Curable resin composition and molded article using the same

Abstract

To provide a curable resin composition capable of obtaining a molded product having both high elastic modulus and toughness without largely increasing the viscosity of the resin composition.SOLUTION: A curable resin composition comprising a urethane-modified epoxy resin (A), a non-urethane-modified epoxy resin (B), and a curing agent (C) as essential components, wherein the urethane-modified epoxy resin (A) has a structure derived from a polyester polyol and a structure derived from a polyisocyanate, a ratio of the structure derived from the polyester polyol is 20 to 50 parts by weight in 100 parts by weight of the urethane-modified epoxy resin (A), and a weight ratio of a urethane bond is 5 to 12 parts by weight in 100 parts by weight of the urethane-modified epoxy resin (A).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a curable resin composition and a molded article using the same. [Background technology]

[0002] Epoxy resins and compositions have excellent heat resistance, electrical insulation, and adhesion to substrates, and are used in a wide range of applications, including electronic materials, paints, composite materials, adhesives, etc. To achieve higher performance in materials, epoxy resins are required to have further improved properties, such as low viscosity, low dielectric constant, high elasticity, high strength, and high toughness.

[0003] Attempts have been made to increase the elasticity and strength of molded articles obtained by curing epoxy resin compositions by incorporating rigid chemical structures into the molecules, by using epoxy resins with low epoxy equivalents, or by increasing the crosslink density by using polyfunctional epoxy resins (Patent Documents 1 and 2). However, these methods often result in high viscosity resin compositions and brittle molded articles after curing, and there is a need for a method of increasing elasticity without reducing toughness and other properties.

[0004] Attempts have been made to improve the toughness of molded articles obtained by curing epoxy resin compositions by adding rubber components, rubber particles, or inorganic compound fillers, or by modifying epoxy resins with polyols or polycarboxylic acids to control the chemical structure and thereby achieve the desired properties (Patent Documents 3 and 4). These methods often result in an increase in the viscosity of the resin composition and a decrease in the elasticity and heat resistance of the molded articles, and therefore a method for improving toughness without reducing the elastic modulus, etc., has been sought.

[0005] Efforts have been made to impart toughness to molded articles by synthesizing urethane-modified epoxy resins from polyols, polyisocyanates, and epoxy resins as raw materials and adding them to resin compositions (Patent Documents 5 and 6). Urethane-modified epoxy resins contain urethane bonds within their structure, and the urethane bonds aggregate together through hydrogen bonding to form hard segments. At the same time, soft segments can be formed by incorporating compounds exhibiting rubber elasticity, such as polyols, into the structure. Furthermore, a crosslinked structure is formed by reacting the urethane-modified epoxy resin with a curing agent, resulting in a cured product containing both hard and soft segments. To achieve both a high modulus of elasticity and toughness in the cured product, it is necessary to pay attention to the ratio of hard and soft segments, i.e., the type and composition of the epoxy resin, polyisocyanate, polyol, and other raw materials used in the urethane-modified epoxy resin, as well as the properties of the curing agent used. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-116349 [Patent Document 2] Japanese Patent Publication No. 2022-164726 [Patent Document 3] Japanese Patent Application Laid-Open No. 2005-255822 [Patent Document 4] Japanese Patent Application Laid-Open No. 2012-219223 [Patent Document 5] Patent No. 6593573 [Patent Document 6] Japanese Patent Publication No. 2022-57431 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a curable resin composition that can give a molded product having both a high elastic modulus and toughness without significantly increasing the viscosity of the resin composition.

[0008] As a result of investigations to solve the above-mentioned problems, the present inventors have focused on the properties of the polyol used in a curable resin composition containing a urethane-modified epoxy resin and the weight ratio of urethane bonds based on the modification ratio of the polyisocyanate, and have found that the resin composition when cured gives a molded product having a high elastic modulus and toughness, thereby solving the above-mentioned problems, and have completed the present invention. [Means for solving the problem]

[0009] That is, the present invention has the following aspects. [1] A curable resin composition comprising, as essential components, a urethane-modified epoxy resin (A), a non-urethane-modified epoxy resin (B), and a curing agent (C), wherein the urethane-modified epoxy resin (A) has a structure derived from a polyester polyol and a structure derived from a polyisocyanate, and wherein, in 100 parts by weight of the urethane-modified epoxy resin (A), the proportion of the structure derived from the polyester polyol is 20 to 50 parts by weight, and, in 100 parts by weight of the urethane-modified epoxy resin (A), the weight proportion of urethane bonds is 5 to 12 parts by weight. [2] The curable resin composition according to [1], characterized in that, of 100 parts by weight of the structure derived from the polyester polyol in the urethane-modified epoxy resin (A), 30 parts by weight or more have a structure derived from a compound of the following formula (1): [ka] Here, R is a divalent hydrocarbon residue having 6 to 14 carbon atoms, which may have a branched structure or an alicyclic structure. [3] The curable resin composition according to [1], wherein the urethane-modified epoxy resin (A) of the present invention has a structure derived from a polyol (a) other than a polyester polyol, the proportion of the structure derived from the component (a) is 1 to 5 parts by weight per 100 parts by weight of the urethane-modified epoxy resin (A), and the hydroxyl group equivalent of the component (a) is 30 to 100 g / eq. [4] The curable resin composition according to [1], wherein the urethane-modified epoxy resin (A) has an epoxy equivalent of 250 to 400 g / eq and a viscosity at 100°C of 50 Pa·s or less. [5] The curable resin composition according to [1], wherein the curing agent (C) is at least one selected from the group consisting of phenolic curing agents, aromatic amines, dicyandiamide, and derivatives of dicyandiamide. [6] A molded product obtained by curing the curable resin composition has a tensile modulus of elasticity at 23°C of 3.1 GPa or more and a fracture toughness of 1.0 MPa m 0.5 The curable resin composition according to [1], characterized in that:

[0010] [7] A molded product obtained by curing the curable resin composition according to any one of [1] to [6], Tensile modulus at 23°C of 3.1 GPa or more and fracture toughness of 1.0 MPa m 0.5 A molded article characterized by the above. [Effects of the Invention]

[0011] According to the curable resin composition of the present invention, by optimizing the properties and reaction ratios of the constituent components of the urethane-modified epoxy resin (A) used, a molded article having both a high elastic modulus and high toughness can be obtained when the epoxy resin composition is cured. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail. The present invention provides a curable resin composition comprising, as essential components, a urethane-modified epoxy resin (A), a non-urethane-modified epoxy resin (B), and a curing agent (C), wherein the urethane-modified epoxy resin (A) has a structure derived from a polyester polyol and a structure derived from a polyisocyanate, wherein, per 100 parts by weight of the urethane-modified epoxy resin (A), the proportion of the structure derived from the polyester polyol is 20 to 50 parts by weight, and per 100 parts by weight of the urethane-modified epoxy resin (A), the proportion of the structure derived from a urethane bond is 5 to 12 parts by weight.

[0013] The curable resin composition of the present invention contains, as essential components, a urethane-modified epoxy resin (A), a non-urethane-modified epoxy resin (B), and a curing agent (C). Hereinafter, the urethane-modified epoxy resin (A), the non-urethane-modified epoxy resin (B), and the curing agent (C) will also be referred to as component (A), component (B), and component (C), respectively.

[0014] The urethane-modified epoxy resin (A) used in the present invention preferably has a weight-average molecular weight Mw measured by gel permeation chromatography (GPC) of 5,000 to 100,000, more preferably 10,000 to 50,000. If Mw is less than 5,000, the resin composition will have high elasticity when cured, but toughness will tend not to be improved, and if Mw exceeds 100,000, the viscosity of component (A) will tend to be significantly high.

[0015] In addition, the proportion of the structure derived from polyester polyol (polyester polyol ratio) in 100 parts by weight of the urethane-modified epoxy resin (A) used in the present invention is 20 to 50 parts by weight, preferably 24 to 45 parts by weight, and more preferably 26 to 42 parts by weight. By keeping the polyester polyol ratio within this range, the phase derived from the polyester polyol structure is properly dispersed when the resin composition is cured, enabling both high elastic modulus and toughness to be achieved. Here, the "structure derived from polyester polyol" refers to the remaining structure obtained by removing at least one hydroxyl group (which may include a portion of the hydroxyl group) from the molecular terminal of the polyester polyol, which is a constituent of component (A).

[0016] The polyester polyol used in the urethane-modified epoxy resin (A) of the present invention can be obtained by polymerizing a polybasic acid compound and a polyol as reaction raw materials through a transesterification reaction or a polycondensation reaction. Specific examples of the polybasic acid compound used as a reaction raw material include polycarboxylic acid compounds such as adipic acid, sebacic acid, oxalic acid, malonic acid, succinic acid, maleic acid, fumaric acid, phthalic acid, tetrahydrophthalic acid, isophthalic acid, terephthalic acid, hexahydrophthalic acid, methyltetrahydrophthalic acid, glutaric acid, pimelic acid, suberic acid, and azelaic acid, as well as alkyl ester derivatives thereof. These polycarboxylic acid compounds can be used alone or in combination of two or more. Specific examples of polyols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,12-dodecanediol, diethylene glycol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-ethyl-1,3-hexanediol, 2,4-diethyl-1,5-pentanediol, 1,4-cyclohexanedimethanol, 1,4-benzenedimethanol, polyethylene glycol, polypropylene glycol, polytrimethylene glycol, polytetramethylene glycol, etc. These polyols may be used alone or in combination of two or more. The polyester polyol used in the present invention preferably has an average hydroxyl functionality of 1.6 to 2.4 and a hydroxyl equivalent of 250 to 2500 g / eq, more preferably 400 to 2000 g / eq, and even more preferably 600 to 1600 g / eq. When the average functionality and hydroxyl equivalent are within these ranges, a cured product with a high elastic modulus can be obtained without increasing the viscosity of the resin composition, which is desirable.

[0017] The polyester polyol used in the urethane-modified epoxy resin (A) of the present invention preferably has a structure derived from the following formula (1) in 100 parts by weight of the polyester polyol, because this facilitates the formation of soft segments due to hydrocarbon groups and improves toughness. That is, of 100 parts by weight of the polyester polyol-derived structures in the urethane-modified epoxy resin (A), 30 parts by weight or more preferably have a structure derived from the compound of formula (1). That is, of the 100 parts by weight total of the polybasic acid compound and polyol used to form the polyester polyol-derived structure, preferably 30 parts by weight or more preferably have a structure derived from the compound represented by formula (1). It is more preferably 37 parts by weight or more, and even more preferably 44 parts by weight or more. On the other hand, the upper limit of the content of the structure derived from the compound represented by formula (1) is not limited and can be adjusted appropriately depending on the amount of other polybasic acid compounds or polyols that may be used. However, it is preferably 50 parts by weight or less of the 100 parts by weight total of the polybasic acid compound and polyol. Among the compounds represented by formula (1), azelaic acid and sebacic acid, which have a linear hydrocarbon group as R, are more preferred. [ka] Here, R is a divalent hydrocarbon residue having 6 to 14 carbon atoms, which may have a branched structure or an alicyclic structure.

[0018] The polyisocyanate used in the present invention may be a known polyisocyanate compound used in the production of polyurethane resins. Specific examples of polyisocyanates include toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, a mixture thereof (TDI), 4-methoxy-1,3-phenylene diisocyanate, 4-isopropyl-1,3-phenylene diisocyanate, 4-butoxy-1,3-phenylene diisocyanate, 2,4-diisocyanate diphenyl ether, 4,4'-methylenebis(phenylene isocyanate) (MDI), crude or polymeric MDI, xylylene diisocyanate (XDI), and 1,5-naphthalene diisocyanate. Examples of the polyisocyanate include aromatic diisocyanates such as those listed above, aliphatic diisocyanates such as methylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, and 1,10-decamethylene diisocyanate, and alicyclic diisocyanates such as 1,4-cyclohexylene diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,5-tetrahydronaphthalene diisocyanate, isophorone diisocyanate (IPDI), and hydrogenated XDI, and one or more polyisocyanate compounds selected from these. One polyisocyanate may be used alone, or two or more may be used in combination.

[0019] Furthermore, the weight ratio of urethane bonds (urethane bond ratio) in 100 parts by weight of the urethane-modified epoxy resin (A) used in the present invention is 5 to 12 parts by weight, preferably 5.2 to 10 parts by weight. If it is less than 4 parts by weight, aggregation due to hydrogen bonds caused by the urethane bonds, so-called hard segments, will not be formed, and the elastic modulus will tend not to be increased. If it exceeds 10 parts by weight, aggregation due to hydrogen bonds caused by the urethane bonds will tend to increase the viscosity of the resin composition, which may impair handleability during the curing reaction and result in a non-uniform cured product upon curing.

[0020] Here, the ratio of urethane bonds in the urethane-modified epoxy resin (A) used in the curable resin composition (urethane bond ratio) is calculated by the following formula using the molecular weight (59) of the urethane bond (—NH—C(═O)—O—). Urethane bond ratio = 100 x (weight of polyisocyanate used in synthesizing urethane-modified epoxy resin x (59 / isocyanate equivalent of polyisocyanate used in synthesizing urethane-modified epoxy resin)) / total weight of raw materials used in synthesizing urethane-modified epoxy resin

[0021] The polyisocyanate used in the present invention may be a known polyisocyanate compound used in the production of polyurethane resins. Specific examples of polyisocyanates include toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, a mixture thereof (TDI), 4-methoxy-1,3-phenylene diisocyanate, 4-isopropyl-1,3-phenylene diisocyanate, 4-butoxy-1,3-phenylene diisocyanate, 2,4-diisocyanate diphenyl ether, 4,4'-methylenebis(phenylene isocyanate) (MDI), crude or polymeric MDI, xylylene diisocyanate (XDI), and 1,5-naphthalene diisocyanate. Examples of the polyisocyanate include aromatic diisocyanates such as those listed above, aliphatic diisocyanates such as methylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, and 1,10-decamethylene diisocyanate, and alicyclic diisocyanates such as 1,4-cyclohexylene diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,5-tetrahydronaphthalene diisocyanate, isophorone diisocyanate (IPDI), and hydrogenated XDI, and one or more polyisocyanate compounds selected from these. One polyisocyanate may be used alone, or two or more may be used in combination.

[0022] It is more desirable to use a polyol (a) other than the polyester polyols described above as a constituent of the urethane-modified epoxy resin (A). The proportion of the polyol (a) other than polyester polyols is preferably 1 to 5 parts by weight, more preferably 1.2 to 4 parts by weight, and even more preferably 1.4 to 3.5 parts by weight, of the structure derived from the component (a) (the component (a) proportion), per 100 parts by weight of the component (A). The hydroxyl equivalent of the component (a) is preferably 30 to 100 g / eq, more preferably 40 to 80 g / eq. Furthermore, the weight ratio of the component (a) to the polyester polyol is preferably 2:98 to 12:88. By ensuring the proportion of the component (a) and the hydroxyl equivalent of the component (a) within the above ranges and taking into consideration the weight ratio to the polyester polyol, urethane bonds are incorporated into the resulting urethane-modified epoxy resin molecules at high density, forming hard segments in the cured product where the urethane bonds aggregate together through hydrogen bonding, which is desirable, thereby enhancing the toughness and elastic modulus of the cured product. Here, the structure derived from component (a) refers to the remaining structure obtained by removing at least one hydroxyl group (which may include part of a hydroxyl group) at the molecular terminal of component (a), which is a constituent of component (A).

[0023] Examples of polyol (a) other than polyester polyols include polyols having a hydroxyl group equivalent of 30 to 100 g / eq, such as ethylene glycol, propanediol, butanediol, pentanediol, methylpentanediol, hexanediol, nonanediol, decanediol, cyclohexanediol, resorcinol, catechol, hydroquinone, naphthalenediol, trimethylolpropane, glycerin, and pentaerythritol. Polyol (a) may be used alone or as a mixture of two or more kinds.

[0024] The epoxy equivalent of the urethane-modified epoxy resin (A) used in the present invention is preferably 250 to 400 g / eq, more preferably 300 to 350 g / eq. Within this range, a cured product with high toughness can be obtained, and the elastic modulus of the cured product can also be increased. If the epoxy equivalent is less than 250 g / eq, the crosslink density increases during curing, resulting in a decrease in toughness. If it exceeds 400 g / eq, toughness can be increased, but the elastic modulus of the cured product tends to decrease.

[0025] It is preferable that the viscosity of the urethane-modified epoxy resin (A) at 100°C is 50 Pa or less, because when components (A), (B), and (C) are mixed together, a homogeneous resin composition is formed, and when cured, a molded product with a high elastic modulus is obtained in which hard segments resulting from urethane bonds are formed.

[0026] The urethane-modified epoxy resin (A) is obtained by thermally reacting at least an epoxy resin having a hydroxyl group in the molecule, a polyester polyol having a hydroxyl group in the molecule, and a polyisocyanate. Known conditions for the thermal reaction can be appropriately adopted. The urethane-modified epoxy resin may contain unmodified epoxy resin that is not bonded to polyurethane.

[0027] The urethane-modified epoxy resin (A) is obtained by thermally reacting the above-described components. While the specific molecular structure is not limited, depending on the production procedure, conditions, components used, and their proportions, it typically has the following molecular structure: That is, the hydroxyl group of an epoxy resin having a hydroxyl group in the molecule reacts with a polyol component such as the polyester polyol and a polyisocyanate component to form a urethane bond. The structure (e.g., chain length) and terminal structure (e.g., functional groups) of the resulting polyurethane may vary depending on the proportions of the components used and the reaction conditions during polyurethane formation. When an epoxy resin reacts with the resulting polyurethane, the resulting polyurethane may have different chain lengths, or may have a mixture of polyurethanes with or without an epoxy resin (epoxy resin-derived structure) attached to the terminal. Furthermore, if an epoxy resin without a hydroxyl group is included, the resulting mixture will contain an unmodified epoxy resin that is not bonded to a polyurethane, as described above. Here, the structure derived from the epoxy resin refers to the remaining structure of the epoxy resin after removing at least one hydroxyl group (which may include a portion of the hydroxyl group). Thus, the urethane-modified epoxy resin (A) of the present invention has a complex structure formed by the reaction of any or all of the constituent components, and is obtained as a mixture of these components. Furthermore, it is understood to be in the form of a mixture containing the above-mentioned epoxy resin without hydroxyl groups (unmodified epoxy resin) in a state that is difficult to completely distinguish or exclude, although it is not thought to be directly involved in the reaction or the expression of function. In light of these facts, there are some circumstances that make it impossible or impractical to directly identify the component (A) by its structure or properties (so-called impossible or impractical circumstances).

[0028] The epoxy resin having a hydroxyl group in the molecule (hereinafter also referred to as the raw epoxy resin) that is the raw material for the urethane-modified epoxy resin (A) is not limited and known materials can be used, but bisphenol-type epoxy resins having a hydroxyl group in the molecule are preferred. The use of such resins increases the toughness of the cured product without reducing the heat resistance. The hydroxyl equivalent of the raw epoxy resin is preferably 500 to 10,000 g / eq, more preferably 1,000 to 5,000 g / eq. If the hydroxyl equivalent is less than 500 g / eq, the viscosity of the urethane-modified epoxy resin (A) tends to increase, while if it is more than 10,000 g / eq, the toughness of the cured product tends to decrease. The epoxy equivalent of the raw epoxy resin is preferably 100 to 300 g / eq, more preferably 160 to 260 g / eq.

[0029] The polyol (a) other than polyester polyol and polyisocyanate (hereinafter also referred to as raw material polyol (a) and raw material polyisocyanate, respectively), which are raw materials for the urethane-modified epoxy resin (A), can be those listed above, and various known materials can be used without any particular limitation as long as the desired urethane-modified epoxy resin (A) can be obtained.

[0030] The amount of urethane-modified epoxy resin (A) used in the curable resin composition of the present invention is preferably 15 to 50 parts by weight, and more preferably 20 to 46 parts by weight, per 100 parts by weight of the total amount of components (A), (B), and (C). If the amount is less than 15 parts by weight, the elastic modulus of the cured product when the resin composition is cured tends to decrease, while if the amount is more than 50 parts by weight, the viscosity of the resin composition becomes too high, raising the concern that the cured product may be non-uniform.

[0031] The non-urethane-modified epoxy resin (B) used in the present invention may be an epoxy compound having two or more epoxy groups in one molecule and not urethane-modified. For example, bisphenol-type epoxy resins such as bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, bisphenol E-type epoxy resin, bisphenol S-type epoxy resin, bisphenol Z-type epoxy resin, and isophorone bisphenol-type epoxy resin; halogenated or alkyl-substituted bisphenols, hydrogenated products, high molecular weight compounds having multiple repeating units (not limited to monomers), glycidyl ethers of alkylene oxide adducts; novolac-type epoxy resins such as phenol novolac-type epoxy resin, cresol novolac-type epoxy resin, and bisphenol A novolac-type epoxy resin; 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate; ... Alicyclic epoxy resins such as epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate and 1-epoxyethyl-3,4-epoxycyclohexane; aliphatic epoxy resins such as trimethylolpropane polyglycidyl ether, pentaerythritol polyglycidyl ether, and polyoxyalkylene diglycidyl ether; glycidyl esters such as phthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, and dimer acid glycidyl ester; and glycidyl amines such as tetraglycidyldiaminodiphenylmethane, tetraglycidyldiaminodiphenyl sulfone, triglycidylaminophenol, triglycidylaminocresol, and tetraglycidylxylylenediamine. Among these epoxy resins, bisphenol A epoxy resins and bisphenol F epoxy resins are preferred because they are economical, have low viscosity as a resin composition, are easy to handle, and are unlikely to cause a decrease in heat resistance during curing. These resins may be used alone or in combination.

[0032] The amount of the non-urethane-modified epoxy resin (B) used in the curable resin composition of the present invention is preferably 30 to 80 parts by weight, more preferably 35 to 75 parts by weight, per 100 parts by weight of the total amount of the components (A), (B), and (C).

[0033] The curing agent (C) used in the present invention is a compound that reacts with the epoxy groups of components (A) and (B) upon heating to cause a curing reaction, and two or more curing agents may be used. Examples of component (C) include phenolic resins, amine compounds, guanidine compounds, urea compounds, acid anhydrides, cyanate compounds, and active ester compounds.

[0034] When a phenolic curing agent, aromatic amine, dicyandiamide and / or a derivative of dicyandiamide is used as the curing agent (C), hard segments resulting from urethane bonds are formed in the cured product without excessive aggregation, and therefore the elastic modulus and toughness can be increased, and this is preferably used.

[0035] The phenolic curing agent is not particularly limited as long as it is a compound having two or more phenolic hydroxyl groups in one molecule. Examples include phenols having two or more phenolic hydroxyl groups in one molecule, bisphenol-type phenolic resins (e.g., bisphenol A-type resin, bisphenol E-type resin, bisphenol F-type resin, bisphenol S-type resin, etc.), phenolic novolac resins (e.g., phenol novolac resin, naphthol novolac resin, cresol novolac resin, etc.), naphthalene-type phenolic resins, anthracene-type phenolic resins, dicyclopentadiene-type phenolic resins, biphenyl-type phenolic resins, alicyclic phenolic resins, polyol-type phenolic resins, aralkyl-type phenolic resins, and phenol-modified aromatic hydrocarbon formaldehyde resins. These phenolic compounds may be used alone or in combination of two or more.

[0036] The amount of phenolic curing agent used is preferably such that the phenolic hydroxyl group equivalent of the phenolic compound is 0.8 to 1.1 equivalents relative to the total epoxy group equivalent of the urethane-modified epoxy resin (A) and the non-urethane-modified epoxy resin (B). If the equivalent ratio is less than 0.8 equivalents, the elastic modulus tends to decrease, while if it exceeds 1.1 equivalents, the water absorption rate after curing increases, tending to impair the stability of the cured product.

[0037] In the curable resin composition of the present invention, an imidazole compound or a phosphorus compound curing accelerator may be used as a curing accelerator to accelerate the reactivity of the phenolic curing agent.

[0038] As examples of imidazole-based curing accelerators, from the viewpoint of ease of handling during blending, it is preferred to use one or more imidazole compounds selected from the group consisting of 2-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-6-4',5'-dihydroxymethylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole.

[0039] Examples of phosphorus-based curing accelerators that are selected from the viewpoint of ease of handling during compounding include tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetraphenylphosphonium bromide, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, triphenylphosphine, tributylphosphine, tri-tert-butylphosphine, trioctylphosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, dibutylphenylphosphine, di-tert-butyl ethylphenylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, butyldiphenylphosphine, diphenylcyclohexylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tris(4-ethylphenyl)phosphine, tris(4-propylphenyl)phosphine, tris(4-isopropylphenyl)phosphine, tris(4-butylphenyl)phosphine, tris(4-tert-butylphenyl)phosphine, tris(2,4-dimethylphenyl)phosphine tris(2,5-dimethylphenyl)phosphine, tris(2,6-dimethylphenyl)phosphine, tris(3,5-dimethylphenyl)phosphine, tris(2,4,6-trimethylphenyl)phosphine, tris(2,6-dimethyl-4-ethoxyphenyl)phosphine, tris(2-methoxyphenyl)phosphine, tris(4-methoxyphenyl)phosphine, tris(4-ethoxyphenyl)phosphine, tris(4-tert-butoxyphenyl)phosphine, diphenyl-2-pyridylphosphine, 1,It is preferable to use one or more phosphorus-based compounds selected from the group consisting of 2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, and 2,2'-bis(diphenylphosphino)diphenyl ether.

[0040] Examples of aromatic amine compounds include tetrachloro-p-xylylenediamine, m-xylylenediamine, p-xylylenediamine, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, 2,4-toluenediamine, benzyldimethylamine, 2-(dimethylaminomethyl)phenol, diethyltoluenediamine, methylbenzylamine, bis(methylthio)toluenediamine, and 4,4'-methylenebis(N-sec-butylaniline).

[0041] The amount of aromatic amine compound to be blended is preferably such that the active hydrogen group equivalent of the amine compound is 0.8 to 1.2 equivalents relative to the total epoxy group equivalent of the urethane-modified epoxy resin (A) and the non-urethane-modified epoxy resin (B). If the equivalent ratio is less than 0.8 equivalents, toughness tends to decrease, while if it exceeds 1.2 equivalents, water absorption after curing tends to increase and the stability of the cured product tends to be impaired.

[0042] Dicyandiamide or a derivative thereof is preferably used as the curing agent (C) in the curable resin composition of the present invention. Dicyandiamide is a solid curing agent at room temperature and is practically insoluble in epoxy resins at room temperature. However, when heated to 180°C or higher, it dissolves and reacts with epoxy groups. This latent curing agent has excellent storage stability at room temperature. Furthermore, N-substituted dicyandiamide derivatives such as N-hexyldicyandiamide, as described in JP-A-11-119429, can be used as its derivatives.

[0043] The amount of dicyandiamide or its derivative (C) blended is preferably 0.3 to 0.8 equivalents in terms of active hydrogen group equivalent per 1 equivalent of the total epoxy groups in the urethane-modified epoxy resin (A) and non-urethane-modified epoxy resin (B). If the equivalent ratio is less than 0.3 equivalents, poor curing and a decrease in elastic modulus and toughness are likely to occur, while if it exceeds 0.8 equivalents, the water absorption rate of the cured product increases, and the elastic modulus tends to decrease due to water absorption over time during storage.

[0044] The curable resin composition of the present invention may contain an aromatic urea compound, an imidazole compound or a phosphorus-based compound as a curing aid in order to adjust the reactivity of dicyandiamide or its derivatives.

[0045] The content of the aromatic urea compound as a curing aid in the curable resin composition of the present invention is preferably 5 to 100 parts by weight, more preferably 45 to 90 parts by weight, per 100 parts by weight of dicyandiamide or its derivative. When the aromatic urea compound is contained within this range, a molded product that is excellent in curing properties in a short time and has high heat resistance when heat-cured can be obtained.

[0046] Examples of aromatic urea compounds include 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, N-phenyl-N',N'-dimethylurea, N-(4-chlorophenyl)-N',N'-dimethylurea, N-(3,4-dichlorophenyl)-N',N'-dimethylurea, N-(3-chloro-4-methylphenyl)-N',N'-dimethylurea, and N-(3-chloro-4-ethylphenyl)-N',N' Examples of suitable methyl methyl ethers include 3-(3,4-dichlorophenyl)-1,1-dimethylurea, N-(3-chloro-4-methoxyphenyl)-N',N'-dimethylurea, N-(4-methyl-3-nitrophenyl)-N',N'-dimethylurea, 2,4-bis(N',N'-dimethylureido)toluene, and methylene-bis(p-N',N'-dimethylureidophenyl), and among these, 3-(3,4-dichlorophenyl)-1,1-dimethylurea and 3-(3,4-dichlorophenyl)-1,1-dimethylurea are preferred. These may be used alone or in combination of two or more, and are not limited to the above.

[0047] The content of the imidazole curing aid in the curable resin composition of the present invention is preferably 5 to 100 parts by weight, more preferably 40 to 80 parts by weight, per 100 parts by weight of dicyandiamide or its derivative. When the content of the imidazole curing aid is within this range, a molded product that is excellent in curing properties in a short time and has high heat resistance when cured by heating can be obtained.

[0048] As the imidazole curing aid, in order to more satisfactorily achieve rapid curing during heat curing and heat resistance during curing in the present invention, 2-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-6-4',5'-dihydroxymethylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1- It is preferable to use one or more imidazole compounds selected from the group consisting of cyanoethyl-2-ethyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, and the like.

[0049] The content of the phosphorus-based curing aid in the curable resin composition of the present invention is preferably 5 to 100 parts by weight, more preferably 40 to 80 parts by weight, per 100 parts by weight of dicyandiamide or its derivative. When the content of the phosphorus-based curing aid is within this range, a molded product that is excellent in curing properties in a short time and has high heat resistance when cured by heating can be obtained.

[0050] As the phosphorus-based curing aid, in order to more satisfies the fast curing property during heat curing and the heat resistance during curing in the present invention, tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetraphenylphosphonium bromide, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, triphenylphosphine, tributylphosphine, triphenylphosphonium thiocyanate, triphenylphosphine, triphenylphosphine, triphenylphosphonium tetraphenylborate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, triphenylphosphine, tributylphosphine, triphenylphosphonium tetraphenylborate, triphenylethyl ... -tert-butylphosphine, trioctylphosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, dibutylphenylphosphine, di-tert-butylphenylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, butyldiphenylphosphine, diphenylcyclohexylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tris(4-ethylphenyl)phosphine, tris(4-propylphenyl)phosphine, tris(4-isopropylphenyl)phosphine, tris(4-butylphenyl)phosphine, tris(4-tert-butylphenyl)phosphine, tris(2,4-dimethylphenyl)phosphine, tris(2,5-dimethylphenyl)phosphine, tris(2,6-dimethylphenyl)phosphine, tris(3,5-dimethylphenyl)phosphine, tris(2,4,6-trimethylphenyl)phosphine, tris(2,It is preferable to use one or more phosphorus compounds selected from the group consisting of 6-dimethyl-4-ethoxyphenyl)phosphine, tris(2-methoxyphenyl)phosphine, tris(4-methoxyphenyl)phosphine, tris(4-ethoxyphenyl)phosphine, tris(4-tert-butoxyphenyl)phosphine, diphenyl-2-pyridylphosphine, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, and 2,2'-bis(diphenylphosphino)diphenyl ether.

[0051] The curable resin composition of the present invention may further contain other curable resins, such as, but not limited to, unsaturated polyester resins, curable acrylic resins, curable amino resins, curable melamine resins, curable urea resins, curable cyanate ester resins, curable urethane resins, curable oxetane resins, and curable epoxy / oxetane composite resins.

[0052] The curable resin composition of the present invention is produced by uniformly mixing at least the above-mentioned components (A), (B), and (C).

[0053] The molded article of the present invention is obtained by subjecting the above-mentioned curable resin composition to a curing reaction. The method for obtaining the molded article may conform to a general method for curing a curable resin composition. For example, the heating temperature conditions may be appropriately selected depending on the type of curing agent to be combined, the intended use, and the like. For example, a method may be used in which the curable resin composition is heated at a temperature ranging from room temperature to approximately 250°C for 0.5 to 6.0 hours. A general method for curable resin compositions may also be used for molding.

[0054] The molded article obtained by curing the curable resin composition of the present invention has a tensile modulus of elasticity of 3.1 GPa or more at 23°C and a fracture toughness of 1.0 MPa m 0.5The above values ​​are preferable because, for example, when the curable resin composition of the present invention is used as an adhesive, it exhibits high adhesive shear strength. Measurement of the tensile modulus and fracture toughness value is not limited and can be performed by known methods. Specifically, the methods described in the examples can be used as reference or in accordance with them.

[0055] According to the curable resin composition of the present invention, by containing a polyester polyol structure as a constituent component of the urethane-modified epoxy resin (A) and by adjusting the weight ratio of the urethane bond, it is possible to obtain a molded article that exhibits an elastic modulus and toughness equivalent to or greater than those of conventional curable epoxy resin compositions. [Example]

[0056] Next, the present invention will be described in detail based on examples, but the present invention is not limited to the following examples as long as it does not deviate from the gist of the invention. The parts indicating the blending amount are parts by weight unless otherwise specified. The unit of equivalent is g / eq.

[0057] The abbreviations for the components used in the examples are as follows:

[0058] [Non-urethane modified epoxy resin (B)] YD-128: Bisphenol A epoxy resin (Nippon Steel Chemical & Material Co., Ltd., epoxy equivalent weight 187g / q) YDF-170: Bisphenol F epoxy resin (Nippon Steel Chemical & Material Co., Ltd., epoxy equivalent weight 168g / q) YDF-170B: Bisphenol F epoxy resin (Nippon Steel Chemical & Material Co., Ltd., epoxy equivalent weight 192 g / q)

[0059] [Polyester polyol] EsO1: Sebacic acid-based polyester polyol with an average functionality of 2 and a hydroxyl equivalent of 997 g / eq (Ito Oil Mills, SE-2013C) EsO2: Sebacic acid-based polyester polyol with an average functionality of 2 and a hydroxyl equivalent of 1496 g / eq (Kuraray Co., Ltd., P-2050) EsO3: Terephthalic acid-based polyester polyol with an average functionality of 2 and a hydroxyl equivalent of 1004 g / eq (Kuraray Co., Ltd., P-2020) EsO4: Adipic acid-based polyester polyol with an average functionality of 2 and a hydroxyl equivalent of 992 g / eq (Kuraray Co., Ltd., P-2010)

[0060] [Polyether polyol] P-2000: Polypropylene glycol with an average functionality of 2 and a hydroxyl equivalent of 1020 g / eq

[0061] [Polyol (a) other than polyester polyol] BD: 1,4-butanediol, hydroxyl equivalent 45g / eq

[0062] [Polyisocyanate] TDI: Toluene diisocyanate (isocyanate group equivalent weight 87g / eq) MDI: 4,4'-diphenylmethane diisocyanate (isocyanate group equivalent weight 125g / eq)

[0063] [Curing agent (C)] PN: Phenol novolac resin (phenolic hydroxyl group equivalent weight 104g / eq, softening point 81℃) TDA: Diethyltoluenediamine (active hydrogen equivalent 45g / eq) DICY: Dicyandiamide (active hydrogen equivalent 21g / eq)

[0064] [Curing accelerator] TPP: Phosphorus compound Triphenylphosphine DCMU: Aromatic urea 3-(3,4-dichlorophenyl)-1,1-dimethylurea

[0065] Synthesis Example 1 A separable glass flask equipped with a stirrer, thermometer, reflux condenser, nitrogen gas inlet, and feed port was charged with 200 parts of YD-128 and 87 parts of EsO1, and the mixture was heated to 110°C with stirring. Next, 31.1 parts of TDI were added through the feed port, and after 1 hour, 7.8 parts of BD were added. The reaction temperature was maintained at 130°C and the reaction was continued for another 2 hours, yielding 321 parts of a urethane-modified epoxy resin with a weight-average molecular weight (Mw) of 17,300, a polyester polyol ratio of 26% by weight, a urethane bond ratio of 6.5% by weight, and an epoxy equivalent of 306 g / eq. This urethane-modified epoxy resin (Component (A)) is designated EPU1. The polyester polyol ratio is the part by weight of the polyester polyol used out of 100 parts by weight of the urethane-modified epoxy resin (A), and the urethane bond ratio was calculated from the following formula. Urethane bond ratio = 100 x (weight of polyisocyanate used in synthesizing urethane-modified epoxy resin x (59 / isocyanate equivalent of polyisocyanate used in synthesizing urethane-modified epoxy resin)) / total weight of raw materials used in synthesizing urethane-modified epoxy resin

[0066] Synthesis Example 2 An apparatus similar to that used in Synthesis Example 1 was charged with 166 parts of YDF-170 and 111 parts of EsO1, and the mixture was heated to 110°C with stirring. Next, 24.1 parts of TDI were added through the feed port, and after 1 hour, 3.9 parts of BD were added. The reaction temperature was maintained at 130°C and the reaction was continued for another 2 hours, yielding 299 parts of a urethane-modified epoxy resin with a weight-average molecular weight (Mw) of 30,300, a polyester polyol ratio of 36% by weight, a urethane bond ratio of 5.4% by weight, and an epoxy equivalent of 310 g / eq. This urethane-modified epoxy resin (A) component is designated EPU2.

[0067] Synthesis Example 3 An apparatus similar to that used in Synthesis Example 1 was charged with 146 parts of YD-128 and 126 parts of EsO2, and the mixture was heated to 110°C with stirring. Next, 26.3 parts of TDI were added through the feed port, and after one hour, 6.5 parts of BD were added. The reaction temperature was maintained at 130°C and the reaction was continued for another two hours, yielding 299 parts of a urethane-modified epoxy resin with a weight-average molecular weight (Mw) of 34,400, a polyester polyol ratio of 42% by weight, a urethane bond ratio of 5.9% by weight, and an epoxy equivalent of 396 g / eq. This urethane-modified epoxy resin (A) is designated EPU3.

[0068] Synthesis Example 4 An apparatus similar to that used in Synthesis Example 1 was charged with 245 parts of YD-128 and 40.1 parts of EsO1, and the mixture was heated to 110°C with stirring. Next, 23.4 parts of TDI were added through the feed port, and after one hour, 4.9 parts of BD were added. The reaction temperature was maintained at 130°C and the reaction was continued for another two hours, yielding 306 parts of a urethane-modified epoxy resin with a weight-average molecular weight (Mw) of 6,400, a polyester polyol ratio of 13% by weight, a urethane bond ratio of 5.1% by weight, and an epoxy equivalent of 243 g / eq. This urethane-modified epoxy resin (Component (A')) is designated EPU4.

[0069] Synthesis Example 5 An apparatus similar to that used in Synthesis Example 1 was charged with 116 parts of YDF-170 and 171 parts of EsO2, and the mixture was heated to 110°C with stirring. Next, 19.9 parts of TDI were added through the feed port, and after one hour had passed, 2.6 parts of BD were added. The reaction temperature was maintained at 130°C and the reaction was continued for another two hours, yielding 300 parts of a urethane-modified epoxy resin with a weight-average molecular weight (Mw) of 48,100, a polyester polyol ratio of 56% by weight, a urethane bond ratio of 4.4% by weight, and an epoxy equivalent of 461 g / eq. This urethane-modified epoxy resin (A') component is designated EPU5.

[0070] Synthesis Example 6 An apparatus similar to that used in Synthesis Example 1 was charged with 578 parts of YDF-170B, 178 parts of EsO, and 89 parts of P-2000, and the mixture was heated to 110°C with stirring. Next, 135 parts of MDI were added through the charging port, and after 1 hour, 20 parts of BD were added. The reaction temperature was maintained at 130°C and the reaction was continued for another 2 hours, yielding 986 parts of a urethane-modified epoxy resin with a weight-average molecular weight (Mw) of 8,300, a polyester polyol ratio of 18% by weight, a urethane bond ratio of 6.4% by weight, and an epoxy equivalent of 335 g / eq. This urethane-modified epoxy resin (A') component is designated EPU6.

[0071] Synthesis Example 7 An apparatus similar to that used in Synthesis Example 1 was charged with 317 parts of YD-128 and 159 parts of EsO4, and the temperature was raised to 110°C with stirring. Next, 23 parts of TDI were added through the charging port, and after 1 hour, 2.6 parts of BD were added. The reaction temperature was maintained at 130°C and the reaction was continued for another 2 hours, yielding 490 parts of a urethane-modified epoxy resin with a weight-average molecular weight (Mw) of 7,900, a polyester polyol ratio of 32% by weight, a urethane bond ratio of 3.1% by weight, and an epoxy equivalent of 285 g / eq. This urethane-modified epoxy resin (A') component is designated EPU7.

[0072] (Measurement of weight average molecular weight Mw) The weight-average molecular weight Mw of the urethane-modified epoxy resin (A) or (A') was measured using a Tosoh Corporation gel permeation chromatograph HLC-8420GPC equipped with Tosoh Corporation TSKgel G4000HXL, TSKgel G3000HXL, and TSKgel G2000HXL columns in series. The column temperature was set to 40°C, and tetrahydrofuran was used as the eluent at a flow rate of 1 mL / min. Gel permeation chromatography was performed using an RI (differential refractometer) detector. The weight-average molecular weight Mw was calculated relative to polystyrene standards by excluding only the peak for the n=0 isomer of the epoxy resin used as the raw material and adding up all other peaks.

[0073] (Viscosity measurement at 100°C) The viscosity of the urethane-modified epoxy resin (A) or (A') at 100°C was measured using a cone-plate viscometer (CV-1S manufactured by Toa Kogyo Co., Ltd.).

[0074] Example 1 (Production of Curable Resin Composition) 44 parts of EPU1 obtained in Synthesis Example 1 as component (A), 56 parts of YD-128 as component (B), and 46 parts of PN as component (C) were placed in a Teflon container and stirred at 80°C for 1 hour, after which 0.4 parts of TPP was added and stirred for 10 minutes to obtain a curable resin composition. (Production of a flat molded product) The curable resin composition was poured into a 200 mm x 200 mm mold with a 4 mm thick spacer cut out in the shape of a flat plate. After the spacer was sandwiched between the molds, the composition was cured for 1.5 hours using a vacuum press KVHC-III (Kitagawa Seiki Co., Ltd.) at a vacuum of 5 kPa, a press pressure of 2.0 MPa, and a temperature of 175°C to form a flat molded plate, which was used to measure the tensile modulus and fracture toughness.

[0075] Examples 2 to 3, Comparative Examples 1 to 5 A curable resin composition was obtained in the same manner as in Example 1 except that the blending weights shown in Tables 1 and 2 below were used, and then a flat plate-shaped molded product was produced in the same manner as in Example 1 and used to measure the tensile modulus and fracture toughness.

[0076] Example 4 (Production of Curable Resin Composition) 32 parts of EPU1 obtained in Synthesis Example 1 as the component (A), 68 parts of YD-128 as the component (B), 5.0 parts of DICY as the component (C), and 3.2 parts of DCMU as a curing accelerator were placed in a 150 mL plastic container and mixed with stirring at room temperature for 5 minutes using a vacuum mixer "Awatori Rentaro" (manufactured by Thinky Corporation) to obtain a curable resin composition. (Production of a flat molded product) The curable resin composition was poured into a mold measuring 180 mm in length and 200 mm in width, which had a 4 mm thick spacer cut out in the shape of a flat plate, and cured in an oven at 140°C for 4 hours to prepare a molded plate for measurement, which was used to measure the tensile modulus and fracture toughness.

[0077] Examples 5 to 8, Comparative Examples 6 to 10 A curable resin composition was obtained in the same manner as in Example 4 except that the blending weights shown in Tables 1 and 2 below were used, and then a flat plate-shaped molded product was produced in the same manner as in Example 4 and used to measure the tensile modulus and fracture toughness.

[0078] Example 9 (Production of Curable Resin Composition) 39 parts of EPU1 obtained in Synthesis Example 1 as component (A), 61 parts of YDF-170 as component (B), and 22 parts of TDA as component (C) were placed in a 150 mL plastic container and mixed with stirring at room temperature for 5 minutes using a vacuum mixer "Awatori Rentaro" (manufactured by Thinky Corporation) to obtain a curable resin composition. (Production of a flat molded product) The curable resin composition was poured into a mold measuring 180 mm in length and 200 mm in width, which had a 4 mm thick spacer cut out in the shape of a flat plate, heated in an oven at 100°C for 2 hours, and then cured at 180°C for 4 hours to prepare a molded plate for measurement, which was used to measure the tensile modulus and fracture toughness.

[0079] Example 10, Comparative Examples 11 to 15 A curable resin composition was obtained in the same manner as in Example 9, except that the blending weights were as shown in Tables 1 and 3 below. Then, a flat plate-shaped molded product was produced in the same manner as in Example 9 and used to measure the tensile modulus and fracture toughness.

[0080] (Measurement of tensile modulus) The obtained molded plate was cut using a milling machine KitMill CL100 (Original Mind) to cut dumbbell-shaped test specimens with dimensions conforming to the test specimen type 1A specified in JIS K 7161 to prepare tensile test specimens. The tensile test specimens were subjected to a tensile test using a universal testing machine (Autograph AGS-H manufactured by Shimadzu Corporation) at a temperature of 23°C according to the method conforming to JIS K 7161, and the tensile modulus and tensile strength were calculated.

[0081] (Measurement of fracture toughness) The obtained molded plate was cut into a size of 50 mm x 10 mm using a milling machine KitMill CL100 (manufactured by Original Mind Co., Ltd.), and a crack was made in accordance with ASTM E399. The fracture toughness was measured using a universal material testing machine (Autograph AGS-H manufactured by Shimadzu Corporation) at a temperature of 23°C.

[0082] The test results for Examples 1 to 10 and Comparative Examples 1 to 15 are shown in Tables 1, 2, and 3, respectively.

[0083] [Table 1]

[0084] [Table 2]

[0085] [Table 3] [Industrial Applicability]

[0086] The molded article obtained by curing the curable resin composition of the present invention can be preferably used for applications requiring high elastic modulus and toughness. In addition, since the composition is preferably made from naturally derived raw materials, it is possible to reduce the burden on the environment.

Claims

1. A curable resin composition comprising, as essential components, a urethane-modified epoxy resin (A), a non-urethane-modified epoxy resin (B), and a curing agent (C), wherein the urethane-modified epoxy resin (A) has a structure derived from a polyester polyol and a structure derived from a polyisocyanate, and wherein, in 100 parts by weight of the urethane-modified epoxy resin (A), the proportion of the structure derived from the polyester polyol is 20 to 50 parts by weight, and the weight proportion of urethane bonds in 100 parts by weight of the urethane-modified epoxy resin (A) is 5 to 12 parts by weight.

2. 2. The curable resin composition according to claim 1, wherein, of 100 parts by weight of the structure derived from the polyester polyol in the urethane-modified epoxy resin (A), 30 parts by weight or more have a structure derived from a compound of the following formula (1): 【Chemistry 1】 Here, R is a divalent hydrocarbon residue having 6 to 14 carbon atoms, which may have a branched structure or an alicyclic structure.

3. The curable resin composition according to claim 1, characterized in that the urethane-modified epoxy resin (A) has a structure derived from a polyol (a) other than a polyester polyol, the proportion of the structure derived from component (a) is 1 to 5 parts by weight per 100 parts by weight of the urethane-modified epoxy resin (A), and the hydroxyl group equivalent of component (a) is 30 to 100 g / eq.

4. 2. The curable resin composition according to claim 1, wherein the urethane-modified epoxy resin (A) has an epoxy equivalent of 250 to 400 g / eq and a viscosity at 100°C of 50 Pa·s or less.

5. 2. The curable resin composition according to claim 1, wherein the curing agent (C) is at least one selected from the group consisting of phenolic curing agents, aromatic amines, dicyandiamide, and derivatives of dicyandiamide.

6. The molded product obtained by curing the curable resin composition has a tensile modulus of elasticity at 23°C of 3.1 GPa or more and a fracture toughness of 1.0 MPa m ０．５ 2. The curable resin composition according to claim 1, wherein the curable resin composition is a curable resin composition comprising:

7. A molded product obtained by curing the curable resin composition according to any one of claims 1 to 6, Tensile modulus at 23°C of 3.1 GPa or more and fracture toughness of 1.0 MPa m ０．５ A molded article characterized by the above.

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