Phosphorus-containing compound, phosphorus-containing composition, epoxy resin curing agent, epoxy resin composition, and coating material

Abstract

To provide a phosphorus-containing compound which can provide an epoxy resin composition excellent in transparency and flame retardancy when used as an epoxy resin curing agent, and to provide a phosphorus-containing composition, an epoxy resin curing agent, an epoxy resin composition, and a coating material containing the compound.SOLUTION: There are provided: a phosphorus-containing compound represented by the following general formula (1); and a phosphorus-containing composition, an epoxy resin curing agent, an epoxy resin composition, and a coating material containing the compound. (In the formula, R1 represents a hydrocarbon group; X represents a phenylene group or a cyclohexylene group; and n represents a number of 1-5.)SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a phosphorus-containing compound, a phosphorus-containing composition, an epoxy resin curing agent, an epoxy resin composition, and a coating material. [Background technology]

[0002] In recent years, wood has been actively used for interior and exterior materials and structural components of public facilities, etc. However, because public facilities and other buildings are large in scale and attract large numbers of people, fire prevention restrictions are often imposed by the Building Standards Act. To make wood flame-retardant, fire retardants such as boric acid compounds are usually injected into the wood to make it non-combustible. However, there is an issue with the fire retardant bleeding out of the wood over time, causing the wood to look white (efflorescence). To prevent the flame retardant from bleeding out, it is common to paint the fire-retardant wood, and a fire-resistant paint must be used to prevent the fire retardant from being lost. Fireproof paints are generally opaque and filled with inorganic substances, but there is also a strong demand for fireproof paints that can retain the grain of wood from an appearance perspective, and therefore highly transparent fireproof paints are in demand.

[0003] The use of epoxy resin compositions as coatings is known, and flame-retardant epoxy resin compositions using phosphorus-containing compounds as flame retardants are also known. For example, Patent Document 1 discloses that a flame-retardant epoxy resin composition containing a phosphoric acid amide compound having a specific structure exhibits good flame retardancy without containing halogen, and is excellent in mechanical strength, etc. Patent Document 2 discloses that an epoxy resin composition containing an epoxy resin, a curing agent, and a phosphorus-containing compound having a specific structure has good workability and moldability, and also has an improved Tg of the cured product. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-354836 A [Patent Document 2] International Publication No. 2016 / 152839 Summary of the Invention [Problem to be solved by the invention]

[0005] The phosphoric acid amide compounds and phosphorus-containing compounds disclosed in Patent Documents 1 and 2 are used as a third component other than the epoxy resin and the epoxy resin curing agent, and are components that do not act as an epoxy resin curing agent. An object of the present invention is to provide a phosphorus-containing compound which, when used as an epoxy resin curing agent, can provide an epoxy resin composition having excellent transparency and flame retardancy, and a phosphorus-containing composition, an epoxy resin curing agent, an epoxy resin composition, and a coating material each containing the compound. [Means for solving the problem]

[0006] The present inventors have discovered that a phosphorus-containing compound having a specific structure and a primary amino group can solve the above problems. That is, the present invention relates to the following. [1] A phosphorus-containing compound represented by the following general formula (1): [ka] (In the formula, R 1 represents a hydrocarbon group, X represents a phenylene group or a cyclohexylene group, and n is a number from 1 to 5. [2] R in the general formula (1) 1 is an aryl group having 6 to 18 carbon atoms. [3] The phosphorus-containing compound according to the above [1] or [2], wherein X in the general formula (1) is a phenylene group. [4] A phosphorus-containing composition comprising the phosphorus-containing compound according to any one of the above [1] to [3]. [5] An epoxy resin curing agent comprising the phosphorus-containing compound according to any one of the above [1] to [3] or the phosphorus-containing composition according to the above [4]. [6] An epoxy resin composition comprising an epoxy resin and the epoxy resin curing agent described in [5] above. [7] A paint comprising the epoxy resin composition described in [6] above. Effect of the Invention

[0007] According to the present invention, it is possible to provide a phosphorus-containing compound which, when used as an epoxy resin curing agent, can provide an epoxy resin composition having excellent transparency and flame retardancy, as well as a phosphorus-containing composition, an epoxy resin curing agent, an epoxy resin composition, and a coating material each containing the compound. [Brief description of the drawings]

[0008] [Figure 1] 1 is a 1H-NMR spectrum of the phosphorus-containing composition A obtained in Example 1. [Diagram 2] 2 is a field desorption mass spectrometry (FD-MS) spectrum of the phosphorus-containing composition A obtained in Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Phosphorus-containing compounds] The phosphorus-containing compound of the present invention is a compound represented by the following general formula (1). [ka] (In the formula, R 1 represents a hydrocarbon group, X represents a phenylene group or a cyclohexylene group, and n is a number from 1 to 5. When the above compound is used as an epoxy resin curing agent, an epoxy resin composition having excellent transparency and flame retardancy can be provided. Hereinafter, the phosphorus-containing compound of the present invention may be simply referred to as the "compound of the present invention."

[0010] The reason why the use of the compound of the present invention as an epoxy resin curing agent results in an epoxy resin composition having excellent transparency and flame retardancy is not clear, but is thought to be as follows. The compound of the present invention is a compound obtained by modifying xylylenediamine or bis(aminomethyl)cyclohexane, which are amine-based epoxy resin curing agents, with a specific reactive phosphorus compound. The compound of the present invention has active hydrogen derived from primary amino groups at both ends, and therefore acts as an epoxy resin curing agent. Since the compound of the present invention is a modified compound, it is believed that the curing speed and hardness of the coating film are maintained or improved compared to the case of xylylenediamine or bis(aminomethyl)cyclohexane alone, and furthermore, flame retardancy derived from phosphorus is imparted. For example, xylylenediamine has a problem that it is prone to whitening due to the formation of carbonates by reaction with carbon dioxide in the air, but this problem can be avoided by making it a modified compound represented by general formula (1). In addition, since the compound of the present invention reacts with the epoxy resin and is fixed in the cured product of the epoxy resin composition, no bleed-out occurs, unlike in the case where a flame retardant is added to the epoxy resin composition, and it is considered that transparency is further improved.

[0011] R in the general formula (1) 1 Examples of the hydrocarbon group in R include an alkyl group having 1 to 22 carbon atoms, an aryl group having 6 to 18 carbon atoms, and an aralkyl group having 7 to 20 carbon atoms. 1 is preferably an aryl group having 6 to 18 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, more preferably an aryl group having 6 to 18 carbon atoms, and even more preferably an aryl group having 6 to 10 carbon atoms. Examples of the aryl group include a phenyl group, a toluyl group, a mesityl group, a biphenyl group, and a naphthyl group, and the phenyl group is preferred.

[0012] X in the general formula (1) is a phenylene group or a cyclohexylene group. Specifically, X in the general formula (1) is at least one selected from the group consisting of a 1,2-phenylene group, a 1,3-phenylene group, a 1,4-phenylene group, a 1,2-cyclohexylene group, a 1,3-cyclohexylene group, and a 1,4-cyclohexylene group, and from the viewpoint of obtaining a coating film having high transparency, flame retardancy, chemical resistance, etc., X is preferably a phenylene group, more preferably at least one selected from the group consisting of a 1,2-phenylene group, a 1,3-phenylene group, and a 1,4-phenylene group, and further preferably a 1,3-phenylene group. In this specification, the cyclohexylene group includes both cis and trans isomers.

[0013] From the viewpoint of obtaining a coating film having high transparency, flame retardancy, chemical resistance, etc., the compound of the present invention is preferably a phosphorus-containing compound represented by the following general formula (2). [ka] (In the formula, n is a number from 1 to 5.)

[0014] [Phosphorus-containing composition] The phosphorus-containing composition of the present invention contains a phosphorus-containing compound represented by the general formula (1). For example, the phosphorus-containing composition may be a composition containing a mixture of two or more phosphorus-containing compounds having different numbers of n in the general formula (1). Composition analysis of two or more phosphorus-containing compounds having different numbers of n in the phosphorus-containing composition can be carried out by using field desorption mass spectrometry (FD-MS) according to the method described in the Examples.

[0015] The phosphorus-containing composition may contain, in addition to the phosphorus-containing compound represented by the general formula (1), by-products and unreacted raw materials such as diamine represented by the general formula (3) described below. However, from the viewpoints of fast curing when used as an epoxy resin curing agent, and improving the hardness, transparency and flame retardancy of the coating film of the obtained epoxy resin composition, the content of the phosphorus-containing compound represented by the general formula (1) in the phosphorus-containing composition is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, and 100% by mass or less.

[0016] The content of the compound represented by the general formula (1) in the phosphorus-containing composition and the content of the diamine represented by the general formula (3), which is the unreacted raw material, can be measured by GC analysis.

[0017] <Method of producing phosphorus-containing compound and phosphorus-containing composition> The method for producing the phosphorus-containing compound and the phosphorus-containing composition preferably includes a step of reacting a diamine represented by the following general formula (3) with a compound represented by the following general formula (4). NH2-CH2-X-CH2-NH2(3) (In the formula, X is the same as defined above.) [ka] (In the formula, R 1 is the same as above.)

[0018] A specific example of the diamine represented by the general formula (3) is at least one selected from the group consisting of xylylenediamine and bis(aminomethyl)cyclohexane, and more specifically, at least one selected from the group consisting of orthoxylylenediamine, metaxylylenediamine, paraxylylenediamine, 1,2-bis(aminomethyl)cyclohexane, 1,3-bis(aminomethyl)cyclohexane, and 1,4-bis(aminomethyl)cyclohexane. Among these, from the viewpoint of obtaining a coating film having high transparency, flame retardancy, chemical resistance, etc., the diamine represented by the general formula (3) is preferably xylylenediamine, more preferably at least one selected from the group consisting of metaxylylenediamine and paraxylylenediamine, and even more preferably metaxylylenediamine.

[0019] Specific examples of the compound represented by the general formula (4) include alkyl dichlorophosphates such as ethyl dichlorophosphate, and aryl dichlorophosphates such as phenyl dichlorophosphate.

[0020] In the reaction, from the viewpoint of obtaining the phosphorus-containing compound represented by the general formula (1) and the phosphorus-containing composition containing the same in high yield, it is preferable to react 1.5 to 6.0 moles of the diamine represented by the general formula (3) with 1.0 mole of the compound represented by the general formula (4). From the viewpoint of obtaining the phosphorus-containing compound represented by the general formula (1) with n=1 and the composition containing the compound in high yield, the amount of the diamine represented by the general formula (3) reacted with 1.0 mole of the compound represented by the general formula (4) is more preferably 1.5 to 5.0 moles, still more preferably 1.8 to 4.0 moles, still more preferably 1.8 to 3.0 moles, and still more preferably 1.8 to 2.5 moles.

[0021] The reaction between the diamine represented by the general formula (3) and the compound represented by the general formula (4) is preferably carried out in a solvent from the viewpoint of controlling the reaction rate. The solvent is preferably an aprotic solvent from the viewpoint of dissolving the diamine represented by the general formula (3) and the compound represented by the general formula (4) and from the viewpoint of avoiding side reactions. Examples of aprotic solvents include ethers (tetrahydrofuran, dioxane, diethyl cellosolve, dioxolane, trioxane, dibutyl cellosolve, diethyl carbitol, dibutyl carbitol, etc.), ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, etc.), esters (methyl acetate, ethyl acetate, n-butyl acetate, etc.), and other polar solvents (acetonitrile, dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, etc.), among which ethers are preferred, and tetrahydrofuran is more preferred.

[0022] From the viewpoint of controlling the reaction rate, the reaction is preferably carried out under stirring at a low temperature. The reaction temperature is preferably in the range of −30 to 25° C., more preferably −10 to 15° C. The reaction time can be appropriately selected depending on the scale, etc., but is usually in the range of 0.5 to 12 hours. After the reaction, the salt formed and the reaction solvent are removed, and further purification is carried out as necessary to obtain the phosphorus-containing compound or the phosphorus-containing composition.

[0023] [Epoxy resin hardener] The epoxy resin curing agent of the present invention (hereinafter also referred to as "the curing agent of the present invention") contains the phosphorus-containing compound or the phosphorus-containing composition. The content of the phosphorus-containing compound or the phosphorus-containing composition in all the curing agent components contained in the curing agent of the present invention is, from the viewpoint of obtaining a coating film having high transparency and flame retardancy, preferably 50 mass % or more, more preferably 60 mass % or more, even more preferably 70 mass % or more, still more preferably 80 mass % or more, still more preferably 90 mass % or more, still more preferably 95 mass % or more, and is 100 mass % or less. In this specification, the curing agent component contained in the curing agent means a component contained in the curing agent that has two or more active hydrogens that can react with the epoxy group in the epoxy resin. Also, the content of the phosphorus-containing compound or the phosphorus-containing composition relative to the total amount of the curing agent components contained in the curing agent means the content of the phosphorus-containing compound or the phosphorus-containing composition relative to the total amount of the curable components contained in the curing agent.

[0024] The curing agent of the present invention may be a curing agent made of the phosphorus-containing compound or the phosphorus-containing composition, or may contain other curing agent components, such as polyamine-based curing agents, phenol-based curing agents, acid anhydride-based curing agents, and hydrazide-based curing agents other than the phosphorus-containing compound or the phosphorus-containing composition.

[0025] From the viewpoint of obtaining good coating film properties, the active hydrogen equivalent of the curing agent of the present invention is preferably 50 or more, more preferably 70 or more, and from the viewpoint of improving curing properties, it is preferably 200 or less, more preferably 150 or less, even more preferably 120 or less, and even more preferably 100 or less. The active hydrogen equivalent (hereinafter also referred to as "AHEW") is the mass per mole of active hydrogen of the epoxy resin curing agent.

[0026] [Epoxy resin composition] The epoxy resin composition of the present invention contains an epoxy resin and the epoxy resin curing agent. A coating film formed by the epoxy resin composition of the present invention has high transparency and flame retardancy, and is suitably used, for example, as a paint.

[0027] <Epoxy resin> The epoxy resin, which is 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 coating film having high transparency, flame retardancy, chemical resistance, etc., an epoxy resin containing an aromatic ring or alicyclic structure in the molecule is preferred. Specific examples of the epoxy resin include at least one resin selected from the group consisting of epoxy resins having a glycidylamino group derived from metaxylylenediamine, epoxy resins having a glycidylamino group derived from paraxylylenediamine, 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 paraaminophenol, 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. The above epoxy resins can also be used in combination of two or more kinds.

[0028] Among the above, from the viewpoint of obtaining a coating film having high transparency, flame retardancy, chemical resistance, etc., the epoxy resin is preferably one having as a main component at least one selected from the group consisting of epoxy resins having a glycidylamino group derived from meta-xylylenediamine, epoxy resins having a glycidylamino group derived from para-xylylenediamine, epoxy resins having a glycidyloxy group derived from bisphenol A, and epoxy resins having a glycidyloxy group derived from bisphenol F, and from the viewpoint of obtaining a coating film having high transparency, flame retardancy, chemical resistance, etc., availability and economical aspects, one having as a main component an epoxy resin having a glycidyloxy group derived from bisphenol A is more preferred. The term "main component" used here means that other components may be contained within a range that does not deviate from the spirit of the present invention, and preferably means 50 to 100% by mass, more preferably 70 to 100% by mass, and even more preferably 90 to 100% by mass of the total.

[0029] The epoxy resin may be either a solid epoxy resin or a liquid epoxy resin. In the present invention, the term "solid epoxy resin" refers to an epoxy resin that is solid at room temperature (25° C.), and the term "liquid epoxy resin" refers to an epoxy resin that is liquid at room temperature (25° C.).

[0030] The epoxy equivalent of the epoxy resin is preferably 150 g / equivalent or more from the viewpoint of obtaining a coating film having high transparency, flame retardancy, chemical resistance, etc., and from the viewpoint of curability, it is preferably 1000 g / equivalent or less, more preferably 800 g / equivalent or less, even more preferably 500 g / equivalent or less, still more preferably 300 g / equivalent or less, and even more preferably 250 g / equivalent or less.

[0031] <Content> In the epoxy resin composition of the present invention, 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.

[0032] The content of the epoxy resin in the epoxy resin composition is not limited as long as the above (number of active hydrogens in the epoxy resin curing agent / number of epoxy groups in the epoxy resin) is preferably within the above range, but is preferably 50 to 85 mass%, more preferably 60 to 80 mass%, and even more preferably 65 to 75 mass%.

[0033] The content of the epoxy resin curing agent in the epoxy resin composition is not limited as long as the above (number of active hydrogens in the epoxy resin curing agent / number of epoxy groups in the epoxy resin) is preferably within the above range, but is preferably 15 to 50 mass%, more preferably 20 to 40 mass%, and even more preferably 25 to 35 mass%.

[0034] The epoxy resin composition of the present invention may further contain other components according to the application, such as known curing accelerators, non-reactive diluents such as benzyl alcohol, fillers, modifying components such as plasticizers, flow adjusting components such as thixotropic agents, pigments, leveling agents, tackifiers, and elastomer fine particles, within the scope of not impairing the effects of the present invention. 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, even more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, and is 100% by mass or less.

[0035] In order to obtain a coating film having high transparency, flame retardancy, chemical resistance, etc., it is preferable that the epoxy resin composition of the present invention has a small content of water and organic solvent. The content of water and organic solvent in the epoxy resin composition is preferably 10% by mass or less, more preferably 5.0% by mass or less, even more preferably 3.0% by mass or less, still more preferably 2.0% by mass or less, and even more preferably 1.0% by mass or less, from the viewpoint of obtaining a coating film having high transparency, flame retardancy, chemical resistance, etc.

[0036] <Method for preparing epoxy resin composition> There is no particular limitation on the method for preparing the epoxy resin composition, and the epoxy resin, the epoxy resin curing agent, and other components as necessary can be mixed and produced using a known method and device. There is also no particular limitation on the order of mixing the components contained in the epoxy resin composition, and the epoxy resin curing agent may be mixed with the epoxy resin after being prepared, or the epoxy resin may be simultaneously mixed with each component constituting the epoxy resin curing agent and other components.

[0037] The coating film, which is the cured product of the epoxy resin composition of the present invention, can be obtained by curing the above-mentioned epoxy resin composition of the present invention by a known method. The curing conditions of the epoxy resin composition are appropriately selected depending on the application and form, and are not particularly limited. The coating film which is the cured product of the epoxy resin composition of the present invention has excellent transparency and flame retardancy, is resistant to whitening, and has a high oxygen index.

[0038] <Flame retardancy> The epoxy resin composition of the present invention has high flame retardancy. Specifically, the oxygen index of a cured product of the epoxy resin composition having a thickness of 3 mm, measured in accordance with JIS K 7201:1995, is preferably 22 or more, more preferably 23 or more, and even more preferably 24 or more. The degree of flame retardancy can be confirmed by measuring the oxygen index, which is one of the indicators of flame retardancy. The oxygen index indicates the concentration of oxygen required to continue combustion, and if it exceeds 21, combustion in air will not continue under normal conditions. Specifically, the oxygen index can be measured by the method described in the Examples.

[0039] [paint] The present invention provides a coating material containing the epoxy resin composition. The coating material of the present invention contains the epoxy resin composition, and thereby the transparency and flame retardancy of the coating film obtained are excellent. Examples of the coating material include wood coating materials used as interior and exterior materials and structural members of buildings, marine coating materials, heavy-duty anticorrosive coating materials, tank coating materials, pipe interior coating materials, exterior coating materials, and floor coating materials. In order to effectively obtain the effects of the present invention, the paint according to the present invention is preferably a transparent flame-retardant paint.

[0040] From the viewpoint of improving transparency and flame retardancy, the content of the epoxy resin composition in the coating material of the present invention is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, still more preferably 90% by mass or more, and even more preferably 95% by mass or more, and 100% by mass or less.

[0041] <Application> The epoxy resin composition can be suitably used for applications such as the coating material, adhesives, flooring materials, sealants, polymer cement mortar, gas barrier coatings, primers, screeds, top coats, sealing materials, crack repair materials, concrete materials, and the like. EXAMPLES

[0042] 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. Measurements and evaluations in the examples were carried out by the following methods.

[0043] (Structural analysis of phosphorus-containing compounds) The structural analysis of the phosphorus-containing compound in the phosphorus-containing composition is 1 The measurement conditions were as follows: Nuclear magnetic resonance spectrometer: AVANCEIII-500 manufactured by Bruker Biospin Corporation Probe: 5mmφ double resonance multinuclear probe (BBFO Plus Smart probe) Deuterated solvent; deuterated chloroform Measurement nucleus; 1H Measurement temperature; room temperature

[0044] (Compositional Analysis of Phosphorus-Containing Composition) The presence or absence of the compound in which n=1 to 5 in the general formula (1) and the unreacted raw material meta-xylylenediamine in the phosphorus-containing composition was analyzed by field desorption mass spectrometry (FD-MS) under the following measurement conditions. FD-MS:AccuTOF GCV 4G (JMS-T100GCV) JEOL Ionization mode:Field Desorption (Positive) Range: m / z=30-1600 Emitter current:0mA~40mA 51.2mA / min Resolution:8000 (at m / z=501.9711(C9F20N)) Counter electrode Voltage:-10kV Detector voltage: 2000V Sampling interval: 0.25ns Recording interval: 0.5s Drift compensation:m / z=501.9711 (C9F20N)

[0045] (Measurement of active hydrogen equivalent (AHEW)) The AHEW of the phosphorus-containing composition (curing agent) was calculated from the total amine value and secondary and tertiary amine value determined using an automatic potentiometric titrator "AT-710S" manufactured by Kyoto Electronics Manufacturing Co., Ltd. The total amine value was measured using a 0.1 mol / L perchloric acid / acetic acid solution (manufactured by Kanto Chemical Co., Ltd.), and the secondary and tertiary amine values ​​were measured using 0.1 mol / L hydrochloric acid (2-propanol).

[0046] (Dry to the touch) A zinc phosphate-treated steel plate (SPCC-SD PB-N144 0.8×70×150 mm, manufactured by Paltec Co., Ltd.) was used as the substrate. The epoxy resin composition of each example was applied onto the substrate using an applicator to form a coating (coating thickness immediately after application: 200 μm). This coating was stored under conditions of 23°C and 50% RH, and evaluated by touch after one day according to the following criteria. Ex: Excellent (Even when pressed with a force of about 50N using a thumb, the coating does not become sticky and no fingerprints remain) G: Good (the coating is not sticky when the thumb is pressed against it with a force of about 50N, but fingerprints remain after touching it) F: Fair (the coating is sticky when you press your thumb against it with a force of about 50N) P: Poor (the coating is sticky when pressed with a thumb with a force of about 5N)

[0047] (Pencil hardness) Each epoxy resin composition was applied to a substrate (zinc phosphate-treated steel plate) in the same manner as above to form a coating (thickness immediately after application: 200 μm). This coating was stored under conditions of 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.

[0048] (Water resistance spot test) The epoxy resin composition of each example was applied to a substrate (zinc phosphate-treated steel plate) in the same manner as above to form a coating (thickness immediately after application: 200 μm). This coating was stored under conditions of 23°C and 50% RH, and after 1, 2, and 7 days, 2 to 3 drops of pure water were dropped onto the coating surface with a dropper, and the area was covered with a 50 mL screw cap. After 24 hours, the water was wiped off, and the appearance was visually observed and evaluated according to the following criteria. Ex: Excellent (no change at all) G: Good (slight changes, but no problems in use) F: Fair (slightly whitened) P: Poor (whitening)

[0049] (RCI curing time) The epoxy resin composition of each example was applied to a glass plate (25 x 348 x 2.0 mm, manufactured by Taiyu Kizai Co., Ltd.) using a 76 μm applicator at 23°C and 50% RH to form a coating film. The glass plate on which the coating film was formed was set in a paint drying time measuring device (manufactured by Taiyu Kizai Co., Ltd.), and the time to reach each drying stage (Set to Touch, Dust Free, Dry Through) was measured according to the following criteria by observing the marks left when the needle of the measuring device scratched the coating film surface. A shorter time indicates a faster curing speed. Set to Touch: The time it takes for the needle to start leaving a mark on the glass plate. Dust Free: The time it takes for the needle mark to appear on the surface of the coating. Dry Through: The time it takes for the needle mark on the coating to disappear

[0050] (Coating appearance) Each epoxy resin composition was applied to a substrate (zinc phosphate-treated steel plate) in the same manner as above to form a coating (thickness immediately after application: 200 μm). This coating was stored under conditions of 23° C. and 50% RH, and the appearance of the coating after 7 days was visually observed and the smoothness was evaluated according to the following criteria. <Transparency> Ex: Excellent (no turbidity) G: Good (slightly cloudy, but no problem in use) F: Fair (some parts are cloudy) P: Poor (all surfaces are cloudy) <Smoothness> Ex: Excellent (no unevenness) G: Good (slightly uneven, but no problem in use) F: Acceptable (some unevenness) P: Poor (cracking or unevenness on the entire surface) <Glossiness> Ex: Excellent (glossy) G: Good (slightly less glossy, but no problems in use) F: Fair (low gloss) P: Poor (no gloss)

[0051] (Oxygen Index) The epoxy resin composition of each example was heated at 80° C. for 1 hour to cure, and then molded into a test piece of 70 mm×6.5 mm×3 mm. Using the above test specimen, the oxygen index was measured by a candle combustion tester type D (manufactured by Toyo Seiki Seisakusho) according to a method conforming to JIS K 7201: 1995. A higher oxygen index means better flame retardancy.

[0052] Example 1 (Synthesis of phosphorus-containing composition A) In a 200mL three-neck flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, a dropping funnel and a cooling tube, 27.2g (0.2 mol) of metaxylylenediamine (MXDA, manufactured by Mitsubishi Gas Chemical Co., Ltd.) was mixed with 100mL of THF. In a state cooled to 0°C, 10.56g (0.1 mol) of phenyl dichlorophosphate dissolved in 50mL of THF was carefully dropped. After completion of the dropping, the temperature was returned to room temperature and stirring was performed for 6 hours. The salt formed was then filtered, and the solvent was removed from the filtrate with an evaporator. The obtained liquid was vacuum dried at 45°C for 3 hours to obtain a phosphorus-containing composition A containing a phosphorus-containing compound represented by the following formula (2) where n = 1, 2, 3, 4, 5. The AHEW of the phosphorus-containing composition A was 81.9.

[0053] [ka] (In the formula, n is a number from 1 to 5.)

[0054] FIG. 1 shows the phosphorus-containing composition A. 1 H-NMR spectrum: δ 2.51 ppm (s, -NH2, -NH-), δ 3.36 ppm (s, -CH2-NH-Ph), 3.81 ppm (s, -Ph-CH2-NH2), 7.0-7.4 ppm (m, -C6H4-, -C6H5O-) In addition, in Fig. 1 1 The H-NMR spectrum also contains a peak of the unreacted raw material, meta-xylylenediamine.

[0055] Figure 2 shows the FD-MS spectrum of phosphorus-containing composition A. In addition to the unreacted raw material metaxylylenediamine, peaks of phosphorus-containing compounds represented by the above formula (2) where n = 1, 2, 3, 4, 5 were detected. Specifically, the peaks corresponding to each compound were identified as follows. m / z=137.10: meta-xylylenediamine (Mw136.19) m / z=411.18: Compound in which n=1 in the formula (2) (Mw 410.19) m / z=685.28: Compound in which n=2 in the formula (2) (Mw 684.27) m / z=959.37: Compound in which n=3 in the formula (2) (Mw 958.35) m / z=1233.46: Compound in which n=4 in the formula (2) (Mw 1232.43) m / z=1507.54: Compound in which n=5 in the formula (2) (Mw 1506.51)

[0056] Example 2 (Preparation and Evaluation of Epoxy Resin Composition) A polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol A ("jER828" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 186 g / equivalent) was used as the epoxy resin, which is the main component of the epoxy resin composition. The phosphorus-containing composition A obtained in Example 1 was used as the epoxy resin curing agent. An epoxy resin composition was prepared by mixing the epoxy resin and the epoxy resin curing agent in the amounts of mass % shown in Table 1. 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) was 1 / 1. The obtained epoxy resin composition was subjected to various evaluations by the above-mentioned methods, and the results are shown in Table 1.

[0057] Comparative Example 1 Epoxy resin compositions were prepared and various evaluations were carried out in the same manner as in Example 1, except that the components and amounts used in Example 1 were changed as shown in Table 1. The results are shown in Table 1.

[0058] [Table 1]

[0059] The components used in Table 1 are as follows: *1: Multifunctional epoxy resin with glycidyloxy groups derived from bisphenol A ("jER828" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 186g / equivalent) *2: Phosphorus-containing composition A synthesized in Example 1 (AHEW: 81.9) *3: Metaxylylenediamine (MXDA, Mitsubishi Gas Chemical Co., Ltd., AHEW:34)

[0060] From Table 1, it can be seen that the phosphorus-containing composition of this example has the same or improved performance as an epoxy resin curing agent (curing speed, hardness, water resistance, and appearance of the resulting coating film) compared to metaxylylenediamine. In addition, it can be seen that the cured product of the epoxy resin composition containing the curing agent of this example has good transparency and flame retardancy. [Industrial Applicability]

[0061] According to the present invention, it is possible to provide a phosphorus-containing compound which, when used as an epoxy resin curing agent, can provide an epoxy resin composition having excellent transparency and flame retardancy, as well as a phosphorus-containing composition, an epoxy resin curing agent, an epoxy resin composition, and a coating material each containing the compound.

Claims

1. A phosphorus-containing compound represented by the following general formula (1): 【Chemical 1】 (In the formula, R １ represents a hydrocarbon group, X represents a phenylene group or a cyclohexylene group, and n is a number from 1 to 5.

2. R in the general formula (1) １ The phosphorus-containing compound according to claim 1, wherein is an aryl group having 6 to 18 carbon atoms.

3. 3. The phosphorus-containing compound according to claim 1, wherein X in the general formula (1) is a phenylene group.

4. A phosphorus-containing composition comprising the phosphorus-containing compound of claim 1.

5. An epoxy resin curing agent comprising the phosphorus-containing compound according to claim 1 or the phosphorus-containing composition according to claim 4.

6. An epoxy resin composition comprising an epoxy resin and the epoxy resin curing agent according to claim 5.

7. A paint comprising the epoxy resin composition according to claim 6.

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