Thermosetting epoxy resin composition and fiber-reinforced composite material

Abstract

Provided is a thermosetting epoxy resin composition containing a main agent and a curing agent, wherein the biomass degree is 50% or more, and the main agent contains a sorbitol-type epoxy resin and can form a cured product having a glass transition temperature of 90°C or higher.

Description

Thermosetting epoxy resin composition and fiber-reinforced composite material CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This disclosure claims the benefit of priority to Japanese Patent Application No. 2023-093277, filed on June 6, 2023, in the Japan Patent Office, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a thermosetting epoxy resin composition and a fiber-reinforced composite material.

[0003] Patent Document 1 proposes a curing agent consisting of a reaction product of a naturally occurring polyfunctional carboxylic acid, a hydroxyl group-containing solvent, and an epoxidized triglyceride, the curing agent being characterized by including an ester bond formed between the hydroxyl group-containing solvent and the naturally occurring polyfunctional carboxylic acid.

[0004] Special Publication No. 2021-532199

[0005] An object of the present invention is to provide a thermosetting epoxy resin composition and a fiber-reinforced composite material that have a high biomass content and excellent strength.

[0006] One aspect of the present disclosure relates to a thermosetting epoxy resin composition comprising a base agent and a curing agent, wherein the base agent comprises a sorbitol-type epoxy resin and the thermosetting epoxy resin composition is capable of forming a cured product having a glass transition temperature of 90°C or higher.

[0007] Another aspect of the present disclosure relates to a fiber-reinforced composite material comprising fibers and a thermosetting epoxy resin composition impregnated into the fibers, wherein the thermosetting epoxy resin composition comprises a base resin and a curing agent, the thermosetting epoxy resin composition has a biomass degree of 50% or more, the base resin comprises a sorbitol-type epoxy resin, and the thermosetting epoxy resin composition is capable of forming a cured product having a glass transition temperature of 90°C or higher.

[0008] The present invention provides a thermosetting epoxy resin composition and a fiber-reinforced composite material having a high biomass content and excellent strength. The novel features of the present invention are set forth in the appended claims, but the present invention, both in terms of structure and content, together with other objects and features of the present invention, will be better understood from the following detailed description taken in conjunction with the drawings.

[0009] The following describes embodiments of the present disclosure using examples, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be exemplified, but other numerical values ​​and materials may be applied as long as the effects of the present disclosure are obtained. In this specification, the expression "numerical value A to numerical value B" includes numerical value A and numerical value B and can be read as "numerical value A or more and numerical value B or less." In the following description, when lower and upper limits of numerical values ​​related to specific physical properties or conditions are exemplified, any of the exemplified lower limits and any of the exemplified upper limits can be arbitrarily combined, as long as the lower limit is not equal to or greater than the upper limit.

[0010] The present disclosure relates to the following: [1] A thermosetting epoxy resin composition comprising a base agent and a curing agent, wherein the base agent contains a sorbitol-type epoxy resin and the thermosetting epoxy resin composition is capable of forming a cured product having a glass transition temperature of 90°C or higher.

[0011] [2] The thermosetting epoxy resin composition according to [1], wherein the biomass degree is 70% or more and 100% or less.

[0012] [3] The thermosetting epoxy resin composition according to [1] or [2], wherein the biomass degree is 90% or more and 100% or less.

[0013] [4] The thermosetting epoxy resin composition according to any one of [1] to [3], wherein the sorbitol-type epoxy resin has an epoxy equivalent of 162 g / eq or more and 200 g / eq or less.

[0014] [5] The thermosetting epoxy resin composition according to any one of [1] to [4], wherein the sorbitol-type epoxy resin has an epoxy equivalent of 162 g / eq or more and 182 g / eq or less.

[0015] [6] The thermosetting epoxy resin composition according to any one of [1] to [5], wherein the curing agent contains at least one of an amine compound and an acid anhydride compound.

[0016] [7] The thermosetting epoxy resin composition according to any one of [1] to [6], wherein the amine compound forms a complex with a Lewis acid.

[0017] [8] The thermosetting epoxy resin composition according to [7], wherein the activation temperature of the complex is 90°C or higher.

[0018] [9] The thermosetting epoxy resin composition according to [7] or [8], wherein the complex is a complex of a tertiary amine containing at least one alkyl group having 6 or more carbon atoms and a Lewis acid, and the Lewis acid is at least one compound selected from the group consisting of boron and aluminum.

[0019]

[10] The thermosetting epoxy resin composition according to any one of [1] to [9], wherein the amine compound is a primary polyamine compound having two or more primary amino groups and no ether bond.

[0020]

[11] The thermosetting epoxy resin composition according to

[10] , wherein the primary polyamine compound is at least one selected from the group consisting of aromatic diamine compounds and alicyclic diamine compounds.

[0021]

[12] The thermosetting epoxy resin composition according to

[10] , wherein the primary polyamine compound is an aliphatic diamine compound having a branched structure and a main chain having 6 or more carbon atoms.

[0022]

[13] The thermosetting epoxy resin composition according to any one of [1] to

[12] , which is used for a fiber-reinforced composite material.

[0023]

[14] A fiber-reinforced composite material comprising: fibers; and a thermosetting epoxy resin composition impregnated into the fibers; wherein the thermosetting epoxy resin composition comprises a base agent and a curing agent; the biomass degree of the thermosetting epoxy resin composition is 50% or more; the base agent comprises a sorbitol-type epoxy resin; and the thermosetting epoxy resin composition is capable of forming a cured product having a glass transition temperature of 90°C or more.

[0024] (Thermosetting Epoxy Resin Composition) The thermosetting epoxy resin composition according to the present disclosure (hereinafter also referred to as "resin composition (HB)") comprises a base agent and a curing agent, and comprises a sorbitol-type epoxy resin as at least a part of the base agent. The biomass degree of the sorbitol-type epoxy resin is, for example, from 70% to 100%, or from 90% to 100%, and can also be from 99% to 100%.

[0025] By using a sorbitol-type epoxy resin as the main component of the base resin, the biomass degree of the resin composition (HB) as a whole is significantly increased. The biomass degree of the resin composition (HB) is, for example, 70% to 100%, or 90% to 100%, and can also be 95% to 100%, or 99% to 100%. For example, by making the components other than the sorbitol-type epoxy resin 10% by mass or less, or even 9% or less, or 8% or less, the biomass degree of the resin composition (HB) can easily be 90% or more. The components other than the sorbitol-type epoxy resin are mainly curing agents and may contain small amounts of additives.

[0026] In one embodiment of the resin composition (HB), the "main agent" may be referred to as an "epoxy resin." The "main component" of the main agent refers to a component that accounts for 60% by mass or more, preferably 70% by mass or more or 90% by mass or more, of the main agent (or epoxy resin). In other words, 60% by mass or more, preferably 70% by mass or more or 90% by mass or more (or 100%) of the main agent contained in one embodiment of the resin composition (HB) is a sorbitol-type epoxy resin.

[0027] The degree of biomass can be measured by testing the biobased carbon content of biobased products using radiocarbon measurements, based on ASTM D6866-22 Method B.

[0028] The sorbitol-type epoxy resin is an epoxy resin having a sorbitol skeleton represented by the following structural formula (1).

[0029] Structural formula (1):

[0030]

[0031] Sorbitol-type epoxy resins can be obtained, for example, by reacting sorbitol with epichlorohydrin to epoxidize the hydroxyl groups. The following structural formula (2) shows an example of a sorbitol-type epoxy resin in which four hydroxyl groups have been epoxidized.

[0032] Structural formula (2):

[0033]

[0034] An example of a commercially available sorbitol-type epoxy resin is the EX-600 series of "Denacol (registered trademark)" manufactured by Nagase ChemteX Corporation. The sorbitol-type epoxy resin preferably has an average of 3.8 to 4.2 (preferably an average of 4.0) epoxy groups (glycidyl ether groups) per molecule. Such a sorbitol-type epoxy resin is preferred from the viewpoint of realizing a cured product having a high Tg and a high elastic modulus.

[0035] From another perspective, the epoxy equivalent of the sorbitol-type epoxy resin may be, for example, 162 g / eq or more and 200 g / eq or less. If the epoxy equivalent is within this range, a cured product having a high Tg and a high elastic modulus can be obtained.

[0036] The epoxy equivalent of the sorbitol-type epoxy resin is preferably 162 g / eq or more and 182 g / eq or less. A sorbitol-type epoxy resin having an epoxy equivalent in this range can produce a cured product having a high Tg and a high elastic modulus in a good balance.

[0037] Unlike petroleum-derived epoxy resins with a low biomass content, sorbitol-based epoxy resins with a high biomass content generally have low heat resistance, making it difficult to obtain cured products with a high Tg. However, in practice, sorbitol-based epoxy resins are promising alternatives to petroleum-derived epoxy resins. In particular, sorbitol-based epoxy resins with approximately four epoxy groups per molecule can form cured products with an excellent balance of physical properties, including Tg, elastic modulus, and adhesiveness to fibers. Furthermore, by appropriately selecting the type of curing agent, it is possible to design physical properties according to the desired application.

[0038] In the present disclosure, the curing agent is selected so that the resin composition (HB) can form a cured product having a glass transition temperature (Tg) of 90°C or higher. If the Tg of the cured product of the resin composition (HB) is 90°C or higher, it can be said that the cured product satisfies the generally required mechanical strength and heat resistance. A cured product of the resin composition (HB) having a Tg of 90°C or higher is suitable, for example, as a structural material (building material, housing, car body, etc.). A resin composition (HB) having a cured product Tg of 90°C or higher is particularly suitable as a material for fiber-reinforced composite materials. The higher the Tg of the cured product of the resin composition (HB), the more preferable it is, and it may be 100°C or higher, 120°C or higher, or 150°C or higher.

[0039] The case where the resin composition (HB) can form a cured product having a glass transition temperature (Tg) of 90° C. or higher refers to, for example, a case where the resin composition (HB) is heated at 140° C. for 3 hours and cured, and the cured product has a Tg of 90° C. or higher as measured by a differential scanning calorimeter (DSC). The curing conditions for the resin composition (HB) are typically, but not limited to, 140° C. for 3 hours.

[0040] The amine compound used as a curing agent may form a complex with a Lewis acid. A complex with a high ionic strength is less likely to precipitate in the liquid resin composition (HB) and is soluble. That is, until the complex reaches a predetermined activation temperature, the complex is dissolved in the liquid resin composition (HB) in a stable state in which the lone electron pair of the amine compound is coordinated to the vacant orbital of the Lewis acid. When the complex in the resin composition (HB) reaches a predetermined activation temperature, the amine compound and the Lewis acid dissociate, and the amine compound and the Lewis acid exhibit a catalytic effect that promotes the polymerization reaction of the epoxy resin. A complex of an amine compound and a Lewis acid having such properties is suitable for so-called one-component epoxy resin compositions (liquids in which the base resin and the curing agent are mixed).

[0041] The activation temperature of the complex (i.e., the temperature at which the amine compound and the Lewis acid dissociate) may be, for example, 90°C or higher. The higher the activation temperature, the more stable the resin composition (HB) is and the better its storage properties are. In this case, the resin composition (HB) may be a one-component liquid resin composition.

[0042] It is desirable that the amine compound constituting the complex has steric hindrance while rapidly contributing to the reaction after dissociation. Such an amine compound may be, for example, an amine containing at least one alkyl group having 6 or more carbon atoms. Examples of such amine compounds include dimethyloctylamine and di(2-ethylhexyl)amine. Among these, from the viewpoint of suppressing reactivity at room temperature, tertiary amines containing at least one alkyl group having 6 or more carbon atoms are preferred. The alkyl group having 6 or more carbon atoms may be an alkyl group having 6 to 20 carbon atoms or an alkyl group having 6 to 15 carbon atoms. It is preferable that the alkyl group having 6 or more carbon atoms has a branched structure. The amine compound may further have two or less alkyl groups having 3 or less carbon atoms.

[0043] The Lewis acid is not particularly limited, but may be a compound of at least one element selected from the group consisting of boron and aluminum. Specific examples of boron compounds include boron trifluoride, boron trichloride, boron tribromide, and boron triiodide. Specific examples of aluminum compounds include aluminum trifluoride, aluminum trichloride, aluminum tribromide, and aluminum triiodide. Other examples that may be used include silicon tetrafluoride, silicon tetrachloride, silicon tetrabromide, silicon tetraiodide, phosphorus pentafluoride, and antimony pentafluoride.

[0044] When a complex of an amine compound and a Lewis acid is used as the curing agent, the amount of the curing agent may be small. The amount of the complex used may be, for example, 3 parts by mass or more and 20 parts by mass or less, 4 parts by mass or more and 17 parts by mass or less, or 8 parts by mass or more and 17 parts by mass or less per 100 parts by mass of the resin composition (HB). In this case, the biomass content of the resin composition (HB) may be, for example, 85% or more, 90% or more, or even 95% or more.

[0045] Specific examples of the complex include a boron trichloride-dimethyloctylamine complex, a boron trichloride-monomethylamine complex, and a boron trifluoride-monoethylamine complex.

[0046] The amine compound may be a primary polyamine compound having two or more primary amino groups. However, from the viewpoint of achieving a higher Tg, it is desirable that the primary polyamine compound does not have an ether bond. Hereinafter, a primary polyamine compound having two or more primary amino groups but no ether bond will also be referred to as a "non-ether primary polyamine." The molecular weight of the non-ether primary polyamine may be, for example, 150 to 300, or 150 to 270, taking into consideration the balance between the viscosity, stability, and biomass content of the resin composition (HB).

[0047] The non-ether primary polyamine may be, for example, at least one selected from the group consisting of aromatic diamine compounds and alicyclic diamine compounds, both of which are suitable for obtaining a cured product with a high Tg.

[0048] The aromatic diamine compound preferably has one or two aromatic rings in consideration of the balance of the viscosity, biomass degree, etc. of the resin composition (HB). The aromatic ring may be a benzene ring or a naphthalene ring. The aromatic diamine compound preferably has one or two aromatic rings per aromatic ring or benzene ring. ２ It is preferable that the copolymer has two or more NH groups in order to increase Tg. ２ The nitrogen atom of the group is preferably directly bonded to the aromatic ring. Specifically, the aromatic diamine compound may be 4,4'-methylenebis(2-methylaniline), diethylmethylbenzenediamine, or the like.

[0049] The alicyclic diamine compound may be a monocycloamine compound or a bicycloamine compound. The alicyclic diamine compound has NH ２ It is preferable that the copolymer has two or more NH groups in order to increase Tg. ２ The nitrogen atom of the group may be directly bonded to the aliphatic ring or may be bonded via an alkylene group such as a methylene group, e.g., CH ２ -NH ２ The alicyclic diamine compound may be bonded as a group such as a methyl group. The alicyclic diamine compound is desirably thick and preferably has an alkyl group such as a methyl group directly bonded to the aliphatic ring. The number of alkyl groups may be 2 or more and 5 or less. Specifically, 2,2'-dimethyl-4,4'-methylenebis(cyclohexylamine), isophoronediamine, etc. may be used as the alicyclic diamine compound.

[0050] Specifically, as the aromatic diamine compound or alicyclic diamine compound, 4,4'-methylenebis(2-methylaniline), diethylmethylbenzenediamine, 2,2'-dimethyl-4,4'-methylenebis(cyclohexylamine), isophoronediamine, etc. can be used.

[0051] Alternatively, the non-ether primary polyamine may be, for example, an aliphatic diamine compound having a main chain with a branched structure and 6 or more carbon atoms. The number of carbon atoms in the main chain may be 6 or more and 13 or less, or 6 or more and 10 or less. The number of carbon atoms in the side chain in the branched structure may be the same as or less than that of the main chain, and may be 1 or more. The number of carbon atoms in the side chain may be, for example, 1 to 3, or may be 1 or 2. More specifically, trimethylhexamethylenediamine or the like may be used as such an aliphatic diamine compound.

[0052] When a non-ether primary polyamine is used as the curing agent, the amount of curing agent used is, for example, 0.7 to 1.5 equivalents of hydrogen bonded to a nitrogen atom of the amine compound (hereinafter also referred to as "active hydrogen") per 1 epoxy equivalent of the sorbitol-type epoxy resin. From the viewpoint of increasing the biomass content of the resin composition (HB), it is preferable that the active hydrogen equivalent per 1 epoxy equivalent is 1.1 or less.

[0053] Acid anhydride compounds that can be used as curing agents are preferably acid anhydrides having a ring structure. The ring structure may be an aliphatic ring or an aromatic ring. A functional group or an alkyl group may be bonded to the ring structure. The number of carbon atoms in the alkyl group may be, for example, 1 to 5, 1 to 3, or 1 or 2. More specific examples include methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and 5-norbornene-2,3-dicarboxylic anhydride.

[0054] The viscosity of the resin composition (HB) measured using an E-type viscometer at a temperature of 25° C. is, for example, 20,000 mPa·s or less, preferably 16,000 mPa·s or less, and the lower the viscosity, the more preferable. Furthermore, when providing a fiber-reinforced composite material, a higher curing temperature of the resin composition (HB) is preferable in that the rate of impregnation into fibers becomes faster.

[0055] However, it is desirable that the curing reaction does not proceed too rapidly. For example, the time until the viscosity doubles at 25°C (the time until the viscosity doubles) is preferably 10 minutes or more, and more preferably 50 minutes or more.

[0056] By using the resin composition (HB), a fiber-reinforced composite material with a high biomass degree can be obtained. The fiber-reinforced composite material includes fibers and the resin composition (HB) impregnated into the fibers. To further increase the biomass degree, the biomass degree of the fibers themselves may be 50% or more, 90% or more, or even 99% or more or 100%. As a result, the biomass degree of the fiber-reinforced composite material can be, for example, 70% or more, 90% or more, or even 99% or more.

[0057] Fibers with a high biomass content are derived from plants, such as hemp, basalt, palm, and bamboo. Other examples include aliphatic polyester fibers such as polylactic acid fiber made from starch-derived lactic acid, polytrimethylene terephthalate (PTT) fiber made from starch-derived 1,3-propanediol, and castor oil-derived polyamide fiber, as well as cellulosic fibers such as regenerated cellulose fiber and cellulose acetate fiber. Plant fibers such as straw, rush grass, and palm may also be used. Fibers are not limited to plant-derived fibers; carbon fiber and glass fiber may also be used.

[0058] The content of fibers in the fiber-reinforced composite material is not particularly limited, but may be, for example, 20% by volume or more and 70% by volume or less, or 30% by volume or more and 60% by volume or less.

[0059] [Examples] The present invention will be described below with reference to examples, but the present invention is not limited to the following examples. Table A shows the components, roles and structural formulas of the raw materials used.

[0060]

[0061] Example A1 As the base resin, a sorbitol-type epoxy resin (GEX-600 series manufactured by Nagase ChemteX Corporation) represented by the structural formula (2) was used.

[0062] As a curing agent, a boron trichloride-dimethyloctylamine complex, which is a complex of an amine compound and a Lewis acid, was used.

[0063] A one-component liquid resin composition (HB) (hereinafter also referred to as "resin composition A1") was prepared by blending 4.2 parts by mass of a boron trichloride-dimethyloctylamine complex (curing agent) with 100 parts by mass of a sorbitol-type epoxy resin (GEX-600 series) as a main component, and dissolving the curing agent.

[0064] (Viscosity) The viscosity of Resin Composition A1 was measured at 25° C. using an E-type viscometer and was found to be 15,000 mPa·s.

[0065] (Gel Time) The gel time of resin composition A1 was measured. The gel time is the time it takes for the viscosity of resin composition A1 to increase rapidly and gel during the intermediate stage of curing by heating. The gel time was measured using a torque-type gel time tester manufactured by Yasuda Seiki Seisakusho Co., Ltd. Specifically, 2 mL of a sample of resin composition A1 was placed in a glass tube, a glass rod was inserted, and the tube was placed in an oil bath at 140°C. The rotor was rotated, and the time until the reaction of resin composition A1 progressed and a specified torque was applied to the torque detector was measured. The gel time was measured twice for the same sample and the average value was calculated. The gel time was 17 minutes.

[0066] (Tg) Resin composition A1 was heated at 140°C for 3 hours to obtain a cured product. The Tg of the cured product was measured by DSC and found to be 90°C.

[0067] Examples A2 and A3, Comparative Examples A1 and A2 Resin compositions A2 and A3 of Examples A2 and A3 and resin compositions CA1 and CA2 of Comparative Examples A1 and A2 were prepared and evaluated in the same manner as in Example A1, except that the amount of curing agent relative to the base resin was changed to the amount (parts by mass) shown in Table 1. The results are shown in Table 1.

[0068] Reference Example 1 A resin composition RE1 of Reference Example 1 was prepared in the same manner as in Example A1, except that a petroleum-derived bisphenol A epoxy resin was used as the base resin instead of the sorbitol epoxy resin, and evaluated in the same manner. The results are shown in Table 1.

[0069]

[0070] Example B1 As the base resin, a sorbitol-type epoxy resin represented by the structural formula (2) (GEX-600 series manufactured by Nagase ChemteX Corporation) was used.

[0071] Diethylmethylbenzenediamine (also known as diethyltoluenediamine) was used as the curing agent.

[0072] A two-component liquid resin composition (HB) (hereinafter also referred to as "resin composition B1") was prepared by blending 100 parts by mass of a first component of a sorbitol-type epoxy resin (GEX-600 series) as the base resin with 30.33 parts by mass of diethylmethylbenzenediamine (curing agent) as the second component. The active hydrogen equivalent per epoxy equivalent (eq / eq ratio) was 1.06.

[0073] The viscosity, gel time and Tg were evaluated in the same manner as in Example A1, and the viscosity at 25°C was 15,500 mPa·s, the gel time at 140°C was 7.1 minutes and the Tg was 155°C.

[0074] Examples B2 to B7 Resin compositions B2 to B7 of Examples B2 to B7 were prepared and evaluated in the same manner as in Example B1, except that the amount of curing agent relative to the base resin was changed to the amount (parts by mass) shown in Table 2, and the type of curing agent was changed in Examples B6 and B7. The results are shown in Table 2.

[0075]

[0076] Examples C1 to C5, Comparative Examples C1 to C5 Resin compositions C1 to C5 of Examples C1 to C5 and resin compositions CC1 to CC5 of Comparative Examples C1 to C5 were prepared in the same manner as in Example 1B, except that the curing agents shown below were used in the amounts (parts by mass) shown in Table 3, and Tg was evaluated in the same manner. Stability and adhesive strength were also evaluated. The results are shown in Table 3.

[0077] (Stability) The resin composition was left to stand at 25° C., and the time until the viscosity doubled was determined. The stability until the viscosity doubled is preferably 10 minutes or more, and ideally 50 minutes or more.

[0078] (Adhesion Strength) The adhesive strength was evaluated by tensile shear adhesive strength. The resin composition was applied to adherend 1, and adherend 2 was attached to the applied resin composition. An aluminum plate with a thickness of 1.5 mm, a width of 25 mm, and a length of 150 mm, the surface of the adhesive portion of which was polished, was used as the adherend. The adhesive was then heated at 140°C for 3 hours to cure. The tensile shear adhesive strength was measured at a pulling rate of 5 mm / min using a tensile tester (manufactured by Instron). When the resin composition is used in, for example, a fiber-reinforced composite material, taking into account the adhesiveness to the fiber, an adhesive strength of 2 MPa or more is preferable, and 5 MPa or more is ideal.

[0079]

[0080] The thermosetting epoxy resin composition according to the present disclosure has a high biomass content and is suitable for fiber-reinforced composite materials.

[0081] While the present invention has been described in terms of presently preferred embodiments, such disclosure is not to be interpreted as limiting. Various changes and modifications will no doubt become apparent to those skilled in the art to which the present invention pertains upon reading the above disclosure. It is therefore intended that the appended claims be interpreted to cover all changes and modifications that do not depart from the true spirit and scope of the invention.

Claims

1. A thermosetting epoxy resin composition comprising a base agent and a curing agent, The biomass ratio is 70% or more, The base resin contains a sorbitol-type epoxy resin, A thermosetting epoxy resin composition capable of forming a cured product having a glass transition temperature of 90°C or higher.

2. A thermosetting epoxy resin composition comprising a base agent and a curing agent, The biomass ratio is 50% or more, The base resin contains a sorbitol-type epoxy resin (excluding sorbitol-type epoxy resins having an average number of hydroxyl groups per molecule of 1.0 to 2.5), A thermosetting epoxy resin composition capable of forming a cured product having a glass transition temperature of 90°C or higher.

3. 3. The thermosetting epoxy resin composition according to claim 2, wherein the biomass degree is 70% or more and 100% or less.

4. 3. The thermosetting epoxy resin composition according to claim 1, wherein the biomass degree is 90% or more and 100% or less.

5. 3. The thermosetting epoxy resin composition according to claim 1, wherein the sorbitol-type epoxy resin has an epoxy equivalent of 162 g / eq or more and 200 g / eq or less.

6. 3. The thermosetting epoxy resin composition according to claim 1, wherein the sorbitol-type epoxy resin has an epoxy equivalent of 162 g / eq or more and 182 g / eq or less.

7. 3. The heat-curable epoxy resin composition according to claim 1, wherein the curing agent comprises at least one of an amine compound and an acid anhydride compound.

8. 3. The thermosetting epoxy resin composition according to claim 1, wherein the amine compound forms a complex with a Lewis acid.

9. 8. The heat-curable epoxy resin composition according to claim 7, wherein the activation temperature of the complex is 90° C. or higher.

10. the complex is a complex of a tertiary amine containing at least one alkyl group having 6 or more carbon atoms and a Lewis acid, 8. The thermosetting epoxy resin composition according to claim 7, wherein the Lewis acid is at least one compound selected from the group consisting of boron and aluminum.

11. 3. The thermosetting epoxy resin composition according to claim 1, wherein the amine compound is a primary polyamine compound having two or more primary amino groups and no ether bond.

12. The thermosetting epoxy resin composition according to claim 10, wherein the primary polyamine compound is at least one selected from the group consisting of an aromatic diamine compound and an alicyclic diamine compound.

13. 11. The thermosetting epoxy resin composition according to claim 10, wherein the primary polyamine compound is an aliphatic diamine compound having a branched structure and a main chain having 6 or more carbon atoms.

14. 3. The thermosetting epoxy resin composition according to claim 1 or 2, which is used for a fiber-reinforced composite material.

15. A fiber and a thermosetting epoxy resin composition impregnated in the fiber, The thermosetting epoxy resin composition includes a base agent and a curing agent, The biomass ratio of the thermosetting epoxy resin composition is 70% or more, The base resin contains a sorbitol-type epoxy resin, The thermosetting epoxy resin composition is capable of forming a cured product having a glass transition temperature of 90° C. or higher.

16. A fiber and a thermosetting epoxy resin composition impregnated in the fiber, The thermosetting epoxy resin composition includes a base agent and a curing agent, The biomass ratio of the thermosetting epoxy resin composition is 50% or more, The base resin contains a sorbitol-type epoxy resin (excluding sorbitol-type epoxy resins having an average number of hydroxyl groups per molecule of 1.0 to 2.5), The thermosetting epoxy resin composition is capable of forming a cured product having a glass transition temperature of 90° C. or higher.