding it by a melt casting method, transfer molding method, injection molding method, compression molding method, etc., and further heating it at 80 to 200°C for 2 to 10 hours.

Additionally, the curable resin composition of the present invention may contain a solvent as needed. A curable resin composition (epoxy resin varnish) containing a solvent is impregnated into a fibrous material (base material) such as glass fiber, carbon fiber, polyester fiber, polyamide fiber, alumina fiber, or paper, and the prepreg obtained by heat drying is heat 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 about 10 to 70% by weight, preferably about 15 to 70% by weight, based on internal division. Examples of solvents include amide-based solvents such as γ-butyrolactone, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and N,N-dimethylimidazolidinone; Sulfones such as tetramethylene sulfone; Ether-based solvents such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether monoacetate, and propylene glycol monobutyl ether, preferably lower (1 to 3 carbon atoms) alkylene. Mono or desiccant (carbon number 1 to 3) alkyl ethers of glycols; A ketone solvent such as methyl ethyl ketone or methyl isobutyl ketone, preferably the two alkyl groups may be the same or different. Dieser-grade (carbon number 1 to 3) alkyl ketone; Aromatic solvents such as toluene and xylene can be mentioned. These may be used alone or as a mixed solvent of two or more.

Additionally, a sheet-like adhesive can be obtained by applying the above-mentioned epoxy resin varnish on a release film, removing the solvent under heating, and performing B-staging. This sheet-like adhesive can be used as an interlayer insulating layer in a multilayer substrate or the like.

The cured product obtained in the present invention can be used for various purposes. In detail, general applications for which thermosetting resins such as epoxy resins are used include adhesives, paints, coatings, molding materials (including sheets, films, FRP, etc.), and insulating materials (printed boards, wire coatings, etc.). (including), additives to other resins in addition to the sealant, etc.

Adhesives include adhesives for civil engineering, construction, automotive, general office, and medical applications, as well as adhesives for electronic materials. Among these, adhesives for electronic materials include interlayer adhesives for multilayer boards such as build-up boards, die bonding agents, semiconductor adhesives such as underfills, underfills for BGA reinforcement, anisotropic conductive films (ACF), and anisotropic conductive pastes (ACP). Adhesives for mounting, etc. can be mentioned.

Sealants include potting, dipping and transfer mold sealing for condensers, transistors, diodes, light emitting diodes, ICs and LSIs, potting sealing for ICs and LSIs such as COB, COF and TAB, underfill for flip chips, QFP, BGA, etc. Examples include sealing (including reinforcing underfill) when mounting IC packages such as CSP.

Example

Next, the present invention will be described in more detail by way of examples, but hereinafter, parts refer to parts by weight unless otherwise specified. Additionally, the present invention is not limited to these examples.

ㆍEpoxy equivalent

Measured by a method according to JIS K-7236.

ㆍYeonhwa Branch

It was measured using a softening point measuring instrument FP90 from METLER TOLEDO.

ㆍHydroxyl equivalent

The sample is acetylated using acetic anhydride in a pyridine solution, and the remaining acid anhydride is decomposed with water after acetylation is completed. The amount of acetic acid in the free was measured by titrating this with a 0.5N KOH ethanol solution using a potentiometric titrator, and the hydroxyl equivalent amount was obtained from the results.

ㆍGPC (Gel Permeation Chromatography)

(Measurement condition 1)

Device Waters e2695

Column: SHODEX GPC KF-401HQ, KF-402HQ, KF-403HQ, KF-404HQ total 4

Flow rate 0.3 ml/min

Column temperature: 40℃

Solvent used: THF (tetrahydrofuran)

Detector: UV 254nm

(Measurement condition 2)

Device Tosoh Corporation HLC-8220GPC

Column: Tosoh Corporation TSK gel G3000HXL 1 piece TSK gel G2000HXL 2 pieces

Total 3

Flow rate 1.065ml/min

Column temperature: 40℃

Solvent used: THF (tetrahydrofuran)

Detector: UV 254nm

(Measurement condition 3)

Device Tosoh Corporation HLC-8420GPC

Column: Tosoh Corporation TSK gel G3000HXL 1 piece TSK gel G2000HXL 2 pieces

Total 3

Flow rate 1.065ml/min

Column temperature: 40℃

Solvent used: THF (tetrahydrofuran)

Detector: UV 254nm

Standard polystyrene (Tosoh Corporation)

PStQuickC, PStQuickD (molecular weight measurement was corrected by adding styrene as an internal standard)

[Synthesis Example 1]

While purging nitrogen into a flask equipped with a thermometer, cooling pipe, flow pipe, and stirrer, 137.2 parts of 3-methyl-6-t-butylphenol, 0.16 parts of 4-methyl-2-t-butylphenol, and p-hydroxy 60 parts of benzaldehyde, 142 parts of toluene, and 1.4 parts of p-toluenesulfonic acid were added, and reaction was performed at 110 to 115°C for 8 hours. After completion of the reaction, 25% NaOH water was added, and toluene was distilled off by azeotropic dehydration. After that, 75% sulfuric acid was added, the pH was adjusted to 5 to 7, and the precipitated resin powder was filtered and dried at 60°C to obtain 186 parts of phenol resin (P1). The obtained phenol resin (PI) was in powder form, had a softening point of 150°C or higher, a hydroxyl equivalent weight of 155 g/eq., and n=1 by GPC was 48.8 area%. The GPC chart (measurement condition 1) is shown in Figure 1.

[Synthesis Example 2]

While purging nitrogen into a flask equipped with a thermometer, cooling pipe, flow pipe, and stirrer, 153.1 parts of 3-methyl-6-t-butylphenol, 0.17 parts of 4-methyl-2-t-butylphenol, and p-hydroxy 60 parts of benzaldehyde, 142 parts of toluene, and 0.6 parts of p-toluenesulfonic acid were added, and reaction was performed at 100 to 105°C for 6 hours. After completion of the reaction, 25% NaOH water was added, and toluene was distilled off by azeotropic dehydration. After that, 75% sulfuric acid was added, the pH was adjusted to 5 to 7, and the precipitated resin powder was filtered and dried at 60°C to obtain 198 parts of phenol resin (P2). The obtained phenol resin (P2) was in powder form, had a softening point of 150°C or higher, a hydroxyl equivalent weight of 144 g/eq., and n=1 by GPC was 51.7 area%. The GPC chart (measurement condition 1) is shown in Figure 2.

[Synthesis Example 3]

While purging nitrogen into a flask equipped with a thermometer, cooling pipe, flow pipe, and stirrer, 137.2 parts of 3-methyl-6-t-butylphenol, 0.16 parts of 4-methyl-2-t-butylphenol, and p-hydroxybenzaldehyde were added. 60 parts, 142 parts of toluene, and 1.4 parts of p-toluenesulfonic acid were added, and reaction was performed at 110 to 115°C for 8 hours. After completion of the reaction, 25% NaOH water was added, and toluene was distilled off by azeotropic dehydration. After that, 75% sulfuric acid was added, the pH was adjusted to 5 to 7, and the precipitated resin powder was filtered and dried at 60°C to obtain 180 parts of phenol resin (P3). The obtained phenol resin (P3) was in powder form, had a softening point of 150°C or higher, a hydroxyl equivalent weight of 153 g/eq., and n=1 by GPC was 47.6 area%. The GPC chart (measurement condition 1) is shown in Figure 3.

[Example 1]

While purging nitrogen into a flask equipped with a thermometer, cooling pipe, flow pipe, and stirrer, 310 parts of the phenol resin (P1) obtained in Synthesis Example 1, 973 parts of epichlorohydrin, 274 parts of dimethyl sulfoxide, and 15 parts of water were added. , the internal temperature was raised to 45°C. 16 parts of sodium hydroxide was added in portions over 1.5 hours, and then reacted at 45°C for 2 hours and at 70°C for 1 hour. Unreacted epichlorohydrin and solvent were distilled off under heating and reduced pressure. 1040 parts of MIBK were added, and the organic layer was washed once with 440 parts of water. The organic layer was returned to the reaction container, 20 parts of 30% by weight sodium hydroxide aqueous solution was added, and reaction was performed at 70°C for 2 hours. After cooling, the organic layer was washed four times with 130 parts of water, and the solvent was distilled off under heating and reduced pressure to obtain 170 parts of epoxy resin (E1) as a solid resin. The epoxy equivalent was 214 g/eq., the ICI viscosity (150°C) was 0.57 Pa·s, the softening point was 100°C, and the parameter A was 2.14. The average repeat unit n roughly calculated from GPC (detector UV 254 nm) was 2.4, n = 1 was 42.3 area%, and n = 1 was 1.57 area%. The GPC chart (measurement condition 2) is shown in Figure 4.

[Example 2]

While purging nitrogen into a flask equipped with a thermometer, a cooling tube, a flow pipe, and a stirrer, 310 parts of the phenol resin (P1) obtained in Synthesis Example 1, 584 parts of epichlorohydrin, 274 parts of dimethyl sulfoxide, and 15 parts of water were added. , the internal temperature was raised to 45°C. After adding 16 parts of sodium hydroxide in portions over 1.5 hours, it was reacted at 45°C for 2 hours and at 70°C for 1 hour. Unreacted epichlorohydrin and solvent were distilled off under heating and reduced pressure. 1040 parts of MIBK were added, and the organic layer was washed once with 440 parts of water. The organic layer was returned to the reaction vessel, 20 parts of 30 wt% sodium hydroxide aqueous solution was added, and reaction was performed at 70°C for 2 hours. After standing to cool, the organic layer was washed four times with 130 parts of water, and the solvent was distilled off under heating and reduced pressure to obtain 141 parts of epoxy resin (E2) as a solid resin. The epoxy equivalent was 225 g/eq., the ICI viscosity (150°C) was 1.92 Pa·s, the softening point was 110°C, and the parameter A was 2.05. The average repeat unit n roughly calculated from GPC (detector UV 254 nm) was 2.9, n = 1 was 31.1 area%, and n = 1 was 1.28 area%. The GPC chart (measurement condition 2) is shown in Figure 5.

[Example 3]

While purging nitrogen into a flask equipped with a thermometer, a cooling tube, a flow pipe, and a stirrer, 310 parts of the phenol resin (P3) obtained in Synthesis Example 3, 778 parts of epichlorohydrin, 274 parts of dimethyl sulfoxide, and 15 parts of water were added. And the internal temperature was raised to 45°C. 16 parts of sodium hydroxide was added in portions over 1.5 hours, and then reacted at 45°C for 2 hours and at 70°C for 1 hour. Unreacted epichlorohydrin and solvent were distilled off under heating and reduced pressure. 1040 parts of MIBK were added, and the organic layer was washed once with 440 parts of water. The organic layer was returned to the reaction container, 20 parts of 30% by weight sodium hydroxide aqueous solution was added, and reaction was performed at 70°C for 2 hours. After cooling, the organic layer was washed four times with 130 parts of water, and the solvent was distilled off under heating and reduced pressure to obtain 303 parts of epoxy resin (E3) as a solid resin. The epoxy equivalent was 216 g/eq., the total chlorine was 440 ppm (based on ISO21627-3), the inorganic chlorine ion concentration was 0.3 ppm, the ICI viscosity (150°C) was 0.64 Pa·s, the softening point was 100°C, and the parameter A was 2.16. Mn roughly calculated from GPC (detector UV 254nm) was 1059, Mw was 2001 (polystyrene conversion), n=1 was 39.5 area%, and less than n=1 was 1.95 area%. The GPC chart (measurement condition 3) is shown in Figure 6.

[Comparative Synthesis Example 1]

While purging nitrogen into a flask equipped with a thermometer, cooling pipe, flow pipe, and stirrer, 288 parts of the phenol resin (P2) obtained in Synthesis Example 2, 584 parts of epichlorohydrin, 274 parts of dimethyl sulfoxide, and 15 parts of water were added. , the internal temperature was raised to 45°C. 16 parts of sodium hydroxide was added in portions over 1.5 hours, and then reacted at 45°C for 2 hours and at 70°C for 1 hour. Unreacted epichlorohydrin and solvent were distilled off under heating and reduced pressure. 1040 parts of MIBK were added, and the organic layer was washed once with 440 parts of water. The organic layer was returned to the reaction container, 20 parts of 30% by weight sodium hydroxide aqueous solution was added, and reaction was performed at 70°C for 2 hours. After cooling, the organic layer was washed four times with 130 parts of water, and the solvent was distilled off under heating and reduced pressure to obtain 165 parts of epoxy resin (E4) as a solid resin. The epoxy equivalent was 223 g/eq., the ICI viscosity (150°C) was 0.60 Pa·s, the softening point was 99.7°C, and the parameter A was 2.24. The average repeat unit n roughly calculated from GPC was 2.4, n=1 was 43.9 area%, and n=1 or less was 1.9 area%. The GPC chart (measurement condition 2) is shown in Figure 7.

[Comparative Synthesis Example 2]

While purging nitrogen into a flask equipped with a thermometer, cooling pipe, flow pipe, and stirrer, 288 parts of the phenol resin (P2) obtained in Synthesis Example 2, 487 parts of epichlorohydrin, 274 parts of dimethyl sulfoxide, and 15 parts of water were added. , the internal temperature was raised to 45°C. 16 parts of sodium hydroxide was added in portions over 1.5 hours, and then reacted at 45°C for 2 hours and at 70°C for 1 hour. Unreacted epichlorohydrin and solvent were distilled off under heating and reduced pressure. 1040 parts of MIBK were added, and the organic layer was washed once with 440 parts of water. The organic layer was returned to the reaction container, 20 parts of 30% by weight sodium hydroxide aqueous solution was added, and reaction was performed at 70°C for 2 hours. After cooling, the organic layer was washed four times with 130 parts of water, and the solvent was distilled off under heating and reduced pressure to obtain 161 parts of epoxy resin (E5) as a solid resin. The epoxy equivalent was 224 g/eq., the ICI viscosity (150°C) was 0.66 Pa·s, the softening point was 100.9°C, and the parameter A was 2.22. The average repeat unit n estimated from GPC was 2.3, n = 1 was 43 area%, and less than n = 1 was 2.1 area%. The GPC chart (measurement condition 2) is shown in Figure 8.

[Examples 4 and 5, Comparative Examples 1 and 2]

As the epoxy resins E1, E2, E4 and E6 obtained in the examples and synthesis examples, FAE-2500 (manufactured by Nippon Explosives, analysis results are described later) was used, and trisphenolmethane type phenol resin (KAYAHARD KTG-105, manufactured by Nippon Explosives) was used as a curing agent. Using triphenylphosphine as a catalyst, trisphenolmethane-type phenol resin was mixed in an equivalent amount with respect to the epoxy resin, and triphenylphosphine was mixed in an equivalent amount with respect to the epoxy resin, and mixed and kneaded uniformly using a mixing roll. Additionally, after demolding, it was cured at 160°C for 2 hours and at 180°C for 6 hours to obtain a test piece for evaluation.

The epoxy equivalent of FAE-2500 was 213 g/eq., the ICI viscosity (150°C) was 0.30 Pa·s, the softening point was 93.5°C, and the parameter A was 2.28. The GPC chart (measurement condition 2) is shown in Figure 9.

The results of measuring the test pieces for evaluation under the following conditions are shown in Table 1. Additionally, the TMA chart is shown in Figure 10.

<Dynamic viscoelasticity measurement (DMA)>

The glass transition temperature (temperature at which tanδ is at its maximum value) and the value of tanδ at that time were measured using a dynamic viscoelasticity tester.

ㆍDynamic viscoelasticity measuring instrument: DMA-2980 manufactured by TA-instruments

ㆍTemperature increase rate: 2℃/min

<Thermomechanical property measurement (TMA)>

Glass transition temperature (Tg) and change in linear expansion (CTE) were evaluated using a thermomechanical property measurement device.

<Thermogravimetric differential thermal measurement (TG-DTA)>

The pyrolysis temperature and residual carbon amount at 500°C were measured using TG-DTA.

Measurement sample: 5 to 10 mg powder (through 100㎛ mesh, 75㎛ mesh on)

Measurement conditions: Temperature increase rate 10℃/min Air flow 200ml

[Example 6, Comparative Example 3]

Epoxy resin (E1), epoxy resin (E6, FAE-2500 (manufactured by Nippon Explosives)), xyloc-type phenolic resin (MEHC-7800SS manufactured by Meiwa Kasei) as a curing agent, and triphenylphosphine (TPP, manufactured by Tokyo Kasei) as a catalyst. ), silica gel (fused silica MSR-2212, manufactured by Tatsumori) as an inorganic filler, carnava wax (manufactured by Cerarikanoda) as a mold release agent, and a silane coupling agent (product name: KBM-303 manufactured by Shin-Etsu Chemical Industry) as an additive. A curable resin composition was obtained by uniformly mixing and kneading using a mixing roll.

This curable resin composition was pulverized and tableted using a tablet machine. The tableted curable resin composition was transfer molded (175°C for 60 to 150 minutes), and after demolding, it was cured under the conditions of 160°C x 2 hours + 180°C x 6 hours to obtain a test piece for evaluation. The following evaluation was performed using this test piece. The measurement results are listed in Table 2.

<Testing resistance to tracking>

Compliance standard IEC-Pub. 60112-2003 (4th edition) and JIS-C2134-2007

Target test voltage 400V ~ 600V

Test solution ammonium chloride 0.1% aqueous solution

If the test piece was destroyed with less than 50 drops of dripping water, it was judged to be NG.

Test room temperature and humidity 21℃ ~ 23℃ 40 ~ 45%RH

Testing device YST-112 type anti-tracking tester manufactured by Yamayo Testing Machine Co., Ltd.

Test sample shape diameter 50mm thickness 3mm

Measure 1 point per sheet

From the results in Table 1, the epoxy resin of the present invention was confirmed to have high heat resistance and dimensional stability (low linear expansion). Additionally, from the results in Table 2, it was confirmed that the epoxy resin of the present invention has high anti-tracking performance.

[Synthesis Example 4]

While purging nitrogen into a flask equipped with a thermometer, cooling pipe, flow pipe, and stirrer, 130.3 parts of 3-methyl-6-t-butylphenol, 0.2 parts of 4-methyl-2-t-butylphenol, and p-hydroxybenzaldehyde were added. 60 parts, 142 parts of toluene, and 1.4 parts of p-toluenesulfonic acid were added, and reaction was performed at 110 to 115°C for 8 hours. After completion of the reaction, 25% NaOH water was added, and toluene was distilled off by azeotropic dehydration. After that, 75% sulfuric acid was added, the pH was adjusted to 5 to 7, and the precipitated resin powder was filtered and dried at 60°C to obtain 186 parts of phenol resin (P4). The obtained phenol resin (P4) was in powder form, had a softening point of 200°C or higher, a hydroxyl equivalent weight of 160 g/eq., and n=1 by GPC was 37.0 area%. The GPC chart (measurement condition 1) is shown in Figure 11.

[Example 7]

While purging nitrogen into a flask equipped with a thermometer, cooling pipe, flow pipe, and stirrer, 320 parts of the phenol resin (P4) obtained in Synthesis Example 4, 973 parts of epichlorohydrin, 274 parts of dimethyl sulfoxide, and 15 parts of water were added. , the internal temperature was raised to 45°C. 16 parts of sodium hydroxide was added in portions over 1.5 hours, and then reacted at 45°C for 2 hours and at 70°C for 1 hour. Unreacted epichlorohydrin and solvent were distilled off under heating and reduced pressure. 1040 parts of MIBK were added, and the organic layer was washed once with 440 parts of water. The organic layer was returned to the reaction container, 20 parts of 30% by weight sodium hydroxide aqueous solution was added, and reaction was performed at 70°C for 2 hours. After cooling, the organic layer was washed four times with 130 parts of water, and the solvent was distilled off under heating and reduced pressure to obtain 107 parts of epoxy resin (E7) as a solid resin. The epoxy equivalent was 220 g/eq., the ICI viscosity (150°C) was 0.8 Pa·s or more, the softening point was 108.5°C, and the parameter A was 2.03. The average repeat unit n roughly calculated from GPC (detector UV 254 nm) was 3.4, n=1 was 24.9 area%, and less than n=1 was 2.91 area%. The GPC chart (measurement condition 3) is shown in FIG. 12. In addition, each peak had a retention time of 35.619 minutes, which accounted for 1.75%, and other peaks accounted for less than 1.5 area%.

[Example 8, 9]

Epoxy resins E3 and E7 obtained in the above examples, trisphenolmethane type phenolic resin (KAYAHARD KTG-105 hydroxyl equivalent 102 g/eq. manufactured by Nippon Explosives), and biphenyl aralkyl type phenol resin (KAYAHARD GPH-65 curing agent manufactured by Nippon Explosives) as a curing agent. Hydroxyl equivalent weight 200 g/eq.), triphenylphosphine (TPP, manufactured by Tokyo Kasei Co., Ltd.) as a catalyst, silica gel (fused silica MSR-2212, manufactured by Tatsumori Co., Ltd.) as an inorganic filler, and carnaba wax (produced by Cerarikanoda Co., Ltd.) as a release agent. , using a silane coupling agent (trade name: KBM-303 manufactured by Shin-Etsu Chemical Industry) as an additive, mixing it in the ratio (parts by weight) in Table 3, mixing and kneading uniformly using a mixing roll, and after demoulding, 160 A test piece for evaluation was obtained by curing under conditions of 2 hours at ℃ and 6 hours at 180℃. A tracking resistance test was conducted using this test piece. The measurement results are listed in Table 3.

[Example 9, Comparative Example 4]

Epoxy resin E1 obtained in the above example, biphenyl aralkyl type epoxy resin (NC-3000 manufactured by Nippon Explosives), xyloc type phenolic resin (MEHC-7800SS manufactured by Meiwa Kasei) as a curing agent, and triphenylphosphine (TPP) as a catalyst. , manufactured by Tokyo Kasei Co., Ltd.), silica gel (fused silica MSR-2212, manufactured by Tatsumori Co., Ltd.) as an inorganic filler, carnava wax (produced by Cerarikanoda Co., Ltd.) as a mold release agent, and silane coupling agent (product name: KBM-303, manufactured by Shin-Etsu Chemical Co., Ltd.) as an additive. ) and uniformly mixed and kneaded using a mixing roll to obtain a curable resin composition.

This curable resin composition was pulverized and tableted using a tablet machine. The tableted curable resin composition was subjected to transfer molding (175°C, 60 to 15 minutes), and after demolding, it was cured under the conditions of 160°C x 2 hours + 180°C x 6 hours, and a test piece for evaluation was obtained. A tracking resistance test was conducted using this test piece. The measurement results are listed in Table 4.

[Examples 10 to 13, Comparative Examples 5 to 8]

Epoxy resin E1 obtained in the above example, biphenyl aralkyl type epoxy resin (NC-3000, manufactured by Nippon Explosives), and as a curing agent, xyloc type phenol resin (MEHC-7800SS, manufactured by Meiwa Kasei), and biphenyl aralkyl type phenol resin (Japan) KAYAHARD GPH-65 manufactured by Gunpowder), triphenylphosphine (TPP, manufactured by Tokyo Kasei Co., Ltd.) as a catalyst, silica gel (fused silica MSR-2212, manufactured by Tatsumori Co., Ltd.) as an inorganic filler, and carnaba wax (produced by Celarikanoda) as a mold release agent. , a silane coupling agent (trade name: KBM-303 manufactured by Shin-Etsu Chemical Industry) was used as an additive, and the mixture was uniformly mixed and kneaded using a mixing roll to obtain a curable resin composition.

This curable resin composition was pulverized and tableted using a tablet machine. The tableted curable resin composition was subjected to transfer molding (175°C, 60 to 15 minutes), and after demolding, it was cured under the conditions of 160°C x 2 hours + 180°C x 6 hours, and a test piece for evaluation was obtained. A tracking resistance test was conducted using this test piece. Especially regarding CTI, IEC-Pub. Measurements were performed using a measurement method based on 60112-2003 (4th edition). The measurement results are shown in Table 5 and Figure 13.

From the above results, the cured product using the epoxy resin of the present invention maintains a relatively high CTI, and in particular, the rate of increase in CTI increases compared to other compositions when the inorganic filler content is 74% by weight or more, more preferably 78% by weight or more. Confirmed.

The epoxy resin of the present invention is useful for automotive materials, especially materials surrounding power devices, and is particularly effective for applications requiring heat resistance and a high comparative tracking index (CTI).

Claims (4)

An epoxy resin represented by the following formula (1), where the value obtained by dividing the epoxy equivalent (g/eq.) by the softening point (°C) is 2.0 or more and less than 2.2.
[Formula 1]

(In formula (1), multiple R exists independently and represents a methyl group or a hydrogen atom. n is the average value of the number of repetitions and is a real number from 1 to 10.) A curable resin composition containing the epoxy resin according to claim 1. The curable resin composition according to claim 2, wherein the content of the inorganic filler is 74% by weight or more and 95% by weight or less based on the total amount of the curable resin composition. A cured product obtained by curing the curable resin composition according to claim 2 or claim 3.