Epoxy resin curing agent, epoxy resin composition, coating and adhesive

Abstract

An epoxy resin curing agent comprises an amine composition containing meta-xylylenediamine and para-xylylenediamine in a mass ratio of 99 / 1 to 51 / 49 or a modified product thereof; an epoxy resin composition; and a coating and an adhesive containing the same.

Description

Technical Field

[0001] The invention relates to an epoxy resin curing agent, an epoxy resin composition, a coating and an adhesive. Background Art

[0002] Xylylenediamine is a compound useful as a raw material for polyamide resins, epoxy resin curing agents, isocyanate compounds, etc. However, xylylenediamine is known to be easily deteriorated by light, heat, oxygen, etc., and deteriorates by coloring, generating odor, etc. during storage.

[0003] Therefore, for example, Patent Document 1 discloses a solid xylylenediamine in a container, wherein the solid xylylenediamine is prepared by filling a container with liquid xylylenediamine having a hue of 20 or less in terms of APHA and solidifying the container, as a xylylenediamine which does not cause quality deterioration such as coloring even when stored for a long period of time and has excellent storage stability. The solid xylylenediamine is stored in a solid state, and then melted to obtain a hue of 20 or less in terms of APHA when measured as a liquid.

[0004] In addition, polyamide resins using xylylenediamine as a main diamine component are excellent in mechanical properties such as strength and elastic modulus, and are therefore useful as molding materials containing glass fibers or inorganic fillers.

[0005] Patent Document 2 discloses a xylylenediamine composition containing xylylenediamine and a predetermined amount of bis(methylbenzyl)amine, and a method for producing a polyamide resin using the composition, and describes that the polyamide resin is suitable for use as materials such as packaging films, hollow containers, various molding materials, and fibers.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2005-154426

[0009] Patent Document 2: Japanese International Publication No. 2014 / 178270 Summary of the invention

[0010] Problem that the invention aims to solve

[0011] In addition, epoxy resin compositions using various polyamines such as xylylenediamine as epoxy resin curing agents are widely used in the fields of coatings such as anti-corrosion coatings for ships, bridges, and land and sea railway structures, linings, reinforcements, and repair materials for concrete structures, floor materials for buildings, linings for waterways and sewage pipes, paving materials, adhesives, and other civil engineering and construction fields.

[0012] Among them, polyamines for coatings or adhesives are different from polyamines used as raw materials for polyamide resins, and it is important that the obtained coatings or adhesives have good water resistance, coating film appearance, coating film properties, etc. However, in Patent Documents 1 and 2, no research is conducted on the performance of xylylenediamine when used as an epoxy resin curing agent for coatings or adhesives, and there is still room for improvement in water resistance, etc.

[0013] An object of the present invention is to provide an epoxy resin curing agent and an epoxy resin composition capable of obtaining a coating material or an adhesive material having excellent water resistance, and a coating material and an adhesive material containing the same.

[0014] Solutions for solving problems

[0015] The present inventors have found that an epoxy resin curing agent comprising an amine composition containing meta-xylylenediamine and para-xylylenediamine at a predetermined mass ratio or a modified product thereof can solve the above-mentioned problems.

[0016] That is, the present invention relates to the following contents.

[0017] [1] An epoxy resin curing agent comprising an amine composition containing meta-xylylenediamine and para-xylylenediamine in a mass ratio of 99 / 1 to 51 / 49 or a modified product thereof.

[0018] [2] The epoxy resin curing agent according to [1] above, wherein the mass ratio of m-xylylenediamine to p-xylylenediamine in the amine composition is 99 / 1 to 71 / 29.

[0019] [3] The epoxy resin curing agent according to [1] or [2] above, wherein the mass ratio of meta-xylylenediamine to para-xylylenediamine in the amine composition is 85 / 15 to 75 / 25.

[0020] [4] The amine composition according to any one of [1] to [3] above, wherein the total content of meta-xylylenediamine and para-xylylenediamine in the amine composition is 50% by mass or more.

[0021] [5] The epoxy resin curing agent according to any one of [1] to [4] above, wherein the modified product of the amine composition is a reaction product of the amine composition and an epoxy compound having at least one epoxy group.

[0022] [6] An epoxy resin composition comprising an epoxy resin and the epoxy resin curing agent according to any one of [1] to [5] above.

[0023] [7] A coating material comprising the epoxy resin composition described in [6] above.

[0024] [8] An adhesive comprising the epoxy resin composition described in [6] above.

[0025] Effects of the Invention

[0026] The epoxy resin curing agent and epoxy resin composition of the present invention can provide a coating or adhesive having excellent water resistance. The epoxy resin composition of the present invention is suitable for various coatings such as ship coatings, heavy-duty anticorrosive coatings, can coatings, pipe interior coatings, exterior coatings, floor material coatings, and various adhesives for civil engineering and construction fields and film fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a graph showing the relationship between the mass ratio of meta-xylylenediamine and para-xylylenediamine in an amine composition and the freezing point. DETAILED DESCRIPTION

[0028] [Epoxy resin curing agent]

[0029] The epoxy resin curing agent of the present invention comprises an amine composition containing meta-xylylenediamine and para-xylylenediamine in a mass ratio of 99 / 1 to 51 / 49 or a modified product thereof.

[0030] By using the epoxy resin curing agent, a coating or adhesive having excellent water resistance can be provided. Hereinafter, the epoxy resin curing agent of the present invention is also simply referred to as "the curing agent of the present invention".

[0031] The reason why a coating or adhesive having excellent water resistance can be obtained by using the curing agent of the present invention is not yet clear, but it is believed that by mixing meta-xylylenediamine and para-xylylenediamine at an appropriate blending ratio, the three-dimensional crosslinked structure of the cured product of the epoxy resin composition obtained changes, and the water resistance is improved compared to the case of using meta-xylylenediamine or para-xylylenediamine alone.

[0032] In addition, since p-xylylenediamine has a high freezing point, there is room for improvement in operability and storage properties under low temperature conditions. However, the freezing point of the amine composition in which the mass ratio of m-xylylenediamine to p-xylylenediamine is within the specified range of the present invention is low, and in particular, the amine composition in which the mass ratio of m-xylylenediamine to p-xylylenediamine is within the range of 85 / 15 to 75 / 25, further within the range of 85 / 15 to 77 / 23, and 83 / 17 to 77 / 23 has a lower freezing point than the case of m-xylylenediamine alone. Therefore, when the curing agent of the present invention containing the amine composition or its modified product is used, water resistance is improved, and it is difficult to cure under low temperature conditions, and the operability under low temperature conditions is further improved.

[0033] From the viewpoint of obtaining a coating or adhesive having excellent water resistance, the mass ratio of meta-xylylenediamine to para-xylylenediamine (meta-xylylenediamine / para-xylylenediamine) in the amine composition used in the present invention is 99 / 1 to 51 / 49, preferably 99 / 1 to 71 / 29. From the viewpoint of obtaining a coating or adhesive having excellent water resistance and improving workability under low temperature conditions, it is more preferably 85 / 15 to 75 / 25, further preferably 85 / 15 to 77 / 23, and further preferably 83 / 17 to 77 / 23.

[0034] From the viewpoint of obtaining a coating or adhesive having excellent water resistance, the total content of m-xylylenediamine and p-xylylenediamine in the amine composition is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, further preferably 80% by mass or more, further preferably 90% by mass or more, further preferably 95% by mass or more, and may be 100% by mass.

[0035] The method for preparing the amine composition is not particularly limited, and for example, the amine composition can be prepared by mixing predetermined amounts of m-xylylenediamine and p-xylylenediamine, respectively. In addition, if the catalyst used or the production conditions can be adjusted to perform a reaction in parallel to generate m-xylylenediamine and p-xylylenediamine in a predetermined ratio, a method utilizing the reaction can also be cited. In this case, the content and ratio of m-xylylenediamine and p-xylylenediamine in the amine composition can be obtained by gas chromatography analysis or the like.

[0036] Specific examples of modified forms of the amine composition contained in the curing agent of the present invention include reactants obtained by reacting the above-mentioned amine composition with an epoxy compound having at least one epoxy group, an unsaturated hydrocarbon compound, a carboxylic acid or a derivative thereof; and Mannich reactants obtained by reacting the above-mentioned amine composition with a phenol compound and an aldehyde compound.

[0037] Among them, the modified product of the amine composition is preferably a reaction product of the amine composition and an epoxy compound having at least one epoxy group from the viewpoint of obtaining a coating or adhesive having excellent water resistance. Hereinafter, the reaction product is also simply referred to as "the reaction product".

[0038] The epoxy compound used in the reaction product of the amine composition and the epoxy compound having at least one epoxy group may be a compound having at least one epoxy group, and more preferably has two or more epoxy groups.

[0039] Specific examples of the epoxy compound include epichlorohydrin, butyl diglycidyl ether, neopentyl glycol diglycidyl ether, 1,3-propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, biphenol diglycidyl ether, dihydroxynaphthalene diglycidyl ether, dihydroxyanthracene diglycidyl ether, triglycidyl isocyanurate, tetraglycidyl glycoluril, a polyfunctional epoxy resin having a glycidyl amino group derived from m-xylylenediamine, a polyfunctional epoxy resin having a glycidyl amino group derived from 1,3-bis(aminomethyl)cyclohexane, The present invention also includes a polyfunctional epoxy resin having a glycidylamino group derived from diaminodiphenylmethane, a polyfunctional epoxy resin having a glycidylamino group derived from p-aminophenol, a polyfunctional epoxy resin having a glycidyloxy group derived from p-aminophenol, a polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol A, a polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol F, a polyfunctional epoxy resin having a glycidyloxy group derived from phenol novolac, and a polyfunctional epoxy resin having two or more glycidyloxy groups derived from resorcinol. These may be used alone or in combination of two or more.

[0040] From the viewpoint of forming an epoxy resin cured product having excellent water resistance and from the viewpoint of curing properties, as the epoxy compound, a compound containing an aromatic ring or an alicyclic structure in the molecule is more preferred, a compound containing an aromatic ring in the molecule is further preferred, and a polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol A is further preferred.

[0041] The above reaction product can be obtained by subjecting the amine composition to a ring-opening addition reaction with the epoxy compound using a known method. For example, the amine composition is added to a reactor, and the epoxy compound is added thereto at once, or the epoxy compound is added in batches such as by dropwise addition, and then heated to react. The addition reaction is preferably carried out under an inert gas environment such as nitrogen.

[0042] The amount of the amine composition and the epoxy compound used is not particularly limited as long as the ratio of the obtained reaction product to the amino group having active hydrogen is sufficient. From the viewpoint that the obtained reaction product functions as an epoxy resin curing agent, it is preferred to use an excess amount of the amine composition relative to the epoxy equivalent of the epoxy compound in the addition reaction. Specifically, the amine composition and the epoxy compound are used so that the number of active hydrogens in the amine composition relative to the number of epoxy groups in the epoxy compound (the number of active hydrogens in the amine composition / the number of epoxy groups in the epoxy compound) is preferably 50 / 1 to 4 / 1, and more preferably 20 / 1 to 8 / 1.

[0043] The temperature and reaction time during the addition reaction can be appropriately selected, but from the viewpoints of reaction rate, productivity, and prevention of raw material decomposition, the temperature during the addition reaction is preferably 50 to 150° C., more preferably 70 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.

[0044] The curing agent of the present invention may be a curing agent composed of the above-mentioned amine composition or its modified product, and may also contain other curing agent components. The curing agent component refers to a component contained in the curing agent and having two or more functional groups that can react with the epoxy group in the epoxy resin. As other curing agent components, polyamine compounds other than the above-mentioned amine composition and its modified product can be cited.

[0045] However, from the viewpoint of obtaining a coating or adhesive having excellent water resistance, the content of the above-mentioned amine composition and its modified product in the curing agent of the present invention is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, further preferably 80% by mass or more, further preferably 90% by mass or more, further preferably 95% by mass or more, and may be 100% by mass, relative to all curing agent components in the curing agent.

[0046] Furthermore, the curing agent of the present invention may further contain a known curing accelerator, a non-reactive diluent such as benzyl alcohol, or the like, within a range not impairing the effects of the present invention.

[0047] When the curing agent of the present invention contains a modified form of an amine composition, the active hydrogen equivalent of the curing agent is preferably 85 or more, more preferably 90 or more, from the viewpoint of obtaining a coating or adhesive having excellent water resistance, and is preferably 120 or less, more preferably 110 or less, from the viewpoint of improving curability.

[0048] Active hydrogen equivalent (hereinafter also referred to as "AHEW") refers to the mass of the epoxy resin curing agent per 1 mol of active hydrogen. When the curing agent of the present invention uses the above-mentioned non-reactive diluent, the AHEW of the total amount of the curing agent solution containing the diluent is preferably within the above-mentioned range.

[0049] [Epoxy resin composition]

[0050] The epoxy resin composition of the present invention contains an epoxy resin and the epoxy resin curing agent. The epoxy resin composition of the present invention has high water resistance and is suitable for use in coatings or adhesives.

[0051] <Epoxy resin>

[0052] The epoxy resin as the main component of the epoxy resin composition may be any of saturated or unsaturated aliphatic compounds, alicyclic compounds, aromatic compounds, and heterocyclic compounds. From the viewpoint of obtaining a cured product with high water resistance, an epoxy resin containing an aromatic ring or an alicyclic structure in the molecule is preferred.

[0053] Specific examples of the epoxy resin include at least one selected from epoxy resins having a glycidylamino group derived from m-phenylenediamine, epoxy resins having a glycidylamino group derived from p-phenylenediamine, epoxy resins having a glycidylamino group derived from 1,3-bis(aminomethyl)cyclohexane, epoxy resins having a glycidylamino group derived from 1,4-bis(aminomethyl)cyclohexane, epoxy resins having a glycidylamino group derived from diaminodiphenylmethane, epoxy resins having a glycidylamino group and / or a glycidyloxy group derived from p-aminophenol, epoxy resins having a glycidyloxy group derived from bisphenol A, epoxy resins having a glycidyloxy group derived from bisphenol F, epoxy resins having a glycidyloxy group derived from phenol novolac, and epoxy resins having a glycidyloxy group derived from resorcinol. Two or more of the above epoxy resins may be used in combination.

[0054] Among the above, from the viewpoint of obtaining a cured product having high water resistance, the epoxy resin preferably contains as the main component at least one selected from the group consisting of an epoxy resin having a glycidylamino group derived from m-phenylenediamine, an epoxy resin having a glycidylamino group derived from p-phenylenediamine, an epoxy resin having a glycidyloxy group derived from bisphenol A, and an epoxy resin having a glycidyloxy group derived from bisphenol F. From the viewpoint of obtaining a cured product having high water resistance, and from the viewpoint of availability and economic efficiency, it is more preferable to contain as the main component an epoxy resin having a glycidyloxy group derived from bisphenol A.

[0055] The “main component” mentioned here means that other components may be contained within the scope not departing from the gist of the present invention, and the main component is preferably 50 to 100% by mass, more preferably 70 to 100% by mass, and even more preferably 90 to 100% by mass of the whole.

[0056] The content of the epoxy resin curing agent in the epoxy resin composition of the present invention is an amount such that the ratio of the number of active hydrogens in the epoxy resin curing agent to the number of epoxy groups in the epoxy resin (number of active hydrogens in the epoxy resin curing agent / number of epoxy groups in the epoxy resin) is preferably 1 / 0.5 to 1 / 2, more preferably 1 / 0.75 to 1 / 1.5, and even more preferably 1 / 0.8 to 1 / 1.2.

[0057] The epoxy resin composition of the present invention may further contain other components such as fillers, modifying components such as plasticizers, flow control components such as thixotropic agents, pigments, leveling agents, tackifiers, and elastomer fine particles, depending on the intended use.

[0058] However, from the viewpoint of effectively obtaining the effects of the present invention, the total amount of the epoxy resin and the epoxy resin curing agent in the epoxy resin composition is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, further preferably 90% by mass or more, further preferably 95% by mass or more, and may be 100% by mass.

[0059] There is no particular limitation on the preparation method of the epoxy resin composition of the present invention, and the epoxy resin, epoxy resin curing agent and other components as required can be mixed to produce the epoxy resin composition using a known method and apparatus. There is no particular limitation on the mixing order of the components contained in the epoxy resin composition, and the epoxy resin curing agent can be mixed with the epoxy resin after the epoxy resin curing agent is prepared, or the components constituting the epoxy resin curing agent and other components can be mixed with the epoxy resin at the same time to produce the epoxy resin composition.

[0060] [Paints, adhesives]

[0061] The present invention provides a coating material and an adhesive comprising the epoxy resin composition. The coating material and the adhesive of the present invention have high water resistance by comprising the epoxy resin composition.

[0062] The coating material and adhesive containing the epoxy resin composition of the present invention have a low freezing point due to the epoxy resin curing agent of the present invention, and thus can be made into a coating material and adhesive having high workability under low temperature conditions and high water resistance.

[0063] From the viewpoint of improving water resistance, the content of the epoxy resin composition in the coating and the adhesive is preferably 50% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, further preferably 90% by mass or more, further preferably 95% by mass or more, and may be 100% by mass.

[0064] Examples of the coating include marine coatings, heavy-duty anticorrosive coatings, can coatings, pipe interior coatings, exterior coatings, floor coatings, etc. In addition, examples of the adhesive include various adhesives for civil engineering and construction fields and thin film fields.

[0065] Example

[0066] 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. It should be noted that various measurements and evaluations in each Example were performed as follows.

[0067] (Dry to touch)

[0068] A zinc phosphate treated iron plate (manufactured by Paltek Co., Ltd; SPCC-SD PB-N144 0.8×70×150 mm) was used as a substrate. At 23°C and 50% RH, the epoxy resin composition of each example was applied to the substrate using an applicator to form a coating film (the coating film thickness immediately after coating: 200 μm). The coating film was stored at 23°C and 50% RH, and after 1 day, it was evaluated by finger touch according to the following standards. The results are shown in Table 1.

[0069] Ex: Excellent (the coating does not feel sticky and no fingerprints remain when the thumb is pressed with a force of about 50N)

[0070] G: Good (the coating is not sticky when the thumb is pressed with a force of about 50N, but fingerprints remain after touching it)

[0071] F: Yes (the coating becomes sticky when the thumb is pressed with a force of about 50N)

[0072] P: Poor (the coating is sticky when the thumb is pressed with a force of about 5N)

[0073] (Pencil hardness)

[0074] The epoxy resin composition was applied to a substrate (zinc phosphate treated iron plate) in the same manner as above to form a coating film (thickness immediately after coating: 200 μm). The coating film was stored at 23°C and 50% RH, and the pencil hardness was measured after 1, 2, and 7 days in accordance with JIS K5600-5-4:1999. The results are shown in Table 1.

[0075] (Water spot test)

[0076] The epoxy resin composition was applied to the substrate (zinc phosphate treated iron plate) in the same manner as described above to form a coating (thickness immediately after coating: 200 μm). The coating was stored at 23°C and 50% RH. After 1, 2, and 7 days, 2 to 3 drops of pure water were added to the coating surface with a dropper, and a 50 mL spiral tube bottle was placed on the site. After 24 hours, the water was wiped off, the appearance was visually observed, and the evaluation was performed according to the following criteria. The results are shown in Table 1.

[0077] Ex: No change

[0078] G: Slightly changed, but good

[0079] F: There are changes

[0080] (RCI curing speed)

[0081] At 23°C and 50% RH, the epoxy resin composition of each example was applied on a glass plate (25×348×2.0 mm, manufactured by Taiyu Kizai Co., Ltd.) using a 76 μm applicator to form a coating. The glass plate with the coating formed was placed on a coating drying time measuring instrument (manufactured by Taiyu Kizai Co., Ltd.), and the streaks when the needle of the measuring instrument scratched the surface of the coating were observed. The time to reach each drying stage (touch drying, semi-drying, and complete drying) was measured according to the following criteria. The results are shown in Table 1. A shorter time means a faster curing speed.

[0082] Set to Touch: The time when needle marks begin to remain on the glass plate

[0083] Dust Free: The time it takes for the needle marks to emerge from the coating film to the surface of the coating film. Dry hrough: The time it takes for the needle marks to no longer remain on the coating film.

[0084] (Appearance of coating film)

[0085] The epoxy resin composition was applied to a substrate (zinc phosphate treated iron plate) in the same manner as above to form a coating film (thickness immediately after coating: 200 μm). The appearance of the obtained coating film was visually observed after 1 day, and the transparency, smoothness and glossiness were evaluated according to the following criteria.

[0086] <Transparency>

[0087] Ex: No turbidity

[0088] G: Although slightly turbid, there is no problem in using it

[0089] F: White turbidity

[0090] <Smoothness>

[0091] Ex: No bumps

[0092] G: Although it is slightly uneven, there is no problem in use

[0093] F: Concave and convex

[0094] <Glossiness>

[0095] Ex: Glossy

[0096] G: The gloss is slightly worse, but there is no problem in use

[0097] F: Matt

[0098] Example 1 (Preparation and Evaluation of Epoxy Resin Curing Agent and Epoxy Resin Composition (Coating))

[0099] (Preparation of amine composition)

[0100] An amine composition was prepared by blending meta-xylylenediamine (MXDA, manufactured by Mitsubishi Gas Chemical Co., Ltd.) and para-xylylenediamine (PXDA, manufactured by Mitsubishi Gas Chemical Co., Ltd.) at a mass ratio of 90 / 10.

[0101] (Preparation of epoxy resin curing agent)

[0102] In a separable flask with a volume of 1 liter equipped with a stirring device, a thermometer, a nitrogen inlet tube, a dropping funnel and a condenser, 340 g of the above amine composition was added, and the temperature was raised to 80°C while stirring under a nitrogen flow. While maintaining 80°C, 186 g (the number of active hydrogens in the amine composition / the number of epoxy groups in the epoxy compound=10 / 1) of a multifunctional epoxy resin having a glycidyloxy group derived from bisphenol A ("jER828" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 186 g / equivalent) as an epoxy compound was added dropwise over 2 hours. After the addition was completed, the temperature was raised to 100°C and reacted for 2 hours to obtain a reaction product of the above amine composition and jER828. Benzyl alcohol as a non-reactive diluent was added thereto in an amount of 40% by mass of the total amount to dilute the reaction product to obtain an epoxy resin curing agent having a concentration of 60% by mass of the above reaction product. The active hydrogen equivalent weight (AHEW) of the epoxy resin curing agent (including the total amount of benzyl alcohol) was 97.4.

[0103] (Preparation of epoxy resin composition (coating))

[0104] As the epoxy resin as the main component of the epoxy resin composition, a multifunctional epoxy resin having a glycidyloxy group derived from bisphenol A ("jER828" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 186 g / equivalent) was used, and the epoxy resin and the epoxy resin curing agent were blended and mixed in such a manner that the ratio of the number of active hydrogens in the epoxy resin curing agent to the number of epoxy groups in the epoxy resin as the main component (the number of active hydrogens in the epoxy resin curing agent / the number of epoxy groups in the main component epoxy resin) was 1 / 1, thereby preparing an epoxy resin composition (paint).

[0105] The epoxy resin composition thus obtained was used to perform various evaluations by the above-mentioned methods. The results are shown in Table 1.

[0106] Examples 2 to 6, Comparative Examples 1 to 3

[0107] An amine composition was prepared by mixing meta-xylylenediamine and para-xylylenediamine in the mass ratio shown in Table 1. Using the amine composition, an epoxy resin curing agent and an epoxy resin composition were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 1.

[0108] [Table 1]

[0109] Table 1

[0110]

[0111] As shown in Table 1, the epoxy resin compositions containing the epoxy resin curing agent of the present invention have superior water resistance compared to the epoxy resin compositions of Comparative Examples 1 to 3. In addition, the curing speed and coating film properties such as coating film hardness and appearance are at a level that does not cause problems in practical use.

[0112] It should be noted that Figure 1 Graph showing the relationship between the mass ratio of m-xylylenediamine and p-xylylenediamine and the freezing point in an amine composition containing m-xylylenediamine and p-xylylenediamine. Figure 1 As shown in the figure, when the mass ratio of meta-xylylenediamine to para-xylylenediamine (meta-xylylenediamine / para-xylylenediamine) is around 80 / 20, the freezing point is lowered compared with meta-xylylenediamine alone and para-xylylenediamine alone.

[0113] The freezing point of the amine composition is measured by the following method.

[0114] (Determination of Freezing Point)

[0115] The measurement was carried out in accordance with JIS K0065-1992 "Method for determination of freezing point of chemicals".

[0116] Add the sample to the mark on the test tube, and install a silicon plug with a thermometer and a stirring rod inserted. Furthermore, install a large test tube as the outer cover of the test tube. Put it in a bath filled with a coolant and cool it while stirring. As a coolant, use ice water / sodium chloride or water cooled with Coolnics. As the sample begins to solidify, the reading of the thermometer begins to rise, and the temperature when it reaches a constant is taken as the solidification point. When the temperature is not constant and the reading begins to drop, the point obtained by extrapolating the straight line showing the highest reading from the cooling curve is taken as the solidification point. The measurement is performed 3 times and the average value is calculated.

[0117] Industrial Applicability

[0118] The epoxy resin curing agent and epoxy resin composition of the present invention can provide a coating or adhesive having excellent water resistance. The epoxy resin composition of the present invention is suitable for various coatings such as ship coatings, heavy-duty anticorrosive coatings, can coatings, pipe interior coatings, exterior coatings, floor material coatings, and various adhesives for civil engineering and construction fields and film fields.

Claims

1. An epoxy resin curing agent comprising a modified product of an amine composition containing m-xylylenediamine and p-xylylenediamine in a mass ratio of 99 / 1 to 51 / 49, The modified product of the amine composition is a reaction product of the amine composition and an epoxy compound having at least one epoxy group.

2. The epoxy resin curing agent according to claim 1, wherein The mass ratio of m-xylylenediamine to p-xylylenediamine in the amine composition is 99 / 1 to 71 / 29.

3. The epoxy resin curing agent according to claim 1 or 2, wherein The mass ratio of m-xylylenediamine to p-xylylenediamine in the amine composition is 85 / 15 to 75 / 25.

4. The epoxy resin curing agent according to claim 1 or 2, wherein The total content of meta-xylylenediamine and para-xylylenediamine in the amine composition is 50% by mass or more. 5 . The epoxy resin curing agent according to claim 1 , wherein the epoxy compound is an epoxy compound containing an aromatic ring or an alicyclic structure in the molecule. 6 . An epoxy resin composition comprising an epoxy resin and the epoxy resin curing agent according to claim 1 .

7. A coating comprising the epoxy resin composition according to claim 6. An adhesive comprising the epoxy resin composition according to claim 6.

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