JP2011252155A - Epoxy resin composition for optical material, and its cured product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition in which a refractive index of a cured product thereof is very high.SOLUTION: The epoxy resin composition for an optical material includes: a biphenyl novolak type epoxy resin as an epoxy resin; and a phenol resin expressed by formula (2) as a curing agent. In the formula, n denotes a positive number.

Description

The present invention relates to an epoxy resin composition for optical materials that provides a cured product having a high refractive index and high heat resistance.

Epoxy resins are generally cured with various curing agents, resulting in cured products with excellent mechanical properties, water resistance, chemical resistance, heat resistance, electrical properties, etc., adhesives, paints, laminates, moldings It is used in a wide range of fields such as materials and casting materials. In the fields of optical lenses, eyeglass lenses, optical disk substrates, plastic optical fibers, etc., PMMA (polymethyl methacrylate) is used as a general resin material, and PS (polystyrene) is a common resin material when a higher refractive index is required. Have been used.

The epoxy resin composition of the present invention gives a cured product having an extremely high refractive index as compared with epoxy resins that have been generally used conventionally. Therefore, the epoxy resin composition of the present invention is extremely useful for optical material applications such as optical lenses, spectacle lenses, optical disk substrates, and plastic optical fibers.

However, although PMMA and PS are thermoplastic resins, they have flexibility, but have problems in terms of reliability in fields where heat resistance is required. In addition, a cured product of a normal epoxy resin has high reliability, but lacks flexibility, and its refractive index is usually around 1.5, which is insufficient for use in optical materials.

In view of the actual situation, the present inventors have intensively studied for a material having high heat resistance and sufficient flexibility even when formed into a film and having a high refractive index. As a result, the inventors have a specific structure. The inventors have found that a combination of an epoxy resin and a curing agent satisfies these characteristics, and have completed the present invention.

That is, the present invention provides the following formula (1)

（式中ｎは正数を表す。）で表されるエポキシ樹脂及び硬化剤を含有することを特徴とする光学材料用エポキシ樹脂組成物、（２）エポキシ樹脂及び式（２）

(Wherein n represents a positive number) and an epoxy resin composition for an optical material containing an epoxy resin and a curing agent represented by (2) an epoxy resin and a formula (2)

（式中ｎは正数を表す。）で表されるフェノール樹脂を含有することを特徴とする光学材料用エポキシ樹脂組成物、（３）硬化剤が、式（２）で表されるフェノール樹脂である上記（１）記載の光学材料用エポキシ樹脂組成物、（４）フェノール樹脂の重量平均分子量が３０００以上である上記（２）又は（３）記載の光学材料用エポキシ樹脂組成物、（５）溶剤を含有する上記（１）乃至（４）のいずれか1項に記載の光学材料用エポキシ樹脂組成物、（６）上記（１）乃至（５）のいずれか1項に記載のエポキシ樹脂組成物から得られるフィルム状成形物、（７）上記（１）乃至（６）のいずれか1項に記載のエポキシ樹脂組成物を硬化してなる硬化物を提供するものである。

(Wherein n represents a positive number), the epoxy resin composition for optical materials characterized by containing a phenol resin represented by formula (2), wherein the curing agent is represented by formula (2) (4) The epoxy resin composition for optical materials according to (1) above, (4) The epoxy resin composition for optical materials according to (2) or (3) above, wherein the phenol resin has a weight average molecular weight of 3000 or more, (5 (1) The epoxy resin composition for optical materials according to any one of (1) to (4) above, which contains a solvent, (6) The epoxy resin according to any one of (1) to (5) above. A film-like molded article obtained from the composition, and (7) a cured product obtained by curing the epoxy resin composition according to any one of (1) to (6) above.

In the present invention, a known epoxy resin represented by the formula (1) can be used. For example, NC-3000S (epoxy equivalent 284 g / eq, softening point 58 ° C.), NC-3000S-H (epoxy equivalent 290 g / eq, softening point 70 ° C.) manufactured by Nippon Kayaku Co., Ltd. can be mentioned. In addition, in Formula (1), n represents a positive number and is not particularly limited. However, the average value is usually 0.1 to 7, and preferably 0.2 to 6.

A well-known phenol resin represented by the formula (2) can also be used. For example, Meiwa Kasei Co., Ltd. product MEH-7851SS (hydroxyl equivalent 203g / eq, softening point 68 degreeC) etc. are mentioned. Moreover, in order to provide flexibility when it is formed into a film, it is preferable that both the epoxy resin and the phenol resin have a large weight average molecular weight. However, in the case of an epoxy resin, since the synthesis process is more complicated than that of a phenol resin, it is easier to increase the molecular weight of the phenol resin. The phenol resin represented by the formula (2) is represented by the following formula (3).

（式中、Ｘは塩素原子、メトキシ基、エトキシ基、水酸基のいずれかを表す。）で表される化合物とフェノールとを酸触媒の存在下で縮合反応させることにより得ることが出来る。式（２）で表されるフェノール樹脂の重量平均分子量はフェノールと式（３）で表される化合物の仕込み比率によりコントロールすることが出来る。フェノールと式（３）で表される化合物のモル仕込み比率は通常１０：１〜１．０５：１であるが、好ましくは８：１〜１．１：１である。重量平均分子量はＧＰＣを用いて測定することが出来る。通常は５００〜２００００であるが、硬化物をフィルム状に成形してフレキシビリティーを付与したい場合は、通常３０００以上、好ましくは３０００〜２００００である。 尚、式（２）においてｎは正数を表し、特に限定されるものではないが、平均値で通常０．１〜２５、好ましくは０．２〜２０である。

(Wherein X represents a chlorine atom, a methoxy group, an ethoxy group, or a hydroxyl group) and a phenol can be obtained by a condensation reaction in the presence of an acid catalyst. The weight average molecular weight of the phenol resin represented by the formula (2) can be controlled by the charging ratio of the phenol and the compound represented by the formula (3). The molar charge ratio of phenol and the compound represented by formula (3) is usually 10: 1 to 1.05: 1, but preferably 8: 1 to 1.1: 1. The weight average molecular weight can be measured using GPC. Usually, it is 500-20000, but when forming hardened | cured material into a film form and providing flexibility, it is 3000 or more normally, Preferably it is 3000-20000. In the formula (2), n represents a positive number and is not particularly limited. However, the average value is usually 0.1 to 25, and preferably 0.2 to 20.

In the epoxy resin composition of the present invention, other epoxy resins can be used in combination with the epoxy resin represented by the formula (1). When used in combination, the proportion of the epoxy resin represented by formula (1) in the total epoxy resin is preferably 30% by weight or more, particularly preferably 40% by weight or more.

Specific examples of other epoxy resins that can be used in combination with the epoxy resin represented by the formula (1) include cresol novolac type epoxy resins, phenol novolac type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, and triphenyl. Examples include methane type epoxy resins, biphenyl type epoxy resins, dicyclopentadienephenol co-condensation type epoxy resins, aliphatic cyclic epoxy resins, and hydrogenated bisphenol A type epoxy resins.

In the epoxy resin composition of this invention, it is also possible to use other hardening | curing agents together besides the phenol resin represented by Formula (2). When used in combination, the proportion of the phenol resin represented by formula (2) in the total curing agent is preferably 30% by weight or more, particularly preferably 40% by weight or more.

Examples of the curing agent that can be used in combination with the phenol resin represented by the formula (2) include amine compounds, acid anhydride compounds, amide compounds, phenol compounds, and the like. Specific examples of the curing agent that can be used include diaminodiphenylmethane, diethylenetriamine, triethylenetetramine, diaminodiphenylsulfone, isophoronediamine, dicyandiamide, a polyamide resin synthesized from linolenic acid and ethylenediamine, phthalic anhydride, triethylene anhydride. Meritic acid, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methyl nadic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, phenol novolac, and modified products thereof, Examples include, but are not limited to, imidazole, BF ₃ -amine complexes, guanidine derivatives, and the like. These may be used alone or in combination of two or more.

In the epoxy resin composition of the present invention, the amount of the curing agent used is preferably 0.7 to 1.2 equivalents relative to 1 equivalent of the epoxy group of the epoxy resin. When less than 0.7 equivalent or more than 1.2 equivalent with respect to 1 equivalent of epoxy group, curing may be incomplete and good cured properties may not be obtained.

In the epoxy resin composition of the present invention, a curing accelerator may be used. Specific examples of curing accelerators that can be used include imidazoles such as 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2- (dimethylaminomethyl) phenol, 1,8-diaza- Tertiary amines such as bicyclo (5,4,0) undecene-7, phosphines such as triphenylphosphine, metal compounds such as tin octylate, various onium salts such as diazonium salts, iodonium salts, sulfonium salts, etc. Can be mentioned. The curing accelerator is used as necessary in an amount of 0.1 to 5.0 parts by weight based on 100 parts by weight of the epoxy resin.

The epoxy resin composition of the present invention may contain an inorganic filler as necessary. Specific examples of the inorganic filler that can be used include silica, alumina, talc and the like. The inorganic filler is used in an amount of 0 to 90% by weight in the epoxy resin composition of the present invention. Furthermore, various compounding agents such as silane coupling agents, mold release agents such as stearic acid, palmitic acid, zinc stearate, calcium stearate, and pigments can be added to the epoxy resin composition of the present invention.

The epoxy resin composition of this invention is obtained by mixing each component uniformly. The epoxy resin composition of the present invention can be easily made into a cured product by a method similar to a conventionally known method. For example, an epoxy resin and a curing agent and, if necessary, a curing accelerator, an inorganic filler, and a compounding agent are thoroughly mixed using an extruder, a kneader, a roll or the like as necessary until they become uniform. A cured product can be obtained by obtaining a composition, molding the epoxy resin composition using a cast or transfer molding machine after melting, and further heating at 80 to 200 ° C. for 1 to 10 hours. When an onium salt is used as a curing catalyst, a cured product can be obtained not only by heat but also by irradiation with light such as ultraviolet rays.

Moreover, the epoxy resin composition of the present invention is dissolved in a solvent such as toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone to prepare a varnish, and glass fiber, carbon fiber, polyester fiber, polyamide fiber, alumina fiber, paper It is also possible to obtain a cured product by hot press-molding a prepreg obtained by impregnation into a solution and heating and semi-drying. Furthermore, this varnish can be applied to a substrate such as a copper foil, a PET (polyethylene glycol terephthalate) film, a polyimide film and heated to obtain a film-like cured product. For example, it can be used as an adhesive for a substrate of an optical disk. I can do it. The solvent used here is usually 10 to 70% by weight, preferably 15 to 70% by weight in the mixture of the epoxy resin composition of the present invention and the solvent.

EXAMPLES Next, the present invention will be described more specifically with reference to examples. In the following, parts are parts by weight unless otherwise specified.

Example 1 As an epoxy resin represented by the formula (1), NC-3000S (manufactured by Nippon Kayaku Co., Ltd., softening point ° C, epoxy equivalent 280 g / eq) 28 parts, a phenol resin represented by the formula (2) Kayahard HBPN (manufactured by Nippon Kayaku Co., Ltd., softening point 130 ° C., hydroxyl equivalent 242 g / eq, weight average molecular weight 15800 by GPC) 24.2 parts, triphenylphosphine (TPP) 0.28 parts as curing accelerator Then, 52.5 parts of methyl ethyl ketone as a solvent was uniformly dissolved to prepare a varnish (epoxy resin composition of the present invention). Next, it was uniformly coated on a PET film using an applicator so that the thickness after drying was 200 μm, and dried and cured in an oven at 160 ° C. for 2 hours to obtain a film-like cured product. This cured product did not break even when bent, and had sufficient flexibility. It was 161 degreeC when the glass transition temperature of this hardened | cured material was measured using DMA (dynamic viscoelasticity measuring apparatus). The refractive index measured under the following conditions was 1.655.

GPC measurement conditions Model: SYSTEM-21 (manufactured by Shodex) Column: KF-804L + KF-803L (× 2) connection Eluent: THF (1 ml / min., 40 ° C.) Detector: RI (RI-71S) UV ( 254 nm; UV-41) Sample: Approx. 0.4 wt% THF solution (100 μl injection) Calibration curve: Glass transition point measurement conditions using standard polystyrene made by Shodex Model: RHEOLOGPH-SOLID (manufactured by Toyo Seiki) Temperature increase rate: 2 ° C. / Min Frequency: 10 Hz Mode: Tensile mode refractive index measurement conditions Measuring device: Multiwavelength Abbe refractometer DR-M2 (manufactured by Atago Co., Ltd.) Measurement wavelength: 1.589 nm (D line)

Thus, the cured product obtained from the epoxy resin composition of the present invention has flexibility even when formed into a film, and has high heat resistance (determined from the high glass transition point) and high refraction. Showed the rate.

Claims (6)

Epoxy resin and formula (2)

The epoxy resin composition for optical materials characterized by containing the phenol resin represented by (In formula, n represents a positive number.). The epoxy resin is represented by the following formula (1)

The epoxy resin composition for an optical material according to claim 1, wherein the epoxy resin is represented by the formula (n represents a positive number). The epoxy resin composition for an optical material according to claim 1, wherein the phenol resin has a weight average molecular weight of 3000 or more. The epoxy resin composition for optical materials according to any one of claims 1 to 3, comprising a solvent. The film-shaped molding obtained from the epoxy resin composition of any one of Claims 1 thru | or 4. Hardened | cured material formed by hardening | curing the epoxy resin composition of any one of Claims 1 thru | or 4.