Epoxy resin, curable resin composition, cured product, and printed wiring board

Abstract

To provide an epoxy resin capable of yielding a cured product that can achieve high insulation reliability.SOLUTION: The invention relates to an epoxy resin in which a hydroxyl group of a compound represented by general formula (4) is a glycidyl ether group, the epoxy resin having a weight-average molecular weight (Mw) of 1000 or more and 3500 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an epoxy resin, a curable resin composition, a cured product, and a printed wiring board. [Background technology]

[0002] Epoxy resins are used in a wide range of applications, including electrical and electronic materials, adhesives, paints, and films, because the cured products have excellent mechanical and electrical properties.

[0003] Against this background, the development of epoxy resins has been actively pursued, and for example, Patent Document 1 proposes an epoxy resin having a partial structure represented by -C(CF3)H-. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2021 / 193878 Summary of the Invention [Problem to be solved by the invention]

[0005] Epoxy resins are used, for example, as insulating materials for printed wiring boards used in semiconductor packages. In recent years, semiconductor packages have become smaller and smaller in response to the trend toward lighter, thinner, shorter, smaller, higher performance, and more multifunctional electronic devices. In response to this trend, printed wiring boards used in semiconductor packages have become increasingly dense, and vias for interlayer connection have become smaller. Even when used in such miniaturized semiconductor packages, epoxy resins are required to achieve high long-term reliability, specifically high insulation reliability. The epoxy resin in Patent Document 1 leaves room for improvement in this regard.

[0006] An object of the present invention is to provide an epoxy resin that can provide a cured product that can achieve high insulation reliability when used in semiconductor packages, etc. Here, insulation reliability can be evaluated by the method in the examples. [Means for solving the problem]

[0007] The present inventors have discovered that controlling the weight-average molecular weight of an epoxy resin having a specific chemical structure within a predetermined range results in a cured product that can achieve high insulation reliability, and have completed the present invention. The gist and configuration of the present invention are as follows. [1] An epoxy resin represented by general formula (1), wherein the epoxy resin has a weight average molecular weight (Mw) determined by gel permeation chromatography (GPC) of 1,000 or more and 3,500 or less. [ka] (In the formula, m is a number of 0 or more, and n is a number of 0 or more, The bonding form of the units grouped by m and the units grouped by n may be random bonding, block bonding, or a combination of both. [2] The epoxy resin of [1], having an epoxy equivalent of 280 g / eq or more and 350 g / eq or less. [3] The epoxy resin according to [1] or [2], having a polydispersity of 2.0 or more and 3.5 or less. [4] The epoxy resin according to any one of [1] to [3], wherein the total chlorine content in the epoxy resin is 1,500 ppm or less. [5] A curable resin composition containing at least one epoxy resin selected from the group consisting of epoxy resins listed in [1] to [4]. [6] A cured product of the curable resin composition of [5]. [7] A printed wiring board having the cured product of [6]. [Effects of the Invention]

[0008] According to the present invention, there is provided an epoxy resin that can provide a cured product that can achieve high insulation reliability when used in products such as semiconductor packages. Also provided according to the present invention are a curable resin composition containing at least one of the epoxy resins, a cured product of the curable resin composition, and a printed wiring board having the cured product. DETAILED DESCRIPTION OF THE INVENTION

[0009] <Epoxy resin> The epoxy resin of the present invention is represented by the following general formula (1), and has a weight average molecular weight (Mw) of 1,000 or more and 3,500 or less as determined by gel permeation chromatography (GPC). [ka] (In the formula, m is a number of 0 or more, and n is a number of 0 or more.)

[0010] The epoxy resin represented by general formula (1) has repeating units bonded to each other via -C(CF3)H-, and benzene rings in each repeating unit bonded to each other via -C(CF3)2-, and has fluorine atoms incorporated into its structure, which is advantageous in terms of exhibiting excellent heat resistance.

[0011] The epoxy resin of the present invention is characterized in that its weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) is from 1000 to 3500. Mw is a value converted using polystyrene as the standard, and can be measured under the conditions described in the Examples. Having an Mw in the above range makes it possible to produce a cured product that can achieve high insulation reliability. From the viewpoint of high insulation reliability, Mw is preferably 1200 or more, more preferably 1500 or more, and more preferably 3000 or less.

[0012] The polydispersity (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the epoxy resin of the present invention is preferably 3.5 or less, more preferably 3.0 or less. The lower limit of the polydispersity is 1. A polydispersity within the above range makes it easy to form a uniform cured product using the epoxy resin, and is also advantageous in terms of improving the mechanical properties of the cured product. Furthermore, when used in a photosensitive resin composition, improved developability can be expected. Here, the number average molecular weight, like the above Mw, is a converted value using polystyrene as the standard measured by gel permeation chromatography (GPC), and can be measured under the conditions of the examples.

[0013] The epoxy equivalent of the epoxy resin of the present invention is preferably 280 g / eq or more, more preferably 300 g / eq or more, and preferably 350 g / eq or less, more preferably 330 g / eq or less. An epoxy equivalent within the above range is advantageous in that the crosslink density of the cured product is appropriately increased, thereby improving mechanical properties and heat resistance. Here, the epoxy equivalent is a value measured in accordance with JIS K7236:2009.

[0014] The total chlorine content of the epoxy resin of the present invention is preferably 1,500 ppm or less, more preferably 1,300 ppm or less. If the total chlorine content is within this range, corrosion problems can be reduced when the epoxy resin is applied to various applications, and high insulation reliability can be easily achieved. Here, the total chlorine content is a value measured in accordance with JIS K7243-3:2005.

[0015] In general formula (1), m is a number equal to or greater than 0, and n is a number equal to or greater than 0. Here, m and n are average values, and can be controlled so that the Mw of the epoxy resin is 1000 or greater and 3500 or less. Either m or n may be 0.

[0016] In the general formula (1), the bonding form of the units bounded by m and the units bounded by n may be any of random bonding, block bonding, and a combination thereof.

[0017] The epoxy resin of the present invention may contain structural units other than the units bracketed by m and the units bracketed by n, provided that the effects of the present invention are not impaired. For example, such structural units are those in which the glycidyl group in one or both of the units bracketed by m and the units bracketed by n is replaced with a hydrogen atom.

[0018] The present invention includes an epoxy resin represented by general formula (2) or (3). [ka] (In the formula, m is a number of 0 or more, and n is a number of 0 or more.)

[0019] <Epoxy resin manufacturing method> The epoxy resin of the present invention can be produced by reacting 2,2-bis(4-hydroxyphenyl)hexafluoropropane (bisphenol AF) with fluoral in the presence of an acid catalyst to obtain a novolak resin represented by general formula (4) (hereinafter also referred to as "intermediate novolak resin"), and then reacting the intermediate novolak resin with epihalohydrin in the presence of a base.

[0020] The weight-average molecular weight of the epoxy resin of the present invention can be controlled by appropriately adjusting various conditions during production. For example, by adjusting the weight-average molecular weight of the intermediate novolak resin as measured by GPC to 500 or more and 1500 or less, the epoxy resin of the present invention having a weight-average molecular weight of 1000 or more and 3500 or less can be easily produced. [ka] (In the formula, m is a number of 0 or more, and n is a number of 0 or more, The bonding form of the units grouped by m and the units grouped by n may be random bonding, block bonding, or a combination of both.

[0021] (Synthesis of Novolac Resin) The intermediate novolak resin can be obtained by reacting 2,2-bis(4-hydroxyphenyl)hexafluoropropane (bisphenol AF) with fluoral in the presence of an acid catalyst.

[0022] Fluoral refers to trifluoroacetaldehyde. The fluoral used in the synthesis can be synthesized by the method described in WO 2021 / 193878. Fluoral may be used as a mixture with hydrogen fluoride.

[0023] The amount of bisphenol AF and fluoral used in the synthesis can be 0.42 to 0.48 moles, preferably 0.43 to 0.47 moles, of fluoral per mole of bisphenol AF. By using bisphenol AF and fluoral in such amounts, the Mw of the intermediate novolac resin can be easily controlled to 500 to 1500. When the Mw of the intermediate novolac resin is within the above range, the Mw of the final epoxy resin can be easily controlled to 1000 to 3500.

[0024] The synthesis can be carried out, for example, at a temperature of -20°C or higher and 150°C or lower for 2 hours or longer and 30 hours or shorter. The pressure during synthesis can be set at an absolute pressure of 0.1 MPa or higher and 10 MPa or lower. The pressure is preferably 0.1 MPa or higher and 5 MPa or lower, more preferably 0.1 MPa or higher and 1 MPa or lower. Since a reaction at high pressure requires a high-pressure reaction vessel, which increases equipment costs, it is preferable to carry out the reaction at as low a pressure as possible.

[0025] A solvent may be used in the synthesis. Examples of the solvent include ketones such as acetone and methyl ethyl ketone, alcohols such as ethanol and butanol, esters such as ethyl acetate and butyl acetate, ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, diisopropyl ether, and tert-butyl methyl ether, ether alcohols such as ethoxyethyl alcohol, ether esters such as propylene glycol monomethyl ether acetate, amides such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and N,N-dimethylimidazolidinone, nitriles such as acetonitrile, propionitrile, and benzonitrile, sulfoxides such as dimethyl sulfoxide, cyclic sulfones such as sulfolane, nitro hydrocarbons such as nitromethane and nitroethane, and nitro aromatic hydrocarbons such as nitrobenzene. Also preferably used are halogen-based solvents such as 1,2-dichloroethane, chloroform, methylene chloride, carbon tetrachloride, trichloroethane, etc. These may be used alone or in combination of two or more in any ratio.

[0026] Acid catalysts used in the synthesis include inorganic acids such as hydrochloric acid, sulfuric acid, perchloric acid, and phosphoric acid, organic acids such as formic acid, acetic acid, oxalic acid, trichloroacetic acid, and p-toluenesulfonic acid, and divalent metal salts such as zinc acetate, zinc chloride, and magnesium acetate. These may be used alone or in combination of two or more in any ratio. Fluoral may be used as a mixture with hydrogen fluoride, with the hydrogen fluoride functioning as the acid catalyst.

[0027] The amount of the acid catalyst is preferably 0.01 mol or more, more preferably 0.1 mol or more, and even more preferably 0.5 mol or more, per mol of fluoral, and is preferably 100 mol or less, more preferably 30 mol or less, and even more preferably 25 mol or less. If the amount of the acid catalyst is within the above range, fluorine atoms can be efficiently introduced into the novolak resin, which is an intermediate, and therefore fluorine atoms can also be efficiently introduced into the epoxy resin of the present invention.

[0028] It is preferable to remove unreacted substances and impurities from the obtained novolak resin, which is an intermediate, by a combination of a precipitation treatment in which the resin is poured into a poor solvent (typically water), a washing treatment with water or sodium bicarbonate water, a liquid separation operation, etc. Specific methods for these treatments can be appropriately referred to known methods in polymer synthesis.

[0029] (Epoxy resin synthesis) Next, the intermediate novolak resin is reacted with epihalohydrin in the presence of a base, thereby converting the hydrogen atom of the phenolic hydroxy group in general formula (4) to a glycidyl group, thereby obtaining the epoxy resin represented by general formula (1).

[0030] The epihalohydrin used in the reaction includes epichlorohydrin and epibromohydrin. The amount of epihalohydrin is preferably 0.1 moles or more, more preferably 1.0 moles or more, and preferably 100 moles or less, more preferably 50 moles or less, per mole of hydroxy groups in the novolak resin intermediate.

[0031] Examples of the base used in the reaction include alkali metal hydroxides, alkali metal alkoxides, and alkali metal carbonates. Specific examples include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium methoxide, potassium methoxide, lithium methoxide, sodium ethoxide, potassium ethoxide, lithium ethoxide, sodium butoxide, potassium butoxide, lithium butoxide, sodium carbonate, potassium carbonate, and lithium carbonate. These may be used alone or in combination of two or more in any ratio.

[0032] The reaction can be carried out, for example, as follows.

[0033] The reaction system is brought into "alkaline conditions" by adding an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide as a base to the reaction system in the form of a solid or an aqueous solution. The amount of the base is preferably 0.1 moles or more, more preferably 1 mole or more, and is preferably 50 moles or less, more preferably 10 moles or less, per mole of hydroxy groups in the novolak resin intermediate.

[0034] The reaction can be carried out under normal pressure (0.1 MPa; absolute pressure) or under reduced pressure. The reaction temperature can be 20°C or higher and 150°C or lower when the reaction is carried out under normal pressure, and 30°C or higher and 80°C or lower when the reaction is carried out under reduced pressure. During the reaction, the reaction liquid is azeotropically evaporated while maintaining a predetermined temperature as necessary, the evaporating vapor is cooled, and the resulting condensate is separated into oil and water. The oil from which the water has been removed is returned to the reaction system for dehydration. In order to prevent a rapid reaction, the alkali metal hydroxide is preferably added to the reaction system in small amounts intermittently or continuously over a period of 0.1 to 10 hours. The total reaction time can be from 1 hour to 15 hours. The reaction is preferably terminated when it is confirmed using an analytical instrument such as a nuclear magnetic resonance (NMR) spectrometer or liquid chromatography (LC) that the reaction conversion rate has reached a predetermined value. After the reaction is complete, the insoluble by-product salt is preferably removed by filtration or by washing with water. Thereafter, the unreacted epihalohydrin is preferably removed by distillation under reduced pressure. In this way, the desired epoxy resin of the present invention is obtained.

[0035] The reaction may use catalysts such as quaternary ammonium salts such as tetramethylammonium chloride and tetraethylammonium bromide; tertiary amines such as benzyldimethylamine and 2,4,6-tris(dimethylaminomethyl)phenol; imidazoles such as 2-ethyl-4-methylimidazole and 2-phenylimidazole; phosphonium salts such as ethyltriphenylphosphonium iodide; and phosphines such as triphenylphosphine. These may be used alone or in combination of two or more in any ratio.

[0036] In the reaction, inert organic solvents such as alcohols such as ethanol and isopropyl alcohol, ketones such as acetone and methyl ethyl ketone, ethers such as dioxane and ethylene glycol dimethyl ether, glycol ethers such as methoxypropanol, and aprotic polar solvents such as dimethyl sulfoxide and dimethylformamide may be used. These may be used alone or in combination of two or more in any ratio.

[0037] If the amount of saponifiable halogen in the obtained epoxy resin is too large, it is preferable to reprocess it to obtain a purified epoxy resin with a sufficiently reduced amount of saponifiable halogen. The specific steps are as follows: (i) The crude epoxy resin is redissolved in an inert organic solvent such as isopropyl alcohol, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, dioxane, methoxypropanol, or dimethyl sulfoxide to form a solution. (ii) Adding an alkali metal hydroxide to the solution as a solid or in aqueous solution. (iii) Then, a re-cyclization reaction is carried out at a temperature of about 20° C. to 120° C. for 0.5 to 8 hours. (iv) Thereafter, excess alkali metal hydroxide and by-product salts are removed by washing with water or the like, and the organic solvent is further removed by distillation under reduced pressure. As described above, the epoxy resin of the present invention can be obtained in a sufficiently purified state.

[0038] <Curable resin composition> The present invention relates to a curable resin composition containing at least one epoxy resin of the present invention.

[0039] (Curable resin composition of the first embodiment) One embodiment of the curable resin composition of the present invention is a curable resin composition containing the epoxy resin of the present invention and a curing agent.

[0040] The curing agent is not particularly limited, and examples thereof include phenolic resin curing agents, acid anhydride curing agents, amine curing agents, active ester curing agents, imidazole curing agents, etc. These may be used alone or in combination of two or more kinds in any ratio.

[0041] The content of the curing agent can be adjusted appropriately depending on the type of curing agent, but can be 1 part by mass or more and 200 parts by mass or less per 100 parts by mass of the epoxy resin of the present invention. For example, when the curing agent is an imidazole-based curing agent, the content can be 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of the epoxy resin.

[0042] The curable resin composition of this embodiment may contain epoxy resins other than the epoxy resin of the present invention (for example, bisphenol-type epoxy resins such as bisphenol A-type epoxy resins and bisphenol F-type epoxy resins, and hydrogenated epoxy resins thereof, phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, etc.) within the range that does not impair the effects of the present invention.

[0043] The curable resin composition of this embodiment may contain a thermosetting resin other than an epoxy resin (for example, a maleimide resin, a melamine resin, a urea resin, a silicone resin, etc.) within a range that does not impair the effects of the present invention.

[0044] The curable resin composition of this embodiment may contain a solvent (for example, an alcohol-based solvent, an ester-based solvent, a ketone-based solvent, an amide-based solvent, etc.) to improve workability and adjust viscosity during application.

[0045] The curable resin composition of this embodiment may contain known additives such as a curing accelerator, a flame retardant, an inorganic filler, an organic filler, a thickener, an antifoaming agent, a leveling agent, an adhesion imparting agent, a colorant, and a thermoplastic resin.

[0046] The method for producing the curable resin composition of this embodiment is not particularly limited, and examples thereof include a method of mixing and dispersing the ingredients using a planetary centrifugal mixer, a rotary mixer, a roll mill, a ball mill, etc. The curable resin composition of this embodiment can be made into a resin varnish by adding a solvent thereto.

[0047] The curable resin composition of this embodiment can be applied to a substrate, optionally dried, and then heat-treated at 100° C. or higher and 250° C. or lower for 10 minutes to 60 minutes to obtain a cured product.

[0048] (Curable resin composition of second embodiment) Another embodiment of the curable resin composition of the present invention is a curable resin composition containing the epoxy resin of the present invention, a photopolymerizable compound, and a photoinitiator.

[0049] The photopolymerizable compound is not particularly limited, and examples thereof include compounds having an ethylenically unsaturated bond, and for example, compounds having a (meth)acrylate structure are preferred. Here, (meth)acrylate means methacrylate and / or acrylate.

[0050] The compound having a (meth)acrylate structure may be a polymer, for example, an epoxy (meth)acrylate of an epoxy resin represented by general formula (1).

[0051] The photopolymerizable compound may be present in an amount of 1 part by mass or more and 300 parts by mass or less relative to 100 parts by mass of the epoxy resin of the present invention.

[0052] The photoinitiator may be any substance that can generate active species such as radicals and polymerize ethylenically unsaturated bonds when irradiated with high-energy light such as ultraviolet light, and examples thereof include photoradical polymerization initiators.

[0053] The photoinitiator can be used in an amount of 1 part by mass or more and 20 parts by mass or less relative to 100 parts by mass of the epoxy resin of the present invention.

[0054] The curable resin composition of this embodiment may contain epoxy resins other than the epoxy resin of the present invention (for example, bisphenol-type epoxy resins such as bisphenol A-type epoxy resins and bisphenol F-type epoxy resins, and hydrogenated epoxy resins thereof, phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, etc.) within the range that does not impair the effects of the present invention.

[0055] The curable resin composition of this embodiment may contain a solvent (for example, an alcohol-based solvent, an ester-based solvent, a ketone-based solvent, an amide-based solvent, etc.) to improve workability and adjust viscosity during application.

[0056] The curable resin composition of this embodiment may contain known additives such as a curing accelerator, a flame retardant, an inorganic filler, an organic filler, a thickener, an antifoaming agent, a leveling agent, an adhesion imparting agent, a colorant, and a thermoplastic resin.

[0057] The method for producing the curable resin composition of this embodiment is not particularly limited, and examples thereof include a method of mixing and dispersing the ingredients using a planetary centrifugal mixer, a rotary mixer, a roll mill, a ball mill, etc. The curable resin composition of this embodiment can be made into a resin varnish by adding a solvent thereto.

[0058] The curable resin composition of this embodiment can be applied to a substrate, optionally dried, irradiated with actinic rays, and then heat-treated to obtain a cured product.

[0059] The actinic rays are not particularly limited, and examples thereof include ultraviolet rays, visible rays, electron beams, and X-rays, with ultraviolet rays being particularly preferred.

[0060] The cured product of the present invention can achieve high insulation reliability when used in semiconductor packages and the like, and is suitable for, for example, interlayer insulating films for printed wiring boards, solder resists, and sealants. [Example]

[0061] Hereinafter, the present invention will be described more specifically according to Examples, but the present invention is not limited by the Examples. Unless otherwise specified, "parts" represents parts by mass, and "%" represents mass %. Also, the measurement methods were measured by the following methods respectively.

[0062] <GPC Measurement> The weight average molecular weight (Mw) and number average molecular weight (Mn) were measured using gel permeation chromatography (GPC, HLC-8420GPC manufactured by Tosoh Corporation), and are values converted with standard polystyrene. The specific measurement conditions are as follows. Column: TSKgelsupermultipore HZ-M (manufactured by Tosoh Corporation) Column internal temperature: 40 °C Solvent: THF Eluent flow rate: 0.6 mL / min Standard reagent for calibration: Polystyrene Detector wavelength: 254 nm Detector temperature: 40 °C Molecular weight calculation range during analysis: 10 to 18 minutes

[0063] <Epoxy equivalent> The epoxy equivalent was measured based on JIS K 7236:2009.

[0064] <Total chlorine content> The total chlorine content was measured based on JISK7243-3:2005.

[0065] <Hydroxyl equivalent> The hydroxyl equivalent was calculated by measuring the hydroxyl value based on JIS K 0070:1992.

[0066] <Solid content acid value> The solid content acid value was calculated from the acid value of the solution based on JIS K 0070:1992 and the solid content acid value from the solid content concentration.

[0067] <Solid content concentration> The solid content concentration was calculated by dividing the mass of the reaction substrate excluding the solvent by the total mass of the solution containing the solvent.

[0068] The fluoral used in the synthesis of the epoxy resins of the present invention and the comparative epoxy resins was prepared according to the method described in WO 2021 / 193878.

[0069] Synthesis Example 1: Epoxy Resin 1 (Inventive Example) A 100 mL stainless steel autoclave reactor equipped with a pressure gauge, thermometer protection tube, insertion tube, and stirring motor was charged with 12.4 g of a fluoral-containing mixture (44% hydrogen fluoride by mass, 1% hydrogen chloride by mass, 55% organic matter by mass) (fluoral: 0.070 mol, hydrogen fluoride: 0.273 mol), 32.9 g (1.645 mol) of hydrogen fluoride, and 53.8 g (0.160 mol) of 2,2-bis(4-hydroxyphenyl)hexafluoropropane (bisphenol AF). The reaction was carried out at an internal temperature of 30 °C and an absolute pressure of 0.2 MPa for 18 hours. After completion of the reaction, the reaction mixture was added to a mixed solvent of 300 g of methyl isobutyl ketone and 130 g of water and stirred for 30 minutes. The organic layer was separated and recovered. The recovered organic layer was adjusted to pH 6.5-7 with 48% KOH aqueous solution and then separated into two layers. The resulting organic layer was washed twice with 100 g of water. After washing, the organic layer was concentrated to dryness, yielding 57.2 g of the target novolak resin. The hydroxyl equivalent of this novolak resin was 206 g / eq. The number-average molecular weight (Mn) was 716, the weight-average molecular weight (Mw) was 870, and the polydispersity index (Mw / Mn) was 1.2.

[0070] A 300 mL glass flask equipped with a stirrer, dropping funnel, and thermometer was charged with 20 g of the above novolak resin, 53.8 g (0.581 mol) of epichlorohydrin, 4.3 g of 1-butanol, and 40 g of methyl isobutyl ketone, and the flask was heated to an internal temperature of 50°C using a water bath. Then, 21.3 g (0.107 mol) of 20% by weight aqueous sodium hydroxide solution was added dropwise to the flask over 2 hours. The flask was then maintained at 50°C for 1 hour to complete the reaction. After completion of the reaction, the organic layer was recovered by separation and concentrated using an evaporator to obtain a crude epoxy resin. A 300 mL glass flask equipped with a stirrer and thermometer was charged with the above crude epoxy resin, 40.0 g of methyl isobutyl ketone, 7 g of 1-butanol, and 12.5 g of 20% by weight aqueous sodium hydroxide solution. The flask was heated to an internal temperature of 80°C using a water bath, and alkali treatment was performed for 4 hours. Then, 40 g of water was added, and the organic layer was recovered by separation and washed three times with 160 g of water. The recovered organic layer was then concentrated using an evaporator to obtain 22.9 g of the target epoxy resin (epoxy resin represented by general formula (1)). The epoxy equivalent was 307 g / equivalent. The number average molecular weight (Mn) was 825, the weight average molecular weight (Mw) was 2184, and the polydispersity index (Mw / Mn) was 2.6. The total chlorine content was 747 ppm.

[0071] Synthesis Example 2: Epoxy Resin 2 (Inventive Example) A 100 mL stainless steel autoclave reactor equipped with a pressure gauge, thermometer protection tube, insertion tube, and stirrer motor was charged with 13.1 g of a fluoral-containing mixture (hydrogen fluoride: 44 wt%, hydrogen chloride: 1 wt%, organic matter: 55 wt%) (fluoral: 0.074 mol, hydrogen fluoride: 0.288 mol), 32.6 g (1.630 mol) of hydrogen fluoride, and 53.8 g (0.160 mol) of 2,2-bis(4-hydroxyphenyl)hexafluoropropane (bisphenol AF). The reaction was carried out at an internal temperature of 30°C and an absolute pressure of 0.2 MPa for 18 hours. The post-treatment was performed in the same manner as in Synthesis Example 1. As a result, 56.6 g of the target novolac resin was obtained. The hydroxyl equivalent of this novolac resin was 206 g / eq. The number average molecular weight (Mn) was 772, the weight average molecular weight (Mw) was 1143, and the polydispersity index (Mw / Mn) was 1.5.

[0072] A 300 mL glass flask equipped with a stirrer, dropping funnel, and thermometer was charged with 20 g of the above novolak resin, 53.9 g (0.583 mol) of epichlorohydrin, 4.3 g of 1-butanol, and 40 g of methyl isobutyl ketone, and the flask was heated to an internal temperature of 50°C using a water bath. Then, 21.4 g (0.107 mol) of 20% by weight aqueous sodium hydroxide solution was added dropwise to the flask over 2 hours. The flask was then maintained at 50°C for 1 hour to complete the reaction. After the reaction was complete, the organic layer was recovered by separation and concentrated using an evaporator to obtain a crude epoxy resin. A 300 mL glass flask equipped with a stirrer and thermometer was charged with the above crude epoxy resin, 40.0 g of methyl isobutyl ketone, 7 g of 1-butanol, and 12.5 g of 20% by weight aqueous sodium hydroxide solution. The mixture was heated to an internal temperature of 80°C using a water bath and alkali-treated for 4 hours. Then, 40 g of water was added, and the organic layer was recovered by separation and washed twice with 40 g of water. The recovered organic layer was then concentrated using an evaporator to obtain 22.6 g of the target epoxy resin (epoxy resin represented by general formula (1)). The epoxy equivalent was 308 g / equivalent. The number average molecular weight (Mn) was 990, the weight average molecular weight (Mw) was 2818, and the polydispersity index (Mw / Mn) was 2.8. The total chlorine content was 1,220 ppm.

[0073] Synthesis Example 3: Epoxy Resin 3 (Comparative Example) A 100 mL stainless steel autoclave reactor equipped with a pressure gauge, thermometer protection tube, insertion tube, and stirring motor was charged with 14.3 g of the fluoral-containing mixture (hydrogen fluoride: 44% by mass, hydrogen chloride: 1% by mass, organic matter: 55% by mass) obtained in the above "Fluoral Preparation Example" (fluoral: 0.080 mol, hydrogen fluoride: 0.315 mol), 32.1 g (1.605 mol) of hydrogen fluoride, and 53.8 g (0.160 mol) of 2,2-bis(4-hydroxyphenyl)hexafluoropropane (bisphenol AF). The reaction was carried out at an internal temperature of 30°C and an absolute pressure of 0.2 MPa for 18 hours. The post-treatment was performed as in Synthesis Example 1. As a result, 57.5 g of the target novolac resin was obtained. The hydroxyl equivalent of this novolac resin was 204 g / eq. The number average molecular weight (Mn) was 820, the weight average molecular weight (Mw) was 1656, and the polydispersity index (Mw / Mn) was 2.0.

[0074] A 300 mL glass flask equipped with a stirrer, dropping funnel, and thermometer was charged with 20 g of the above novolak resin (hydroxyl equivalent: 204 g / eq.), 54.4 g (0.588 mol) of epichlorohydrin, 4.4 g of 1-butanol, and 40 g of methyl isobutyl ketone, and the flask was heated to an internal temperature of 50°C using a water bath. Then, 21.6 g (0.108 mol) of a 20% by mass aqueous solution of sodium hydroxide was added dropwise to the flask over 2 hours. The flask was then maintained at 50°C for 1 hour to complete the reaction. After completion of the reaction, the organic layer was recovered by separation and concentrated using an evaporator to obtain a crude epoxy resin. The crude epoxy resin, 40.0 g of methyl isobutyl ketone, 7 g of 1-butanol, and 13.3 g of 20% by weight aqueous sodium hydroxide solution were placed in a 300 mL glass flask equipped with a stirrer and thermometer. The mixture was heated to an internal temperature of 80°C in a water bath and alkali-treated for 4 hours. Then, 40 g of water was added, and the organic layer was recovered by separation and washed twice with 40 g of water. The recovered organic layer was then concentrated in an evaporator to obtain 22.3 g of the target epoxy resin (epoxy resin represented by general formula (1)). The epoxy equivalent was 309 g / eq. The number-average molecular weight (Mn) was 1094, the weight-average molecular weight (Mw) was 3934, and the polydispersity index (Mw / Mn) was 3.6. The total chlorine content was 1,654 ppm.

[0075] Examples 1 and 2 and Comparative Example 1: Preparation of curable resin composition The components shown in Table 1 were mixed in the amounts (parts by mass) shown in Table 1 using a rotation-revolution mixer to prepare the respective curable resin compositions.

[0076] The insulating reliability of the obtained curable resin composition was evaluated as follows. The evaluation was performed as follows. The results are shown in Table 1.

[0077] <Insulation reliability> Each of the curable resin compositions prepared above was applied to a 38 μm polyester film using an applicator and dried in a hot air circulation drying oven (80°C for 30 minutes) to produce a dry film with a 20 μm thick resin layer. Each of the prepared dry films was laminated onto a test substrate with a comb-shaped pattern of L / S = 12 / 13 μm formed thereon using a vacuum laminator (CVP-300: manufactured by Nikko Materials Co., Ltd.) in a first chamber at 90°C under conditions of a vacuum pressure of 3 hPa and a vacuum time of 30 seconds, so that the resin layer was in contact with the copper foil, and then pressed under conditions of a pressure of 0.5 MPa and a press time of 30 seconds. Next, after peeling off the polyester film, the substrate was cured by heating at 200° C. for 60 minutes in a hot air circulation drying oven to obtain a substrate for evaluating insulation reliability. Using this substrate, HAST was performed under the conditions of 130°C, 85% RH, an applied voltage of 5V, and measurement in a chamber. The evaluation criteria are as follows: 〇: Insulation resistance after 200 hours is 1×10 6 Ω or more △: Insulation resistance after 100 hours is 1×10 6 Ω or more and less than 200h, insulation resistance is 1×10 6 It will be less than Ω ×: Insulation resistance is 1×10 for less than 100 hours 6 It will be less than Ω

[0078] [Table 1]

[0079] As shown in Table 1, the epoxy resins of Examples 1 and 2 exhibited superior insulation reliability compared to the epoxy resin of Comparative Example 1.

[0080] Examples 3 to 5 and Comparative Examples 2 to 3: Preparation of curable resin compositions The components shown in Table 2 were mixed in the amounts (parts by mass) shown in Table 2 using a planetary centrifugal mixer to prepare the respective curable resin compositions.

[0081] In the table, acrylate resin 1 and acrylate resin 2 were prepared as follows.

[0082] Synthesis Example 4: Acrylate Resin 1 220 parts of cresol novolac epoxy resin (EPICLON N-695, epoxy equivalent: 220, manufactured by DIC Corporation) was placed in a four-neck flask equipped with a stirrer and reflux condenser, and 214 parts of carbitol acetate was added and dissolved by heating. Next, 0.1 parts of hydroquinone as a polymerization inhibitor and 2.0 parts of dimethylbenzylamine as a reaction catalyst were added. This mixture was heated to 95-105°C, and 72 parts of acrylic acid were slowly added dropwise, allowing the reaction to proceed for 16 hours. The reaction product was cooled to 80-90°C, and 106 parts of 1,2,3,6-tetrahydrophthalic anhydride was added. The reaction was allowed to proceed for 8 hours, cooled, and then discharged. The photosensitive resin thus obtained, which had both an ethylenically unsaturated bond and a carboxyl group, had a nonvolatile content of 65%, an acid value of the solid matter of 100 mgKOH / g, and a weight-average molecular weight Mw of 3,500.

[0083] Synthesis Example 5: Acrylate Resin 2 A 100 mL glass flask equipped with a stirrer, reflux condenser, and thermometer was charged with 5.0 g of the epoxy resin obtained in Synthesis Example 1 (epoxy equivalent: 307 g / equivalent), 1.2 g (16 mmol) of acrylic acid, 25 mg of hydroquinone, and 3.3 g of propylene glycol methyl ether acetate. The mixture was heated to an internal temperature of 110°C using an oil bath and stirred to achieve a uniform solution. Next, 20 mg of triphenylphosphine was charged, and the mixture was stirred for 2 hours while introducing dry air. The internal temperature was then raised to 120°C and stirred for an additional 8 hours to complete the reaction. After cooling, the desired epoxy acrylate resin solution was obtained.

[0084] Next, 10.0 g of the resulting epoxy acrylate resin solution and 1.5 g (10 mmol) of 1,2,3,6-tetrahydrophthalic anhydride were placed in a 100 mL glass flask equipped with a stirrer, reflux condenser, and thermometer. The mixture was heated to an internal temperature of 110°C using an oil bath while introducing dry air, and the reaction was carried out for 8 hours. After cooling, the target acid-modified epoxy acrylate resin solution was obtained. The number-average molecular weight (Mn) was 1,487, the weight-average molecular weight (Mw) was 4,390, the polydispersity index (Mw / Mn) was 3.0, the solid acid value was 76 mgKOH / g, and the solid concentration was 67.0% by mass.

[0085] The heat resistance and insulation reliability of the obtained curable resin composition were evaluated as follows. The results are shown in Table 2.

[0086] <Heat resistance> Each of the curable resin compositions prepared above was applied to a 38 μm polyester film using an applicator and dried in a hot air circulation drying oven (80°C for 30 minutes) to produce a dry film having a 20 μm thick resin layer. Each dry film thus produced was laminated onto the glossy side (on the copper foil) of GTS-MP foil (manufactured by Furukawa Circuit Foil Co., Ltd.) using a vacuum laminator (CVP-300: manufactured by Nikko Materials Co., Ltd.) in a first chamber at 90°C under conditions of a vacuum pressure of 3 hPa and a vacuum time of 30 seconds, and then pressed under conditions of a pressure of 0.5 MPa and a press time of 60 seconds, so that the resin layer was in contact with the copper foil. Next, the polyester film was peeled off, and the film was exposed to light in a DI exposure device (light source: high-pressure mercury lamp) at an integrated light dose of 300 mJ. The film was then developed with a 1% by mass aqueous sodium carbonate solution at 30°C for 60 seconds at a spray pressure of 0.2 MPa, washed with water at a spray pressure of 0.1 MPa for 30 seconds, and dried. The film was then placed in a UV conveyor oven at an integrated light dose of 2000 mJ / cm. 2 After irradiating with ultraviolet light under these conditions, the film was cured by heating at 170°C for 60 minutes in a hot air circulation drying oven. The cured film was then peeled off from the copper foil to obtain a sample for evaluating heat resistance. Tg was measured using an RSA-G2 (manufactured by TA Instruments) at a temperature range of 30°C to 300°C, a heating rate of 5°C / min, and a frequency of 1 Hz. The evaluation criteria are as follows: ○ = 160℃ or higher ×=less than 160℃

[0087] <Insulation reliability> A substrate for evaluating insulation reliability was prepared by laminating, exposing, and heat treating it in the same manner as for preparing the sample for evaluating heat resistance, except that a test substrate with a L / S = 12 / 13 μm comb pattern was used instead of copper foil as the substrate to be laminated. HAST was performed using this substrate in a chamber at 130°C, 85% RH, and an applied voltage of 5 V. The evaluation criteria are as follows: The times in parentheses in Table 2 indicate the time when the insulation resistance value was 1×10 6 This means the time when the resistance becomes less than Ω. 〇: Insulation resistance after 200 hours is 1×10 6 Ω or more △: Insulation resistance after 100 hours is 1×10 6 Ω or more and less than 200h, insulation resistance is 1×10 6 It will be less than Ω ×: Insulation resistance is 1×10 for less than 100 hours 6 It will be less than Ω

[0088] [Table 2]

[0089] As shown in Table 2, the epoxy resins of Examples 3, 4 and 5 exhibited superior insulation reliability compared to the epoxy resins of Comparative Examples 2 and 3. [Industrial Applicability]

[0090] According to the present invention, an epoxy resin capable of producing a cured product that can achieve high insulation reliability when used in products such as semiconductor packages is provided, along with a curable resin composition containing at least one of the epoxy resins and a cured product of the curable resin composition. A printed wiring board having the cured product has high insulation reliability and is highly useful in industry.

Claims

1. An epoxy resin represented by general formula (1), wherein the epoxy resin has a weight average molecular weight (Mw) determined by gel permeation chromatography (GPC) of 1,000 or more and 3,500 or less. 【Chemistry 1】 (In the formula, m is a number of 0 or more, and n is a number of 0 or more, The bonding form of the units grouped by m and the units grouped by n may be random bonding, block bonding, or a combination thereof.

2. 2. The epoxy resin according to claim 1, having an epoxy equivalent of 280 g / eq or more and 350 g / eq or less.

3. 2. The epoxy resin according to claim 1, having a polydispersity of 2.0 or more and 3.5 or less.

4. 2. The epoxy resin according to claim 1, wherein the total chlorine content in the epoxy resin is 1,500 ppm or less.

5. A curable resin composition comprising at least one epoxy resin according to any one of claims 1 to 4.

6. A cured product of the curable resin composition according to claim 5.

7. A printed wiring board comprising the cured product according to claim 6.

Images