JP7172180B2 - Epoxy resin composition, curable resin composition, cured product, fiber-reinforced composite material, fiber-reinforced resin molded article, and method for producing fiber-reinforced resin molded article - Google Patents

Description

The present invention provides an epoxy resin composition that has low viscosity and good impregnation into fibers and is capable of forming a cured product having excellent mechanical properties and heat resistance, and a curable resin composition containing the same. , a cured product, a fiber-reinforced composite material, a fiber-reinforced resin molded product, and a method for producing a fiber-reinforced resin molded product.

In recent years, fiber-reinforced resin molded products reinforced with reinforcing fibers have attracted attention due to their light weight and excellent mechanical strength. Usage is expanding. The fiber-reinforced resin molded article can be produced by molding a fiber-reinforced composite material by a molding method such as a filament winding method, a press molding method, a hand lay-up method, a pultrusion method, or an RTM method.

The fiber-reinforced composite material is obtained by impregnating reinforcing fibers with a resin. Since the resin used in the fiber-reinforced composite material is required to have stability at room temperature, durability and strength of the cured product, etc., generally unsaturated polyester resin, vinyl ester resin, epoxy resin, etc. A thermosetting resin is used. Among these, epoxy resins have high strength, high elastic modulus, and excellent heat resistance, and are being put to practical use in various applications as resins for fiber-reinforced composite materials.

As described above, the epoxy resin for the fiber-reinforced composite material is required to have a low viscosity because the reinforcing fibers are impregnated with the resin. In addition, when fiber-reinforced resin molded products are used for structural parts around the engine of automobiles, etc., or for electric wire core materials, heat resistance in cured products is required so that fiber-reinforced resin molded products can withstand harsh usage environments for a long period of time. Resins with excellent properties and mechanical strength are required.

As the epoxy resin, for example, an epoxy resin composition containing a bisphenol-type epoxy resin, an acid anhydride, and an imidazole compound is widely known (see, for example, Patent Document 1). Also known is an epoxy resin composition in which glycidyl ether of dihydric phenol and glycidylamine type epoxy resin are used in combination with a curing agent (see, for example, Patent Document 2). However, the epoxy resin compositions provided in Patent Documents 1 and 2 are highly impregnable into reinforcing fibers, and exhibit certain performance in terms of heat resistance and mechanical strength in cured products. It did not satisfy the increasing demand characteristics.

Therefore, there has been a demand for a material that has both excellent impregnating properties into reinforcing fibers and mechanical strength and heat resistance of the cured product.

JP 2010-163573 A WO2016/148175

Accordingly, the problem to be solved by the present invention is to provide an epoxy resin composition having a low viscosity and good impregnability into fibers, and having excellent mechanical properties and heat resistance in the resulting cured product, and a cured product containing the same. An object of the present invention is to provide a flexible resin composition, a cured product, a fiber-reinforced composite material, a fiber-reinforced resin molded article, and a method for producing a fiber-reinforced resin molded article.

As a result of intensive studies aimed at solving the above problems, the present inventors have found that the above problems can be solved by combining an epoxy resin, which is a reaction product of catechol or pyrogallol and epihalohydrin, with a bisphenol-type epoxy resin. He found this and completed the present invention.

That is, the present invention provides a reaction product of catechol, which may have a methyl group as a substituent on the aromatic ring, or pyrogallol, which may have a methyl group as a substituent on the aromatic ring, and epihalohydrin. An epoxy resin composition characterized by containing an epoxy resin (A) and a bisphenol type epoxy resin (B), a curable resin composition obtained by combining this with a curing agent, and the curable resin composition The present invention relates to a cured product of a product, a fiber-reinforced composite material using the curable resin composition, a fiber-reinforced resin molded product, and a method for producing a fiber-reinforced resin molded product.

The epoxy resin composition of the present invention has a low viscosity and good impregnability into fibers, and the cured product obtained has excellent mechanical properties and heat resistance, so it is suitable for use in fiber-reinforced composite materials and the like. can be done. The term "excellent mechanical properties" as used in the present invention means high strength and high elastic modulus.

2 is a ¹³ C NMR chart of the epoxy resin produced in Synthesis Example 1. FIG. 13 is a ¹³ C NMR chart of the epoxy resin produced in Synthesis Example 2. FIG.

The epoxy resin composition of the present invention comprises catechol optionally having a methyl group as a substituent on the aromatic ring, or pyrogallol optionally having a methyl group as a substituent on the aromatic ring, and epihalohydrin. It is characterized by containing an epoxy resin (A) and a bisphenol-type epoxy resin (B), which are reactants.

As the epoxy resin (A), catechol optionally having a methyl group as a substituent on the aromatic ring, or pyrogallol optionally having a methyl group as a substituent on the aromatic ring, and epihalohydrin. Use the reactants.

The catechol is dihydroxybenzene having hydroxyl groups at the 1- and 2-positions, and the pyrogallol is trihydroxybenzene having hydroxyl groups at the 1-, 2- and 3-positions. In the present invention, each aromatic ring may have a methyl group as a substituent.

When the substituent has a methyl group, the position and the number of substituents are not particularly limited. preferably has one methyl group, and in the case of pyrogallol, it preferably has one methyl group at the 5-position, but in any case, it is most preferred to have no substituent . Moreover, the catechol and the pyrogallol may be used in combination or alone, or may be used in combination with a plurality of compounds having different methyl group positions. In particular, it is preferable to use a reaction product of pyrogallol having no methyl group and epihalohydrin because a cured product having excellent heat resistance can be obtained.

When catechol, which may have a methyl group as a substituent on the aromatic ring, or pyrogallol, which may have a methyl group as a substituent on the aromatic ring, is reacted with the epihalohydrin, the above-mentioned A reaction in which each hydroxyl group becomes a glycidyl ether group proceeds, and simultaneously with the reaction, oligomerization proceeds due to a reaction between the glycidyl ether group and an unreacted hydroxyl group. Different reaction conditions, such as the ring closure step of , lead to different reactants, which are included as by-products. These by-products can be removed from the reaction system and reaction product, but the step of removing only a single component (for example, diglycidyl ether in the case of catechol and triglycidyl ether in the case of pyrogallol) is Industrially, this is a complicated process and is directly linked to product costs, so it is often used as an epoxy resin in a state containing by-products to the extent that it does not adversely affect the resulting cured product.

In addition, the above single components (eg, diglycidyl ether for catechol and triglycidyl ether for pyrogallol) are highly crystalline and may cause problems in handling when used as an epoxy resin composition. From these points of view, it is preferable to use an epoxy resin containing a certain amount of by-products as described above, from the point of view of handling, or from the point of view of obtaining a cured product excellent in mechanical strength.

From such a viewpoint, the epoxy resin (A) used in the present invention includes catechol which may have a methyl group as a substituent on the aromatic ring, or catechol which may have a methyl group as a substituent on the aromatic ring. It preferably contains a cyclic compound (a1) having a cyclic structure containing as constituent atoms two adjacent oxygen atoms derived from pyrogallol, and the cyclic compound (a1) is added to 100 g of the epoxy resin (A). On the other hand, it is more preferably in the range of 0.040 to 0.115 mol. In particular, when pyrogallol having no substituents on the aromatic ring is used as a raw material, the cyclic compound (a1) is included in a certain amount, so that it has a property that crystallization is difficult to occur for a long time even if it is left standing at room temperature. Therefore, it is suitable for handling.

Examples of the cyclic compound (a1) include compounds represented by the following structural formulas.

(Wherein, R is each independently a hydrogen atom or a methyl group, R1 is each independently a hydrogen atom or a methyl group, m is an integer of 1 to 4, n is an integer of 1 to 3 is an integer.)

The cyclic compound (a1) may be contained alone in the epoxy resin (A), or may be contained in combination of two or more.

The content of the cyclic compound (a1) is preferably in the range of 0.04 to 0.115 mol, more preferably in the range of 0.05 to 0.115 mol, and 0.07 per 100 g of the epoxy resin (A). A range of ~0.115 mol is particularly preferred. When the content of the cyclic compound (a1) is within this range, the obtained cured product tends to exhibit suitable heat resistance, and as described above, the effect of suppressing the crystallization of the epoxy resin is obtained. get higher In addition, in this specification, "the content of a cyclic compound (a1)" is the value measured by the method as described in an Example. Moreover, when 2 or more types of cyclic compounds are included, the "content of the cyclic compound (a1)" is the total content thereof.

The content of the cyclic compound (a1) can be controlled by appropriately adjusting the charging ratio of raw materials, catalyst, solvent type and reaction conditions in the reaction with epihalohydrin or the ring closure step, which will be described later.

The epoxy resin (A) used in the present invention is catechol, which may have a methyl group as a substituent on the aromatic ring, or pyrogallol, which may have a methyl group as a substituent on the aromatic ring. And, although it is not limited to anything other than using epihalohydrin, it has good fluidity when it is made into a composition, it is easy to make it liquid even at room temperature, and a cured product with excellent mechanical properties can be obtained. Therefore, the content of the glycidyl ether compound (a2) represented by the following structural formula (1) or (2) is preferably 55% or more in terms of area ratio in GPC measurement, and is 65% or more. is more preferably 70% or more, particularly preferably 78% or more, and most preferably 80 to 95%. As used herein, the term "area ratio in GPC measurement" refers to the ratio of the area occupied by the target compound in the GPC chart obtained by GPC measurement of the reaction product. A specific measuring method is the method described in Examples.

〔式（１）、（２）中、Ｇはグルシジル基であり、Ｒ^１は、それぞれ独立に水素原子またはメチル基であり、ｍは、１～４の整数であり、ｎは、１～３の整数である。〕

[In formulas (1) and (2), G is a glycidyl group, R ¹ is each independently a hydrogen atom or a methyl group, m is an integer of 1 to 4, n is 1 to 3 is an integer of ]

Moreover, the epoxy resin (A) used in the present invention may contain an oligomer (a3). The content of the oligomer (a3) is preferably 12% or less, particularly preferably 10% or less, in terms of area ratio in the same GPC measurement as described above, from the viewpoint that the oligomer (a3) tends to be a factor that increases the viscosity. . The oligomer (a3) is a general term for polynuclear substances containing two or more aromatic rings derived from catechol or pyrogallol used as a raw material in one molecule, and the content of the oligomer (a3) indicates the total amount of those polynuclear bodies.

The epoxy resin (A) used in the present invention may contain other by-products as long as the effects of the present invention are not impaired. Examples of the other by-products include compounds in which only some of the hydroxyl groups of catechol and pyrogallol used as raw materials are glycidyl-etherified, and compounds in which ring closure of epihalohydrin does not proceed only partially. may be included. More specific examples of the other by-products include those represented by the following structural formulas.

(wherein each R is independently a hydrogen atom or a methyl group, each R ¹ is independently a hydrogen atom or a methyl group, m is an integer of 1 to 4, n is 1 to 3 is an integer of

(wherein each R is independently a hydrogen atom or a methyl group, each R ¹ is independently a hydrogen atom or a methyl group, m is an integer of 1 to 4, n is 1 to 3 is an integer of

The epoxy equivalent of the epoxy resin (A) used in the present invention is in the range of 130 to 190 g/equivalent when catechol is used as a raw material, because the viscosity of the composition is good for handleability. When pyrogallol is used as a raw material, it is preferably in the range of 108 to 170 g/equivalent. The viscosity of the epoxy resin (A) is 100 mPa.s when catechol is used as a raw material. s~800mPa.s s, and when pyrogallol is used as a raw material, it is 1,500 mPa.s. s to 20,000 mPa.s. It is preferably in the range of s.

The method for producing the epoxy resin (A) used in the present invention is not particularly limited, and a known method of glycidyl etherification using epihalohydrin can be employed.

Examples of the epihalohydrin include epichlorohydrin, epibromohydrin, β-methylepichlorohydrin, β-methylepibromohydrin and the like. Among these, epichlorohydrin is preferred because of its good reactivity with hydroxyl groups. In addition, the epihalohydrin can be used alone or in combination of two or more.

The amount of the epihalohydrin to be used is, from the viewpoint of easy control of the content of by-products and the balance between yield and catechol optionally having a methyl group as a substituent on the aromatic ring used as a starting material, aromatic With respect to 1 mol of the hydroxyl group of pyrogallol which may have a methyl group as a substituent on the ring, it is preferably in the range of 1.2 to 20 mol, and may be in the range of 1.5 to 10 mol. more preferred.

The reaction between catechol optionally having a methyl group as a substituent on the aromatic ring used as a starting material or pyrogallol optionally having a methyl group as a substituent on the aromatic ring and the epihalohydrin is From the viewpoint of the yield of the epoxy resin (A), the step (1) of reacting in the presence of a quaternary onium salt and / or a basic compound, and the reaction product obtained in the step (1), It is preferable to have a step (2) of ring closure in the presence of a basic compound.

Examples of the reaction solvent in step (1) include alcohols such as methanol, ethanol, isopropyl alcohol and butanol; ketones such as acetone and methyl ethyl ketone; ethers such as dioxane; The reaction solvent can be used alone or in combination of two or more.

The amount of the reaction solvent used is preferably in the range of 5 to 150 parts by mass, more preferably in the range of 7.5 to 100 parts by mass, more preferably 10 to 50 parts by mass, relative to 100 parts by mass of the epihalohydrin. It is more preferably in the range of parts.

Examples of the quaternary onium salts include quaternary ammonium salts and quaternary phosphonium salts. The quaternary onium salts can be used alone or in combination of two or more.

Examples of the quaternary ammonium salts include tetramethylammonium cation, methyltriethylammonium cation, tetraethylammonium cation, tributylmethylammonium cation, tetrabutylammonium cation, phenyltrimethylammonium cation, benzyltrimethylammonium cation, phenyltriethylammonium cation, Benzyltriethylammonium cation, chloride salt of benzyltributylammonium cation, tetramethylammonium cation, trimethylpropylammonium cation, tetraethylammonium cation, bromide salt of tetrabutylammonium cation, and the like.

Examples of the quaternary phosphonium salts include tetraethylphosphonium cation, tetrabutylphosphonium cation, methyltriphenylphosphonium cation, tetraphenylphosphonium cation, ethyltriphenylphosphonium cation, butyltriphenylphosphonium cation, and bromine of benzyltriphenylphosphonium cation. compound salts.

Among these, as the quaternary onium salt, it is preferable to use chloride salts of tetramethylammonium cation, benzyltrimethylammonium cation, benzyltriethylammonium cation, and bromide salt of tetrabutylammonium cation.

The amount of the quaternary onium salt used may have a methyl group as a substituent on the aromatic ring used as a raw material, from the viewpoint of allowing the reaction to proceed well and reducing the residue in the product. It is preferably 0.15 to 5% by mass, preferably 0.18 to 3% by mass, based on the total mass of catechol or pyrogallol, which may have a methyl group as a substituent on the aromatic ring, and epihalohydrin. % is more preferred.

Examples of the basic compound include potassium hydroxide, sodium hydroxide, barium hydroxide, magnesium hydroxide, sodium carbonate, potassium carbonate and the like. Among these, potassium hydroxide and sodium hydroxide are preferred. Moreover, the said basic compound can also be used individually and can also use 2 or more types together.

The amount of the basic compound added is not particularly limited, but from the viewpoint of allowing the reaction to proceed well and reducing the residue in the product, it has a methyl group as a substituent on the aromatic ring used as a raw material. catechol which may be, or, relative to the number of moles of phenolic hydroxyl groups of pyrogallol which may have a methyl group as a substituent on the aromatic ring, it is preferably in the range of 0.01 to 0.3 mol , more preferably in the range of 0.02 to 0.2 mol.

The quaternary onium and the basic compound may be used alone or in combination.

The reaction of step (1) is mainly a reaction in which epihalohydrin is added to a phenolic hydroxyl group. The reaction temperature in step (1) is preferably 20 to 80°C, more preferably 40 to 75°C. The reaction time in step (1) is preferably 0.5 hours or more, more preferably 1 to 50 hours.

The step (2) is a step of ring-closing the reaction product obtained in step (1) in the presence of a basic compound, and the reaction product obtained in step (1) is used as it is or present in the system. Step (2) may be carried out after part or all of the unreacted epihalohydrin and reaction solvent are removed.

Examples of the basic compound used in step (2) include potassium hydroxide, sodium hydroxide, barium hydroxide, magnesium hydroxide, sodium carbonate, potassium carbonate and the like. Among these, potassium hydroxide and sodium hydroxide are preferred. Moreover, the said basic compound can also be used individually and can also use 2 or more types together.

The amount of the basic compound used is not particularly limited, but is preferably in the range of 0.8 to 1.5 mol, more preferably 0.9 to 1.3 mol, relative to the number of moles of the phenolic hydroxyl group of the starting material. is more preferably in the range of It is preferable that the addition amount of the basic compound is 0.8 mol or more because the ring closure reaction in step (2) can proceed favorably. On the other hand, when the amount of the basic compound added is 1.5 mol or less, it is preferable because side reactions can be prevented or suppressed. When a basic compound is used in step (1), it is preferable to use the above-described addition amount including the amount used in step (1).

The reaction temperature in step (2) is not particularly limited, but is preferably 30 to 120°C, more preferably 25 to 80°C. Although the reaction time is not particularly limited, it is preferably 0.5 to 4 hours, more preferably 1 to 3 hours.

After step (2) is performed, the reaction product obtained can be purified, etc., if necessary.

Among the reaction products obtained through the steps (1) and (2) are cyclic compounds (a1 )including. In addition, the aforementioned oligomer (a3) and other by-products are also included. These cyclic compound (a1), oligomer (a3) and the like affect the physical properties of the epoxy resin (A) and the physical properties of its cured product.

As a method for controlling the content of the by-product, for example, step (1) is a step of adding epihalohydrin to the phenolic hydroxyl group as described above, but depending on the reaction conditions, 3-halogeno- A side reaction occurs in which the 2-hydroxypropyl ether group is partially ring-closed to produce an intermediate having a glycidyl group and a hydroxyl group. In this case, the intramolecular reaction of the intermediates obtained by the above reaction results in the formation of a cyclic compound, and the intermolecular reaction results in the formation of the oligomer (a3). Therefore, in step (1), controlling the side reaction that produces an intermediate having a glycidyl group and a hydroxyl group facilitates controlling the amount of the cyclic compound and oligomer (a3). For example, if step (1) is carried out under high-temperature conditions, the side reaction that produces glycidyl groups is promoted, and the content of the cyclic compound and oligomer (a3) in the resulting reaction product increases. On the other hand, when step (1) is carried out under low temperature conditions, the reaction to form glycidyl groups is relatively suppressed, and the content of the cyclic compound and oligomer (a3) in the resulting reaction product is low. In addition, when step (1) is performed for a short time, there are many unreacted hydroxyl groups, and by reacting with the glycidyl groups generated in step (2), the reaction product contains cyclic compounds and oligomers (a3). Quantities tend to be higher.

The content of each component in the reaction product can be controlled by various methods. For example, the ratio of raw materials used in the above step (1), the type and addition method (time) of epihalohydrin, the type and amount of quaternary onium salt and basic compound used, the reaction temperature, the reaction time, etc. can be adjusted to control the reaction. can be controlled. Also, the reaction can be controlled by addition or removal of raw materials, products, etc. in step (1). Furthermore, the reaction can be controlled by adjusting the type and amount of the basic compound used, the reaction temperature, the reaction time, the reaction rate, etc. in the above step (2). In addition, the reaction can be controlled by adding or removing the product of step (2) or the like. As a result, the content of each component in the reaction product can be controlled.

The components and physical properties of the epoxy resin (A) may be adjusted by controlling the reaction, by controlling the purification process, or by adding additional components. At this time, from the viewpoint of efficiently preparing the epoxy resin (A), it is preferable to control the reaction to adjust the contents of the components of the epoxy resin.

Examples of the bisphenol-type epoxy resin (B) used in the present invention include polyglycidyl-etherified bisphenol compounds such as bisphenol A, bisphenol F, and bisphenol S with epihalohydrin. resin, bisphenol F-type epoxy resin, bisphenol S-type epoxy resin, bisphenol AD-type epoxy resin, tetrabromobisphenol A-type epoxy resin, and the like. Among these bisphenol type epoxy resins, bisphenol A type epoxy resins and bisphenol F type epoxy resins are preferable because of their low viscosity and excellent impregnation properties. Moreover, these bisphenol-type epoxy resins can be used alone or in combination of two or more.

As the epihalohydrin, the same ones as those mentioned above can be used.

The amount of the epihalohydrin used should be in the range of 1.2 to 20 mol per 1 mol of the hydroxyl group of the bisphenol compound used as the raw material, from the viewpoint of easily controlling the content of the by-product and the yield. is preferred, and a range of 1.5 to 10 mol is more preferred.

The reaction between the bisphenol compound and the epihalohydrin is carried out at 20 to 120° C. while adding 0.9 to 2.0 mol of a basic catalyst all at once or gradually with respect to 1 mol of the hydroxyl group of the bisphenol compound. A method of reacting at temperature for 0.5 to 10 hours may be mentioned.

Examples of the basic catalyst include alkaline earth metal hydroxides, alkali metal carbonates, alkali metal hydroxides and the like. Among these, alkali metal hydroxides are preferred from the viewpoint of excellent catalytic activity in the epoxy resin synthesis reaction. Examples of the alkali metal hydroxide include sodium hydroxide and potassium hydroxide.

When using the basic catalyst, these basic catalysts may be used in the form of an aqueous solution of about 10 to 55% by mass, or may be used in the form of a solid. When used in the form of an aqueous solution, the basic catalyst is continuously added to the reaction system, and water and epihalohydrin are continuously distilled from the reaction mixture under reduced pressure or normal pressure conditions. may be separated to remove water, and the epihalohydrin may be continuously returned to the reaction mixture.

Moreover, the reaction between the bisphenol compound and the epihalohydrin can be carried out in an organic solvent, if necessary. By carrying out the reaction in an organic solvent, the reaction rate is increased, and the desired epoxy resin can be produced efficiently. Examples of the organic solvent include ketones such as acetone and methyl ethyl ketone; alcohol compounds such as methanol, ethanol, 1-propyl alcohol, isopropyl alcohol, 1-butanol, secondary butanol and tertiary butanol; Examples thereof include cellosolves, ether compounds such as tetrahydrofuran, 1,4-dioxane, 1,3-dioxane and diethoxyethane, and aprotic polar solvents such as acetonitrile, dimethylsulfoxide and dimethylformamide. These organic solvents can be used alone or in combination of two or more.

After the reaction between the bisphenol compound and the epihalohydrin is completed, the resulting reaction product is washed with water, and the unreacted epihalohydrin and the organic solvent are distilled off under heating and reduced pressure conditions to obtain a bisphenol type epoxy resin. can. At this time, in order to further reduce hydrolyzable halogen in the obtained bisphenol type epoxy resin, the obtained bisphenol type epoxy resin is dissolved again in an organic solvent such as toluene, methyl isobutyl ketone or methyl ethyl ketone, and sodium hydroxide, Further reaction can be carried out by adding an aqueous solution of an alkali metal hydroxide such as potassium hydroxide. At this time, a phase transfer catalyst such as a quaternary ammonium salt or crown ether may be present for the purpose of improving the reaction rate. When the phase transfer catalyst is used, the amount used is preferably in the range of 0.1 to 3.0 parts by mass with respect to 100 parts by mass of the epoxy resin used. After completion of the reaction, the salt produced is removed by filtration or washing with water, and the organic solvent is distilled off under heating and reduced pressure conditions to obtain the desired bisphenol type epoxy resin.

Moreover, the said bisphenol-type epoxy resin (B) may use a commercial item. Examples of the commercially available products include "EPICLON 850-S", "EPICLON 860" and "EPICLON 830-S" manufactured by DIC Corporation.

The epoxy equivalent weight of the bisphenol-type epoxy resin (B) is preferably in the range of 158 to 215 g/equivalent, since the viscosity is low, the crystallinity does not become too high, and the heat resistance can be maintained. A range of -195 g/equivalent is more preferred.

In the present invention, a reactant of catechol optionally having a methyl group as a substituent on the aromatic ring or pyrogallol optionally having a methyl group as a substituent on the aromatic ring and epihalohydrin The mass ratio [(A)/(B)] of the epoxy resin (A) and the bisphenol-type epoxy resin (B) is 5 because a cured product having excellent mechanical properties and heat resistance can be obtained. /95 to 95/5, more preferably 10/90 to 90/10.

The epoxy resin composition of the present invention may contain other epoxy resins than the epoxy resin (A) and the epoxy resin (B) as long as the effect of the present invention is not impaired.

Examples of the other epoxy resins include other diglycidyloxybenzene, diglycidyloxynaphthalene, biphenol type epoxy resin, novolac type epoxy resin, triphenolmethane type epoxy resin, tetraphenolethane type epoxy resin, phenol or naphthol aralkyl. type epoxy resin, phenylene or naphthylene ether type epoxy resin, dicyclopentadiene-phenol addition reaction product type epoxy resin, phenolic hydroxyl group-containing compound-alkoxy group-containing aromatic compound co-condensation type epoxy resin, naphthalene skeleton-containing epoxy other than these A resin etc. are mentioned.

Examples of the biphenol type epoxy resin include those obtained by polyglycidyl etherifying a biphenol compound such as biphenol or tetramethylbiphenol with epihalohydrin. Among them, those having an epoxy equivalent in the range of 150 to 200 g/equivalent are preferred.

Examples of the novolak-type epoxy resin include those obtained by polyglycidyl etherifying a novolac resin composed of one or more of various phenolic compounds such as phenol, cresol, naphthol, bisphenol, and biphenol with epihalohydrin.

Examples of the triphenolmethane-type epoxy resin include those having a structural site represented by the following structural formula (3) as a repeating structural unit.

［式中Ｒ^５、Ｒ^６はそれぞれ独立に水素原子又は構造式（３）で表される構造部位と＊印が付されたメチン基を介して連結する結合点の何れかである。ｎは１以上の整数である。］

[In the formula, each of R ⁵ and R ⁶ is independently a hydrogen atom or a bonding point that connects the structural site represented by the structural formula (3) via a methine group marked with *. n is an integer of 1 or more. ]

In the phenol or naphthol aralkyl type epoxy resin, for example, a glycidyloxybenzene or glycidyloxynaphthalene structure is knotted at a structural site represented by any one of the following structural formulas (4-1) to (4-3). Those having a molecular structure are included.

（式中Ｘは炭素原子数２～６のアルキレン基、エーテル結合、カルボニル基、カルボニルオキシ基、スルフィド基、スルホン基の何れかである。］

(In the formula, X is an alkylene group having 2 to 6 carbon atoms, an ether bond, a carbonyl group, a carbonyloxy group, a sulfide group, or a sulfone group.)

Examples of the naphthalene skeleton-containing epoxy resin include epoxy compounds represented by any one of the following structural formulas (5-1) to (5-3).

Among the other epoxy resins, triphenolmethane-type epoxy resins and naphthalene skeleton-containing epoxy resins are preferable because they give cured products having excellent mechanical properties and heat resistance.

The content of the other epoxy resin is preferably 0.1 to 20% by mass in the total mass of the epoxy resin (A), the epoxy resin (B), and the other epoxy resin. 0.5 to 10% by mass is more preferable.

The curable resin composition of the present invention contains the aforementioned epoxy resin composition and a curing agent (C).

As the curing agent (C), it is preferable to use a curing agent (c1) that is liquid at 25° C., since a curable composition having a low viscosity and excellent impregnating properties into reinforcing fibers can be obtained.

Examples of the curing agent (c1) include acid anhydrides such as methyltetrahydrophthalic anhydride, methylendomethylenetetrahydrophthalic anhydride, methylbutenyltetrahydrophthalic anhydride, dodecenylsuccinic anhydride, and methylhexahydrophthalic anhydride; Ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, diethylenetriamine, dipropylenetriamine, triethylenetetramine, tripropylenetetramine, tetraethylenepentamine, hexa Methylenediamine, iminobispropylamine, bis(hexamethylene)triamine, 1,3,6-trisaminomethylhexane, trimethylhexamethylenediamine, polyetherdiamine, diethylaminopropylamine, dimer acid ester of polyethyleneimine, 1,2- Aliphatic amine compounds such as propanediamine and 1,3-butanediamine; mencenediamine, 1,4-cyclohexanediamine, isophoronediamine, bis(aminomethyl)norbornane, bis(4-aminocyclohexyl)methane, N-aminoethyl Piperazine, diaminodicyclohexylmethane, bisaminomethylcyclohexane, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro(5.5)undecane, norbornenediamine, N-methylpiperazine, morpholine , and alicyclic amine compounds such as piperidine. Furthermore, epoxy-amine adducts obtained by reacting mono- or polyepoxy compounds with amino groups, Mannich-modified products obtained by reacting these compounds having amino groups with phenols and formaldehyde, polyamidoamines (reaction product of the polyamine and long-chain carboxylic acid, or reaction product of the epoxy adduct and long-chain carboxylic acid). Among these, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, triethylenetetramine, isophoronediamine, and bisaminomethylcyclohexane are preferable from the viewpoint of low viscosity and excellent heat resistance. These curing agents can be used alone or in combination of two or more.

Further, as the curable resin composition of the present invention, a curing agent or a curing accelerator other than the curing agent (c1) (hereinafter abbreviated as "another curing agent (c2)") may be used. good. The other curing agent (c2) can be used alone or in combination with the curing agent (c1).

As the other curing agent (c2), any of various compounds generally used as curing agents or curing accelerators for epoxy resins can be used. For example, dicyandiamide, or aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, and azelaic acid, fatty acids, obtained by reacting carboxylic acid compounds such as dimer acid with amine compounds. amide compounds;

Polyhydroxybenzene, polyhydroxynaphthalene, biphenol compound, bisphenol compound, phenol, cresol, naphthol, bisphenol, biphenol, etc. Novolac-type phenolic resin, triphenolmethane-type phenolic resin, tetraphenolethane composed of one or more of various phenolic compounds type phenolic resin, phenol or naphthol aralkyl type phenolic resin, phenylene or naphthylene ether type phenolic resin, dicyclopentadiene-phenol addition reaction product type phenolic resin, phenolic hydroxyl group-containing compound - alkoxy group-containing aromatic compound co-condensation type phenol Phenolic resins such as resins;

imidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1,2-dimethylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2 - imidazole derivatives such as methylimidazole, 1-cyanoethyl-2-phenylimidazole;

p-chlorophenyl-N,N-dimethylurea, 3-phenyl-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-N,N-dimethylurea, N-(3-chloro-4-methylphenyl )-N',N'-urea compounds such as dimethylurea;

Phosphorus compounds; organic acid metal salts; Lewis acids; amine complex salts and the like.

The mixing ratio of the other curing agent (c2) is not particularly limited, and can be appropriately adjusted according to the desired cured product performance and application.

The curable resin composition of the present invention may contain resin components other than the epoxy resin composition, the curing agent (c1) and/or the other curing agent (c2). Other resin components include, for example, acid-modified polybutadiene, polyethersulfone resin, polycarbonate resin, and polyphenylene ether resin.

The acid-modified polybutadiene is a component having reactivity with the epoxy resin component, and by using the acid-modified polybutadiene in combination, the resulting cured product can exhibit excellent mechanical strength, heat resistance, and resistance to moist heat. .

Examples of the acid-modified polybutadiene include those having a butadiene skeleton derived from 1,3-butadiene or 2-methyl-1,3-butadiene. Those derived from 1,3-butadiene include those having any one of 1,2-vinyl, 1,4-trans, and 1,4-cis structures, and those having two or more of these structures. mentioned. Those derived from 2-methyl-1,3-butadiene have a structure of either 1,2-vinyl type, 3,4-vinyl type, 1,4-cis type or 1,4-trans type. and those having two or more of these structures.

The acid-modified component of the acid-modified polybutadiene is not particularly limited, but unsaturated carboxylic acids can be mentioned. As the unsaturated carboxylic acid, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, and itaconic anhydride are preferable. From the viewpoint of reactivity, itaconic anhydride and maleic anhydride are preferable, and maleic anhydride is more preferable. .

Regarding the content of unsaturated carboxylic acid in the acid-modified polybutadiene, from the viewpoint of reactivity with epoxy resin, when the acid-modified polybutadiene is derived from 1,3-butadiene, the acid value is 5 mg KOH. /g to 400 mgKOH/g, more preferably 20 mgKOH/g to 300 mgKOH/g, and even more preferably 50 mgKOH/g to 200 mgKOH/g.

Moreover, the unsaturated carboxylic acid component is not limited as long as it is copolymerized in the acid-modified polybutadiene. Examples thereof include random copolymerization, block copolymerization, graft copolymerization (graft modification), and the like.

The average molar mass of the acid-modified polybutadiene is preferably 1,000 to 8,000, and preferably 2,000 to 7,000 when the acid-modified polybutadiene is derived from 1,3-butadiene. is more preferred. When the acid-modified polybutadiene is derived from 2-methyl-1,3-butadiene, it is preferably from 1,000 to 60,000, more preferably from 15,000 to 40,000. . Average molar masses can be determined using gel permeation chromatography (GPC).

Acid-modified polybutadiene is obtained by modifying polybutadiene with an unsaturated carboxylic acid, but commercially available products may be used as they are. Examples of commercially available products include maleic anhydride-modified liquid polybutadiene (Polyvest MA75, Polyvest EP MA120, etc.) manufactured by Evonik Degussa, and maleic anhydride-modified polyisoprene (LIR-403, LIR-410) manufactured by Kuraray. can do.

The content of the acid-modified polybutadiene in the curable resin composition of the present invention is the total mass of the resin components of the curable resin composition from the viewpoint that the resulting cured product has good elongation, heat resistance, and moist heat resistance. When is 100 parts by mass, it is preferably contained at a rate of 1 to 40 parts by mass, more preferably at a rate of 3 to 30 parts by mass. The total resin components of the curable resin composition are the epoxy resin (A), the epoxy resin (B), the curing agent (c1) and/or the other curing agent (c2), the other It is the total of the resin components of

The polyethersulfone resin is a thermoplastic resin, and in the curing reaction of the curable resin composition, it is not included in the crosslinked network, but has an excellent modifier effect with a high Tg. , further excellent mechanical strength and heat resistance can be expressed.

The content of the polyethersulfone resin in the curable resin composition is such that the total mass of the resin components in the curable resin composition is 100, because the resulting cured product has good mechanical strength and heat resistance. It is preferably contained in a proportion of 1 part by mass to 30 parts by mass, more preferably in a proportion of 3 parts by mass to 20 parts by mass.

Examples of the polycarbonate resin include a polycondensate of divalent or bifunctional phenol and carbonyl halide, or a product obtained by polymerizing divalent or bifunctional phenol and carbonic acid diester by transesterification. be done.

The dihydric or difunctional phenols are, for example, 4,4′-dihydroxybiphenyl, bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4 -hydroxyphenyl)propane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 1,1-bis(4- hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)sulfone, bis(4-hydroxyphenyl)sulfoxide, bis(4-hydroxyphenyl)ketone, hydroquinone, resorcinol, catechol and the like. Among these dihydric phenols, bis(hydroxyphenyl)alkanes are preferred, and those using 2,2-bis(4-hydroxyphenyl)propane as the main raw material are particularly preferred.

On the other hand, carbonyl halides or diesters of carbonic acid to be reacted with dihydric or difunctional phenols are, for example, phosgene; and aliphatic carbonate compounds such as dimethyl carbonate, diethyl carbonate, diisopropyl carbonate, dibutyl carbonate, diamyl carbonate and dioctyl carbonate.

Moreover, the polycarbonate resin may have a branched structure in addition to the linear molecular structure of the polymer chain. Such a branched structure has 1,1,1-tris(4-hydroxyphenyl)ethane, α,α',α″-tris(4-hydroxyphenyl)-1,3,5-triisopropylbenzene as raw material components. , phloroglucin, trimellitic acid, isatin bis(o-cresol) and the like.

The polyphenylene ether resins include, for example, poly(2,6-dimethyl-1,4-phenylene) ether, poly(2-methyl-6-ethyl-14-phenylene) ether, poly(2,6-diethyl-1, 4-phenylene) ether, poly(2-ethyl-6-n-propyl-1,4-phenylene) ether, poly(2,6-di-n-propyl-1,4-phenylene) ether, poly(2- methyl-6-n-butyl-1,4-phenylene) ether, poly(2-ethyl-6-isopropyl-1,4-phenylene) ether, poly(2-methyl-6-hydroxyethyl-1,4-phenylene) ) ether and the like.

Among these, poly(2,6-dimethyl-1,4-phenylene) ether is preferable, and 2-(dialkylaminomethyl)-6-methylphenylene ether unit and 2-(N-alkyl-N-phenylaminomethyl)- A polyphenylene ether containing a 6-methylphenylene ether unit or the like as a partial structure may also be used.

In the polyphenylene ether resin, a reactive functional group such as a carboxyl group, an epoxy group, an amino group, a mercapto group, a silyl group, a hydroxyl group, or an anhydride dicarboxyl group is introduced into the resin structure by some method such as graft reaction or copolymerization. Modified polyphenylene ether resins can also be used as long as the objects of the present invention are not impaired.

By containing the polycarbonate resin or polyphenylene ether resin, the curable resin composition of the present invention can exhibit more excellent mechanical strength in the resulting cured product.

The curable resin composition of the present invention can contain flame retardants/flame retardant aids, fillers, additives, organic solvents, and the like within limits that do not impair the effects of the present invention. The order of compounding when producing the curable resin composition is not particularly limited as long as the method can achieve the effects of the present invention. That is, all components may be mixed in advance and used, or may be mixed in order as appropriate. As for the blending method, for example, kneading can be carried out using a kneader such as an extruder, a heating roll, a kneader, a roller mixer, or a Banbury mixer. Various members that can be contained in the curable resin composition of the present invention are described below.

• Flame Retardant/Auxiliary Flame Retardant The curable resin composition of the present invention may contain a non-halogen flame retardant that does not substantially contain halogen atoms in order to exhibit flame retardancy.

Examples of the non-halogen flame retardants include phosphorus flame retardants, nitrogen flame retardants, silicone flame retardants, inorganic flame retardants, organic metal salt flame retardants, and the like. A single flame retardant may be used, or a plurality of flame retardants of the same type may be used, or flame retardants of different types may be used in combination.

Both inorganic and organic flame retardants can be used as the phosphorus-based flame retardant. Examples of inorganic compounds include red phosphorus, monoammonium phosphate, diammonium phosphate, triammonium phosphate, ammonium phosphates such as ammonium polyphosphate, and inorganic nitrogen-containing phosphorus compounds such as phosphoramide. .

In addition, the red phosphorus is preferably surface-treated for the purpose of preventing hydrolysis, etc. Examples of surface treatment methods include (i) magnesium hydroxide, aluminum hydroxide, zinc hydroxide, water (ii) inorganic compounds such as magnesium hydroxide, aluminum hydroxide, zinc hydroxide, titanium hydroxide, and the like, and A method of coating with a mixture of a thermosetting resin such as a phenolic resin, (iii) a coating of an inorganic compound such as magnesium hydroxide, aluminum hydroxide, zinc hydroxide, titanium hydroxide, etc. is coated with a thermosetting resin such as a phenolic resin. A method of double-coating with a resin and the like can be mentioned.

Examples of the organic phosphorus compounds include general-purpose organic phosphorus compounds such as phosphate ester compounds, phosphonic acid compounds, phosphinic acid compounds, phosphine oxide compounds, phosphorane compounds, organic nitrogen-containing phosphorus compounds, and 9,10- Dihydro-9-oxa-10-phosphaphenanthrene = 10-oxide, 10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene = 10-oxide, 10-(2,7 -dihydroxynaphthyl)-10H-9-oxa-10-phosphaphenanthrene=10-oxide and other cyclic organic phosphorus compounds.

When the phosphorus-based flame retardant is used, hydrotalcite, magnesium hydroxide, boric compounds, zirconium oxide, black dye, calcium carbonate, zeolite, zinc molybdate, activated carbon, etc. may be used in combination with the phosphorus-based flame retardant. good.

Examples of the nitrogen-based flame retardant include triazine compounds, cyanuric acid compounds, isocyanuric acid compounds, phenothiazine, etc. Triazine compounds, cyanuric acid compounds, and isocyanuric acid compounds are preferred.

Examples of the triazine compound include melamine, acetoguanamine, benzoguanamine, melon, melam, succinoguanamine, ethylenedimelamine, melamine polyphosphate, triguanamine, and guanylmelamine sulfate, melem sulfate, and melam sulfate. Examples thereof include aminotriazine sulfate compounds, the above aminotriazine-modified phenol resins, and products obtained by further modifying the aminotriazine-modified phenol resins with tung oil, isomerized linseed oil, and the like.

Specific examples of the cyanuric acid compound include cyanuric acid and melamine cyanurate.

The amount of the nitrogen-based flame retardant compounded is appropriately selected depending on the type of the nitrogen-based flame retardant, other components of the curable resin composition, and the desired degree of flame retardancy. It is preferable to blend in the range of 0.05 parts by mass to 10 parts by mass, particularly in the range of 0.1 parts by mass to 5 parts by mass, based on the total 100 parts by mass of the resin components of the resin composition. preferable.

Moreover, when using the said nitrogen-type flame retardant, you may use a metal hydroxide, a molybdenum compound, etc. together.

As the silicone-based flame retardant, any organic compound containing a silicon atom can be used without particular limitation, and examples thereof include silicone oil, silicone rubber, and silicone resin.

The amount of the silicone flame retardant compounded is appropriately selected depending on the type of the silicone flame retardant, other components of the curable resin composition, and the desired degree of flame retardancy. 0.05 parts by mass to 20 parts by mass with respect to a total of 100 parts by mass of the resin components of the resin composition. Moreover, when using the said silicone type flame retardant, you may use a molybdenum compound, an alumina, etc. together.

Examples of the inorganic flame retardant include metal hydroxides, metal oxides, metal carbonate compounds, metal powders, boron compounds, and low-melting glass.

Specific examples of the metal hydroxide include aluminum hydroxide, magnesium hydroxide, dolomite, hydrotalcite, calcium hydroxide, barium hydroxide, and zirconium hydroxide.

Specific examples of the metal oxides include zinc molybdate, molybdenum trioxide, zinc stannate, tin oxide, aluminum oxide, iron oxide, titanium oxide, manganese oxide, zirconium oxide, zinc oxide, molybdenum oxide, and cobalt oxide. , bismuth oxide, chromium oxide, nickel oxide, copper oxide, tungsten oxide, and the like.

Specific examples of the metal carbonate compounds include zinc carbonate, magnesium carbonate, calcium carbonate, barium carbonate, basic magnesium carbonate, aluminum carbonate, iron carbonate, cobalt carbonate, and titanium carbonate.

Specific examples of the metal powder include aluminum, iron, titanium, manganese, zinc, molybdenum, cobalt, bismuth, chromium, nickel, copper, tungsten and tin.

Specific examples of the boron compound include zinc borate, zinc metaborate, barium metaborate, boric acid, and borax.

Specific examples of the low-melting glass include Seapley (Bokusui Brown Co.), hydrated glass SiO ₂ —MgO—H ₂ O, PbO—B ₂ O ₃ system, ZnO—P ₂ O ₅ —MgO system, _P2O5 - _B2O3 - _PbO -MgO system, P-Sn-O-F system, PbO- _{V2O5 - TeO2} system, _{Al2O3 - H2O} system, lead _borosilicate system, etc. can be mentioned.

The amount of the inorganic flame retardant compounded is appropriately selected depending on the type of the inorganic flame retardant, other components of the curable resin composition, and the desired degree of flame retardancy. It is preferable to blend in the range of 0.05 parts by mass to 20 parts by mass, particularly in the range of 0.5 parts by mass to 15 parts by mass, based on the total 100 parts by mass of the resin components of the resin composition. preferable.

Examples of the organometallic salt-based flame retardants include ferrocene, acetylacetonate metal complexes, organometallic carbonyl compounds, organic cobalt salt compounds, organic sulfonate metal salts, metal atoms and aromatic compounds or heterocyclic compounds in ionic bonds or Coordinate bonded compounds and the like can be mentioned.

The amount of the organometallic salt-based flame retardant compounded is appropriately selected depending on the type of the organometallic salt-based flame retardant, other components of the curable resin composition, and the desired degree of flame retardancy. For example, it is preferable to mix 0.005 parts by mass to 10 parts by mass with respect to a total of 100 parts by mass of the resin components of the curable resin composition.

- Filler The curable resin composition of the present invention may contain a filler. When the curable resin composition of the present invention contains a filler, the resulting cured product can exhibit excellent mechanical properties.

Examples of fillers include titanium oxide, glass beads, glass flakes, glass fibers, calcium carbonate, barium carbonate, calcium sulfate, barium sulfate, potassium titanate, aluminum borate, magnesium borate, fused silica, crystalline silica, alumina, nitride Examples include fibrous reinforcing agents such as silicon, aluminum hydroxide, kenaf fiber, carbon fiber, alumina fiber, quartz fiber, and non-fibrous reinforcing agents. These may be used individually by 1 type, or may use 2 or more types together. Moreover, these may be coated with an organic substance, an inorganic substance, or the like.

When glass fiber is used as a filler, it can be selected from long fiber type rovings, short fiber type chopped strands, milled fibers, and the like. It is preferable to use a glass fiber surface-treated for the resin to be used. By blending the filler, the strength of the incombustible layer (or carbonized layer) generated during combustion can be further improved. The incombustible layer (or carbonized layer) once formed during combustion is less likely to be damaged, and a stable heat insulating ability can be exhibited, resulting in a greater flame retardant effect. Furthermore, a high stiffness can be imparted to the material.

- Additives The curable resin composition of the present invention may contain additives. When the curable resin composition of the present invention contains an additive, other properties such as rigidity and dimensional stability are improved in the resulting cured product. Additives include, for example, plasticizers, antioxidants, ultraviolet absorbers, stabilizers such as light stabilizers, antistatic agents, conductivity-imparting agents, stress relaxation agents, release agents, crystallization accelerators, and hydrolysis inhibitors. agents, lubricants, impact agents, slidability improvers, compatibilizers, nucleating agents, reinforcing agents, reinforcing agents, flow control agents, dyes, sensitizers, coloring pigments, rubbery polymers, thickeners , an anti-settling agent, an anti-sagging agent, an anti-foaming agent, a coupling agent, an anti-rust agent, an anti-bacterial/anti-mold agent, an anti-fouling agent, a conductive polymer and the like can be added.

-Organic solvent The curable resin composition of the present invention may contain an organic solvent, for example, when a fiber-reinforced resin molded article is produced by a filament winding method. Examples of organic solvents that can be used here include methyl ethyl ketone acetone, dimethylformamide, methyl isobutyl ketone, methoxypropanol, cyclohexanone, methyl cellosolve, ethyl diglycol acetate, propylene glycol monomethyl ether acetate, and the like. can be appropriately selected depending on the application.

The curable resin composition of the present invention has low viscosity and excellent curability, and the resulting cured product has high mechanical strength and heat resistance. It can be used for various purposes. The curable resin composition of the present invention can be suitably used for fiber-reinforced composite materials, fiber-reinforced resin moldings, and the like, in addition to applications in which the composition itself is cured. These are described below.

- Cured product of the curable resin composition The method for obtaining a cured product from the curable resin composition of the present invention may conform to a general curing method for a curable resin composition. For example, the heating temperature conditions are combined. It may be appropriately selected according to the type and application of the curing agent. For example, a method of heating the curable resin composition in a temperature range of about room temperature to 250° C. can be used. A general method for a curable resin composition can be used as a molding method, and conditions specific to the curable resin composition of the present invention are unnecessary.

- Fiber-reinforced composite material The fiber-reinforced composite material of the present invention is a material in a state before curing after impregnating reinforcing fibers with the curable resin composition. Here, the reinforcing fibers may be twisted yarns, untwisted yarns, or untwisted yarns, but untwisted yarns and untwisted yarns are preferable because they have excellent moldability in the fiber-reinforced composite material. Furthermore, as for the form of the reinforcing fibers, those in which the fiber direction is aligned in one direction or a woven fabric can be used. The woven fabric can be freely selected from plain weave, satin weave, etc., depending on the site and application. Specifically, carbon fiber, glass fiber, aramid fiber, boron fiber, alumina fiber, silicon carbide fiber, etc., which are excellent in mechanical strength and durability, can be used, and two or more of these can be used in combination. . Among these, carbon fiber is particularly preferable because the strength of the molded article is excellent, and various types of carbon fiber such as polyacrylonitrile, pitch, and rayon can be used.

The method for obtaining a fiber-reinforced composite material from the curable resin composition of the present invention is not particularly limited. For example, the components constituting the curable resin composition are uniformly mixed to produce a varnish, A method of immersing the unidirectional reinforcing fibers in which the reinforcing fibers are aligned in one direction in the varnish obtained above (the state before curing by the pultrusion method or the filament winding method), or overlapping the reinforcing fiber fabrics to form a concave shape. A method of setting, sealing with a convex mold, injecting resin and impregnating under pressure (state before curing by RTM method), and the like can be mentioned.

In the fiber-reinforced composite material of the present invention, the curable resin composition does not necessarily impregnate the inside of the fiber bundle, and the curable resin composition is localized near the surface of the fiber. can be

Furthermore, in the fiber-reinforced composite material of the present invention, the volume content of the reinforcing fibers with respect to the total volume of the fiber-reinforced composite material is preferably 40% to 85%, and in terms of strength, it is in the range of 50% to 70%. is more preferred. If the volume content is less than 40%, the content of the curable resin composition is too large, resulting in insufficient flame retardancy of the resulting cured product, or is required for fiber reinforced composite materials with excellent specific elastic modulus and specific strength. In some cases, it may not be possible to satisfy the various characteristics that are required. Moreover, when the volume content exceeds 85%, the adhesiveness between the reinforcing fibers and the curable resin composition may deteriorate.

・Fiber-reinforced resin molded article The fiber-reinforced resin molded article of the present invention is a molded article having reinforcing fibers and a cured product of a curable resin composition, and is obtained by thermosetting a fiber-reinforced composite material. . Specifically, as the fiber-reinforced resin molded product of the present invention, the volume content of the reinforcing fibers in the fiber-reinforced molded product is preferably in the range of 40% to 85%, and from the viewpoint of strength, it is 50% to 70%. A range is particularly preferred. Examples of such fiber-reinforced resin molded products include automobile parts such as front subframes, rear subframes, front pillars, center pillars, side members, cross members, side sills, roof rails and propeller shafts, core members for electric cables, Examples include pipe materials for submarine oil fields, roll and pipe materials for printers, robot fork materials, primary structural materials for aircraft, secondary structural materials, and the like.

A method for obtaining a fiber-reinforced molded article from the curable resin composition of the present invention is not particularly limited, but it is preferable to use a pultrusion method (pultrusion method), a filament winding method, an RTM method, or the like. The pultrusion method is a method of molding a fiber-reinforced resin molded product by introducing a fiber-reinforced composite material into a mold, heating and curing it, and then pulling it out with a drawing device. is a method in which a fiber-reinforced composite material (including unidirectional fibers) is wound while rotating around an aluminum liner, a plastic liner, etc., and then cured by heating to form a fiber-reinforced resin molded product. is a method using two types of molds, a concave mold and a convex mold, in which a fiber-reinforced composite material is heat-cured in the mold to form a fiber-reinforced resin molded product. It is preferable to use the RTM method when molding a large-sized product or a fiber-reinforced resin molded product having a complicated shape.

As the molding conditions for the fiber-reinforced resin molded article, the fiber-reinforced composite material is preferably molded by thermosetting at a temperature range of 50° C. to 250° C., and more preferably molded at a temperature range of 70° C. to 220° C. . This is because if the molding temperature is too low, sufficient rapid curing may not be obtained, and if it is too high, warping due to thermal strain may easily occur. As other molding conditions, the fiber-reinforced composite material is precured at 50° C. to 100° C. to obtain a tack-free cured product, and then further treated at a temperature condition of 120° C. to 200° C., in two stages. A method of curing, etc. can be mentioned.

Other methods for obtaining a fiber-reinforced molded article from the curable resin composition of the present invention include a hand lay-up method and a spray-up method in which a fiber aggregate is laid in a mold and the varnish and fiber aggregate are laminated in multiple layers. , Either male or female molds are used, and the base material made of reinforcing fibers is impregnated with varnish and stacked and molded, covered with a flexible mold that can apply pressure to the molded product, and airtightly sealed. Examples include a vacuum bag method for vacuum (reduced pressure) molding, and an SMC press method for compressing and molding a sheet of varnish containing reinforcing fibers in advance with a mold.

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples.

In addition, in the present Examples, the weight average molecular weight (Mw) is a value measured under the following conditions using a gel permeation chromatograph (GPC).

In addition, in the present invention, GPC and ¹³ CNMR were measured under the following conditions.
<GPC measurement conditions>
Measuring device: "HLC-8220 GPC" manufactured by Tosoh Corporation,
Column: Guard column "HXL-L" manufactured by Tosoh Corporation
+ "TSK-GEL G2000HXL" manufactured by Tosoh Corporation
+ "TSK-GEL G2000HXL" manufactured by Tosoh Corporation
+ "TSK-GEL G3000HXL" manufactured by Tosoh Corporation
+ "TSK-GEL G4000HXL" manufactured by Tosoh Corporation
Detector: RI (differential refractometer)
Data processing: "GPC-8020 model II version 4.10" manufactured by Tosoh Corporation
Measurement conditions: Column temperature 40°C
Developing solvent Tetrahydrofuran
Flow rate 1.0 ml/min Standard: The following monodisperse polystyrene with a known molecular weight was used in accordance with the measurement manual of "GPC-8020 Model II Version 4.10".

(Polystyrene used)
"A-500" manufactured by Tosoh Corporation
"A-1000" manufactured by Tosoh Corporation
"A-2500" manufactured by Tosoh Corporation
"A-5000" manufactured by Tosoh Corporation
"F-1" manufactured by Tosoh Corporation
"F-2" manufactured by Tosoh Corporation
"F-4" manufactured by Tosoh Corporation
"F-10" manufactured by Tosoh Corporation
"F-20" manufactured by Tosoh Corporation
"F-40" manufactured by Tosoh Corporation
"F-80" manufactured by Tosoh Corporation
"F-128" manufactured by Tosoh Corporation
Sample: A 1.0% by mass tetrahydrofuran solution in terms of resin solid content filtered through a microfilter (50 μl).

< ¹³ C-NMR measurement conditions>
Device: JNM-ECA500 manufactured by JEOL Ltd.
Measurement mode: Decoupling with reverse gate Solvent: Deuterated dimethyl sulfoxide Pulse angle: 30° pulse Sample concentration: 30 wt%
Accumulation times: 4000 times Chemical shift standard: Peak of dimethyl sulfoxide: 39.5 ppm

(Synthesis Example 1: Production of epoxy resin (A-1))
Step (1)
165 g (1.50 mol) of catechol and 1388 g (15 mol) of epichlorohydrin were added to a flask equipped with a thermometer, dropping funnel, condenser, nitrogen inlet tube and stirrer, and the temperature was raised to 50°C. Then, 11.2 g (0.06 mol) of benzyltrimethylammonium chloride was added and stirred at 50° C. for 15 hours.

Step (2)
1000 mL of distilled water was poured into the reaction liquid obtained in the step (1), and the mixture was stirred, left to stand, and then the upper layer was removed. 318 g of a 48% sodium hydroxide aqueous solution was added dropwise over 2.5 hours, and the mixture was stirred for 1 hour.

400 mL of distilled water was poured into the resulting solution and left to stand. The lower layer of saline was removed, and epichlorohydrin was recovered by distillation at 120°C. Then, 566 g of methyl isobutyl ketone (hereinafter abbreviated as "MIBK") and 167 g of water were sequentially added and washed with water at 80°C. After removing the washing water of the lower layer, dehydration and filtration were performed, and MIBK was desolvated at 150° C. to obtain an epoxy resin (A-1). manufactured. The obtained epoxy resin (A-1) was visually observed and found to be liquid.

Regarding the obtained epoxy resin (A-1), the content X (mol) of the cyclic compound per 100 g of the epoxy resin was measured. Specifically, it was calculated using the following formula.

In the above formula, X is the cyclic compound content (mol) per 100 g of the epoxy resin, (A) is the cyclic compound (mol) per 1 mol of the aromatic ring, and (B) is the epoxy group per 1 mol of the aromatic ring ( mol) and (C) is the epoxy equivalent weight (g/equivalent).

At this time, (A) was calculated from the integral ratio of the peak derived from the aromatic ring corresponding to the ipso position of catechol around 130 to 150 ppm and the peak derived from the cyclic compound around 60 ppm in the ¹³ C NMR measurement. Further, (B) was calculated from the integral ratio of the peak derived from the aromatic ring corresponding to the ipso position of catechol around 130 to 150 ppm and the peak derived from the epoxy group around 50 ppm. As a result, the content of the cyclic compound was 0.071 mol/100 g. The results [chart] of the ¹³ C NMR measurement are shown in FIG.

In addition, the area ratio of 1,2-diglycidyloxybenzene (diglycidyl form of catechol) in the GPC measurement of the obtained epoxy resin (A-1) was measured. As a result, the content of diglycidyl form of catechol was 88% in terms of area ratio in GPC measurement.

Furthermore, the area ratio in the GPC measurement of the oligomer was measured. As a result, the oligomer content was 1.3% in terms of area ratio in GPC measurement.

Further, the epoxy equivalent was measured for the obtained epoxy resin (A-1). Specifically, the epoxy equivalent of the epoxy resin was measured by the method of JIS K 7236 (2009). As a result, the epoxy equivalent weight of the epoxy resin (A-1) was 138 g/equivalent.

Furthermore, the viscosity of the resulting epoxy resin (A-1) was measured. Specifically, an E-type viscometer ("TV-22" manufactured by Toki Sangyo Co., Ltd.) was used to measure the viscosity of the epoxy resin at 25°C. As a result, the viscosity of the epoxy resin (A-1) was 190 mPa·s.

(Synthesis Example 2: Production of epoxy resin (A-2))
Epoxy was prepared in the same manner as in Synthesis Example 1 except that 165 g (1.50 mol) of catechol in step (1) of Synthesis Example 1 was changed to 126 g (1.00 mol) of pyrogallol, 566 g of MIBK was changed to 500 g, and 167 g of water was changed to 147 g. A resin (A-2) was obtained. Further, in the same manner as in Synthesis Example 1, the content of the cyclic compound, the area ratio of 1,2,3-triglycidyloxybenzene in GPC measurement, the area ratio of the oligomer in GPC measurement, the epoxy equivalent, and the viscosity of the epoxy resin were measured. 0.086 mol/100 g, 77%, 128 g/eq and 3100 mPa.s respectively. was s. The results [chart] of the ¹³ C NMR measurement are shown in FIG.

(Examples 1 to 11: Preparation of curable resin compositions (1) to (11))
Each component was compounded according to the formulation (by mass) shown in Table 1 below, and uniformly stirred and mixed to obtain curable resin compositions (1) to (11).

(Comparative Examples 1 to 5: Preparation of epoxy resin compositions (C1) to (C5))
Each component was blended according to the formulation (by mass) shown in Table 2 below, and uniformly stirred and mixed to obtain curable resin compositions (C1) to (C5).

Using the curable resin compositions obtained in Examples 1 to 11 and Comparative Examples 1 to 5, the following evaluations were performed.

[Measurement of viscosity]
For formulations containing no curing agent, the viscosity of the epoxy resin composition at 25° C. was measured using an E-type viscometer (“TV-22” manufactured by Toki Sangyo Co., Ltd.).

[Heat resistance evaluation method]
The curable resin composition obtained in each example and comparative example was poured into a mold with a width of 90 mm, a length of 110 mm, and a thickness of 2 mm, and dried for a total of 4 hours at 80 ° C. for 2 hours and 120 ° C. for 2 hours. A cured product was obtained by thermally curing in the inside. The resulting cured product was cut with a diamond cutter into a piece having a width of 5 mm and a length of 55 mm, which was used as a test piece. Next, using "DMS6100" manufactured by SII Nanotechnology Co., Ltd., the dynamic viscoelasticity was measured under the following conditions by bending at both ends, and the temperature at which tan δ reached the maximum value was evaluated as the glass transition temperature (Tg).

The measurement conditions for the dynamic viscoelasticity measurement were temperature conditions: room temperature to 260° C., heating rate: 3° C./min, frequency: 1 Hz (sine wave), strain amplitude: 10 μm.

[Method for evaluating mechanical properties]
Mechanical properties were evaluated by measuring flexural strength and flexural modulus.

<Measurement of flexural strength and flexural modulus>
The curable resin composition obtained in each example and comparative example was poured into a mold with a width of 90 mm, a length of 110 mm, and a thickness of 2 mm, and dried for a total of 4 hours at 80 ° C. for 2 hours and 120 ° C. for 2 hours. A cured product was obtained by thermally curing in the inside. The flexural strength and flexural modulus of the cured product were measured according to JIS K 6911 (2006).

Table 1 shows the compositions and evaluation results of the epoxy resin compositions (1) to (11) prepared in Examples 1 to 11.

"Epoxy resin (B-1)" in Table 1 indicates a bisphenol A type epoxy resin ("EPICLON 850-S" manufactured by DIC Corporation, epoxy equivalent: 188 g/equivalent).

"IPDA" in Table 1 indicates isophorone diamine.

"TETA" in Table 1 indicates triethylenetetramine.

"B-570-H" in Table 1 indicates methyltetraphthalic anhydride ("EPICLON B-570-H" manufactured by DIC Corporation).

"1,2-DMZ" in Table 1 indicates 1,2-dimethylimidazole.

"DICY" in Table 1 indicates dicyandiamide.

“DCMU” in Table 1 indicates 3-(3,4-dichlorophenyl)-1,1′-dimethylurea.

Table 2 shows the compositions and evaluation results of the curable resin compositions (C1) to (C5) prepared in Comparative Examples 1 to 5.

"EX-214L" in Table 2 indicates 1,4-butanediol diglycidyl ether ("Denacol EX-214L" manufactured by Nagase ChemteX Corporation, epoxy equivalent: 120 g/equivalent).

"Epoxy resin (B-1)", "IPDA", "B-570-H" and "1,2-DMZ" in Table 2 are the same as in Table 1.

Claims (15)

Epoxy resin (A) which is a reaction product of epihalohydrin with catechol optionally having a methyl group as a substituent on the aromatic ring or pyrogallol optionally having a methyl group as a substituent on the aromatic ring and a bisphenol type epoxy resin (B) ,
An epoxy resin composition characterized in that the mass ratio [(A)/(B)] of the epoxy resin (A) and the bisphenol type epoxy resin (B) is in the range of 3/97 to 95/5. . The epoxy resin (A) is derived from catechol, which may have a methyl group as a substituent on the aromatic ring, or pyrogallol, which may have a methyl group as a substituent on the aromatic ring. 2. The epoxy resin composition according to claim 1, which contains a cyclic compound (a1) having a cyclic structure containing adjacent oxygen atoms as constituent atoms. 3. The epoxy resin composition according to claim 2, wherein the content of said cyclic compound (a1) is in the range of 0.040 to 0.115 mol per 100 g of said epoxy resin (A). Claims 1 to 3, wherein the content of the glycidyl ether compound (a2) represented by the following structural formula (1) or (2) in the epoxy resin (A) is 55% or more in area ratio in GPC measurement. The epoxy resin composition according to any one of claims 1 to 3.

[In formulas (1) and (2), G is a glycidyl group, R ¹ is each independently a hydrogen atom or a methyl group, m is an integer of 1 to 4, and n is an integer of 1 to 3. ] 5. Any one of claims 1 to 4, wherein the epoxy resin (A) further contains an oligomer (a3), and the content of the oligomer (a3) is 12% or less in area ratio as measured by GPC. 2. The epoxy resin composition according to item 1. 6. The epoxy resin composition according to any one of claims 1 to 5, wherein the epoxy resin (A) is a reaction product of pyrogallol and epihalohydrin and has an epoxy equivalent weight of 108 to 170 g/equivalent. A curable resin composition comprising the epoxy resin composition according to any one of claims 1 to 6 and a curing agent (C). The curable resin composition according to claim 7 , wherein the curing agent (C) is a curing agent (c1) that is liquid at 25°C. 9. The curable resin composition according to claim 8 , wherein the curing agent (c1) is one or more curing agents selected from the group consisting of acid anhydrides, aliphatic amine compounds and alicyclic amine compounds. A cured product, which is a cured reaction product of the curable resin composition according to any one of claims 8 to 9 . A fiber-reinforced composite material comprising the curable resin composition according to any one of claims 8 to 9 and reinforcing fibers as essential components. The fiber-reinforced composite material according to claim 11 , wherein the volume content of said reinforcing fibers is in the range of 40 to 85%. A fiber-reinforced resin molded product comprising the cured product according to claim 10 and reinforcing fibers as essential components. 14. The fiber-reinforced resin molded article according to claim 13 , wherein the volume content of said reinforcing fibers is in the range of 40 to 85%. 15. A method for producing a fiber-reinforced resin molded article, comprising thermosetting the fiber-reinforced composite material according to claim 13 or 14 .

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