JP4623484B2 - Epoxy resin, epoxy resin composition and cured product thereof - Google Patents

Description

  The present invention relates to an epoxy resin composition that provides a cured product having excellent heat resistance and sufficient flexibility when formed into a film, and the cured product.

  Epoxy resins are cured with various curing agents, resulting in cured products with excellent mechanical properties, water resistance, chemical resistance, heat resistance, electrical properties, etc., and adhesives, paints, laminates, molding materials, It is used in a wide range of fields such as mold materials. Conventionally, the most commonly used epoxy resin includes bisphenol A type epoxy resin. Further, since higher reliability is required in the electric / electronic parts field, ortho-cresol novolac type epoxy resins have been widely used.

However, although the ortho-cresol novolac type epoxy resin as described above is excellent in heat resistance, the cured product is rigid and lacks flexibility. In recent years, the electrical and electronic components are not limited to conventional large packages and glass fiber-based substrates, but are also applied to polyimide, PET (polyethylene glycol terephthalate) film, and metal foil in a varnish state to remove the solvent. Sheet-like molded products have been developed. In such a case, the resin used is required to have sufficient flexibility. A high molecular weight bisphenol type resin (generally referred to as polyhydroxy polyether resin) (see, for example, Patent Document 1) is often used as a material suitable for such an application, but such a phenoxy resin is substantially used. It is a thermoplastic resin and is extremely inferior in heat resistance.
In addition, low molecular weight novolak type epoxy resins derived from metacresol and low molecular weight novolak type epoxy resins derived from paracresol are conventionally known, but these cannot increase the degree of polymerization and have flexibility. The resin could not be obtained.

JP 2003-119370 A

An object of the present invention is to provide an epoxy resin and an epoxy resin composition which are excellent in heat resistance and give a cured product having sufficient flexibility even when formed into a sheet.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have completed the present invention.

（式中、メチル基はグリシジルエーテル基に対してメタ位もしくはパラ位に位置し、グリシジルエーテル基に対してメタ位にメチル基を有するフェニル基とパラ位にメチル基を有するフェニル基の存在割合は９０：１０〜１０：９０である。ｎは６〜３０の整数を示す。）
で表され、軟化点が１００℃以上であるエポキシ樹脂、
（２）メタクレゾールとパラクレゾール９０〜１０：１０〜９０と、ホルムアルデヒドを反応させて得られるクレゾールノボラック型樹脂を、エピハロヒドリンと反応させることにより得られ、軟化点が１００℃以上であるエポキシ樹脂、
（３）（１）または（２）に記載のエポキシ樹脂と硬化剤を含有するエポキシ樹脂組成物、
（４）硬化促進剤を含有する（２）または（３）に記載のエポキシ樹脂組成物、
（５）（３）または（４）に記載のエポキシ樹脂組成物を溶剤に溶解してなるワニス、
（６）（３）または（４）に記載のエポキシ樹脂組成物、または（５）に記載のワニスを硬化してなる硬化物、
（７）（３）または（４）に記載のエポキシ樹脂組成物を硬化してなるシート状の硬化物、
（８）平面状支持体の両面または片面に（３）または（４）に記載のエポキシ樹脂組成物の硬化物の層を有するシート、
（９）平面状支持体がポリイミドフィルムである（８）に記載のシート、
（１０）平面状支持体が金属箔である（８）に記載のシート、
（１１）平面状支持体が剥離フィルムである（８）に記載のシート、
（１２）（５）に記載のワニスを基材に含浸させ加熱乾燥して得られるプリプレグ、
を提供するものである。 That is, the present invention provides (1) the following formula (1)

(In the formula, the methyl group is located at the meta position or the para position with respect to the glycidyl ether group, and the phenyl group having a methyl group at the meta position and the phenyl group having a methyl group at the para position relative to the glycidyl ether group Is 90:10 to 10:90, and n is an integer of 6 to 30.)
An epoxy resin having a softening point of 100 ° C. or higher,
(2) an epoxy resin obtained by reacting metacresol and paracresol 90 to 10:10 to 90 and cresol novolac resin obtained by reacting formaldehyde with epihalohydrin and having a softening point of 100 ° C. or higher,
(3) An epoxy resin composition containing the epoxy resin according to (1) or (2) and a curing agent,
(4) The epoxy resin composition according to (2) or (3), which contains a curing accelerator,
(5) A varnish obtained by dissolving the epoxy resin composition according to (3) or (4) in a solvent,
(6) The epoxy resin composition according to (3) or (4), or a cured product obtained by curing the varnish according to (5),
(7) A sheet-like cured product obtained by curing the epoxy resin composition according to (3) or (4),
(8) A sheet having a layer of a cured product of the epoxy resin composition according to (3) or (4) on both sides or one side of a planar support,
(9) The sheet according to (8), wherein the planar support is a polyimide film,
(10) The sheet according to (8), wherein the planar support is a metal foil,
(11) The sheet according to (8), wherein the planar support is a release film,
(12) A prepreg obtained by impregnating a base material with the varnish described in (5) and drying by heating.
Is to provide.

  The cured product of the epoxy resin composition of the present invention has sufficient flexibility even when molded into a thin film, and has excellent heat resistance, so that it can be molded, cast, laminated, paint, and adhesive. It is extremely useful for a wide range of applications such as agents and resists.

  The epoxy resin represented by the formula (1) of the present invention has the following formula (2):

（式中、メチル基はグリシジルエーテル基に対してメタ位もしくはパラ位に位置し、グリシジルエーテル基に対してメタ位にメチル基を有するフェニル基とパラ位にメチル基を有するフェニル基の存在割合は９０：１０〜１０：９０である。ｎは６〜３０の整数を示す。）
で表され、軟化点が通常１２０〜１８０℃のクレゾールノボラック型樹脂を、アルカリ金属水酸化物の存在下でエピハロヒドリンと反応させることにより得ることが出来る。

(In the formula, the methyl group is located at the meta position or the para position with respect to the glycidyl ether group, and the phenyl group having a methyl group at the meta position and the phenyl group having a methyl group at the para position relative to the glycidyl ether group Is 90:10 to 10:90, and n is an integer of 6 to 30.)
It can be obtained by reacting a cresol novolac resin having a softening point of usually 120 to 180 ° C. with an epihalohydrin in the presence of an alkali metal hydroxide.

  The cresol novolac resin represented by the formula (2) and having a softening point of usually 120 to 180 ° C. can be obtained by reacting metacresol, paracresol, and formaldehyde in the presence of an acid catalyst.

  The charging ratio of metacresol and paracresol is usually 90 to 10:10 to 90, preferably 80:20 to 20:80.

  Formaldehyde may be a formalin aqueous solution or a polymer, paraformaldehyde. The charge ratio of formaldehyde is usually from 1: 0.1 to 1: 0.95, preferably from 1: 0.15 to 0.005 in terms of the molar ratio in terms of formaldehyde, relative to the total moles of metacresol and paracresol. Nine. As a preparation method, in the case of a formalin aqueous solution, a method of dropping in the system is preferable, and in the case of paraformaldehyde, a method of gradually adding a predetermined amount while paying attention to heat generation is preferable.

  Specific examples of the acid catalyst that can be used include oxalic acid, hydrochloric acid, sulfuric acid, paratoluenesulfonic acid, and the like. The usage-amount of an acid catalyst is 0.01-10 weight part normally with respect to 100 weight part of total amounts of metacresol and paracresol, Preferably it is 0.05-5 weight part.

  The reaction temperature is usually 50 to 180 ° C, preferably 60 to 150 ° C. The reaction time may be determined by using GPC (gel permeation chromatography) or the like as the end point where the molecular weight is not changed. In practice, it is usually 1 to 20 hours, preferably 1.5 to 15 hours. It is preferable to remove the water produced during the reaction using a fractionating tube or the like in order to rapidly advance the reaction.

  After completion of the reaction, the acid catalyst is removed by washing with water (separation). When washing with water, an organic solvent may be used, or an organic solvent may not be used. When an organic solvent is used, methyl isobutyl ketone, toluene, methyl ethyl ketone and the like are preferable. The amount of the organic solvent is usually 10 to 300% by weight, preferably 20 to 200% by weight, based on the total weight of the charged metacresol, paracresol and formalin. After washing with water, unreacted cresol and solvent are removed under reduced pressure by heating using an evaporator or the like.

  In the reaction for obtaining the epoxy resin of the present invention, an aqueous solution of the alkali metal hydroxide may be used. In that case, the aqueous solution of the alkali metal hydroxide is continuously added to the reaction system and under reduced pressure. Alternatively, water and epihalohydrin may be continuously distilled off under normal pressure, followed by liquid separation, removal of water, and epihalohydrin being continuously returned to the reaction system.

  Usually, the amount of epihalohydrin used in these reactions is 2 to 12 mol, preferably 3 to 10 mol, per 1 equivalent of hydroxyl group of the compound represented by formula (2). At this time, in order to increase the solubility of the compound and allow the reaction to proceed smoothly, the reaction is carried out by adding an alcohol such as methanol, ethanol, propanol or butanol or an aprotic polar solvent such as dimethylsulfone or dimethylsulfoxide. It is preferable.

  When using alcohols, the amount used is usually 2 to 50% by weight, preferably 4 to 40% by weight, based on the amount of epihalohydrin, and usually 5 to 100% by weight when an aprotic polar solvent is used. Preferably it is 10 to 90% by weight.

  Further, a quaternary ammonium salt such as tetramethylammonium chloride, tetramethylammonium bromide, trimethylbenzylammonium chloride or the like is added as a catalyst to a mixture of the compound represented by formula (2) and epihalohydrin at 0.5 to 8 at 50 to 150 ° C. Add a solid or aqueous solution of an alkali metal hydroxide to the halohydrin etherified compound of the formula (2) obtained by reacting for a period of time, and react at 20 to 120 ° C. for 1 to 10 hours to dehydrohalogenate (ring closure). The method may be used.

  In this case, the amount of the quaternary ammonium salt used is 0.1 to 10 parts by weight with respect to 100 parts by weight of the compound represented by the formula (2).

  After the reaction product of these epoxidation reactions is washed with water, the epihalohydrin, the solvent and the like are removed under heating and reduced pressure. In order to make the epoxy resin 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. The reaction can be carried out to ensure the ring closure. 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, based on 1 equivalent of the hydroxyl group of the compound of formula (2) used for epoxidation. is there. The reaction temperature is usually 50 to 120 ° C., and the reaction time is usually 0.5 to 2 hours.

After the completion of the reaction, the produced salt is removed by filtration, washing with water, etc., and the solvent is distilled off under heating and reduced pressure to obtain the epoxy resin of the present invention.
In the epoxy resin thus obtained, n in the formula (1) is usually 6 to 30, preferably 8 to 30. The value of n can be calculated from the molecular weight measured by GPC or the like.
Among these, those having a softening point of usually 100 to 180 ° C, preferably 100 to 170 ° C are preferable. Further, the methyl group in the formula (1) is located at the meta position or the para position with respect to the glycidyl ether group, and the ratio of the meta position to the para position is 90:10 to 10:90, preferably 80:20 to 20 : 80. The ratio between the meta position and the para position is considered to reflect the ratio of metacresol and paracresol when the epoxy resin of the present invention is synthesized, and these ratios can be obtained by NMR.

  Hereinafter, the epoxy resin composition of the present invention will be described. In the epoxy resin composition of the present invention, the epoxy resin of the present invention represented by the formula (1) can be used alone or in combination with other epoxy resins. When other epoxy resins are used in combination, the proportion of the epoxy resin represented by the formula (1) of the present invention 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 of the present invention include novolak type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, biphenyl type epoxy resins, triphenylmethane type epoxy resins, and dicyclohexane. Pentadiene / phenol polycondensation type epoxy resins and the like can be mentioned, but these may be used alone or in combination of two or more.

Examples of the curing agent contained in the epoxy resin composition of the present invention 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, polyamide resin synthesized from linolenic acid and ethylenediamine, phthalic anhydride, triethylene anhydride. Merit 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 addition, a curing accelerator may be used in combination with the epoxy resin composition of the present invention. Specific examples of the curing accelerator that can be used include, for example, imidazoles such as 2-methylimidazole, 2-ethylimidazole, and 2-ethyl-4-methylimidazole, 2- (dimethylaminomethyl) phenol, and 1,8-diaza. -Tertiary amines such as bicyclo (5,4,0) undecene-7, phosphines such as triphenylphosphine, and metal compounds such as tin octylate. 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 contains 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 the present invention can be obtained by mixing the respective components in any order.

The varnish of the epoxy resin composition of the present invention is obtained by dissolving the epoxy resin composition described above in a solvent.
Examples of the solvent include toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone and the like. 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.

  In the sheet using the epoxy resin composition of the present invention, the above varnish is dried on a planar support by various coating methods such as a gravure coating method, screen printing, metal mask method, and spin coating method known per se. It is obtained by drying after coating so that the thickness becomes a predetermined thickness, for example, 5 to 100 μm, and which coating method is used is appropriately selected depending on the type, shape, size and thickness of the coating film Is done. As the planar support, for example, various polymers such as polyamide, polyamideimide, polyarylate, polyethylene terephthalate, polybutylene terephthalate, polyetheretherketone, polyetherimide, polyetherketone, polyketone, polyethylene, polypropylene and / or the like Examples thereof include a film made of a copolymer, or a metal foil such as a copper foil, preferably polyimide or a metal foil. Further, a sheet-like cured product can be obtained by further heating. Moreover, you may serve as the drying process and hardening process of a solvent by one time heating. The epoxy resin composition of the present invention is coated and heated on both sides or one side of the above-mentioned planar support by the above-described method, whereby a cured product layer of the composition of the present invention is formed on both sides or one side of the planar support. Can have.

  Further, a prepreg obtained by impregnating a substrate such as glass fiber, carbon fiber, polyester fiber, polyamide fiber, alumina fiber, paper, etc. with the varnish of the present invention and drying by heating is subjected to hot press molding to obtain a cured product. You can also.

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

Example 1
While purging a flask equipped with a thermometer, condenser, and stirrer with nitrogen gas purge, add 108 parts of metacresol, 108 parts of paracresol, and 2 parts of paratoluenesulfonic acid, and heat to 130 ° C. with stirring to 35% 60 parts of a formalin aqueous solution was added dropwise over 30 minutes. Furthermore, after stirring at 130 degreeC for 3 hours, 250 parts of methyl isobutyl ketones were added, and it washed with water 3 times using the separating liquid. Next, unreacted cresol and methyl isobutyl ketone were removed from the oil layer using an evaporator, to obtain 140 parts of a cresol resin represented by the formula (2). The obtained cresol resin had a softening point of 140.6 ° C. and a hydroxyl group equivalent of 120 g / eq.

  To 120 parts of the compound represented by the above formula (2), 370 parts of epichlorohydrin and 26 parts of methanol were added and dissolved under stirring, and the temperature was raised to 70 ° C. Next, 40 parts of flaky sodium hydroxide was added in portions over 100 minutes, and the mixture was further stirred at 70 ° C. for 1 hour to carry out a post reaction. After completion of the reaction, 150 parts of water was added and washed with water. Excess epichlorohydrin and the like were distilled off from the oil layer under reduced pressure at 140 ° C. using a rotary evaporator. To the residue, 352 parts of methyl isobutyl ketone was added and dissolved, and the temperature was raised to 70 ° C. Under stirring, 10 parts of a 30% aqueous sodium hydroxide solution was added and the reaction was carried out for 1 hour, followed by washing with water three times. Using a rotary evaporator, methyl isobutyl ketone was distilled off at 180 ° C. under reduced pressure. 157 parts of the epoxy resin (A) of the present invention represented by 1) was obtained. In the obtained epoxy resin, the ratio of the methyl group in the meta position to the para position relative to the glycidyl ether group is considered to be 1: 1 in view of the synthesis conditions. The value of n obtained from the molecular weight measured by GPC was 12. The epoxy equivalent was 216 g / eq, and the softening point was 114.2 ° C.

Example 2
108 parts of the epoxy resin (A) of the present invention obtained in Example 1 is 53 parts phenol novolak (hydroxyl equivalent: 106 g / eq, softening point: 80 ° C.) as a curing agent, and triphenylphosphine (TPP) as a curing accelerator. One part was mixed with 162 parts of methyl ethyl ketone as a solvent to obtain a varnish of the present invention.

The above varnish of the present invention is applied on a PET film so that the thickness after drying is 50 μm, and heated at 180 ° C. for 1 hour to dry and cure the solvent, and the PET film is removed to remove the sheet. A sample was obtained. The obtained sample did not crack even when bent, and had sufficient film forming ability. Moreover, it was 231 degreeC when the glass transition temperature of this sample was measured by DMA (dynamic viscoelasticity measuring apparatus).

  The cured product of the epoxy resin composition of the present invention has sufficient flexibility even when molded into a thin film, and since the cured product is excellent in heat resistance, it is a molding material, casting material, laminated material. It is extremely useful for a wide range of applications such as paints, adhesives, and resists.

Claims (10)

Metacresol and paracresol 90 to 10:10 to 90 and a cresol novolac resin having a softening point of 120 to 180 ° C. obtained by reacting formaldehyde with epihalohydrin can be obtained by the following formula (1)

(In the formula, the methyl group is located in the meta position or para position with respect to the glycidyl ether group, and the proportion of the phenyl group having a methyl group in the meta position and the phenyl group having a methyl group in the para position with respect to the glycidyl ether group) Is 90:10 to 10:90, n is an integer of 6 to 30, and an epoxy resin composition containing an epoxy resin and a curing agent having a softening point of 100 ° C. or higher. The epoxy resin composition of Claim 1 containing a hardening accelerator. A varnish obtained by dissolving the epoxy resin composition according to claim 1 or 2 in a solvent. A cured product obtained by curing the epoxy resin composition according to claim 1 or 2, or the varnish according to claim 3. A sheet-like cured product obtained by curing the epoxy resin composition according to claim 1. The sheet | seat which has the layer of the hardened | cured material of the epoxy resin composition of Claim 1 or 2 on both surfaces or one side of a planar support body. The sheet according to claim 6, wherein the planar support is a polyimide film. The sheet according to claim 6, wherein the planar support is a metal foil. The sheet according to claim 6, wherein the planar support is a release film. A prepreg obtained by impregnating a base material with the varnish according to claim 3 and drying by heating.