Epoxy resin composition and cured product

Abstract

To provide an epoxy resin composition excellent in handleability, controllability of curing time, and the like in a well-balanced manner, and to provide a cured product thereof.SOLUTION: There are provided: an epoxy resin composition (A) which contains an epoxy resin represented by the following formula (1) and contains 50.0 wt.% or less of a low polymer derived from the epoxy resin represented by the formula (1); an epoxy resin composition (B) which contains 100 pts.mass of the epoxy resin composition (A) and a curing agent; and a cured product of the epoxy resin composition (B). (In the formula (1), R1-R4 each independently represent a hydrogen atom or a C1-4 alkyl group.)SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an epoxy resin composition having a good balance of ease of handling, controllability of curing time, etc., and a cured product thereof. [Background technology]

[0002] Epoxy resins are used in a wide range of fields, including as sealing materials for electrical and electronic components, molding materials, casting materials, laminating materials, composite materials, adhesives, and paints, because they produce cured products with excellent mechanical strength, heat resistance, moisture resistance, and electrical properties.

[0003] Epoxy resins used in composite materials such as carbon fiber reinforced plastic (CFRP) must have low viscosity for ease of handling and impregnation into carbon fibers, and must also have excellent curing reactivity for improved productivity, as well as excellent mechanical properties such as strength and elastic modulus of the cured product. Furthermore, with regard to epoxy resins used in electrical and electronic components, as products become thinner, there is a demand for epoxy resins that have low viscosity for ease of handling and excellent curing reactivity from the perspective of improving productivity.

[0004] Traditionally, bisphenol A diglycidyl ether has been the most commonly used liquid epoxy resin. However, with the recent advances in the formability and processability of carbon fiber reinforced plastics (CFRP) and electrical and electronic components, the epoxy resins used in these components are being required to have even better properties than before. Conventional bisphenol A diglycidyl ethers have been insufficient in terms of viscosity, reactivity, and the mechanical properties of the cured product.

[0005] On the other hand, in addition to bisphenol A diglycidyl ether, diglycidyl compounds having a sulfonamide skeleton are known, for example, in Patent Document 1, as liquid epoxy resins having excellent mechanical properties. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 62-84071 Summary of the Invention [Problem to be solved by the invention]

[0007] Although the diglycidyl compound having a sulfonamide skeleton prepared by the method described in Patent Document 1 (hereinafter, sometimes referred to as "epoxy resin having a sulfonamide skeleton") is liquid, its viscosity at around room temperature (25°C) is not sufficiently low, and its handleability is insufficient. Furthermore, studies by the present inventors have revealed that the epoxy resin having a sulfonamide skeleton prepared by the method described in Patent Document 1 contains a large amount of oligomer components derived from the epoxy resin having a sulfonamide skeleton, which has an adverse effect on the pot life (controllability of curing time).

[0008] The present invention aims to solve the above-mentioned problems of the prior art and to provide an epoxy resin composition that is excellent in terms of handleability, controllability of curing time, etc., in a well-balanced manner, an epoxy resin composition containing this epoxy resin composition and a curing agent, and a cured product thereof. [Means for solving the problem]

[0009] As a result of intensive investigations to solve the above problems, the present inventors have found that an epoxy resin composition containing an epoxy resin having a sulfonamide skeleton and a low polymer derived from the epoxy resin in a specific proportion has excellent handleability and a well-balanced excellent property such as controllability of curing time, and have completed the present invention. That is, the gist of the present invention is as follows [1] to [7].

[0010] [1] An epoxy resin composition (A) comprising an epoxy resin represented by the following formula (1), the epoxy resin composition containing 50.0% by weight or less of a low polymer derived from the epoxy resin represented by the formula (1):

[0011] [ka]

[0012] (In the above formula (1), R 1 ~R 4 each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

[0013] [2] The epoxy resin composition (A) according to [1], wherein the low polymer derived from the epoxy resin represented by the formula (1) is a low polymer represented by the following formula (2):

[0014] [ka]

[0015] (In the above formula (2), R 1 ~R 4 has the same meaning as in the formula (1), and n, m, and l each independently represent 0 to 3, provided that any one of n, m, and l is 1 or more. 1 ~A 3 each independently represents a group represented by the following formula (3) or (4), and in formula (3) and (4), R 1 ~R 4 has the same meaning as in the formula (1), and x and y represent bonding positions.

[0016] [ka]

[0017] [3] The epoxy resin composition (A) according to [1] or [2], having an E-type viscosity at 50°C of 100 Pa·s or less.

[0018] [4] An epoxy resin composition (B) comprising the epoxy resin composition (A) according to any one of [1] to [3] and a curing agent.

[0019] [5] An epoxy resin composition (B) containing 0.1 to 300 parts by weight of the curing agent based on 100 parts by weight of the epoxy resin composition (A).

[0020] [6] The epoxy resin composition (B) according to [4] or [5], wherein the curing agent is at least one selected from the group consisting of polyfunctional phenols, amine compounds, acid anhydride compounds, imidazole compounds, amide compounds, cationic polymerization initiators, and organic phosphines.

[0021] [7] A cured product obtained by curing the epoxy resin composition (B) according to any one of [4] to [6]. [Effects of the Invention]

[0022] According to the present invention, an epoxy resin composition can be provided which has low viscosity and high fluidity, resulting in excellent handleability, and an epoxy resin composition containing the epoxy resin composition and a curing agent has excellent pot life and excellent controllability of curing time. Furthermore, since the epoxy resin composition (A) and the epoxy resin composition (B) containing the curing agent and the cured product thereof also have excellent mechanical properties, they are expected to be suitable for use in fields such as paints, electrical and electronic materials, adhesives, and carbon fiber reinforced plastics (CFRP). DETAILED DESCRIPTION OF THE INVENTION

[0023] The following describes in detail an embodiment of the present invention, but the following description is merely an example of an embodiment of the present invention, and the present invention is not limited to the following description as long as it does not deviate from the gist of the present invention. Note that when the expression "to" is used in this specification, it is used as an expression that includes the numerical values ​​or physical property values ​​before and after it. The epoxy resin of the present embodiment may be either one having a repeating structure or one having a monomolecular structure, but in the art, both epoxy compounds are sometimes referred to and sold as "epoxy resins" or "epoxy resin compositions." In addition, in the art, a mixture further containing an epoxy resin different from the epoxy resin of the present embodiment is sometimes referred to as an "epoxy resin composition," but is also sometimes simply referred to as an "epoxy resin."

[0024] [Epoxy resin composition (A)] The epoxy resin composition (A) of the present invention is an epoxy resin composition containing an epoxy resin represented by the following formula (1) (hereinafter may be abbreviated as "epoxy resin (1)") and a low polymer derived from the epoxy resin (1) (hereinafter may be referred to as "low polymer of epoxy resin (1)"), and is characterized in that the epoxy resin composition contains 50.0 mass % or less of the low polymer.

[0025] [ka]

[0026] (In the above formula (1), R 1 ~R 4 each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

[0027] [Chemical structure] In the above formula (1) representing the epoxy resin (1), R 1 ~R 4 are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. 1 ~R 4 From the viewpoint of ease of handling, each of and is preferably a hydrogen atom, a methyl group, or an ethyl group, and more preferably a hydrogen atom.

[0028] [Low polymer of epoxy resin (1)] The low polymer of epoxy resin (1) is a polymer obtained by polymerization of the above-mentioned epoxy resin (1), and is a low polymer having 2 to 10 repeating units derived from the epoxy resin (1). The number of repeating units is preferably 2 to 8, and more preferably 2 to 5. Specific examples of the low polymer of epoxy resin (1) include polymers represented by the following formula (2).

[0029] [ka]

[0030] (In the above formula (2), R 1 ~R4 has the same meaning as in the formula (1), and n, m, and l each independently represent 0 to 3, provided that any one of n, m, and l is 1 or more. 1 ~A 3 each independently represents a group represented by the following formula (3) or (4), and in formula (3) and (4), R 1 ~R 4 has the same meaning as in the formula (1), and x and y represent bonding positions.

[0031] [ka]

[0032] [Content ratio of epoxy resin (1) and low polymer of epoxy resin (1)] In the epoxy resin composition (A) of the present invention, the epoxy resin (1) is preferably present in an amount of 50.0 to 99.9 mass% based on 100 mass% of the epoxy resin composition (A), and the oligomer of the epoxy resin (1) is preferably present in an amount of 0.1 to 50.0 mass%, particularly 0.1 to 40 mass%, based on 100 mass% of the epoxy resin composition (A).More preferably, the epoxy resin (1) is present in an amount of 60.0 to 99.9 mass% based on 100 mass% of the epoxy resin composition (A), and the oligomer of the epoxy resin (1) is present in an amount of 0.1 to 40.0 mass% based on 100 mass% of the epoxy resin composition (A).

[0033] Unlike the other components described below, the low polymer epoxy resin (1) contained in the epoxy resin composition (A) of the present invention has three or more epoxy groups, which allows it to undergo crosslinking reactions during curing. Therefore, it has little or no effect on the mechanical properties and heat resistance of the cured product. However, the inclusion of the low polymer epoxy resin (1) in the epoxy resin composition (A) of the present invention affects the viscosity increase caused by crosslink formation during curing. In other words, the lower the content of the low polymer epoxy resin (1), the longer the curing time and the lower the curing reactivity. Therefore, a content of 0.1% by mass or more is preferred. Furthermore, if the content of the low polymer epoxy resin (1) exceeds 50.0% by mass, the amount of polyfunctional components increases, resulting in an excessively fast curing rate and poor pot life. Therefore, the content of the low polymer epoxy resin (1) in 100% by mass of the epoxy resin composition (A) of the present invention is set to 50.0% by mass or less. When the epoxy resin composition (A) of the present invention does not contain other components described below, the total amount of the epoxy resin (1) and the low polymer of the epoxy resin (1) is 100% by mass of the epoxy resin composition (A). The contents of the epoxy resin (1), the oligomer of the epoxy resin (1), and other components described below in the epoxy resin composition (A) are measured by the method described in the Examples section below.

[0034] To produce the epoxy resin composition (A) of the present invention containing the epoxy resin (1) and the oligomer of the epoxy resin (1) in such a content ratio, the following operations may be carried out in the method for producing the epoxy resin composition (A) of the present invention described below. That is, for example, by increasing the amount of epihalohydrin used in the reaction or by setting the reaction temperature low within the range of 20°C or higher and 150°C or lower, the content of the epoxy resin (1) in the epoxy resin composition (A) can be increased and the content of the low polymer of the epoxy resin (1) can be decreased. On the other hand, by increasing the amount of alkali metal hydroxide used in the reaction or by setting the reaction temperature higher within the range of 20°C or more and 150°C or less, the content of the epoxy resin (1) in the epoxy resin composition (A) can be reduced and the content of the low polymer of the epoxy resin (1) can be increased.

[0035] [Other ingredients] The epoxy resin composition (A) of the present invention may further contain other components (hereinafter simply referred to as "other components") other than the epoxy resin (1) and the low polymer of the epoxy resin (1). The content of the other components in the epoxy resin composition (A) is preferably 15.0 mass% or less. When the epoxy resin composition (A) contains other components, the total of the epoxy resin (1), the low polymer of the epoxy resin (1), and the other components is 100 mass%.

[0036] The other components include components with only one epoxy group added that are by-produced during the production process of the epoxy resin composition (A) of the present invention, chlorine-containing organic components, components that are difficult to identify (components that cannot be analyzed), etc. The content of these components is more preferably 10.0 mass% or less. If the content of other components is high, there will be many components that cannot form a crosslinked structure during the curing reaction, which will cause the problem of significantly deteriorating the mechanical and thermal properties of the cured product.

[0037] [Epoxy equivalent] The epoxy resin composition (A) of the present invention preferably has an epoxy equivalent of 114 g / equivalent or more, while from the viewpoint of achieving a good viscosity range and good handleability, the epoxy equivalent is preferably 300 g / equivalent or less, and more preferably 200 g / equivalent or less. In the present invention, the term "epoxy equivalent" is defined as "the mass of an epoxy compound containing one equivalent of an epoxy group" and can be measured in accordance with JIS K7236.

[0038] [E type viscosity] From the viewpoint of handleability, the epoxy resin composition (A) of the present invention preferably has an E-type viscosity at 50°C of 100 Pa s or less, more preferably 30 Pa s or less. On the other hand, there is no particular restriction on the lower limit of the E-type viscosity at 50°C, but it is usually 0.5 Pa s or more.

[0039] [Method for producing epoxy resin composition (A)] The method for producing the epoxy resin composition (A) of the present invention is not particularly limited, but it can usually be obtained by reacting a hydroxybenzenesulfonamide compound represented by the following formula (5) with epihalohydrin. Furthermore, an epoxy resin composition according to another aspect of the present invention is obtained by reacting a hydroxybenzenesulfonamide compound represented by the following formula (5) with epihalohydrin, and has an epoxy equivalent of 114 to 300 g / equivalent.

[0040] [ka]

[0041] (In the formula (5), R 1 ~R 4 has the same meaning as in the above formula (1).

[0042] The hydroxybenzenesulfonamide compound represented by formula (5) used as a raw material is not particularly limited, but is typically dissolved in an amount of epihalohydrin corresponding to 0.8 to 30 equivalents, preferably 0.9 to 20 equivalents, and more preferably 1 to 10 equivalents per equivalent of the total active hydrogen of the hydroxyl and sulfonamide groups to form a solution. When the amount of epihalohydrin is equal to or greater than the lower limit, the reaction is easily controlled and an appropriate viscosity can be achieved, which is preferred. On the other hand, when the amount of epihalohydrin is equal to or less than the upper limit, production efficiency tends to be improved, which is preferred. The epihalohydrin used in this reaction is typically epichlorohydrin or epibromohydrin.

[0043] Next, while stirring this solution, an alkali metal hydroxide is added in the form of a solid or an aqueous solution in an amount corresponding to typically 0.5 to 3.0 equivalents, preferably 0.7 to 2.0 equivalents, and more preferably 0.9 to 1.5 equivalents per equivalent of the total active hydrogen of the hydroxy groups and sulfonamide groups of the starting hydroxybenzenesulfonamide compound, and the reaction is allowed to proceed. If the amount of alkali metal hydroxide is above the lower limit, the unreacted sulfonamide groups and the resulting epoxy compound are less likely to react, making the reaction easier to control. Furthermore, if the amount of alkali metal hydroxide is below the upper limit, the formation of impurities due to side reactions is less likely to occur. The alkali metal hydroxide used here is typically sodium hydroxide or potassium hydroxide.

[0044] This reaction can be carried out under normal pressure or under reduced pressure, and the reaction temperature is preferably 20 to 150°C, more preferably 20 to 100°C, and even more preferably 30 to 90°C. A reaction temperature equal to or higher than the lower limit is preferred because the reaction is easily promoted and easily controlled. On the other hand, a reaction temperature equal to or lower than the upper limit is preferred because side reactions are less likely to proceed, and chlorine impurities in particular are easily reduced.

[0045] In this reaction, the reaction solution is azeotropically distilled while maintaining a predetermined temperature as necessary, and the resulting condensate is separated into an oil phase and an aqueous phase by cooling the volatilized vapor. The water is then removed and the oil is returned to the reaction system for dehydration. The alkali metal hydroxide is added in small amounts, intermittently or continuously, over a period of preferably 0.1 to 8 hours, more preferably 0.1 to 7 hours, and even more preferably 0.5 to 6 hours, to prevent a rapid reaction. Addition times above the lower limit are preferred because they prevent the reaction from proceeding too quickly and make it easier to control the reaction temperature. Addition times below the upper limit are preferred because they reduce the generation of chlorine impurities and are also economically advantageous. The total reaction time is typically 1 to 15 hours. After completion of the reaction, the insoluble by-product salt is removed by filtration or washing with water, and the unreacted epihalohydrin is then removed by distillation under reduced pressure to obtain the desired epoxy resin composition (A).

[0046] In addition, this reaction may use a catalyst such as a quaternary ammonium salt such as tetramethylammonium chloride or tetraethylammonium bromide; a tertiary amine such as benzyldimethylamine or 2,4,6-tris(dimethylaminomethyl)phenol; an imidazole such as 2-ethyl-4-methylimidazole or 2-phenylimidazole; a phosphonium salt such as ethyltriphenylphosphonium iodide; or a phosphine such as triphenylphosphine.

[0047] Furthermore, in this reaction, an inert organic solvent such as alcohols such as ethanol and isopropanol; ketones such as acetone and methyl ethyl ketone; ethers such as dioxane and ethylene glycol dimethyl ether; glycol ethers such as methoxypropanol; aprotic polar solvents such as dimethyl sulfoxide and dimethylformamide, and water may also be used.

[0048] If the total chlorine content of the epoxy resin composition (A) obtained as described above needs to be reduced, it can be reprocessed to obtain a purified epoxy resin composition (A) with a sufficiently reduced total chlorine content. Specifically, the crude epoxy resin composition (A) is redissolved in an inert organic solvent such as isopropyl alcohol, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, dioxane, methoxypropanol, or dimethyl sulfoxide, and an alkali metal hydroxide (solid or aqueous solution) is added. The ring-closure reaction is carried out at a temperature of preferably 20 to 120°C, more preferably 30 to 110°C, and even more preferably 30 to 100°C for preferably 0.1 to 15 hours, more preferably 0.3 to 12 hours, and even more preferably 0.5 to 10 hours. The excess alkali metal hydroxide and secondary salts are then removed by water washing or other methods, and the organic solvent is then distilled off under reduced pressure and / or steam distilled to obtain an epoxy resin composition (A) with a reduced amount of hydrolyzable halogen. The organic solvent used to dissolve the crude epoxy resin composition (A) can be a single solvent or a mixture of two or more solvents. The reaction temperature is preferably equal to or higher than the above lower limit and the reaction time is preferably equal to or higher than the above lower limit, since the recyclization reaction proceeds easily. The reaction temperature is preferably equal to or lower than the above upper limit and the reaction time is preferably equal to or lower than the above upper limit, since the reaction is easily controlled.

[0049] [Epoxy resin composition (B)] The epoxy resin composition (B) of the present invention contains at least the above-mentioned epoxy resin composition (A) of the present invention and a curing agent. If necessary, other epoxy resins (epoxy compounds), curing accelerators, other components, etc. may be appropriately blended into the epoxy resin composition (B) of the present invention.

[0050] [Hardening agent] The curing agent used in the epoxy resin composition (B) of the present invention is a substance that contributes to the crosslinking reaction and / or chain extension reaction between epoxy groups of an epoxy compound. In the present invention, even substances that are usually called "curing accelerators" are considered to be curing agents as long as they contribute to the crosslinking reaction and / or chain extension reaction between epoxy groups of an epoxy compound.

[0051] The content of the curing agent in the epoxy resin composition (B) of the present invention is preferably 0.1 to 300 parts by mass, more preferably 250 parts by mass or less, even more preferably 200 parts by mass or less, and particularly preferably 150 parts by mass or less, per 100 parts by mass of the epoxy resin composition (A) of the present invention.

[0052] Furthermore, when the epoxy resin composition (B) of the present invention contains other epoxy resins described below, the content of the curing agent is preferably 0.1 to 100 parts by mass, more preferably 80 parts by mass or less, and even more preferably 60 parts by mass or less, per 100 parts by mass of the total epoxy resin components as solid content. In the present invention, the term "solid content" refers to the components excluding the solvent, and includes not only solid epoxy resins but also semi-solid and viscous liquid substances. Furthermore, the term "total epoxy resin components" refers to the sum of the epoxy resin composition (A) of the present invention and the other epoxy resins described below.

[0053] In the epoxy resin composition (B) of the present invention, it is preferable to use as the curing agent at least one selected from the group consisting of polyfunctional phenols, amine compounds, acid anhydride compounds, imidazole compounds, amide compounds, cationic polymerization initiators, and organic phosphines.

[0054] Examples of polyfunctional phenols include bisphenols such as bisphenol A, bisphenol F, bisphenol S, bisphenol B, bisphenol AD, bisphenol Z, and tetrabromobisphenol A; biphenols such as 4,4'-biphenol and 3,3',5,5'-tetramethyl-4,4'-biphenol; catechol, resorcinol, hydroquinone, and dihydroxynaphthalenes; and compounds in which the hydrogen atoms bonded to the aromatic rings of these compounds are substituted with non-interfering substituents such as halogen groups, alkyl groups, aryl groups, ether groups, ester groups, and organic substituents containing heteroatoms such as sulfur, phosphorus, and silicon. Further examples include novolaks and resols, which are polycondensates of these phenols, monofunctional phenols such as phenol, cresol, and alkylphenols, and aldehydes. These compounds may be used alone or in combination of two or more.

[0055] Examples of amine compounds include aliphatic primary, secondary, and tertiary amines, aromatic primary, secondary, and tertiary amines, cyclic amines, guanidines, and urea derivatives, and specific examples include triethylenetetramine, diaminodiphenylmethane, diaminodiphenyl sulfone, diaminodiphenyl ether, metaxylenediamine, dicyandiamide, 1,8-diazabicyclo(5,4,0)-7-undecene, 1,5-diazabicyclo(4,3,0)-5-nonene, dimethylurea, and guanylurea. These compounds may be used alone or in combination of two or more.

[0056] Examples of acid anhydride compounds include phthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, and condensates of maleic anhydride and unsaturated compounds, etc. These may be used alone or in combination of two or more.

[0057] Examples of imidazole compounds include 1-isobutyl-2-methylimidazole, 2-methylimidazole, 1-benzyl-2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, and benzimidazole. These may be used alone or in combination of two or more. Although imidazoles also function as curing accelerators (described later), they are classified as curing agents in the present invention.

[0058] Examples of amide compounds include dicyandiamide and its derivatives, polyamide resins, etc. These may be used alone or in combination of two or more.

[0059] The cationic polymerization initiator generates cations when exposed to heat or active energy rays, and examples thereof include aromatic onium salts. - , BF4 - , AsF6 - , PF6 - , CF3SO3 2- , B(C6F5)4 - and aromatic cation components containing atoms such as iodine, sulfur, nitrogen, phosphorus, etc. Diaryliodonium salts and triarylsulfonium salts are particularly preferred. These may be used alone or in combination of two or more.

[0060] Examples of organic phosphines include tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine, and phenylphosphine. Examples of phosphonium salts include tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium ethyltriphenylborate, and tetrabutylphosphonium tetrabutylborate. Examples of tetraphenylboron salts include 2-ethyl-4-methylimidazole tetraphenylborate and N-methylmorpholine tetraphenylborate. These may be used alone or in combination of two or more.

[0061] When polyfunctional phenols, amine compounds, or acid anhydride compounds are used, they are preferably used so that the equivalent ratio of functional groups in the curing agent (hydroxyl groups of polyfunctional phenols, amino groups of amine compounds, or acid anhydride groups of acid anhydride compounds) to all epoxy groups in the epoxy resin composition (B) is in the range of 0.8 to 1.5. When imidazole compounds are used, they are preferably used in the range of 0.5 to 10 parts by mass per 100 parts by mass of all epoxy resin components as solids. When amide compounds are used, they are preferably used in the range of 0.1 to 20% by mass of the total amount of all epoxy resin components and amide compounds as solids. When cationic polymerization initiators are used, they are preferably used in the range of 0.01 to 15 parts by mass per 100 parts by mass of all epoxy resin components as solids. When organic phosphines are used, they are preferably used in the range of 0.1 to 20% by mass of the total amount of all epoxy resin components and organic phosphines as solids.

[0062] In addition to the curing agents listed above, the epoxy resin composition (B) of the present invention can also use, as a curing agent, for example, a mercaptan compound, an organic acid dihydrazide, a boron halide amine complex, etc. These curing agents may be used alone or in combination of two or more.

[0063] [Other epoxy resins] The epoxy resin composition (B) of the present invention can use an epoxy resin other than the epoxy resin composition (A) of the present invention (sometimes referred to as "other epoxy resins" in this specification).

[0064] Examples of other epoxy resins include glycidyl ether epoxy resins such as bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol S epoxy resins, biphenyl epoxy resins, phenol novolac epoxy resins, cresol novolac epoxy resins, bisphenol A novolac epoxy resins, tetrabromobisphenol A epoxy resins, and other polyfunctional phenol epoxy resins; epoxy resins obtained by hydrogenating the aromatic rings of the above-mentioned aromatic epoxy resins; glycidyl ester epoxy resins; glycidyl amine epoxy resins (excluding those corresponding to the epoxy compounds of the present invention); linear aliphatic epoxy resins; alicyclic epoxy resins; and heterocyclic epoxy resins. The above-mentioned other epoxy resins may be used alone or in combination of two or more.

[0065] [solvent] Because the epoxy resin composition (A) of the present invention has excellent handleability, it is not essential to use a solvent in the epoxy resin composition (B), but a solvent may be used when it is desired to adjust the viscosity, etc. In the present invention, the term "solvent" and the aforementioned term "solvent" are used to distinguish between them depending on the form of use, but the same or different substances may be used independently.

[0066] Examples of solvents that can be used include ketones such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, and cyclohexanone, esters such as ethyl acetate, ethers such as dioxane and tetrahydrofuran, glycol ethers such as ethylene glycol monomethyl ether, amides such as N,N-dimethylformamide and N,N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, alcohols such as methanol and ethanol, alkanes such as hexane and cyclohexane, aromatics such as toluene and xylene, etc. The above-mentioned solvents may be used alone, or two or more may be mixed in any combination and ratio.

[0067] [Other ingredients] The epoxy resin composition (B) of the present invention may contain other components in addition to the components listed above. Examples of other components include curing accelerators (excluding those corresponding to the curing agents), coupling agents, flame retardants, antioxidants, light stabilizers, plasticizers, reactive diluents, pigments, inorganic fillers, and organic fillers. The other components listed above can be used in appropriate combinations depending on the desired physical properties of the epoxy resin composition (B).

[0068] [Cured product] A cured product can be obtained by curing the epoxy resin composition (B) of the present invention. "Curing" here means intentionally curing the epoxy resin composition (B) with heat and / or light, and the degree of curing can be controlled depending on the desired physical properties and application. The degree of curing may be fully cured or semi-cured, but the reaction rate of the curing reaction between the epoxy groups and the curing agent is usually 5 to 95%.

[0069] The method for curing the epoxy resin composition (B) of the present invention to form a cured product varies depending on the components and amounts of the components in the epoxy resin composition (B), but typically involves heating at 80 to 200°C for 60 to 180 minutes. To ensure that the curing reaction proceeds sufficiently, it is preferable to carry out a two-stage treatment consisting of a primary heating step at 80 to 160°C for 10 to 30 minutes and a secondary heating step at 120 to 200°C, which is 40 to 120°C higher than the primary heating temperature, for 60 to 150 minutes.

[0070] When producing a cured product as a semi-cured product, the curing reaction of the epoxy resin composition (B) may be allowed to proceed to an extent that allows the shape to be maintained by heating, etc. When the epoxy resin composition (B) contains a solvent, most of the solvent is removed by techniques such as heating, reduced pressure, and air drying, but 5% by mass or less of the solvent may remain in the semi-cured product.

[0071] [Application] The epoxy resin composition (A) and the epoxy resin composition (B) of the present invention have a good balance of ease of handling, pot life, i.e., controllability of curing time, etc. Because the epoxy compound and the epoxy compound-containing composition of the present invention exhibit these excellent effects, they can be suitably used in the fields of paints, electric and electronic materials, adhesives, carbon fiber reinforced plastics (CFRP), etc. [Example]

[0072] The present invention will be described in more detail below using 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 values ​​of various production conditions and evaluation results in the following examples represent preferred upper or lower limit values ​​in the embodiments of the present invention, and preferred ranges may be defined by combining the above-mentioned upper or lower limit values ​​with the values ​​in the following examples or values ​​between the examples.

[0073] [Example 1] A 5 L four-neck flask equipped with a stirrer, reflux condenser, and thermometer was charged with 252 g of 4-hydroxybenzenesulfonamide (Tokyo Chemical Industry Co., Ltd.) and 2830 g of epichlorohydrin (7.0 equivalents per total active hydrogen of hydroxyl and sulfonamide groups). The system was then purged with nitrogen under reduced pressure. 16 g of 50.0 wt% aqueous tetramethylammonium chloride solution was added to the mixture, and the mixture was heated to 90°C with stirring and stirred for 8 hours. After stirring, the heating was stopped and the mixture was left at room temperature overnight. The next day, the mixture was heated to 40°C with stirring, and 437 g of 48.5 wt% aqueous sodium hydroxide solution (1.2 equivalents per total active hydrogen of hydroxyl and sulfonamide groups) was slowly added dropwise over 30 minutes. After the dropwise addition, the mixture was maintained at 40°C for 1 hour to complete the reaction. This mixture was washed with water to remove by-product salts and excess sodium hydroxide, and then excess epichlorohydrin was distilled off from the product at 120°C under reduced pressure to obtain a crude epoxy resin composition.

[0074] This crude epoxy resin composition was dissolved in 671 g of methyl isobutyl ketone (MIBK) and 75 g of dimethyl sulfoxide (DMSO), and 14 g of a 48.5% by mass aqueous solution of sodium hydroxide was added and reacted at 40°C for 1 hour. Sodium hydrogen phosphate was added to the reaction solution to neutralize excess sodium hydroxide, and the by-product salt and DMSO were removed by washing with water. Next, the MIBK was completely removed under heating and reduced pressure, yielding 400 g of the target epoxy resin composition (A-1).

[0075] This epoxy resin composition (A-1) was used to evaluate the epoxy equivalent, composition, handleability, and pot life by the methods described below. The results are shown in Table 1. Resin plates were also prepared by the methods described below, and the mechanical properties and heat resistance of the cured product were evaluated. The results are shown in Table 2.

[0076] [Epoxy equivalent] It is defined as "the mass of epoxy resin containing one equivalent of epoxy groups" and was measured in accordance with JIS K7236.

[0077] [Composition of Epoxy Resin Composition (A-1): LC Analysis] The proportions of the epoxy resin (1), the oligomers of the epoxy resin (1), and other components in the epoxy resin composition (A-1) were determined by LC analysis using the following apparatus and conditions in accordance with JIS K0124. The area % of each area in the LC chart represented by the epoxy resin (1), the oligomers of the epoxy resin (1), and other components was taken as the proportion (mass %) of the epoxy resin (1), the oligomers of the epoxy resin (1), and other components. Equipment: Waters ACQUITY UPLC H-Class Column: Waters Acquity UPLC HSS T3 (column dimensions: 2.1 mm x 150 mm) Eluent: Gradient analysis of acetonitrile / 0.1% formic acid water = 20 / 80 to 100 / 0 in 8 minutes Flow rate: 0.5ml / min Detector: UV (254 nm) Temperature: 40℃ Sample concentration: 1.0% Injection volume: 1 μl Peak area analysis software: Waters MassLynx

[0078] [Handling: E-type viscosity] The E-type viscosity (unit: Pa s) of the epoxy resin composition (A-1) at 50°C was measured in accordance with JIS-Z8803 using a viscometer (product name RE-85U) manufactured by Toki Sangyo Co., Ltd., and evaluated according to the following criteria. ○: 100Pa·s or less ×: E-type viscosity cannot be measured due to exceeding 100 Pa·s or torque overload

[0079] [Pot life: gel time] Epoxy resin composition (A-1) and 4,4'-diaminodiphenyl sulfone (4,4'-DDS manufactured by Tokyo Chemical Industry Co., Ltd.) were mixed (1.0 mole of 4,4'-diaminodiphenyl sulfone was mixed per mole of epoxy groups in epoxy resin composition (A-1)), and acetone was added to dissolve the mixture to a solids concentration of 40% by mass. The mixture was then aged at room temperature for 10 minutes. 0.5 mL of the prepared solution was sampled, and the gel time at 180°C was measured using a gelation tester "IMC-A0E2" manufactured by Imoto Machinery Co., Ltd. The pot life was evaluated based on the gelation time using the following criteria. ○: Gel time is 300 seconds (5 minutes) or more ×: Gelation time is less than 300 seconds (5 minutes)

[0080] [Production of Epoxy Resin Composition (B-1)] 50 parts by mass of the epoxy resin composition (A-1), 50 parts by mass of a bisphenol A liquid epoxy resin (jER (registered trademark) 828 manufactured by Mitsubishi Chemical Corporation), and 4,4'-diaminodiphenyl sulfone (4,4'-DDS manufactured by Tokyo Chemical Industry Co., Ltd.) were kneaded together (mixing was carried out so that the amount of 4,4'-diaminodiphenyl sulfone in the mixture was 1.0 mole per mole of epoxy groups in the epoxy resin composition (A-1)) to obtain an epoxy resin composition (B-1).

[0081] [Creating resin board (cured product)] Two glass plates were prepared, each with a release PET film attached to one side. One of the plates was placed with the film facing up. A silicone tube was placed on top of the glass plate in a U-shape, and metal spacers were placed at the four corners of the glass plate. The other glass plate with the film facing the other was then placed on top of the other glass plate. The two glass plates were then clamped together with a small vice to prepare a mold for producing the cured product. The thickness of the resin plate was varied by changing the thickness of the metal spacer and the diameter of the silicone tube. The resin plate was then prepared in molds with a thickness of 4 mm for the bending test and 2 mm for the heat resistance test. Next, epoxy resin composition (B-1) was heated to 120°C on a hot plate to dissolve the solids, degassed under reduced pressure, and poured into the mold. The resin plate was then cured by heating at 180°C for 120 minutes in a safe bend dryer.

[0082] [Mechanical property evaluation: bending test] A 4 mm thick resin plate was cut into a length of 100 mm and a width of 10 mm, and the cut surface was treated with sandpaper #1200 to prepare a test piece. A bending test was performed on this test piece using an Instron precision universal testing machine, "INSTRON 5582 Model," in accordance with JIS K7161, using a three-point bending jig at a temperature of 23°C and a humidity of 50%RH, to measure the bending strength, bending at break, and bending modulus.

[0083] [Heat resistance: Glass transition temperature] Test specimens were prepared by cutting a 2 mm thick resin plate into a length of 50 mm and a width of 10 mm. Measurements were performed on these specimens using a dynamic viscoelasticity measuring device (SII NanoTechnology EXSTAR DMS6100) under the following conditions: frequency of 1 Hz, temperature range of 30 to 280°C, heating rate of 2°C / min, and double-support bending mode. The temperature at which the temperature-tan δ curve showed a maximum was taken as the glass transition temperature (Tg).

[0084] [Comparative Example 1] The epoxy equivalent, composition, handleability, and pot life were evaluated in the same manner as in Example 1, except that epoxy resin composition (A-1) was replaced by epoxy resin composition (A-2) synthesized according to the example described in JP-A-62-84071 using 4-hydroxybenzenesulfonamide as a raw material. The results are shown in Table 1. Furthermore, a cured product was prepared in the same manner as in Example 1, except that epoxy resin composition (B-2) was prepared using epoxy resin composition (A-2) instead of epoxy resin composition (A-1), and its mechanical properties and heat resistance were evaluated. The results are shown in Table 2.

[0085] [Table 1]

[0086] [Table 2]

[0087] [Evaluation results] As shown in Table 1, the epoxy resin composition (A-1) of Example 1 has fluidity and gelation time within preferred ranges, and is easy to handle and has a good pot life. On the other hand, the epoxy resin composition (A-1) of Comparative Example 1 is poor in handleability and pot life. Furthermore, Table 2 shows that the mechanical properties and heat resistance of the cured products of Example 1 and Comparative Example 1 are comparable. In other words, it is clear that the epoxy resin composition (A) and the epoxy resin composition (B) of the present invention can provide epoxy resin compositions that are excellent in handleability and pot life, i.e., controllability of curing time, without impairing the mechanical properties and heat resistance of the cured product. [Industrial Applicability]

[0088] The epoxy resin composition (A) and the epoxy resin composition (B) of the present invention have a good balance of ease of handling, controllability of curing time, etc. Because the epoxy resin composition (A) and the epoxy resin composition (B) of the present invention exhibit these excellent effects, they can be suitably used in the fields of paints, electric and electronic materials, adhesives, carbon fiber reinforced plastics (CFRP), etc.

Claims

1. An epoxy resin composition comprising an epoxy resin represented by the following formula (1), the composition containing 50.0% by weight or less of a low polymer derived from the epoxy resin represented by the formula (1): The epoxy resin composition (A) is such that the low polymer derived from the epoxy resin represented by formula (1) is a low polymer represented by the following formula (2): 【Chemistry 1】 (In the above formula (1), R １ ~R ４ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. 【Chemistry 2】 (In the above formula (2), R 1 to R 4 have the same meanings as in the formula (1), and n, m, and l each independently represent 0 to 3, provided that any one of n, m, and l is 1 or greater. Also, A 1 to A 3 each independently represent a group represented by the following formula (3) or (4), and in formulas (3) and (4), R 1 to R 4 have the same meanings as in the formula (1), and x and y represent bonding positions.) 【Transformation 3】

2. 2. The epoxy resin composition (A) according to claim 1, having an E-type viscosity at 50°C of 100 Pa·s or less.

3. An epoxy resin composition (B) comprising the epoxy resin composition (A) according to claim 1 or 2 and a curing agent.

4. The epoxy resin composition (B) according to claim 3, comprising 0.1 to 300 parts by weight of the curing agent per 100 parts by weight of the epoxy resin composition (A).

5. 5. The epoxy resin composition (B) according to claim 3 or 4, wherein the curing agent is at least one selected from the group consisting of polyfunctional phenols, amine compounds, acid anhydride compounds, imidazole compounds, amide compounds, cationic polymerization initiators, and organic phosphines.

6. A cured product obtained by curing the epoxy resin composition (B) according to any one of claims 3 to 5.

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