JP7748855B2 - Dihydroxy compound, epoxy resin, production method thereof, epoxy resin composition, and cured product - Google Patents

Description

The present invention relates to dihydroxy compounds and epoxy resins that exhibit excellent moldability and provide cured products with excellent heat resistance, low thermal expansion, and moisture resistance, as well as epoxy resin compositions and cured products using these compounds. These compounds are suitable for use in fields such as printed wiring boards, insulating materials in the electrical and electronic fields (e.g., semiconductor encapsulation), and carbon fiber composite materials.

In recent years, advances in the field of advanced materials, in particular, have led to a demand for the development of higher-performance base resins. In addition to improved functionality such as heat resistance and moisture resistance, there is also a demand for resins with excellent flame retardancy from the perspectives of environmental friendliness and safety. Another important issue is improving ease of handling, such as solvent solubility, when preparing epoxy resin compositions.

However, none of the epoxy resins known to date fully satisfy these requirements. For example, Patent Document 1 proposes an epoxy resin derived from a phenol aralkyl resin, but its heat resistance and moisture resistance are insufficient. Patent Document 2 proposes an epoxy resin containing an ether ether ketone group, a unit of super engineering plastics, but it suffers from moldability problems and still lacks heat resistance. Patent Document 3 proposes an epoxy resin composition using a bisphenol compound with an imide ring as a curing agent, but due to the inclusion of an isopropylidene structure, its heat resistance is insufficient. Patent Document 4 discloses a bisphenol-based epoxy compound with an imide group, but due to the inclusion of an isopropylidene structure, its heat resistance is also insufficient. Patent Document 5 proposes a specific bisimide phenol derivative, but when made into an epoxy resin, its solvent solubility and compatibility with the curing agent remain poor, making it difficult to prepare the epoxy resin composition and resulting in insufficient heat resistance, such as thermal decomposition stability. Patent Document 6 proposes an epoxy resin containing an imide skeleton, but because the structure is one in which bisphenols are copolymerized to ensure solvent solubility, heat resistance such as thermal decomposition stability is still insufficient. Non-Patent Document 1 proposes an epoxy resin obtained from N,N'-bis(5-hydroxy-1-naphthyl)pyromellitdiimide, but due to the high rigidity of the pyromellitimide group, there are still issues with solvent solubility and compatibility with curing agents.

Japanese Unexamined Patent Publication No. 63-238122 JP 2012-46615 A Japanese Patent Application Publication No. 4-328121 Japanese Patent Application Publication No. 4-36753 JP 2011-173827 A JP 2010-90360 A

H. Ren, J. Sun, Q. Zhao, Q. Zhou, Qi. Ling, Polymer 49 (2008) 5249-5253

The object of the present invention is to provide dihydroxy compounds and epoxy resins that have good solvent solubility and moldability, and can produce cured products that exhibit excellent heat resistance and moisture resistance, making them useful for applications such as lamination, molding, casting, and adhesion. The object of the present invention is to provide methods for producing these compounds and epoxy resin compositions using these compounds, as well as cured products thereof.

That is, the present invention relates to a novel dihydroxy compound represented by the following general formula (1).
(wherein X represents a single bond, —CH—, —O—, —CO—, —SO—, or —C(CF)—, and A represents a naphthylene group which may have a substituent.)

The present invention also relates to a novel epoxy resin represented by the following general formula (2):
(wherein A and X have the same meanings as in formula (1), and n represents a number from 0 to 50.)

The present invention also relates to a method for producing an epoxy resin represented by the general formula (2) above, which comprises reacting a dihydroxy compound represented by the general formula (1) above with epichlorohydrin.

Furthermore, the present invention relates to an epoxy resin composition containing the dihydroxy compound of general formula (1) above or the epoxy resin of general formula (2) above as an essential component of the epoxy resin in the epoxy resin component or the curing agent in the curing agent component, and also to a cured product obtained by curing such an epoxy resin composition.

The cured product obtained by curing the epoxy resin composition of the present invention, which contains as essential components an epoxy resin or dihydroxy compound having a naphthalene and imide structure, has good solvent solubility and moldability, as well as excellent heat resistance, low thermal expansion, moisture resistance, etc., and is suitable for use in applications such as lamination, molding, casting, and adhesion.

1 shows an IR chart of epoxy resin A obtained in Example 1. 1 shows an IR spectrum of epoxy resin A obtained in Example 3. 1 shows the H-NMR spectrum of epoxy resin A obtained in Example 3.

The present invention will be described in detail below.
The dihydroxy compound of the present invention is represented by the general formula (1).

Here, X represents a single bond, -CH2-, -O-, -CO-, -SO2-, or -C(CF3)2-. From the viewpoint of heat resistance, a single bond, -O-, or -CO- is preferred, while from the viewpoints of solvent solubility and moldability, -O-, -SO2-, or -C(CF3)2- is preferred. Furthermore, A represents a naphthylene group which may have a substituent. Examples of naphthylene groups include 1,4-substituted, 1,5-substituted, 1,6-substituted, 2,6-substituted, and 2,7-substituted groups, with the 1,5-substituted group being preferred from the viewpoint of solvent solubility and heat resistance. In other words, it is preferable that the 1st and 5th positions of the naphthalene are bonded to a hydroxy group or an imide group. Furthermore, examples of the substituent include an alkyl group.

The dihydroxy compound of the present invention preferably has a hydroxyl group equivalent weight in the range of 250 to 3,000 g/eq., more preferably 280 to 1,000 g/eq., and even more preferably 290 to 500. The melting point or softening point is preferably in the range of 120 to 350°C, and more preferably 150 to 300°C.

The epoxy resin of the present invention is represented by general formula (2).
Here, X and A have the same meanings as in formula (1).

In general formula (2), n represents the repeating number and represents a number between 0 and 50. In the case of a mixture of multiple compounds with different repeating numbers, the average value of n (Σn/Σ number of molecules) is between 0 and 50. The preferred value or average value of n varies depending on the intended application. For example, for semiconductor encapsulation applications requiring a high filler loading, a low viscosity is desirable, and the value or average value of n is between 0 and 15, preferably between 0.1 and 10.0, and more preferably between 0.1 and 5.0. Conventional epoxy resins are often obtained by a sequential reaction in which a compound with n = 0 is produced, which is then polymerized to produce a compound with n = 1. Such epoxy resins can also be advantageously used in the present invention. Furthermore, for applications such as printed wiring boards, high-molecular-weight epoxy resins are preferably used; in this case, the value of n is between 2 and 50, preferably between 5 and 50, and more preferably between 10 and 40.

The epoxy resin of the present invention preferably has a weight-average molecular weight in the range of 500 to 6,000, more preferably 500 to 3,000. The epoxy equivalent is preferably in the range of 300 to 3,000, more preferably 300 to 2,000, and particularly preferably 400 to 1,000. If it is greater than this, the viscosity and softening point will be high, making it difficult to prepare the epoxy resin composition and reducing moldability. The epoxy resin of the present invention preferably has a softening point or melting point in the range of 80 to 350°C, more preferably 100 to 300°C. The hydrolyzable chlorine content is preferably 1,000 ppm or less, more preferably 500 ppm or less.

The epoxy resin of the present invention can be produced by reacting a dihydroxy compound represented by general formula (1) with epichlorohydrin, although this reaction is not particularly limited. This reaction can be carried out in the same manner as a conventional epoxidation reaction.

For example, a dihydroxy compound represented by general formula (1) can be dissolved in excess epichlorohydrin and then reacted in the presence of an alkali metal hydroxide, such as sodium hydroxide or potassium hydroxide, at 50 to 150°C, preferably 60 to 120°C, for 1 to 10 hours. The alkali metal hydroxide is used in an amount of 0.8 to 2 moles, preferably 0.9 to 1.2 moles, per mole of hydroxyl groups in the dihydroxy compound. Epichlorohydrin is used in excess relative to the hydroxyl groups in the dihydroxy compound, typically 1.5 to 15 moles, preferably 2 to 8 moles, per mole of hydroxyl groups in the dihydroxy compound. A quaternary ammonium salt or the like can also be added during the reaction. Examples of quaternary ammonium salts include tetramethylammonium chloride, tetrabutylammonium chloride, and benzyltriethylammonium chloride. The amount of the quaternary ammonium salt added is preferably 0.1 to 2.0 wt % of the dihydroxy compound. If the amount is less than this, the effect of adding the quaternary ammonium salt is small; if it is more than this, the amount of hardly hydrolyzable chlorine produced increases, making it difficult to achieve high purity. Furthermore, polar solvents such as dimethyl sulfoxide and diglyme may be used, and the amount added is preferably in the range of 10 to 200 wt% relative to the dihydroxy compound. If the amount is less than this, the effect is small; if it is more than this, the volume efficiency decreases, which is undesirable from an economic standpoint. After the reaction is complete, the excess epichlorohydrin is distilled off, and the residue is dissolved in a solvent such as toluene or methyl isobutyl ketone, filtered, washed with water to remove inorganic salts, and the solvent is then distilled off to obtain the desired epoxy resin.

The epoxy resin composition of the present invention comprises an epoxy resin and a curing agent, and contains, as an essential component, an epoxy resin represented by general formula (2) or a dihydroxy compound represented by general formula (1).

When the epoxy resin represented by general formula (2) is used as an essential component, any curing agent generally known as an epoxy resin curing agent can be used. Examples include dicyandiamide, polyhydric phenols, acid anhydrides, aromatic and aliphatic amines, etc. Specific examples of polyhydric phenols include dihydric phenols such as bisphenol A, bisphenol F, bisphenol S, fluorene bisphenol, 4,4'-biphenol, 2,2'-biphenol, hydroquinone, resorcinol, and naphthalenediol; trihydric or higher phenols such as tris-(4-hydroxyphenyl)methane, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, phenol novolac, o-cresol novolac, naphthol novolac, and polyvinylphenol; and phenols, naphthols, bisphenol A, bisphenol B, bisphenol C, bisphenol D, bisphenol E, bisphenol F, bisphenol F, bisphenol F, bisphenol S, fluorene bisphenol, 4,4'-biphenol, 2,2'-biphenol, hydroquinone, resorcinol, and naphthalenediol. and polyhydric phenolic compounds synthesized by condensing dihydric phenols such as phenol F, bisphenol S, fluorene bisphenol, 4,4'-biphenol, 2,2'-biphenol, hydroquinone, resorcinol, and naphthalenediol with condensing agents such as formaldehyde, acetaldehyde, benzaldehyde, p-hydroxybenzaldehyde, and p-xylylene glycol. Acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylhimic anhydride, nadic anhydride, and trimellitic anhydride. Examples of amines include aromatic amines such as 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylsulfone, m-phenylenediamine, and p-xylylenediamine; aliphatic amines such as ethylenediamine, hexamethylenediamine, diethylenetriamine, and triethylenetetramine; and dihydroxy compounds represented by general formula (1). The resin composition of the present invention can contain one or more of these curing agents in combination. When the dihydroxy resin of the present invention is used as a curing agent, its amount is preferably 5 to 100 wt %, more preferably 30 to 100 wt %, of the total curing agent.

In addition to the epoxy resin represented by general formula (2), the epoxy resin composition of the present invention can use any conventional epoxy resin having two or more epoxy groups in the molecule. Examples include dihydric phenols such as bisphenol A, bisphenol S, fluorene bisphenol, 4,4'-biphenol, 2,2'-biphenol, hydroquinone, and resorcinol; trihydric or higher phenols such as tris-(4-hydroxyphenyl)methane, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, phenol novolac, and o-cresol novolac; and glycidyl ethers derived from halogenated bisphenols such as tetrabromobisphenol A. These epoxy resins can be used alone or in combination. In this case, the amount of the epoxy resin represented by formula (2) of the present invention is preferably 5 to 100 wt %, more preferably 50 to 100 wt %, of the total epoxy resin.

When the dihydroxy compound represented by general formula (1) is used as an essential component of the epoxy resin, any ordinary epoxy resin having two or more epoxy groups in the molecule can be used.

In the epoxy resin composition of the present invention, a compound generally known as a curing agent for epoxy resins can also be used in combination with the dihydroxy compound represented by general formula (1), as described above.

The blending ratio of epoxy resin to curing agent is preferably in the range of 0.8 to 1.5 in terms of equivalent ratio of epoxy groups to functional groups in the curing agent. Outside this range, unreacted epoxy groups or functional groups in the curing agent may remain after curing.

The epoxy resin composition of the present invention may contain oligomers or polymers such as polyesters, polyamides, polyimides, polyethers, polyurethanes, petroleum resins, indene coumarone resins, and phenoxy resins, as appropriate, and may also contain additives such as inorganic fillers, pigments, flame retardants, thixotropy-imparting agents, coupling agents, and flowability improvers. Examples of inorganic fillers include silica powders such as spherical or crushed fused silica and crystalline silica, alumina powders, glass powders, mica, talc, calcium carbonate, alumina, and hydrated alumina. Examples of pigments include organic or inorganic extender pigments and flake pigments. Examples of thixotropy-imparting agents include silicone-based agents, castor oil-based agents, aliphatic amide waxes, oxidized polyethylene waxes, and organic bentonite-based agents.
Furthermore, if necessary, conventionally known curing accelerators can be used. Examples include amines, imidazoles, organic phosphines, Lewis acids, etc. The amount added is usually in the range of 0.2 to 5 parts by weight per 100 parts by weight of the epoxy resin.
Furthermore, if necessary, the resin composition of the present invention may contain a release agent such as carnauba wax or OP wax, a coupling agent such as γ-glycidoxypropyltrimethoxysilane, a colorant such as carbon black, a flame retardant such as antimony trioxide, a stress reducing agent such as silicone oil, a lubricant such as calcium stearate, or the like.

The cured product of the present invention can be obtained by molding the above-mentioned epoxy resin composition using methods such as casting, compression molding, and transfer molding. The molding temperature is typically in the range of 120 to 280°C.

The present invention will be specifically described below based on examples and comparative examples.
Example 1 (Production of dihydroxy compound A)
In a separable flask, 47.5 g of 4,4'-oxydiphthalic dianhydride and 50.3 g of 5-amino-1-naphthol were dissolved in 150 mL of N-methylpyrrolidone and reacted at 80°C for 2 hours. 75 mL of toluene was added to the reaction solution, and the temperature was raised while removing the water generated by azeotropy. The temperature was then raised to 160°C and the reaction was continued for 3 hours. During this time, the water generated was removed from the system. After cooling to room temperature, 750 mL of distilled water was added, and the precipitate was collected by filtration, washed with water, and dried to obtain 84.0 g of a powdery product (dihydroxy compound A). The melting point of the resulting dihydroxy compound A was 211°C, and the hydroxyl equivalent was 306 g/eq. GPC measurement indicated that the purity was 100%. The infrared absorption spectrum is shown in Figure 1.
The melting point was measured using a Hitachi High-Tech Science DSC7020 differential scanning calorimeter, and the endothermic peak temperature measured at a heating rate of 10°C/min was taken as the melting point. The hydroxyl group equivalent was measured by potentiometric titration with potassium hydroxide in an acetyl chloride solution. The infrared absorption spectrum was measured by the KBr tablet method using a JASCO FT/IR-6100 infrared absorption analyzer.

Example 2 (Production of dihydroxy compound B)
A reaction similar to that in Example 1 was carried out using 45.0 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride and 50.3 g of 5-amino-1-naphthol in a separable flask, yielding 82.8 g of a powdery product (dihydroxy compound B). The melting point of the resulting dihydroxy compound B was 210°C, and the hydroxyl equivalent was 296 g/eq. GPC measurement revealed that the purity was 100%.

Example 3 (Synthesis of Epoxy Resin A)
20 g of dihydroxy compound A obtained in Example 1 was dissolved in 125 g of epichlorohydrin and 75 g of N-methylpyrrolidone, and 5.5 g of 48.6% aqueous sodium hydroxide solution was added dropwise over 4 hours at 65°C under reduced pressure (approximately 130 mmHg). During this time, the water produced was removed from the system by azeotropy with epichlorohydrin, and the distilled epichlorohydrin was returned to the system. After the reaction, the epichlorohydrin was distilled off under reduced pressure, and the reaction solution was added dropwise to a large amount of distilled water. The product was filtered, washed with water, and dried to obtain 19 g of a yellowish-brown epoxy resin (epoxy resin A). The resulting epoxy resin had a melting point of 185°C, an epoxy equivalent of 362 g/eq., and a hydrolyzable chlorine content of 560 ppm. GPC analysis revealed that 89% of the general formula (2) was n=0 and 9% was n=1. The GPC measurement was carried out using an apparatus: HLC-8320 (manufactured by Tosoh Corporation) and columns: two TSKgel Super HZ2500 columns and two TSKgel Super HZ2000 columns (both manufactured by Tosoh Corporation) under the conditions of a solvent: tetrahydrofuran, a flow rate: 0.35 ml/min, a temperature: 40°C, and a detector: RI. The infrared absorption spectrum is shown in Figure 2.
Here, the epoxy equivalent was measured by potentiometric titration with perchloric acid in an acetic acid solution of tetraethylammonium bromide. Hydrolyzable chlorine was determined by dissolving 0.5 g of a resin sample in 30 ml of 1,4-dioxane, boiling and refluxing the solution with 5 ml of a 1N-KOH/methanol solution for 30 minutes, and then potentiometric titration with a silver nitrate solution. ¹ H-NMR measurements were performed using a JNM-ECA600 measuring apparatus manufactured by JEOL RESONANCE, using DMSO-d6 as the solvent. The measurement results are shown in Figure 3.

Example 4 (Synthesis of Epoxy Resin B)
A reaction was carried out in the same manner as in Example 3 using 23 g of dihydroxy compound B obtained in Example 2, 150 g of epichlorohydrin, 75 g of N-methylpyrrolidone, and 6.6 g of 48.6% aqueous sodium hydroxide solution, to obtain 22 g of a brownish-white epoxy resin (epoxy resin B). The resulting epoxy resin had a melting point of 159°C, an epoxy equivalent of 347 g/eq., and a hydrolyzable chlorine content of 340 ppm. GPC measurement revealed that 88% of the general formula (2) was n=0 and 11% was n=1.

Reference Example 1 (Production of Dihydroxy Compound C)
The same reaction as in Example 1 was carried out using 51.0 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride and 42.7 g of 4-amino-m-cresol to obtain 81 g of a powdery product (dihydroxy compound C). GPC measurement revealed that the purity was 100%.

Reference Example 2 (Synthesis of Epoxy Resin C)
Using 20 g of dihydroxy compound C obtained in Reference Example 1, 180 g of epichlorohydrin, 90 g of N-methylpyrrolidone, and 6.5 g of a 48.6% aqueous solution of sodium hydroxide, a reaction was carried out in the same manner as in Example 3 to obtain 34 g of a brownish-white epoxy resin (epoxy resin C). The resulting epoxy resin had a melting point of 260°C and an epoxy equivalent of 328 g/eq.

Reference Example 3 (Production of dihydroxy compound D)
Using 51.0 g of 4,4'-oxydiphthalic dianhydride and 40.5 g of 4-amino-m-cresol, a reaction similar to that in Example 1 was carried out to obtain 77 g of a powdery product (dihydroxy compound D). GPC measurement revealed that the purity was 100%.

Reference Example 4 (Synthesis of Epoxy Resin D)
A reaction was carried out in the same manner as in Example 3 using 15 g of dihydroxy compound D obtained in Reference Example 3, 105 g of epichlorohydrin, 30 g of N-methylpyrrolidone, and 4.4 g of a 48.6% aqueous solution of sodium hydroxide to obtain 16 g of a brown epoxy resin (epoxy resin D). The melting point of the obtained epoxy resin was 170°C, and the epoxy equivalent was 324 g/eq.

Examples 5 to 7 and Comparative Examples 1 to 3
The epoxy resins synthesized in Examples 3 and 4 and Reference Examples 3 and 4 (epoxy resins A to D), diphenyl ether-based epoxy resin (epoxy resin E: manufactured by Nippon Steel Chemical & Material Co., Ltd., YSLV-80DE, epoxy equivalent 163, melting point 81°C), o-cresol novolac-type epoxy resin (epoxy resin F: manufactured by Nippon Kayaku Co., Ltd., EOCN-1020, epoxy equivalent 200, softening point 55°C), the dihydroxy compound synthesized in Example 1 (curing agent A), and phenol novolac (curing agent B: manufactured by Aica Kogyo Co., Ltd., BRG-557, hydroxyl group equivalent 104, softening point 83°C) were used as curing accelerators.
1636678999873_0
The components were weighed out in the proportions shown in Table 1 using a thermoplastic polymer (TMP), and mixed with stirring at 180° C. to prepare a resin composition.
The resulting mixture was molded in a press (190°C, 5 minutes), and then post-cured (175°C, 4 hours) to obtain test pieces, which were then subjected to various physical property tests. The test methods were as follows. The results are shown in Table 1.

[evaluation]
(1) Kneadability The components in the formulation shown in Table 1 were weighed out and mixed in powder form, and the mixture was stirred and mixed at 180° C. The state of the melted mixture was observed. The evaluation was as follows:
◯: The epoxy resin and hardener were melted and mixed uniformly.
Δ: A small amount of unmixed epoxy resin and curing agent remained.
×: The epoxy resin and the curing agent were not uniformly melted, and unmixed portions remained.
(2) Moldability The resin composition was pulverized into powder and charged into a mold heated to 190°C, followed by press molding. The surface condition of the molded test piece was visually observed. The evaluation was as follows:
◯: No unfilled areas in the mold. The surface smoothness of the molded product is good.
△: There are unfilled areas in the four corners of the mold. The surface of the molded product is uneven.
×: Unfilled areas were found throughout the mold, voids were generated throughout the molded product, and the molded product was brittle.
(3) Linear expansion coefficient and glass transition temperature: Measurements were made using a Hitachi High-Tech Science TMA7100 thermomechanical measuring device at a temperature rise rate of 10° C./min.
(4) Thermal decomposition temperature and residual carbon ratio Using a Hitachi High-Tech Science TG/DTA7300 thermogravimetric analyzer, the thermal decomposition temperature at which a weight loss of 10 wt % was achieved and the residual carbon ratio at 700°C were determined under conditions of a nitrogen gas flow and a heating rate of 10°C/min.
(5) Water Absorption Rate A disk having a diameter of 50 mm and a thickness of 3 mm was molded, and after post-curing, the weight change rate after absorbing moisture for 100 hours under conditions of 85°C and a relative humidity of 85% was measured.

Claims (3)

The following general formula (2):
(wherein X represents a single bond or —O—, A represents a naphthylene group which may have a substituent, and n represents a number from 0 to 50.)
An epoxy resin characterized by being represented by the formula: 10. An epoxy resin composition comprising an epoxy resin and a curing agent, wherein the epoxy resin according to claim 1 is blended as an epoxy resin component. A cured product obtained by curing the epoxy resin composition according to claim 2 .