Thermosetting epoxy resin compositions and fiber-reinforced composite materials

Abstract

The present invention provides a thermosetting epoxy resin composition and a fiber-reinforced composite material that have a high biomass content and excellent strength. [Solution] A thermosetting epoxy resin composition comprising a main component and a curing agent, wherein the biomass content is 50% or more, the main component comprises a sorbitol-type epoxy resin, and the composition is capable of forming a cured product having a glass transition temperature of 90°C or higher.

Description

Cross - reference to related applications

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

Technical Field

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

Background Art

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

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

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

Means for Solving the Problems

[0006] One aspect of the present disclosure relates to a thermosetting epoxy resin composition comprising a main agent and a curing agent, having a biomass content of 50% or more, wherein the main agent comprises a sorbitol - type epoxy resin and can form 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 in the fibers, wherein the thermosetting epoxy resin composition comprises a main component and a curing agent, the biomass content of the thermosetting epoxy resin composition is 50% or more, the main component comprises a sorbitol-type epoxy resin, and the thermosetting epoxy resin composition can form a cured product having a glass transition temperature of 90°C or higher. [Effects of the Invention]

[0008] The present invention provides a thermosetting epoxy resin composition and a fiber-reinforced composite material that have a high biomass content and excellent strength. Novel features of the present invention are described in the appended claims, but the present invention, both in terms of structure and content, and in conjunction with other objects and features of the present invention, will be better understood by the following detailed description in conjunction with the drawings. [Modes for carrying out the invention]

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

[0010] This disclosure relates to the following: [1] A thermosetting epoxy resin composition comprising a main component and a curing agent, The biomass content is 50% or more. The main component comprises 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.

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

[0012] [3] The thermosetting epoxy resin composition according to [1] or [2], wherein the biomass content 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 epoxy equivalent of the sorbitol-type epoxy resin is 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 epoxy equivalent of the sorbitol-type epoxy resin is 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 comprises at least one 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 complex is a complex of a tertiary amine containing at least one alkyl group having 6 or more carbon atoms and a Lewis acid, The thermosetting epoxy resin composition according to [7] or [8], wherein 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 an aromatic diamine compound and an alicyclic diamine compound.

[0021]

[12] The thermosetting epoxy resin composition according to

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

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

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

[0025] By using sorbitol-type epoxy resin as the main component of the resin, the overall biomass content of the resin composition (HB) can be significantly increased. The biomass content 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 limiting the content of components other than sorbitol-type epoxy resin to 10% by mass or less, and even 9% or 8%, the biomass content of the resin composition (HB) can easily reach 90% or more. The components other than 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 term "main component" may be replaced with "epoxy resin." The "main component" of the main component refers to the component that accounts for 60% or more by mass, preferably 70% or more by mass, or 90% or more by mass, of the main component (or epoxy resin). In other words, 60% or more by mass, preferably 70% or more by mass, or 90% or more by mass (100% is also acceptable) of the main component contained in one embodiment of the resin composition (HB) is a sorbitol-type epoxy resin.

[0027] The biomass content can be measured by radiocarbon dating of bio-based products, based on ASTM D6866-22 Method B.

[0028] Sorbitol-type epoxy resins are epoxy resins that have sorbitol, shown in the following structural formula (1), as their base structure.

[0029] Structural formula (1):

[0030] [ka]

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

[0032] Structural formula (2):

[0033] [ka]

[0034] As an example of a commercially available sorbitol-type epoxy resin, we can mention the EX-600 series of "Denacol®" manufactured by Nagase ChemteX Corporation. It is preferable that the sorbitol-type epoxy resin has an average of 3.8 to 4.2 epoxy groups (preferably an average of 4.0 epoxy groups) in its molecule. Such a sorbitol-type epoxy resin is preferable from the viewpoint of achieving a cured product with a high Tg and high elastic modulus.

[0035] From another perspective, the epoxy equivalent of the sorbitol-type epoxy resin may be, for example, between 162 g / eq and 200 g / eq. Within this epoxy equivalent range, a cured product with a high Tg and high elastic modulus can be achieved.

[0036] The epoxy equivalent of the sorbitol-type epoxy resin is preferably 162 g / eq to 182 g / eq. Sorbitol-type epoxy resins with an epoxy equivalent in this range can produce cured products that have a good balance between high Tg and high elastic modulus.

[0037] It should be noted that sorbitol-type epoxy resins with a high biomass content, unlike petroleum-derived epoxy resins with a low biomass content, generally have low heat resistance, and it is considered difficult to obtain cured products with high Tg. However, in reality, sorbitol-type epoxy resins are promising as alternative materials to petroleum-derived epoxy resins. In particular, sorbitol-type epoxy resins with approximately four epoxy groups introduced into the molecule can form cured products with an excellent balance of physical properties such as Tg, elastic modulus, and adhesion to fibers. Furthermore, by appropriately selecting the type of curing agent, it is possible to design the physical properties according to the desired application.

[0038] In this disclosure, the curing agent is selected such 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. Cured products of resin compositions (HB) with a Tg of 90°C or higher are suitable, for example, as materials for structures (building materials, housings, car bodies, etc.). Resin compositions (HB) with a cured product Tg of 90°C or higher are particularly suitable as materials for fiber-reinforced composite materials. The higher the Tg of the cured product of the resin composition (HB), the better; it may be 100°C or higher, 120°C or higher, or 150°C or higher.

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

[0040] The amine compound used as a curing agent may form a complex with a Lewis acid. The complex is less likely to precipitate in the liquid resin composition (HB) and is soluble. That is, until the complex reaches a predetermined activation temperature, a stable complex, in which the lone pair of electrons of the amine compound is coordinated to the empty orbital of the Lewis acid, is dissolved in the liquid resin composition (HB). When the complex in the resin composition (HB) reaches a predetermined activation temperature, the amine compound and Lewis acid dissociate, and the amine compound and Lewis acid exhibit catalytic activity that promotes the polymerization reaction of the epoxy resin. Complexes of amine compounds and Lewis acids having such properties are suitable for so-called one-component epoxy resin compositions (liquid mixture of main agent and curing agent).

[0041] The activation temperature of the complex (i.e., the temperature at which the amine compound and 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. In that case, the resin composition (HB) may be a one-component liquid resin composition.

[0042] The amine compound constituting the complex is preferably sterically hindered but rapidly contributes 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, tertiary amines containing at least one alkyl group having 6 or more carbon atoms are preferred from the viewpoint of suppressing reactivity at room temperature. 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 fewer alkyl groups having 3 or fewer carbon atoms.

[0043] Lewis acids are not particularly limited, but include compounds 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 possible substances 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 a curing agent, the amount of curing agent used may be small. The amount of complex used may be, for example, 3 to 20 parts by mass, 4 to 17 parts by mass, or 8 to 17 parts by mass per 100 parts by mass of the resin composition (HB). In that case, the biomass content of the resin composition (HB) may be, for example, 85% or more, and may reach 90% or 95% or more.

[0045] Specific examples of complexes include boron trichloride-dimethyloctylamine complex, boron trichloride-monomethylamine complex, and 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 linkage. Hereinafter, a primary polyamine compound having two or more primary amino groups and not having an ether linkage will also be referred to as a "non-ether primary polyamine." The molecular weight of the non-ether primary polyamine is, for example, 150 to 300, and may also be 150 to 270, considering the balance of 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 aromatic diamine compounds and alicyclic diamine compounds are suitable for obtaining cured products with high Tg.

[0048] Aromatic diamine compounds preferably have one or two aromatic rings, considering the balance of viscosity, biomass content, etc., of the resin composition (HB). The aromatic rings may be benzene rings or naphthalene rings. Aromatic diamine compounds preferably have two or more NH2 groups per aromatic ring or benzene ring, in terms of high Tg. It is preferable that the nitrogen atom of the NH2 group is directly bonded to the aromatic ring. Specifically, 4,4'-methylenebis(2-methylaniline) and diethylmethylbenzenediamine can be used as aromatic diamine compounds.

[0049] The alicyclic diamine compound may be a monocycloamine compound or a bicycloamine compound. In terms of high Tg, it is preferable for the alicyclic diamine compound to have two or more NH2 groups per aliphatic ring. The nitrogen atom of the NH2 group may be directly bonded to the aliphatic ring, or it may be bonded via an alkylene group such as a methylene group, for example, as a CH2-NH2 group. The alicyclic diamine compound is preferably tall and preferably has an alkyl group such as a methyl group directly bonded to the aliphatic ring. The number of alkyl groups may be between two and five. Specifically, examples of alicyclic diamine compounds include 2,2'-dimethyl-4,4'-methylenebis(cyclohexylamine) and isophoronediamine.

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

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

[0052] When a non-ether primary polyamine is used as a curing agent, the amount of curing agent used is such that, for example, the equivalent amount of hydrogen bonded to the nitrogen atom of the amine compound (hereinafter also referred to as "active hydrogen") per epoxy equivalent of sorbitol-type epoxy resin is 0.7 equivalents or more and 1.5 equivalents or less, but may also be 0.8 equivalents or more and 1.3 equivalents or 0.8 equivalents or more and 1.1 equivalents or less. From the viewpoint of increasing the biomass content of the resin composition (HB), it is preferable to set the equivalent amount of active hydrogen per epoxy equivalent to 1.1 or less.

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

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

[0055] However, it is desirable that the curing reaction does not proceed excessively rapidly. For example, the time until viscosity doubles at 25°C 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 content can be obtained. The fiber-reinforced composite material includes fibers and the resin composition (HB) impregnated into the fibers. To further increase the biomass content, the biomass content of the fibers themselves may be 50% or more, 90% or more, or even increased to 99% or 100%. As a result, the biomass content of the fiber-reinforced composite material can be, for example, 70% or more, 90% or more, or even 99% or more.

[0057] High biomass fibers are plant-derived fibers, such as hemp, basalt, palm, and bamboo. Other examples include polylactic acid fibers made from starch-derived lactic acid, polytrimethylene terephthalate (PTT) fibers made from starch-derived 1,3-propanediol, aliphatic polyester fibers such as castor oil-derived polyamide fibers, and cellulosic fibers such as regenerated cellulose fibers and cellulose acetate fibers. Plant fibers such as straw, rush, and palm may also be used. In addition to plant-derived fibers, carbon fibers and glass fibers may also be used.

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

[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] [Table A]

[0061] <Example A1> As the main component, a sorbitol-type epoxy resin (GEX-600 series manufactured by Nagase ChemteX Corporation), as shown in the structural formula (2) described above, 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 mixing 100 parts by mass of sorbitol-type epoxy resin (GEX-600 series), which is the main component, with 4.2 parts by mass of boron trichloride-dimethyloctylamine complex (curing agent), 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] (Geltime) The gel time of resin composition A1 was measured. Gel time is the time it takes for resin composition A1 to rapidly increase in viscosity and become gel-like 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 a 140°C oil bath. The rotor was rotated, and the time it took for the reaction of resin composition A1 to proceed and for a specified torque to be applied to the torque detection unit 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, A3, Comparative Examples A1, A2> Except for changing the amount of curing agent to the main component to the amount (parts by mass) shown in Table 1, resin compositions A2 and A3 of Examples A2 and resin compositions CA1 and CA2 of Comparative Examples A1 and A2 were prepared and evaluated in the same manner as in Example A1. The results are shown in Table 1.

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

[0069] [Table 1]

[0070] <Example B1> As the main component, a sorbitol-type epoxy resin (GEX-600 series manufactured by Nagase ChemteX Corporation), as shown in the structural formula (2) described above, was used.

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

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

[0073] When viscosity, gel time, and Tg were evaluated in the same manner as in Example A1, the viscosity at 25°C was 15500 mPa·s, the gel time at 140°C was 7.1 minutes, and the Tg was 155°C.

[0074] <Examples B2-B7> The amount of curing agent mixed with the main component was changed to the amount (parts by mass) shown in Table 2. Except for changing the type of curing agent in Examples B6 and B7, resin compositions B2 to B7 were prepared in the same manner as in Example B1 and evaluated in the same way. The results are shown in Table 2.

[0075] [Table 2]

[0076] <Examples C1-C5, Comparative Examples C1-C5> Resin compositions C1-C5 of Examples C1-C5 and resin compositions CC1-CC5 of Comparative Examples C1-C5 were prepared in the same manner as in Example 1B, except that the curing agent shown below was used in the amounts (parts by mass) shown in Table 3. The 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 at 25°C, and the time it took for the viscosity to double was determined. A stability of 10 minutes or more until the viscosity doubles is preferred, and 50 minutes or more is ideal.

[0078] (Adhesive strength) The adhesion strength was evaluated by tensile shear bond strength. The resin composition was applied to the adherend 1, and adherend 2 was bonded onto the applied resin composition. As the adherend, an aluminum plate measuring 1.5 mm thick × 25 mm wide × 150 mm long with a polished surface at the bonding area was used. The bond was then cured by heating at 140°C for 3 hours. The tensile shear bond strength was measured using a tensile testing machine (manufactured by Instron) at a tensile speed of 5 mm / min. When the resin composition is used, for example, in a fiber-reinforced composite material, considering the adhesion to the fibers, an adhesion strength of 2 MPa or higher is preferable, and 5 MPa or higher is ideal.

[0079] [Table 3] [Industrial applicability]

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

[0081] Although the present invention has been described in relation to preferred embodiments at present, such disclosure should not be interpreted restrictively. Various modifications and alterations will undoubtedly become apparent to those skilled in the art in the field to which the invention pertains by reading the above disclosure. Accordingly, the appended claims should be interpreted as encompassing all modifications and alterations without departing from the true spirit and scope of the invention.

Claims

1. A thermosetting epoxy resin composition comprising a main component and a curing agent, The biomass content is 50% or more. The main component comprises 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. The thermosetting epoxy resin composition according to claim 1, wherein the biomass content is 70% or more and 100% or less.

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

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

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

6. The thermosetting epoxy resin composition according to claim 1, wherein the curing agent comprises at least one amine compound and an acid anhydride compound.

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

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

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

10. 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 not having an ether bond.

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

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

13. A thermosetting epoxy resin composition according to any one of claims 1 to 12, for use in fiber-reinforced composite materials.

14. The material comprises fibers and a thermosetting epoxy resin composition impregnated into the fibers, The thermosetting epoxy resin composition comprises a main component and a curing agent, The biomass content of the aforementioned thermosetting epoxy resin composition is 50% or more. The main component comprises a sorbitol-type epoxy resin. The thermosetting epoxy resin composition is a fiber-reinforced composite material capable of forming a cured product having a glass transition temperature of 90°C or higher.

Images