Epoxy resin curing agent composition, epoxy resin composition and cured product thereof, article having said cured product, and method for producing article

Abstract

Provided are: an epoxy resin curing agent composition containing an amine-based curing agent (A) and carbon nanotubes (B), the amine-based curing agent (A) containing at least one xylylenediamine-modified product (A1) selected from the group consisting of xylylenediamine epoxy-modified products and xylylenediamine Mannich-modified products; an epoxy resin composition and a cured product thereof; an article having the cured product; and a method for producing the article.

Description

Epoxy resin curing agent composition, epoxy resin composition and cured product thereof, article having the cured product, and method for manufacturing the article.

[0001] The present invention relates to an epoxy resin curing agent composition, an epoxy resin composition and its cured product, an article having the cured product, and a method for manufacturing the article.

[0002] In gas, water, and other pipelines, or in oil pipelines, a lining process is applied to the inner surface of the pipes to improve their airtightness and durability. It is known that resin materials are used for lining pipes. For example, Patent Document 1 discloses a pipe lining agent consisting of a polyurethane elastomer obtained by reacting an isocyanate group-containing prepolymer with an active hydrogen compound, wherein the isocyanate group-containing prepolymer is obtained by reacting an organic polyisocyanate with an aliphatic hydrocarbon polymer polyol having side-chain aliphatic hydrocarbon groups, and that this agent has sufficient airtightness and can significantly extend the life of the pipe. Patent Document 2 discloses a lining material consisting of a main component containing at least a urethane-modified epoxy resin and / or a rubber-modified epoxy resin, and a curing agent containing a polyamine, which, in a method of lining the inside of existing pipes using water pressure, does not foam during construction and is less prone to damage after construction.

[0003] Incidentally, in recent years, the adoption of environmentally friendly natural gas vehicles (CNG vehicles) and fuel cell vehicles (FCVs) has been progressing. Fuel cell vehicles use fuel cells as their power source, and the development of hydrogen stations, which compress hydrogen, the fuel for these fuels, to high pressure and refuel the vehicles, is essential. Furthermore, efforts are being made to utilize hydrogen as an energy source in order to realize a clean environment, and it is expected that hydrogen gas storage tanks and hydrogen gas pipelines will be developed as infrastructure in the future.

[0004] In hydrogen stations for fuel cell vehicles, CNG vehicles, on-board fuel tanks for fuel cell vehicles, high-pressure gas containers for hydrogen gas storage, and hydrogen gas piping, it is crucial to prevent embrittlement due to contact with hydrogen gas. Therefore, it is conceivable to provide a lining material on the contact surface with hydrogen gas in hydrogen gas tanks, piping, etc., to suppress hydrogen gas embrittlement. The resin material used to form this lining material should be a material that can form the lining material without undergoing heating processes such as placing it in a furnace after coating the material to be coated, as the lining process is applied to large tanks, piping, etc., and it is desirable that it also possesses hydrogen gas barrier properties.

[0005] In Patent Document 3, a thermosetting epoxy resin composition is proposed that contains predetermined amounts of an epoxy resin having a glycidyloxy group derived from resorcinol and an epoxy resin having a glycidyloxy group derived from bisphenol F as the main epoxy resin, and has a hydrogen gas permeability coefficient of less than or equal to a predetermined value when cured. This composition is suitable for RTM molding due to its low viscosity and moldability, and is capable of achieving high hydrogen gas barrier properties.

[0006] Japanese Patent Publication No. 2004-075896, Japanese Patent Publication No. 2020-200409, International Publication No. 2023 / 062999

[0007] However, the thermoplastic resin composition (epoxy resin composition) disclosed in Patent Document 3 is mainly used for RTM molding and is not suitable as a resin composition for coating the inner surfaces of tanks, pipes, etc. Furthermore, while metaxylylenediamine, which is disclosed as a suitable epoxy resin curing agent in this resin composition, can exhibit high hydrogen gas barrier properties, it has the problem of readily reacting with carbon dioxide in the air to form carbonates. The formation of these carbonates may cause blushing (whitening) in the resulting cured product, which may worsen the appearance of the cured product.

[0008] Furthermore, when the interior of hydrogen gas tanks and piping is constructed with insulating materials such as resins, static electricity tends to accumulate when an insulating fluid flows through them, posing a risk of ignition and explosion due to discharge. To avoid this, it is desirable that the resin material has antistatic properties. However, conventional technologies have not yet realized epoxy resin curing agents or epoxy resin compositions that possess high hydrogen gas barrier properties and antistatic properties, while also forming cured products with a good appearance.

[0009] The object of the present invention is to provide an epoxy resin curing agent composition, an epoxy resin composition and its cured product, an article having the cured product, and a method for manufacturing the article, which can form a cured product having high hydrogen gas barrier properties and antistatic properties and good appearance.

[0010] The present inventors have found that an epoxy resin curing agent composition containing a specific amine-based curing agent and carbon nanotubes can solve the above problems. That is, the present invention relates to the following: [1] An epoxy resin curing agent composition containing an amine-based curing agent (A) and carbon nanotubes (B), wherein the amine-based curing agent (A) comprises at least one xylylenediamine modified product (A1) selected from the group consisting of epoxy modified products of xylylenediamine and Mannich modified products of xylylenediamine. [2] The epoxy resin curing agent composition according to [1], wherein the content of the xylylenediamine modified product (A1) in the amine-based curing agent (A) is 20% by mass or more. [3] The epoxy resin curing agent composition according to [1] or [2], wherein the viscosity of the amine-based curing agent (A) at 25°C is 300 to 4,000 mPa·s. [4] The epoxy resin curing agent composition according to any one of [1] to [3], wherein the epoxy modified product of xylylenediamine is a modified product obtained by reacting xylylenediamine with an epoxy compound in a range where [moles of xylylenediamine / moles of epoxy compound] is 1 / 1 to 12 / 1. [5] The epoxy resin curing agent composition according to any one of [1] to [4], wherein the Mannich modified product of xylylenediamine is a modified product obtained by reacting 0.3 to 2 moles of a phenol compound and 0.3 to 2 moles of an aldehyde compound with 1 mole of xylylenediamine. [6] The epoxy resin curing agent composition according to any one of [1] to [5], wherein the content of the carbon nanotube (B) in the total amount of the amine curing agent (A) and the carbon nanotube (B) is 0.001 to 0.05% by mass. [7] The epoxy resin composition obtained by mixing the epoxy resin curing agent composition according to any one of [1] to [6] with an epoxy resin (C). [8] The epoxy resin composition according to [7], wherein the epoxy resin (C) comprises at least one epoxy resin (C1) selected from the group consisting of polyfunctional epoxy resins having glycidyloxy groups derived from resorcinol and polyfunctional epoxy resins having glycidyloxy groups derived from bisphenol F, and the content of the epoxy resin (C1) in the epoxy resin (C) is 50% by mass or more.[9] The epoxy resin composition according to [7] or [8], which is used by applying it to a material to be coated.

[10] The hydrogen gas permeability coefficient of the cured epoxy resin composition is 5.0 × 10. －１１ [cc・cm / (cm ２ An epoxy resin composition according to any one of items [7] to [9], wherein the epoxy resin composition is less than or equal to [s・cmHg].

[11] A cured product of the epoxy resin composition according to any one of items [7] to

[10] .

[12] An article having the cured product according to

[11] on at least a portion of the surface of a material to be coated.

[13] The article according to

[12] , wherein the shape of the material to be coated is at least one selected from the group consisting of tanks and pipes.

[14] The article according to

[12] or

[13] , wherein the cured product is a lining material.

[15] A method for manufacturing an article according to any one of items

[12] to

[14] , comprising the steps of coating the epoxy resin composition on at least a portion of the surface of the material to be coated to form an uncured layer, and then curing the uncured layer.

[0011] According to the present invention, it is possible to provide an epoxy resin curing agent composition, an epoxy resin composition and its cured product, an article having the cured product, and a method for manufacturing the article, which can form a cured product having high hydrogen gas barrier properties and antistatic properties, and having a good appearance. The epoxy resin composition of the present invention is suitable for use by coating the inner surface of hydrogen gas tanks, pipes, etc., and can form a lining material with excellent hydrogen gas barrier properties, antistatic properties, and appearance.

[0012] [Definitions] In this specification, "epoxy resin curing agent composition" means a composition that contains an epoxy resin curing agent but does not contain an epoxy resin. The epoxy resin referred to here means the main epoxy resin corresponding to component (C) described later. For example, this does not exclude the possibility that an epoxy compound, which is an unreacted raw material for the xylylenediamine modified product (A1), may be unintentionally mixed into the epoxy resin curing agent composition. In this specification, "epoxy resin composition" means a composition that contains at least an epoxy resin curing agent and a main epoxy resin. In this specification, an epoxy resin composition used for coating a material to be coated (for example, the inner surface of a tank or pipe for hydrogen gas) means an epoxy resin composition used for coating a material to be coated and then curing to form a cured product on the surface of the material to be coated. Therefore, an epoxy resin composition used for coating a material to be coated is distinguished from, for example, an epoxy resin composition used for mold molding.

[0013] In this specification, hydrogen gas barrier properties are evaluated by the hydrogen gas permeability coefficient measured at 23°C and in a dry state for a 1 mm thick cured epoxy resin composition. A smaller value of the hydrogen gas permeability coefficient indicates higher hydrogen gas barrier properties. In this specification, antistatic properties are evaluated using the surface resistance value of the cured epoxy resin composition as an indicator. If the surface resistance value is 1.0 × 10⁻⁶ １１ If the value is Ω or less, it is judged to have antistatic properties. In this specification, a good appearance of the cured epoxy resin composition means that no brushing is observed in the coating film made of the epoxy resin composition (coating film applied at 23°C and 50% R.H. and after 1 day). The hydrogen gas barrier properties, antistatic properties, and appearance of the cured epoxy resin composition can be specifically evaluated by the methods described in the examples.

[0014] [Epoxy Resin Curing Agent Composition] The epoxy resin curing agent composition of the present invention (hereinafter also referred to as "(the curing agent composition of the present invention)") is an epoxy resin curing agent composition containing an amine-based curing agent (A) and carbon nanotubes (B), wherein the amine-based curing agent (A) contains at least one xylylenediamine modified product (A1) selected from the group consisting of epoxy modified products of xylylenediamine and Mannich modified products of xylylenediamine. By having the above configuration, the curing agent composition of the present invention can provide an epoxy resin composition that has high hydrogen gas barrier properties and antistatic properties, and can form a cured product with a good appearance.

[0015] The reason why the above effects are obtained in the present invention is not clear, but it is thought to be as follows. The amine-based curing agent (A) used in the curing agent composition of the present invention contains a specific xylylenediamine modified product (A1). The xylylenediamine modified product (A1) has a structure derived from xylylenediamine (-N-CH ２ -C ６ H ４ -CH ２ The curing agent composition of the present invention, which has the structure (-N-), is thought to be able to exhibit high hydrogen gas barrier properties. When xylylenediamine is used as an epoxy resin curing agent, it has the problem of being prone to brushing as described above, but by using a xylylenediamine modified product (A1) with a specific structure, it is thought that the occurrence of brushing can be suppressed and a cured epoxy resin composition with a good appearance can be formed. Carbon nanotubes (B) provide an antistatic effect. It is thought that the good dispersibility of carbon nanotubes (B) in the amine-based curing agent (A) allows for the expression of higher antistatic properties. Furthermore, the inventors have found that in the curing agent composition of the present invention, when carbon nanotubes (B) are combined with a specific amine-based curing agent (A), they unexpectedly contribute to improving hydrogen gas barrier properties.

[0016] Furthermore, the epoxy resin composition of the present invention, as described later, is obtained by mixing the curing agent composition of the present invention with an epoxy resin (C). That is, epoxy resin compositions prepared by simultaneously mixing, for example, an amine-based curing agent (A), carbon nanotubes (B), and epoxy resin (C) are excluded from the epoxy resin composition of the present invention. In the epoxy resin composition of the present invention, it is believed that sufficient hydrogen gas barrier properties and antistatic properties can be obtained by having good dispersibility of carbon nanotubes (B). Furthermore, it is believed that by preparing a curing agent composition in which carbon nanotubes (B) are dispersed in an amine-based curing agent (A) in advance, and then mixing the curing agent composition with the epoxy resin (C), the good dispersion state of the carbon nanotubes (B) is maintained, and the hydrogen gas barrier properties and antistatic properties of the resulting epoxy resin composition are further improved.

[0017] <Amine-based curing agent (A)> The amine-based curing agent (A) used in the curing agent composition of the present invention includes at least one xylylenediamine modified product (A1) selected from the group consisting of epoxy-modified xylylenediamine and Mannich-modified xylylenediamine, from the viewpoint of improving the hydrogen gas barrier properties, antistatic properties, and appearance of the cured epoxy resin composition obtained.

[0018] (Xylylenediamine modified product (A1)) Xylylenediamine modified product (A1) is at least one selected from the group consisting of epoxy modified products of xylylenediamine and Mannich modified products of xylylenediamine.

[0019] [Epoxy Modified Xylylenediamine] An epoxy modified xylylenediamine is a reaction composition containing the reaction product of xylylenediamine and an epoxy compound. This reaction composition includes not only the reaction product (adduct) of xylylenediamine and the epoxy compound, but also by-products other than the reaction product and unreacted xylylenediamine as a raw material. The epoxy compound used in the epoxy modified product may be any compound having at least one epoxy group, and preferably a polyepoxy compound having two or more epoxy groups. Furthermore, both chain-like epoxy compounds and ring-structure-containing epoxy compounds can be used as the epoxy compound, but from the viewpoint of improving the hydrogen gas barrier properties and appearance of the cured epoxy resin composition obtained, a ring-structure-containing epoxy compound is preferred.

[0020] Specific examples of chain-like epoxy compounds among the epoxy compounds include at least one selected from the group consisting of epichlorohydrin, butyl diglycidyl ether, neopentyl glycol diglycidyl ether, 1,3-propanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, and 1,6-hexanediol diglycidyl ether. Specific examples of ring-structure-containing epoxy compounds include biphenol diglycidyl ether, dihydroxynaphthalene diglycidyl ether, dihydroxyanthracene diglycidyl ether, triglycidyl isocyanurate, tetraglycidyl glycol uryl, polyfunctional epoxy resin having a glycidylamino group derived from metaxylylenediamine, polyfunctional epoxy resin having a glycidylamino group derived from paraxylylenediamine, polyfunctional epoxy resin having a glycidylamino group derived from 1,3-bis(aminomethyl)cyclohexane, and polyfunctional epoxy resin having a glycidylamino group derived from 1,4-bis(aminomethyl)cyclohexane. At least one selected from the group consisting of epoxy resins, polyfunctional epoxy resins having glycidylamino groups derived from diaminodiphenylmethane, polyfunctional epoxy resins having glycidylamino groups and / or glycidyloxy groups derived from paraaminophenol, polyfunctional epoxy resins having glycidyloxy groups derived from bisphenol A or their hydrogenated products, polyfunctional epoxy resins having glycidyloxy groups derived from bisphenol F or their hydrogenated products, polyfunctional epoxy resins having glycidyloxy groups derived from phenol novolac, and polyfunctional epoxy resins having glycidyloxy groups derived from resorcinol.

[0021] Among the above, from the viewpoint of improving the hydrogen gas barrier properties and appearance of the cured epoxy resin composition obtained, the epoxy compound used in the epoxy modified product preferably includes a ring structure-containing polyepoxy compound, more preferably includes at least one selected from the group consisting of a polyfunctional epoxy resin having a glycidylamino group derived from metaxylylenediamine, a polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol A, and a polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol F, and even more preferably includes a polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol A.

[0022] An epoxy-modified product of xylylenediamine can be produced by a known ring-opening addition reaction between xylylenediamine and the epoxy compound. For example, xylylenediamine is charged into a reactor, and the epoxy compound is added all at once or in stages by dropwise addition, and the mixture is heated to allow the reaction to occur. This ring-opening addition reaction is preferably carried out under an inert atmosphere such as nitrogen gas.

[0023] In the above ring-opening addition reaction, from the viewpoint of improving the hydrogen gas barrier properties and appearance of the cured epoxy resin composition obtained, the reaction is carried out in a range where [moles of xylylenediamine / moles of epoxy compound] is preferably 1 / 1 to 12 / 1, more preferably 2 / 1 to 10 / 1, even more preferably 3 / 1 to 8 / 1, even more preferably 4 / 1 to 8 / 1, and even more preferably 5 / 1 to 7 / 1. That is, the epoxy modified product of xylylenediamine includes a modified product obtained by reacting xylylenediamine and an epoxy compound in a range where [moles of xylylenediamine / moles of epoxy compound] is preferably 1 / 1 to 12 / 1, more preferably 2 / 1 to 10 / 1, even more preferably 3 / 1 to 8 / 1, even more preferably 4 / 1 to 8 / 1, and even more preferably 5 / 1 to 7 / 1.

[0024] The temperature and reaction time during the ring-opening addition reaction can be appropriately selected, but from the viewpoint of reaction rate, productivity, and preventing decomposition of the raw materials, the temperature during the ring-opening addition reaction is preferably 25 to 150°C, more preferably 40 to 120°C. The reaction time is preferably 0.5 to 12 hours, more preferably 1 to 6 hours, after the addition of the epoxy compound is completed.

[0025] The active hydrogen equivalent (AHEW) of the epoxy-modified xylylenediamine is preferably 200 or less, more preferably 180 or less, even more preferably 150 or less, even more preferably 120 or less, even more preferably 100 or less, even more preferably 90 or less, even more preferably 80 or less, and even more preferably 70 or less, from the viewpoint of improving curability and low viscosity. Furthermore, from the viewpoint of improving the appearance of the cured product, it is preferably 40 or more, more preferably 45 or more, and even more preferably 50 or more.

[0026] The AHEW of the amine-based curing agent (A) and the curing agent components contained herein can be determined, for example, by titration. Specifically, the total amine value and secondary and tertiary amine values ​​of the amine-based curing agent (A) or the curing agent components are measured using an automatic potentiometric titrator "AT-610" (manufactured by Kyoto Electronics Manufacturing Co., Ltd.). The total amine value is measured by potentiometric titration with a 0.1 mol / L perchloric acid / acetic acid solution (manufactured by Kanto Chemical Co., Ltd.). The secondary and tertiary amine values ​​are measured by dissolving the sample in 2-propanol, adding salicylaldehyde, letting it stand for 30 minutes, and then performing potentiometric titration with 0.1 mol / L 2-propanolic hydrochloric acid. The AHEW can be calculated from these results.

[0027] [Mannich-modified xylylenediamine] A Mannich-modified xylylenediamine is a reaction composition obtained by reacting xylylenediamine with a phenol compound and an aldehyde compound in a Mannich reaction. This reaction composition includes not only the Mannich reaction product but also by-products other than the reaction product and unreacted raw materials.

[0028] Specific examples of phenol compounds used in the Mannich modified product include naturally occurring phenol compounds such as phenol, alkylphenol, alkenylphenol, terpenephenol, and cardanol. In alkylphenols, the number of carbon atoms in the alkyl group is preferably 1 to 24, more preferably 1 to 18, and in alkenylphenols, the number of carbon atoms in the alkenyl group is preferably 2 to 24, more preferably 2 to 18. Specific examples of phenol compounds include at least one selected from the group consisting of phenol, cresol, ethylphenol (p-ethylphenol, etc.), isopropylphenol (o-isopropylphenol, p-isopropylphenol, etc.), butylphenol (p-tert-butylphenol, p-sec-butylphenol, o-tert-butylphenol, o-sec-butylphenol, etc.), amylphenol (p-tert-amylphenol, o-tert-amylphenol, etc.), p-octylphenol, nonylphenol, p-cumylphenol, decylphenol, undecylphenol, p-dodecylphenol, tridecylphenol, tetradecylphenol, pentadecylphenol, pentadecenylphenol, pentadecadienylphenol, pentadecadrienylphenol, pentadecatrienylphenol, hexadecylphenol, heptadecylphenol, octadecylphenol, octadecenylphenol, terpenephenol, and cardanol. Among the above, from the viewpoint of reactivity with xylylenediamine and improvement of hydrogen gas barrier properties and appearance of the cured epoxy resin composition obtained, the phenol compound used in the Mannich modified product preferably includes at least one selected from the group consisting of phenol, cresol, p-tert-butylphenol, nonylphenol, and cardanol, and more preferably includes phenol.

[0029] Examples of the aldehyde compound used in the Mannich modified product include formaldehyde; formaldehyde-releasing compounds such as trioxane and paraformaldehyde; and other aldehydes such as benzaldehyde. Among the above, the aldehyde compound preferably contains at least one selected from the group consisting of formaldehyde and formaldehyde-releasing compounds, and more preferably contains formaldehyde. When the aldehyde compound contains formaldehyde, it is more preferred to carry out the Mannich reaction using an aqueous formaldehyde solution from the viewpoint of improving workability in the Mannich reaction.

[0030] A preferred combination of xylylenediamine, phenolic compound and aldehyde compound is a combination in which the xylylenediamine contains meta-xylylenediamine, the phenolic compound contains phenol, and the aldehyde compound contains formaldehyde.

[0031] The Mannich modified product of xylylenediamine can be produced by subjecting xylylenediamine, a phenolic compound and an aldehyde compound to a Mannich reaction. A known method can be used for the Mannich reaction. For example, the aldehyde compound or a solution thereof is added dropwise or the like to a mixture of xylylenediamine and a phenolic compound, preferably at 90°C or lower, more preferably at 85°C or lower, and after the completion of the addition, the temperature is preferably raised to 80 to 180°C, more preferably 90 to 160°C, and the reaction is carried out for 1 to 10 hours while removing the distillate (water produced as a by-product) from the reaction system. The Mannich reaction may be carried out in a solvent or in the absence of a solvent. The reaction is preferably carried out under an inert atmosphere such as nitrogen gas.

[0032] The reaction molar ratios of xylylenediamine, phenolic compound, and aldehyde compound in the Mannich reaction are not particularly limited as long as the resulting Mannich modified product contains amino groups having active hydrogen, but from the viewpoints of reactivity with xylylenediamine, and improvement of hydrogen gas barrier properties and appearance of the cured product of the resulting epoxy resin composition, the ranges below are preferred. The phenolic compound is preferably used in a range of 0.3 to 2 mol, more preferably 0.5 to 1.5 mol, and still more preferably 0.6 to 1.2 mol, relative to 1 mol of xylylenediamine. The aldehyde compound is preferably used in a range of 0.3 to 2 mol, more preferably 0.5 to 1.5 mol, and still more preferably 0.6 to 1.2 mol, relative to 1 mol of xylylenediamine.

[0033] That is, the Mannich modified product of xylylenediamine preferably includes a modified product obtained by reacting 0.3 to 2 mol of the phenolic compound and 0.3 to 2 mol of the aldehyde compound relative to 1 mol of xylylenediamine, more preferably includes a modified product obtained by reacting 0.5 to 1.5 mol of the phenolic compound and 0.5 to 1.5 mol of the aldehyde compound relative to 1 mol of xylylenediamine, and still more preferably includes a modified product obtained by reacting 0.6 to 1.2 mol of the phenolic compound and 0.6 to 1.2 mol of the aldehyde compound relative to 1 mol of xylylenediamine.

[0034] The active hydrogen equivalent (AHEW) of the Mannich modified product of xylylenediamine is preferably 120 or less, more preferably 100 or less, and still more preferably 90 or less, from the viewpoints of improving curability and low viscosity. Also, from the viewpoint of improving the appearance of the cured product, it is preferably 50 or more, more preferably 60 or more, and still more preferably 70 or more.

[0035] The content of xylylenediamine modified product (A1) in the amine-based curing agent (A) is preferably 15% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, even more preferably 40% by mass or more, even more preferably 50% by mass or more, even more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more, and 100% by mass or less, from the viewpoint of improving the hydrogen gas barrier properties and appearance of the cured epoxy resin composition obtained.

[0036] (Amine-based curing agents other than (A1) (A2)) The amine-based curing agent (A) may further include amine-based curing agents other than xylylenediamine modified product (A1), as long as the effects of the present invention are not impaired. Examples of amine-based curing agents (A2) include polyamine compounds having two or more amino groups having active hydrogen or modified products thereof (excluding xylylenediamine modified product (A1)). Examples of the polyamine compounds include linear aliphatic polyamine compounds such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexamethylenediamine, 2-methylpentamethylenediamine, and trimethylhexamethylenediamine; isophoronediamine (IPDA), mensendiamine, norbornanediamine, tricyclodecanediamine, adamantanediamine, diaminocyclohexane, 1,2-bis(aminomethyl)cyclohexane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-3,6-diethylcyclohexane, diaminodiethylmethylcyclohexane, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane (bis(4-amino-3-methylcyclohexyl)methane), and 3,3',5,5'-tetradiethylmethylcyclohexane. Examples include polyamine compounds having an alicyclic structure such as tramethyl-4,4'-diaminodicyclohexylmethane and 4,4'-diaminodicyclohexylmethane; aromatic ring-containing polyamine compounds such as orthoxylylenediamine, metaxylylenediamine, paraxylylenediamine, phenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, diethyltoluenediamine, and 2,2'-diethyl-4,4'-methylenedianiline; polyamine compounds having a heterocyclic structure such as N-aminoethylpiperazine and N,N'-bis(aminoethyl)piperazine; and linear polyether polyamine compounds such as poly(oxyethylene)diamine, poly(oxypropylene)diamine, poly(oxyethylene-oxypropylene)diamine, poly(oxypropylene-oxytetramethylene)diamine, trimethylolpropanepoly(oxypropylene)triamine, and glycerylpoly(oxypropylene)triamine.Furthermore, the modified product of the polyamine compound may be at least one selected from the group consisting of epoxy-modified products, Mannich-modified products, Michael addition reaction products, and polycondensation reaction products with polymerized fatty acids (dimer acids) of the above-mentioned polyamine compound.

[0037] Among the above, the amine-based curing agent (A2) preferably includes at least one selected from the group consisting of aromatic ring-containing polyamine compounds, linear polyether polyamine compounds, and modified products thereof, from the viewpoint of improving the hydrogen gas barrier properties and appearance of the cured epoxy resin composition. From the viewpoint of improving hydrogen gas barrier properties, the amine-based curing agent (A2) more preferably includes at least one selected from the group consisting of aromatic ring-containing polyamine compounds and modified products thereof, even more preferably includes an aromatic ring-containing polyamine compound, even more preferably includes at least one selected from the group consisting of metaxylylenediamine, paraxylylenediamine, phenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, diethyltoluenediamine, and 2,2'-diethyl-4,4'-methylenedianiline, and even more preferably includes at least one selected from the group consisting of metaxylylenediamine and paraxylylenediamine. From the viewpoint of improving the appearance of the cured product, the amine-based curing agent (A2) more preferably comprises at least one selected from the group consisting of linear polyether polyamine compounds and modified products thereof, even more preferably comprises a linear polyether polyamine compound, and even more preferably comprises at least one selected from the group consisting of poly(oxyethylene)diamine, poly(oxypropylene)diamine, poly(oxyethylene-oxypropylene)diamine, poly(oxypropylene-oxytetramethylene)diamine, trimethylolpropanepoly(oxypropylene)triamine, and glycerylpoly(oxypropylene)triamine, and even more preferably comprises at least one selected from the group consisting of poly(oxyethylene)diamine, poly(oxypropylene)diamine, poly(oxyethylene-oxypropylene)diamine, and poly(oxypropylene-oxytetramethylene)diamine.

[0038] Furthermore, when the amine-based curing agent (A) contains the amine-based curing agent (A2), the content of the amine-based curing agent (A) in the amine-based curing agent (A) is preferably 1% by mass or more, and from the viewpoint of improving the hydrogen gas barrier properties and appearance of the cured epoxy resin composition obtained, it is preferably 85% by mass or less, more preferably 80% by mass or less, even more preferably 70% by mass or less, even more preferably 60% by mass or less, even more preferably 50% by mass or less, even more preferably 40% by mass or less, even more preferably 30% by mass or less, even more preferably 20% by mass or less, even more preferably 10% by mass or less, and even more preferably 5% by mass or less.

[0039] The active hydrogen equivalent (AHEW) of the amine-based curing agent (A2) is preferably 130 or less, more preferably 120 or less, and even more preferably 110 or less, from the viewpoint of improving curability and low viscosity. Furthermore, from the viewpoint of improving the appearance of the cured product, it is preferably 30 or more.

[0040] [Viscosity] The viscosity of the amine-based curing agent (A) at 25°C is preferably 100 to 7,000 mPa·s, more preferably 200 to 6,000 mPa·s, even more preferably 300 to 5,000 mPa·s, even more preferably 300 to 4,000 mPa·s, and even more preferably 400 to 3,500 mPa·s. The low viscosity of the amine-based curing agent (A) improves the dispersibility of the carbon nanotubes (B), thereby further improving the hydrogen gas barrier properties and antistatic properties of the cured epoxy resin composition. On the other hand, if the viscosity of the amine-based curing agent (A) at 25°C is 100 mPa·s or higher, there are advantages such as good sprayability of the resulting epoxy resin composition. The viscosity of the amine-based curing agent (A) at 25°C can be measured using an E-type viscometer, specifically by the method described in the examples.

[0041] [AHEW] The active hydrogen equivalent (AHEW) of the amine-based curing agent (A) is preferably 130 or less, more preferably 120 or less, even more preferably 110 or less, even more preferably 100 or less, and even more preferably 90 or less, from the viewpoint of improving curability and low viscosity. Furthermore, from the viewpoint of improving the appearance of the cured product, it is preferably 30 or more, more preferably 35 or more.

[0042] <Carbon Nanotubes (B)> The curing agent composition of the present invention contains carbon nanotubes as component (B) from the viewpoint of improving the hydrogen gas barrier properties and antistatic properties of the cured epoxy resin composition obtained. Carbon nanotubes (B) (hereinafter also referred to as "CNT") may be single-walled carbon nanotubes (SWCNTs) or multi-walled carbon nanotubes with two or more layers. The number of layers of the multi-walled carbon nanotubes is not particularly limited, but is preferably 2 to 40, more preferably 2 to 20, even more preferably 2 to 10, and even more preferably 2 to 5. From the viewpoint of improving the antistatic properties and appearance of the cured epoxy resin composition obtained, the CNTs preferably contain carbon nanotubes with 1 to 40 layers, more preferably 1 to 20 layers, even more preferably 1 to 10 layers, and even more preferably 1 to 5 layers, and even more preferably contain single-walled carbon nanotubes.

[0043] The diameter of the carbon nanotube (B) is preferably in the range of 0.5 to 100 nm, more preferably 1 to 50 nm, even more preferably 1 to 25 nm, even more preferably 1 to 20 nm, even more preferably 1 to 10 nm, and even more preferably 1 to 6 nm, from the viewpoint of improving the hydrogen gas barrier properties and antistatic properties of the cured epoxy resin composition. This diameter refers to the central diameter of the carbon nanotube (B). The aspect ratio of the carbon nanotube (B) is preferably 5 or more, more preferably 10 or more, even more preferably 20 or more, even more preferably 50 or more, preferably 2000 or less, more preferably 1000 or less, and even more preferably 500 or less, from the viewpoint of improving the hydrogen gas barrier properties and antistatic properties of the cured epoxy resin composition.

[0044] Commercially available carbon nanotubes (B) can also be used. Examples of commercially available CNTs include "EC2.0" from Osaka Soda Co., Ltd., and "TUBALL 01RW02" and "TUBALL 01RW03" from OCSiAl.

[0045] <Other ingredients> The curing agent composition may further contain surfactants, defoamers, leveling agents, etc., to the extent that it does not impair the effects of the present invention.

[0046] The curing agent composition is preferably solvent-free from the viewpoint of environmental considerations, and from the viewpoint of improving the hydrogen gas barrier properties, antistatic properties, and appearance of the cured epoxy resin composition. The content of the organic solvent in the curing agent composition is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less, with a lower limit of 0% by mass.

[0047] From the viewpoint of use in forming lining materials, and from the viewpoint of improving the hydrogen gas barrier properties, antistatic properties, and appearance of the cured epoxy resin composition, it is preferable that the curing agent composition has a low content of non-reactive diluents such as benzyl alcohol. The content of non-reactive diluents in the curing agent composition is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less, even more preferably 2% by mass or less, and even more preferably 1% by mass or less, with a lower limit of 0% by mass.

[0048] The curing agent composition is preferably a non-aqueous curing agent composition from the viewpoint of improving the hydrogen gas barrier properties, antistatic properties, and appearance of the cured epoxy resin composition. The water content in the curing agent composition is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less, with a lower limit of 0% by mass. However, the water content refers to the amount of water intentionally added and does not exclude, for example, the water content already present in each component.

[0049] <Content> The content of the amine-based curing agent (A) in the curing agent composition of the present invention is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and also preferably 99.999% by mass or less, from the viewpoint of improving curability and improving the hydrogen gas barrier properties of the cured epoxy resin composition.

[0050] The amount of carbon nanotubes (B) in the total amount of amine-based curing agent (A) and carbon nanotubes (B) in the curing agent composition is preferably 0.001 to 0.1% by mass, more preferably 0.001 to 0.08% by mass, even more preferably 0.001 to 0.05% by mass, even more preferably 0.002 to 0.05% by mass, and even more preferably 0.004 to 0.05% by mass, from the viewpoint of improving the hydrogen gas barrier properties, antistatic properties, and appearance of the cured epoxy resin composition.

[0051] The total content of the amine-based curing agent (A) and carbon nanotubes (B) in the curing agent composition of the present invention is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more, and 100% by mass or less, from the viewpoint of improving curability, hydrogen gas barrier properties, antistatic properties, and appearance of the cured epoxy resin composition obtained. That is, the curing agent composition of the present invention may be a composition consisting of component (A) and component (B). The curing agent composition is preferably a liquid composition at 25°C. In this specification, liquid means having fluidity at 25°C.

[0052] <Method for Producing the Curing Agent Composition> The curing agent composition of the present invention can be produced by mixing an amine-based curing agent (A), carbon nanotubes (B), and other components used as necessary, using known methods and apparatus. From the viewpoint of improving the dispersibility of carbon nanotubes (B) in the amine-based curing agent (A), the method for producing the curing agent composition of the present invention preferably comprises the following steps (I) and (II) in order. Step (I): A step of dispersing carbon nanotubes (B) in a dispersion medium to prepare a dispersion liquid, and mixing the dispersion liquid with the amine-based curing agent (A) to prepare a dispersion 1. Step (II): A step of removing the dispersion medium from the dispersion 1.

[0053] (Step (I)) In Step (I), carbon nanotubes (B) are dispersed in a dispersion medium to prepare a dispersion, and the dispersion is mixed with an amine-based curing agent (A) to prepare dispersion 1. Examples of dispersion mediums used for dispersing carbon nanotubes (B) include organic solvents capable of dispersing CNTs. From the viewpoint of ease of removal of the dispersion medium in Step (II), the dispersion medium preferably contains an organic solvent with a boiling point of 120°C or less at atmospheric pressure (1 atm), and more preferably contains at least one selected from the group consisting of alcohols, ketones, and esters with a boiling point of 100°C or less at atmospheric pressure.

[0054] Specific examples of dispersion media used for dispersing carbon nanotubes (B) include ethanol, 1-propanol, 2-propanol (isopropyl alcohol), 1-butanol, 2-butanol, propylene glycol monomethyl ether, acetone, methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, ethyl acetate, etc., and one or more of these can be used. Among the above, the dispersion media preferably contains an alcohol with a boiling point of 100°C or less at atmospheric pressure, more preferably contains at least one selected from the group consisting of ethanol, 1-propanol, 2-propanol, 1-butanol, and 2-butanol, and even more preferably contains at least one selected from the group consisting of ethanol and 2-propanol.

[0055] The concentration of carbon nanotubes (B) in the dispersion prepared in step (I) is not particularly limited, but from the viewpoint of improving dispersibility and ease of removing the dispersion medium in step (II), it is preferably in the range of 0.01 to 1% by mass, more preferably 0.05 to 0.8% by mass, and even more preferably 0.1 to 0.5% by mass.

[0056] In the preparation of dispersion 1, the dispersion of carbon nanotubes (B) in the dispersion medium and the mixing of the dispersion with the amine-based curing agent (A) can be carried out by known methods using known dispersion or stirring devices. When two or more amine-based curing agents are used as the amine-based curing agent (A), the two or more amine-based curing agents may be mixed beforehand and then mixed with the dispersion, or the two or more amine-based curing agents may be individually added to the dispersion and then mixed. Step (I) can preferably be carried out at ambient temperature in the range of -10 to 40°C.

[0057] (Step (II)) In step (II), the dispersion medium is removed from the dispersion 1 obtained in step (I). The dispersion medium is removed by distillation under conditions in which the amine-based curing agent (A) and other components do not volatilize. Methods for distilling off the dispersion medium include vacuum distillation and using an evaporator. From the viewpoint of improving production efficiency, step (II) is preferably carried out under reduced pressure conditions. The temperature when carrying out step (II) may be ambient temperature, or it may be carried out under heating conditions of 40 to 150°C.

[0058] If any additional components other than the amine-based curing agent (A) and carbon nanotubes (B) are added, the timing of the addition of these additional components is not particularly limited, but it is preferable to add them after step (II). The curing agent composition obtained by steps (I) and (II) can be used in the production of the epoxy resin composition described below.

[0059] [Epoxy Resin Composition] The epoxy resin composition of the present invention is obtained by mixing the curing agent composition of the present invention with an epoxy resin (C). This is expected to maintain a good dispersion state of carbon nanotubes (B), thereby further improving the hydrogen gas barrier properties and antistatic properties of the resulting epoxy resin composition.

[0060] <Epoxy Resin (C)> The epoxy resin (C) used in the epoxy resin composition of the present invention preferably includes a liquid epoxy resin from the viewpoint of improving the paintability on the material to be coated. Here, "liquid" means having fluidity at 25°C.

[0061] (Epoxy resin (C1)) The epoxy resin (C) preferably comprises at least one epoxy resin (C1) selected from the group consisting of a polyfunctional epoxy resin having a glycidyloxy group derived from resorcinol and a polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol F, from the viewpoint of improving the hydrogen gas barrier properties, antistatic properties, and appearance of the cured epoxy resin of the epoxy resin composition, and more preferably comprises a polyfunctional epoxy resin having a glycidyloxy group derived from resorcinol. The content of epoxy resin (C1) in epoxy resin (C) is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more, and 100% by mass or less, from the viewpoint of improving the hydrogen gas barrier properties, antistatic properties, and appearance of the cured epoxy resin composition.

[0062] Among the epoxy resins (C1), the polyfunctional epoxy resin having a glycidyloxy group derived from resorcinol preferably contains resorcinol diglycidyl ether, and may also contain oligomers in addition to resorcinol diglycidyl ether. A commercially available epoxy resin having a glycidyloxy group derived from resorcinol is "Denacol EX-201" manufactured by Nagase ChemteX Co., Ltd. The polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol F preferably contains bisphenol F diglycidyl ether, and may also contain oligomers in addition to bisphenol F diglycidyl ether. A commercially available polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol F is "jER807" manufactured by Mitsubishi Chemical Corporation.

[0063] The epoxy resin (C1) preferably includes a polyfunctional epoxy resin having a glycidyloxy group derived from resorcinol, from the viewpoint of improving hydrogen gas barrier properties, and more preferably includes a polyfunctional epoxy resin having a glycidyloxy group derived from resorcinol and a polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol F, from the viewpoint of improving hydrogen gas barrier properties and suppressing heat generation during curing. Epoxy resins having a glycidyloxy group derived from resorcinol tend to generate heat during the curing reaction because they cure quickly, but heat generation during curing can be suppressed by using other resins, such as polyfunctional epoxy resins having a glycidyloxy group derived from bisphenol F, in combination. When the epoxy resin (C1) contains both a polyfunctional epoxy resin having a glycidyloxy group derived from resorcinol and a polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol F, the content of the polyfunctional epoxy resin having a glycidyloxy group derived from resorcinol in the epoxy resin (C1) is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, from the viewpoint of improving hydrogen gas barrier properties, and preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 60% by mass or less, even more preferably 50% by mass or less, even more preferably 40% by mass or less, and even more preferably 30% by mass or less, from the viewpoint of suppressing heat generation during curing.

[0064] The epoxy equivalent of epoxy resin (C1) is preferably 400 g / equivalent or less, more preferably 300 g / equivalent or less, even more preferably 250 g / equivalent or less, even more preferably 220 g / equivalent or less, and even more preferably 200 g / equivalent or less, from the viewpoint of improving curability and hydrogen gas barrier properties. Furthermore, from the viewpoint of suppressing heat generation during curing, it is preferably 115 g / equivalent or more. When two or more epoxy resins are used as epoxy resin (C1), the epoxy equivalent of epoxy resin (C1) refers to the weighted average value of the epoxy equivalents of the epoxy resins constituting epoxy resin (C1).

[0065] (Epoxy resin (C2)) The epoxy resin (C) may further include epoxy resins other than epoxy resin (C1) as epoxy resin (C2). Examples of epoxy resin (C2) include epoxy resins other than epoxy resin (C1) that contain aromatic rings, and aliphatic epoxy resins that do not contain aromatic rings. From the viewpoint of improving hydrogen gas barrier properties, epoxy resin (C2) preferably includes epoxy resins that contain aromatic rings. Specifically, examples of epoxy resins that contain aromatic rings include epoxy resins that contain at least one aromatic ring and at least two epoxy groups.

[0066] Specific examples of epoxy resin (C2) include at least one selected from the group consisting of a polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol A, a polyfunctional epoxy resin having a glycidylamino group derived from metaxylylenediamine, a polyfunctional epoxy resin having a glycidylamino group derived from paraxylylenediamine, a polyfunctional epoxy resin having a glycidylamino group derived from diaminodiphenylmethane, a polyfunctional epoxy resin having a glycidylamino group and a glycidyloxy group derived from paraaminophenol, and a polyfunctional epoxy resin having a glycidyloxy group derived from phenol novolac. Among the above, from the viewpoint of improving hydrogen gas barrier properties, epoxy resin (C2) preferably includes at least one selected from the group consisting of a polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol A, a polyfunctional epoxy resin having a glycidylamino group derived from metaxylylenediamine, and a polyfunctional epoxy resin having a glycidylamino group derived from paraxylylenediamine, and more preferably includes a polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol A.

[0067] Furthermore, when epoxy resin (C) contains epoxy resin (C2), from the viewpoint of improving hydrogen gas barrier properties, the content of epoxy resin (C2) in epoxy resin (C) is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, even more preferably 20% by mass or less, even more preferably 10% by mass or less, and even more preferably 5% by mass or less.

[0068] The epoxy equivalent of epoxy resin (C2) is preferably 120 to 800 g / equivalent, more preferably 140 to 600 g / equivalent, even more preferably 150 to 500 g / equivalent, and even more preferably 150 to 300 g / equivalent or less, from the viewpoint of improving curability and hydrogen gas barrier properties, and from the viewpoint of suppressing heat generation during curing. The epoxy equivalent of epoxy resin (C) is preferably 400 g / equivalent or less, more preferably 300 g / equivalent or less, even more preferably 250 g / equivalent or less, even more preferably 220 g / equivalent or less, and even more preferably 200 g / equivalent or less, from the viewpoint of improving curability and hydrogen gas barrier properties. Furthermore, from the viewpoint of suppressing heat generation during curing, it is preferably 115 g / equivalent or more. When two or more epoxy resins are used as epoxy resin (C), the epoxy equivalent of epoxy resin (C) means the weighted average value of the epoxy equivalents of the epoxy resins constituting epoxy resin (C).

[0069] <Content> The content ratio of epoxy resin (C) to the curing agent composition in the epoxy resin composition is such that, from the viewpoint of improving curability, hydrogen gas barrier properties, antistatic properties, and appearance of the cured product, the ratio of the number of active hydrogens in the curing agent composition to the number of epoxy groups in the epoxy resin (C) [number of active hydrogens in the curing agent composition / number of epoxy groups in epoxy resin (C)] is preferably 0.5 / 1 to 2 / 1, more preferably 0.75 / 1 to 1.5 / 1, and even more preferably 0.8 / 1 to 1.2 / 1.

[0070] The content of the curing agent composition in the epoxy resin composition is preferably 5 to 50% by mass, more preferably 10 to 40% by mass, even more preferably 10 to 35% by mass, and even more preferably 15 to 35% by mass, from the viewpoint of improving curability, hydrogen gas barrier properties, antistatic properties, and appearance of the cured product.

[0071] The content of epoxy resin (C) in the epoxy resin composition is preferably 50 to 95% by mass, more preferably 60 to 90% by mass, even more preferably 65 to 90% by mass, and even more preferably 65 to 85% by mass, from the viewpoint of improving curability, hydrogen gas barrier properties, antistatic properties, and appearance of the cured product.

[0072] From the viewpoint of effectively exhibiting the effects of the present invention, the total content of the curing agent composition and epoxy resin (C) in the epoxy resin composition is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 85% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more, and 100% by mass or less.

[0073] <Other Components> The epoxy resin composition may further contain other components depending on the application, such as fillers, plasticizers and other modifying components, thixotropes and other flow adjusting components, curing accelerators, pigments, leveling agents, tackifiers, and stress relaxation components.

[0074] Among the above, examples of curing accelerators include phenolic compounds such as bisphenol A and styrene-phenol and their salts; sulfonic acid compounds such as p-toluenesulfonic acid and methanesulfonic acid and their salts or esters; carboxylic acid compounds such as salicylic acid and benzoic acid and their salts; mercaptan-terminated polysulfide compounds; guanidine compounds; and alkanolamine compounds. These can be used individually or in combination of two or more. When the epoxy resin composition contains a curing accelerator, the content of the curing accelerator in the epoxy resin composition is preferably 0.01 to 15% by mass, more preferably 0.1 to 10% by mass. Examples of stress-relaxing components include elastomer particles such as silicone, butyl acrylate, polyetheramine, and rubber particles.

[0075] The epoxy resin composition of the present invention may contain an organic solvent, but from the viewpoint of consideration for the environment, as well as from the viewpoints of improving the hydrogen gas barrier property, antistatic property, and appearance of the cured product, it is preferably a solvent-free type. The content of the organic solvent in the epoxy resin composition is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, even more preferably 2% by mass or less, and still even more preferably 1% by mass or less, with the lower limit being 0% by mass.

[0076] From the viewpoint of use for forming lining materials and the like, as well as from the viewpoints of improving the hydrogen gas barrier property, antistatic property, and appearance of the cured product, the epoxy resin composition of the present invention preferably has a low content of non-reactive diluents such as benzyl alcohol. The content of the non-reactive diluent in the epoxy resin composition is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, even more preferably 2% by mass or less, and still even more preferably 1% by mass or less, with the lower limit being 0% by mass.

[0077] The epoxy resin composition of the present invention is preferably a non-aqueous epoxy resin composition from the viewpoints of improving the hydrogen gas barrier property, antistatic property, and appearance of the cured product. The content of water in the epoxy resin composition is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, even more preferably 2% by mass or less, and still even more preferably 1% by mass or less, with the lower limit being 0% by mass.

[0078] In addition, the epoxy resin composition of the present invention is preferably used by being applied to a material to be coated. Therefore, from the viewpoint of improving coatability, the epoxy resin composition of the present invention is preferably liquid at 25°C.

[0079] <Hydrogen Gas Permeability Coefficient> The cured product of the epoxy resin composition of the present invention exhibits high hydrogen gas barrier properties. The hydrogen gas permeability coefficient of the cured product of the epoxy resin composition of the present invention is preferably 5.0×10 －１１ [cc·cm / (cm ２ ·s·cmHg)] or less, more preferably 4.5×10 －１１ [cc·cm / (cm ２(s・cmHg) Further preferably 4.0 × 10 －１１ [cc・cm / (cm ２ (s・cmHg) Further preferably 3.5 × 10 －１１ [cc・cm / (cm ２ (s・cmHg) Further preferably 3.0 × 10 －１１ [cc・cm / (cm ２ The hydrogen gas permeability coefficient of the cured epoxy resin composition can be measured using a cured product with a thickness of 1 mm under drying conditions of 23°C by the method described in the examples.

[0080] <Surface Resistance Value> The cured product of the epoxy resin composition of the present invention exhibits antistatic properties. Specifically, the surface resistance value of the cured product of the epoxy resin composition of the present invention is preferably 1.0 × 10⁻⁶. ４ ~1.0 x 10 １１ Ω, more preferably 1.0 × 10 ４ ~1.0 x 10 １０ Ω, more preferably 1.0 × 10 ４ ~1.0 x 10 ８ The range is Ω. The surface resistance of the cured epoxy resin composition can be measured specifically by the method described in the examples.

[0081] <Method for Producing Epoxy Resin Composition> The epoxy resin composition of the present invention is obtained by mixing the epoxy resin curing agent composition and epoxy resin (C). Specifically, it can be produced by mixing the epoxy resin curing agent composition produced by the above method and epoxy resin (C) using a known stirring device. The temperature when mixing the epoxy resin curing agent composition and epoxy resin (C) can be appropriately adjusted according to the viscosity of the epoxy resin (C), but from the viewpoint of suppressing viscosity increase due to the progress of the thermosetting reaction, it is preferably 100°C or lower, more preferably 80°C or lower, and from the viewpoint of ease of stirring, it is preferably 20°C or higher, more preferably 25°C or higher. The mixing time is preferably in the range of 0.1 minutes to 2 hours, more preferably 0.2 minutes to 30 minutes.

[0082] <Usage> The epoxy resin composition of the present invention has high hydrogen gas barrier properties and antistatic properties, and also suppresses the occurrence of brushing, so it is preferable to use it as a lining composition for suppressing hydrogen embrittlement. That is, the present invention also provides the use of the epoxy resin composition as a lining composition for suppressing hydrogen embrittlement. The lining composition is used by coating at least a portion of the surface that comes into contact with hydrogen gas of a material to be coated, such as a hydrogen gas tank or piping.

[0083] [Cured Product] The cured product of the epoxy resin composition of the present invention (hereinafter also simply referred to as "the cured product of the present invention") is obtained by curing the epoxy resin composition of the present invention described above by a known method. The curing conditions for the epoxy resin composition are appropriately selected according to the application and form, but from the viewpoint of use as a lining for hydrogen gas tanks, pipes, etc., it is preferably cured at ambient temperature and atmospheric pressure. One embodiment of these curing conditions is as described in the article manufacturing method described later. The form of the cured product of the present invention is not particularly limited and can be selected according to the shape of the material to be coated, etc., but from the viewpoint of applying the epoxy resin composition to the material to be coated and then curing it to obtain a cured product, it is usually in the form of a film or layer. When the epoxy resin composition of the present invention is used as a lining composition, the cured product of the present invention is a lining material.

[0084] [Article] The present invention provides an article having a cured epoxy resin composition on at least a portion of the surface of the material to be coated. Here, the surface of the material to be coated is not limited to the outer surface. For example, if the shape of the material to be coated is cylindrical, hollow container, etc., the surface of the material to be coated also includes the inner surface. Furthermore, from the viewpoint of suppressing hydrogen embrittlement of the material to be coated by the cured epoxy resin composition, the article preferably has the cured material on at least a portion of the surface of the material to be coated that is in contact with hydrogen gas, and more preferably has the cured material on the entire surface of the material to be coated that is in contact with hydrogen gas.

[0085] <Material to be coated> The material of the material to be coated used in the present invention can be selected according to the application and shape of the article, but from the viewpoint of forming a lining material for hydrogen gas tanks, pipes, etc. by coating with the epoxy resin composition, the material of the material to be coated preferably includes at least one selected from the group consisting of steel and fiber-reinforced or unreinforced plastic materials, and more preferably includes steel. Examples of the matrix resin in fiber-reinforced plastic materials (FRP) and the fiber-unreinforced plastic material include at least one selected from the group consisting of thermoplastic resins and cured products of thermosetting resins. Known resins can be used as the thermoplastic resin and thermosetting resin.

[0086] Examples of materials for the reinforcing fibers in fiber-reinforced plastics include inorganic fibers such as carbon fibers, glass fibers, basalt fibers, metal fibers, boron fibers, and ceramic fibers; and organic fibers such as aramid fibers, polyoxymethylene fibers, aromatic polyamide fibers, poly(p-phenylenebenzobisoxazole) fibers, and ultra-high molecular weight polyethylene fibers. Among these, from the viewpoint of obtaining high strength, the reinforcing fibers preferably include inorganic fibers, and more preferably include at least one selected from the group consisting of carbon fibers, glass fibers, and basalt fibers, as they are lightweight, high-strength, and have a high modulus of elasticity. From the viewpoint of strength and lightness, carbon fibers are even more preferably included. Examples of carbon fibers include polyacrylonitrile-based carbon fibers and pitch-based carbon fibers. In addition, carbon fibers made from plant-derived raw materials such as lignin and cellulose can also be used.

[0087] The reinforcing fibers may be treated with a treatment agent. Examples of treatment agents include surface treatment agents and sizing agents. As the surface treatment agent, silane coupling agents are preferred, and examples include silane coupling agents having vinyl groups, silane coupling agents having amino groups, silane coupling agents having epoxy groups, silane coupling agents having (meth)acrylic groups, and silane coupling agents having mercapto groups. As the sizing agent, examples include at least one selected from the group consisting of urethane-based sizing agents, epoxy-based sizing agents, acrylic-based sizing agents, polyester-based sizing agents, vinyl ester-based sizing agents, polyolefin-based sizing agents, polyether-based sizing agents, and carboxylic acid-based sizing agents. Examples of sizing agents combining two or more types include urethane / epoxy-based sizing agents, urethane / acrylic-based sizing agents, and urethane / carboxylic acid-based sizing agents.

[0088] From the viewpoint of improving interfacial adhesion with the matrix resin in the fiber-reinforced plastic material, the amount of the treatment agent in the reinforcing fibers is preferably in the range of 0.001 to 5% by mass, more preferably 0.1 to 3% by mass, and even more preferably 0.5 to 2% by mass, relative to the reinforcing fibers.

[0089] The shape of the material to be coated used in the present invention can also be selected according to the application of the article. From the viewpoint of forming a lining material for hydrogen gas tanks, pipes, etc. by coating with the epoxy resin composition, the shape of the material to be coated preferably includes at least one selected from the group consisting of tanks and pipes.

[0090] The cured epoxy resin composition in the article of the present invention is preferably a lining material, and more specifically, a lining material for suppressing hydrogen embrittlement of the material to be coated. That is, the article of the present invention is preferably a tank or pipe having a lining material made of a cured epoxy resin composition of the present invention, and more preferably a tank or pipe having the lining material preferably on the inner surface (the surface in contact with hydrogen gas). The tank can be suitably used as a hydrogen gas storage tank, and the pipe can be suitably used as a hydrogen gas piping.

[0091] The thickness of the lining material, which is made from a cured epoxy resin composition of the present invention, is preferably in the range of 0.1 to 20 mm, more preferably 0.2 to 10 mm, and even more preferably 0.4 to 8 mm, from the viewpoint of suppressing hydrogen embrittlement of the material to be coated.

[0092] [Method for Manufacturing Articles] The present invention further provides a method for manufacturing articles, comprising the steps of applying the epoxy resin composition to at least a portion of the surface of the material to be coated to form an uncured layer, and then curing the uncured layer. Examples of known coating methods for applying the epoxy resin composition to at least a portion of the surface of the material to be coated include, but are not limited to, spray coating, dipping coating, electrostatic coating, flow coater coating, and roller coater coating. For example, an uncured layer made of the epoxy resin composition is formed on at least a portion of the surface of the material to be coated by the above coating method. The thickness of the uncured layer varies depending on the use and shape of the article, but when the cured product of the epoxy resin composition is a lining material, the uncured layer can be formed such that the thickness of the cured product is preferably in the range of 0.1 to 20 mm, more preferably 0.2 to 10 mm, and even more preferably 0.4 to 8 mm. The application of the epoxy resin composition can be repeated two or more times.

[0093] Next, the uncured layer is cured to form a cured layer of the epoxy resin composition. The curing temperature of the uncured layer is not particularly limited, but from the viewpoint of forming a cured layer without going through a heating process such as placing it in a furnace, it is preferable to cure it at room temperature. Room temperature here preferably means ambient temperature. The curing temperature (ambient temperature) is preferably selected between -10 and 40°C. The curing time of the uncured layer is also not particularly limited, but is preferably selected in the range of 0.5 hours to 14 days.

[0094] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The measurements and evaluations in these examples were performed by the following methods.

[0095] (1) An amine-based curing agent (A) with the composition listed in the viscosity table was prepared. The viscosity of the amine-based curing agent (A) at 25°C was measured using an E-type viscometer "TVE-22H type viscometer cone plate type" (manufactured by Toki Sangyo Co., Ltd.).

[0096] (2) Hydrogen gas permeability coefficient [cc・cm / (cm ２ [ s・cmHg ] The epoxy resin composition prepared in each example was poured into a mold (120 mm × 120 mm × 1 mm) coated with a release agent (Henkel "FREKOTE 770-NC"), and heated at 120°C for 1 hour to cure, obtaining a plate-shaped test specimen (1 mm thick). The hydrogen gas permeability coefficient [ cc・cm / (cm) ] was measured on this test specimen using a gas permeability measuring device (GTR-30X manufactured by GTR Tech) by the differential pressure method in a dry state at 23°C. ２ The hydrogen gas barrier properties (s / cmHg) were measured. A smaller value indicates superior hydrogen gas barrier performance.

[0097] (3) Surface resistance value Using the test specimen prepared in (2) above, the surface resistance value was measured using a surface resistance meter (HOZAN Corporation "F-109") in accordance with the standard RCJS-5-1 (2nd edition):2014 at 23°C and 50% R.H. The average of the measured values ​​for N=3 is shown in the table. Surface resistance value of 1.0 × 10 ４ ~1.0 x 10 １１ Within the range of Ω, it is determined that it has an antistatic effect.

[0098] (4) Appearance of the coating film (presence or absence of brushing) The epoxy resin composition prepared in each example was dropped onto a zinc phosphate treated steel plate (SPCC-SD PB-N144 Φ5-1, manufactured by Paltec Co., Ltd., 70 mm x 150 mm x 0.8 mm thick), and a coating film was formed by coating using a 200 μm applicator (coating film thickness immediately after application: 200 μm). This coating film was left to stand at 23°C and 50% R.H. conditions, and after one day the appearance of the coating film was visually observed and evaluated according to the following criteria. An A rating is considered acceptable. (Evaluation criteria) A: No brushing is observed, and a coating film with a good appearance can be formed. B: A smooth coating film can be formed, but brushing is observed on the surface of the coating film. C: Brushing occurs significantly, and a smooth coating film cannot be formed due to the presence of uncured components, wrinkles, etc.

[0099] (5) Reaction completion time when heated at 40°C 2 to 10 g of the epoxy resin composition prepared in each example was used as the measurement sample. Using a differential thermal and calorific value simultaneous measurement device (Shimadzu Corporation "DTG-60"), the measurement sample was kept at 40°C under a nitrogen atmosphere and DSC measurement was performed, and the time when the exothermic peak disappeared was defined as the reaction completion time. A shorter reaction completion time indicates faster curing and a better result.

[0100] Production Example 1 (Production of MXDA-Epoxy Modified Product) 40.8 g (0.3 mol) of metaxylylenediamine (MXDA, manufactured by Mitsubishi Gas Chemical Co., Ltd.) was charged into a 1-liter separable flask equipped with a stirrer, thermometer, nitrogen inlet tube, dropping funnel, and condenser, and the temperature was raised to 80°C while stirring under a nitrogen stream. While maintaining the temperature at 80°C, 18.6 g of a polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol A ("jER828," manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 186 g / equivalent) (an amount such that the number of moles of MXDA / the number of moles of epoxy compound = 6 / 1) was added dropwise over 2 hours. After the dropwise addition was complete, the temperature was raised to 100°C and the reaction was carried out for 2 hours to obtain an MXDA-epoxy modified product. The active hydrogen equivalent (AHEW) of the obtained MXDA-epoxy modified product was 54.

[0101] Production Example 2 (Production of MXDA Mannich Modified Product) 612.9 g (4.5 mol) of metaxylylenediamine (MXDA, manufactured by Mitsubishi Gas Chemical Co., Ltd.) and 423.45 g (4.5 mol) of phenol were charged into a 2-liter flask equipped with a stirrer, thermometer, nitrogen inlet tube, dropping funnel, and condenser. The mixture was heated to 80°C while stirring under a nitrogen stream. Next, 243.3 g (3.0 mol) of formalin (37% aqueous solution containing 8% methanol) was added dropwise over 1.5 hours at 80°C. After the addition was complete, the temperature was raised to 100°C and the reaction was carried out for 1.5 hours. The temperature was raised to 150°C over 2 hours while distilling off the water, and the reaction was carried out at the same temperature for 1 hour to obtain the MXDA Mannich modified product. The AHEW of the obtained MXDA Mannich modified product was 77.4.

[0102] Comparative Manufacturing Example 3 (Preparation of IPDA-Epoxy Modified Product) 68.6 g (0.40 mol) of isophorone diamine (IPDA, manufactured by Tokyo Chemical Industry Co., Ltd.) was charged into a 1-liter separable flask equipped with a stirrer, thermometer, nitrogen inlet tube, dropping funnel, and condenser, and the temperature was raised to 80°C while stirring under a nitrogen stream. While maintaining the temperature at 80°C, 18.6 g of a polyfunctional epoxy resin having glycidyloxy groups derived from bisphenol A ("jER828," manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 186 g / equivalent) (an amount such that the number of amino groups in IPDA / the number of epoxy groups in the epoxy compound = 8 / 1) was added dropwise over 2 hours. After the dropwise addition was complete, the temperature was raised to 100°C and the reaction was carried out for 2 hours to obtain an IPDA-epoxy modified product. The active hydrogen equivalent (AHEW) of the obtained IPDA-epoxy modified product was 57.8.

[0103] Examples 1-10, Comparative Examples 1, 6-7 (Preparation of Epoxy Resin Curing Agent Compositions) Amine-based curing agent (A) with the composition shown in the table was prepared. A 0.2% by mass dispersion of single-walled carbon nanotubes (SWCNTs) ("EC2.0" manufactured by Osaka Soda Co., Ltd.) (dispersion medium: isopropyl alcohol) was added to the mixture so that the amount of CNTs was as shown in the table, and the mixture was stirred at room temperature (25°C). After the mixture became homogenized, the isopropyl alcohol (IPA) was removed by distillation using an evaporator to obtain the epoxy resin curing agent composition shown in the table.

[0104] (Preparation and Evaluation of Epoxy Resin Composition) The epoxy resin (C), which is the main component listed in the table, and the epoxy resin curing agent composition were mixed in the proportions listed in the table and stirred at room temperature (25°C) to prepare the epoxy resin composition. The evaluation described above was performed using the obtained epoxy resin composition. The results are shown in the table below.

[0105] Comparative Examples 2-4: Epoxy resin curing agent compositions and epoxy resin compositions were prepared using the components listed in Table 2-4, except that SWCNTs were not included in the epoxy resin curing agent composition. The evaluation described above was performed using the obtained epoxy resin compositions. The results are shown in the table below.

[0106] Comparative Example 5 (Preparation and Evaluation of Epoxy Resin Composition) An amine-based curing agent (A) with the composition shown in the table was prepared. To this, the epoxy resin (C) shown in the table and a 0.2% by mass dispersion of single-walled carbon nanotubes (SWCNTs) ("EC2.0" manufactured by Osaka Soda Co., Ltd.) (dispersion medium: IPA) were added and the mixture was stirred at room temperature (25°C). After the mixture was visually homogenized, the IPA was removed by distillation using an evaporator to obtain the epoxy resin composition shown in the table. The evaluation described above was performed using the obtained epoxy resin composition. The results are shown in the table below. Note that the amounts (parts by mass) listed in the table are all amounts of active ingredients.

[0107]

[0108]

[0109]

[0110]

[0111] The components listed in the table are as follows: <Epoxy Resin (C)> (Epoxy Resin (C1)) ・Liquid epoxy resin having a glycidyloxy group derived from bisphenol F (Mitsubishi Chemical Corporation's "jER807", epoxy equivalent: 168 g / equivalent) ・Liquid epoxy resin having a glycidyloxy group derived from resorcinol (Nagase ChemteX Corporation's "Denacol EX-201", epoxy equivalent: 115 g / equivalent) (Epoxy Resin (C2)) ・Liquid epoxy resin having a glycidyloxy group derived from bisphenol A (Mitsubishi Chemical Corporation's "jER828", epoxy equivalent: 186 g / equivalent)

[0112] <Amine-based curing agents (A)> (Amine-based curing agents other than (A1) (A2)) ・Metaxylylenediamine (Manufactured by Mitsubishi Gas Chemical Co., Ltd., MXDA) ・Isophoronediamine (Manufactured by Tokyo Chemical Industries, Ltd., IPDA) ・D-230 (Polyoxypropylenediamine, manufactured by HUNTSMAN, "Jeffamine D-230", AHEW: 60) ・Diethylenetriamine (Manufactured by Tokyo Chemical Industries, Ltd., DETA)

[0113] <Carbon Nanotubes (B)> - SWCNT (Single-Walled Carbon Nanotube, "EC2.0" manufactured by Osaka Soda Co., Ltd.)

[0114] The table shows that the cured epoxy resin composition obtained using the epoxy resin curing agent composition of the present invention exhibits high hydrogen gas barrier properties, good antistatic properties, and furthermore, less brushing and a good coating appearance. The epoxy resin composition of the present invention also has the advantage of curing quickly at 40°C. A comparison of Example 3 and Comparative Example 4 shows that the epoxy resin composition of Example 3 containing carbon nanotubes (B) improves not only antistatic properties but also hydrogen gas barrier properties.

[0115] In contrast, the epoxy resin composition of Comparative Example 1 resulted in brushing during film formation, and a good-looking coating could not be obtained. The epoxy resin compositions of Comparative Examples 2 to 4, which did not contain carbon nanotubes (B), did not provide an antistatic effect, and the appearance of the coating deteriorated in Comparative Examples 2 and 3. As shown in the comparison between Example 5 and Comparative Example 5, in Comparative Example 5, where carbon nanotubes were added to the epoxy resin composition rather than the curing agent composition, the hydrogen gas barrier properties of the resulting cured product decreased. Furthermore, the epoxy resin compositions of Comparative Examples 6 and 7, which used isophorone diamine or its modified form instead of xylenediamine modified product (A1), did not provide sufficient hydrogen barrier properties. In addition, the curing rate at 40°C was also reduced compared to the epoxy resin compositions of the Examples.

[0116] According to the present invention, it is possible to provide an epoxy resin curing agent composition, an epoxy resin composition and its cured product, an article having the cured product, and a method for manufacturing the article, which can form a cured product having high hydrogen gas barrier properties and antistatic properties, and having a good appearance. The epoxy resin composition of the present invention is suitable for use by coating the inner surface of hydrogen gas tanks, pipes, etc., and can form a lining material with excellent hydrogen gas barrier properties, antistatic properties, and appearance.

Claims

1. An epoxy resin curing agent composition containing an amine-based curing agent (A) and carbon nanotubes (B), wherein the amine-based curing agent (A) comprises at least one xylylenediamine modified product (A1) selected from the group consisting of epoxy-modified xylylenediamine and Mannich-modified xylylenediamine.

2. The epoxy resin curing agent composition according to claim 1, wherein the content of the xylylenediamine modified product (A1) in the amine curing agent (A) is 20% by mass or more.

3. The epoxy resin curing agent composition according to claim 1, wherein the viscosity of the amine-based curing agent (A) at 25°C is 300 to 4,000 mPa·s.

4. The epoxy resin curing agent composition according to claim 1, wherein the epoxy modified product of xylylenediamine includes a modified product obtained by reacting xylylenediamine with an epoxy compound in a range where the ratio of moles of xylylenediamine to moles of epoxy compound is 1 / 1 to 12 / 1.

5. The epoxy resin curing agent composition according to claim 1, wherein the Mannich modified product of xylylenediamine includes a modified product obtained by reacting 0.3 to 2 moles of a phenol compound and 0.3 to 2 moles of an aldehyde compound with 1 mole of xylylenediamine.

6. The epoxy resin curing agent composition according to claim 1, wherein the content of carbon nanotubes (B) in the total amount of the amine-based curing agent (A) and the carbon nanotubes (B) is 0.001 to 0.05% by mass.

7. An epoxy resin composition obtained by mixing the epoxy resin curing agent composition according to any one of claims 1 to 6 with an epoxy resin (C).

8. The epoxy resin composition according to claim 7, wherein the epoxy resin (C) comprises at least one epoxy resin (C1) selected from the group consisting of polyfunctional epoxy resins having glycidyloxy groups derived from resorcinol and polyfunctional epoxy resins having glycidyloxy groups derived from bisphenol F, and the content of the epoxy resin (C1) in the epoxy resin (C) is 50% by mass or more.

9. The epoxy resin composition according to claim 7, which is used by being applied to a material to be coated.

10. The hydrogen gas permeability coefficient of the cured epoxy resin composition is 5.0 × 10⁻⁶. －１１ [cc・cm / (cm ２ The epoxy resin composition according to claim 7, wherein the value is less than or equal to [s・cmHg].

11. A cured product of the epoxy resin composition according to claim 7.

12. An article having the cured product described in claim 11 on at least a portion of the surface of the material to be coated.

13. The article according to claim 12, wherein the shape of the material to be painted includes at least one selected from the group consisting of tanks and pipes.

14. The article according to claim 12, wherein the cured product is a lining material.

15. A method for manufacturing an article according to claim 12, comprising the steps of applying the epoxy resin composition to at least a portion of the surface of the material to be coated to form an uncured layer, and then curing the uncured layer.

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