Epoxy resin curing catalyst and method for producing thermosetting epoxy resin composition

Abstract

To provide an epoxy curing catalyst that can suppress a catalyst cost in an epoxy resin by single use and a reduction of use amount of a catalyst, is excellent in storage stability, and is small in skin irritation and environmental load.SOLUTION: It was found that a specific metal chelate coordinated with an aromatic sulfonic acid compound shows sufficient curing catalyst activity in a smaller amount than conventional epoxy curing catalysts, and has excellent storage stability, skin irritation and low environmental load.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a curing catalyst used in curing an epoxy resin and a method for producing an epoxy resin composition. [Background technology]

[0002] Epoxy resins have excellent electrical, mechanical and thermal properties, and are relatively inexpensive, so they are widely used industrially as electrical insulating materials, structural members, adhesives, etc. In order to synthesize epoxy resins, catalysts such as hardeners and hardening accelerators are generally used because the reactivity is low when epoxy monomers are heated alone. As hardeners and hardening accelerators, thiol compounds, amine compounds, acid anhydride compounds, phenolic compounds, complexes of aluminum chelates and silane compounds, boron complexes, and phosphorus compounds are used.

[0003] Curing agents such as amine compounds, acid anhydride compounds, and phenol compounds have a mechanism whereby the curing agent itself is incorporated into the epoxy resin to harden it. Therefore, the amount of curing agent needs to be high, 20-100% of the epoxy resin, making it difficult to utilize the mechanical and thermal properties specific to epoxy resins, and there are also problems such as the high cost of the catalyst in the epoxy resin. In addition, there are concerns about skin irritation with amines, and there is a problem with acid anhydrides polluting the work environment due to their volatility and sublimation. (Non-Patent Document 1 and Patent Document 1)

[0004] Therefore, a cationic curing catalyst using an aluminum chelate and a silane compound as an auxiliary curing agent was reported in 1982-10623. However, the highly active phenyl-containing silane compound is extremely expensive, and its advantage in terms of production costs is very low. Furthermore, there are environmental issues, such as the inclusion of harmful substances such as PCBs during production. (Patent Document 2)

[0005] In addition, when a thermosetting resin is used latentally, if the resin and the curing agent are mixed and stored in advance, the viscosity increases over time, resulting in low storage stability and limited usage conditions. As a means of solving such problems, curing agent particles in which the curing agent is microencapsulated are used. However, microcapsules have problems such as being easily permeated by organic solvents and resins, and having a limit to the amount of hardener they can hold. Furthermore, the increased number of special processes required to prepare such microcapsules poses problems in terms of workability and cost. (Patent Document 3 and Patent Document 4)

[0006] There are several known compounds that have activity as epoxy polymerization catalysts, representative examples of which include boron fluoride amine salts and dicyandiamide (DICY). However, because these are solid, highly polar compounds, they are not easily dissolved in resins, and DICY in particular has an issue with its low dispersibility, and in addition, it requires treatment at high temperatures, often requiring a separate accelerator. (Non-Patent Document 2) [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 4826256 [Patent Document 2] Patent Publication No. 57-10623 [Patent Document 3] Patent Publication 2008-156570 [Patent Document 4] International Publication No. 2005 / 033173 [Non-patent literature]

[0008] [Non-Patent Document 1] Journal of the Adhesion Society of Japan Vol.53 No.4(2017) [Non-Patent Document 2] Network Polymer Vol.30 No.6(2009) Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention provides an epoxy curing catalyst which exhibits high curing catalytic activity by itself without using an auxiliary curing agent such as an expensive silane compound or other curing agents in combination, and has high storage stability and latent curing activity; and a method for producing a thermosetting epoxy resin composition which uses the epoxy curing catalyst and can produce an epoxy resin cured product having excellent mechanical and thermal properties and which can be produced at low total production costs by not using an expensive silane compound or the like. [Means for solving the problem]

[0010] The present inventors have conducted intensive research aimed at developing the epoxy curing catalyst described above and an epoxy resin composition using the same, and as a result have found that a metal chelate coordinated with an aromatic sulfonic acid compound is an epoxy curing catalyst that exhibits curing catalytic activity by itself without the need for the use of an expensive auxiliary curing agent such as a silane compound or other curing agent, and has high storage stability and latent curing activity. Furthermore, by using this epoxy resin curing catalyst, they have found a method for producing a thermosetting epoxy resin composition that can produce an epoxy resin cured product that has excellent mechanical and thermal properties inherent to epoxy resins and can be produced at low total production costs, thereby completing the present invention.

[0011] That is, the epoxy curing catalyst of the present invention is (1) A catalyst metal chelate compound for epoxy curing in which an aromatic sulfonic acid compound represented by general formula (a) is coordinated to a metal atom. JPEG0007670505000001.jpg3080 (n in the formula is an integer between 0 and 5. R 1 is not particularly limited, and may represent a linear or branched alkyl group having 1 to 20 carbon atoms, an acyl group, a phenyl group, etc. In addition, when n is 2 or more, R 1 do not necessarily have to be of the same structure.)

[0012] (2) The epoxy curing catalyst metal chelate compound according to (1), wherein the metal atom of the metal chelate is selected from aluminum, zinc, and titanium.

[0013] (3) The epoxy curing catalyst metal chelate compound according to (1), wherein the average molecular coordination number of the aromatic sulfonic acid compound to each metal atom according to (2) above is 0.2 to 3.0 for aluminum, 0.2 to 2.0 for zinc, and 0.2 to 4.0 for titanium.

[0014] (4) An epoxy curing catalyst metal chelate compound according to any one of (1) to (3) above, wherein the metal atom of the metal chelate is aluminum.

[0015] (5) A method for producing a thermosetting epoxy resin composition, which uses the epoxy curing catalyst metal chelate compound according to (1) to (4) in an amount of 0.1 to 20 wt % based on the epoxy resin. Effect of the Invention

[0016] The present invention is a metal chelate catalyst that is not an amine or an acid anhydride, which have been used as epoxy curing catalysts in the past, and which exhibits high curing catalytic activity with a small amount of the metal chelate compound alone without the need for combined use of an expensive auxiliary curing agent such as a silane compound or other curing agents, and is an epoxy curing catalyst metal chelate that has high storage stability and latent curing activity. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present invention will be described in more detail below with reference to specific examples, but the present invention is not limited to these descriptions in any way.

[0018] The metal chelate catalyst for epoxy curing of the present invention is one in which an aromatic sulfonic acid compound represented by the following general formula (a) is coordinated to a metal atom. JPEG0007670505000002.jpg3080In the general formula (a), n is an integer of 0 to 5, and R 1is not particularly limited since it has little effect on the curing activity, but may be an aromatic sulfonic acid compound represented by an alkyl group, an alkyl ether group, an alkenyl group, a phenyl group, etc. having 1 to 20 carbon atoms. 1 are not necessarily all the same. Specific examples include benzenesulfonic acid, p-toluenesulfonic acid, ethylbenzenesulfonic acid, propylbenzenesulfonic acid, octylbenzenesulfonic acid, dodecylbenzenesulfonic acid, p-xylene-2-sulfonic acid, m-xylene-4-sulfonic acid, mesitylenesulfonic acid, 4-acetylbenzenesulfonic acid, and 2-naphthalenesulfonic acid. As long as it satisfies the general formula (a) and is coordinated to a metal atom, it can be used sufficiently as an epoxy curing catalyst. However, the smaller the molecular weight of the epoxy curing metal chelate catalyst, the less the weight of the epoxy curing metal chelate catalyst required at a minimum for curing the resin. As a result, the ratio of epoxy resin to the cured product increases, making it easier to maintain the original properties of the resin. For this reason, n is preferably 0 to 2, and R 1 The number of carbon atoms in is preferably 1 to 5. Specific examples include benzenesulfonic acid, p-toluenesulfonic acid, ethylbenzenesulfonic acid, propylbenzenesulfonic acid, p-xylene-2-sulfonic acid, and m-xylene-4-sulfonic acid. From the viewpoint of raw material procurement, n is preferably 0 to 1, R is preferably 1 to 5, and R is preferably 1 to 5 because they are inexpensive and easily available. 1 is more preferably an alkyl group, and specific examples thereof include p-toluenesulfonic acid and ethylbenzenesulfonic acid.

[0019] The metal atom in the epoxy curing metal chelate catalyst of the present invention is preferably aluminum, zinc or titanium, and aluminum is more preferred because it has high curing catalytic activity and causes the least coloring of the resin.

[0020] Examples of the raw material for the aforementioned metal atoms include metal hydroxides, metal oxides, metal salts, and metal alkoxy chelate compounds, with metal alkoxy chelate compounds being more preferred due to the ease of subsequent steps.

[0021] Specific examples of metal hydroxides include aluminum hydroxide, titanium oxyhydroxide, and zinc hydroxide.

[0022] As the metal oxide, aluminum oxide such as boehmite, bayerite, gibbsite, γ-alumina, δ-alumina, θ-alumina, etc. is preferable. As the titanium oxide, anatase type, rutile type, and brookite type are preferable. As the zinc oxide, there is no limitation.

[0023] Specific examples of metal salts include chlorides, nitrates, sulfates, carbonates, etc. Specific examples include aluminum chloride, aluminum nitrate, aluminum sulfate, zinc chloride, zinc nitrate, zinc sulfate, carbonic acid, ammonium aluminum carbonate, ammonium titanium lactate, titanium lactate, etc.

[0024] Specific examples of aluminum alkoxides in metal alkoxy chelate compounds include aluminum ethoxide, aluminum isopropoxide, aluminum n-butoxide, aluminum sec-butoxide, etc., and specific examples of aluminum chelates include cyclic aluminum oligomers, diisopropoxy(ethylacetoacetato)aluminum, and tris(ethylacetoacetato)aluminum. Specific examples of titanium alkoxy chelate compounds include tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetraoctyl titanate, titanium acetylacetonate, titanium ethylacetoacetate, and titanium octylene glycolate. Specific examples of zinc alkoxy compounds include zinc dimethoxide and zinc diethoxide.

[0025] In the epoxy curing catalyst metal chelate compound of the present invention, the aromatic sulfonic acid compound must be coordinated to a metal atom in order to exhibit curing activity. Examples of other compounds that coordinate to the same metal atom as the aromatic sulfonic acid compound include β-ketoester compounds represented by general formula (b), β-diketone compounds represented by general formula (c), and alcohols represented by general formula (d). The β-ketoester compound represented by general formula (b) is as follows. R 2 -O-CO-CH 2 -CO-R 3 General formula (b) R in the formula 2 , R 3 is preferably a β-ketoester compound represented by an alkyl group, an alkenyl group, or an aromatic group having 1 to 30 carbon atoms. If the average molecular weight of the synthesized epoxy curing metal chelate catalyst is small, the minimum weight of the epoxy curing metal chelate catalyst required to cure the resin is small, and the ratio of the epoxy resin to the cured product is accordingly high. This makes it easier to maintain the original properties of the resin. 2 , R 3 More preferably, R has 1 to 18 carbon atoms. These are also easy to obtain and excellent in terms of cost. Specific examples include ethyl acetoacetate, butyl acetoacetate, octyl acetoacetate, lauryl acetoacetate, myristyl acetoacetate, stearyl acetoacetate, oleyl acetoacetate, methyl propionyl acetate, ethyl propionyl acetate, methyl isobutyryl acetate, and methyl pivaloyl acetate. In particular, the synthesized epoxy curing metal chelate catalyst is in a liquid state, which is advantageous when mixed with the resin and in other handling. Therefore, R 2 is even more preferably an alkyl group or alkenyl group having a carbon number of 14 to 18. Specific examples include myristyl acetoacetate, stearyl acetoacetate, and oleyl acetoacetate.

[0026] The β-diketone compound represented by general formula (c) is as follows. R 4 -CO-CHR 5 -CO-R6 General formula (c) R in the formula 4 , R 5 and R 6 is a β-diketone compound represented by a hydrogen atom or an alkyl group, alkenyl group or aromatic group having 1 to 24 carbon atoms, and specific examples include acetylacetone, benzoylacetone, dibenzoylmethane, etc. If the average molecular weight of the synthesized epoxy curing metal chelate catalyst is small, the minimum weight of the epoxy curing metal chelate catalyst required to cure the resin is small, and the ratio of epoxy resin to the cured product is accordingly high. This makes it easier to maintain the original properties of the resin. Therefore, R 4 , R 5 and R 6 is more preferably a hydrogen atom or an alkyl or alkenyl group having a carbon number of 1 to 5, which has a relatively small molecular weight. Specific examples include acetylacetone and dipivaloylmethane.

[0027] The alcohol compound represented by general formula (d) is as follows. H.O.R. 7 General formula (d) R in the formula 7is preferably an alcohol compound represented by an alkyl group, alkenyl group or aromatic group having 1 to 24 carbon atoms. If the carbon number is small, the resulting epoxy curing catalyst metal chelate compound may be easily solidified and its dispersibility in the resin may decrease, making it difficult to handle, and if the carbon number is large, the melting point may increase and it may be difficult to synthesize aluminum alkoxide, so the carbon number is more preferably 3 to 18. Specific examples include methanol, ethanol, n-propanol, 2-propanol, n-butanol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, 1-hexanol, lauryl alcohol, myristyl alcohol, stearyl alcohol, oleyl alcohol, behenyl alcohol, 1-tetracosanol, cyclohexanol, phenol, cresol, and quinolinol. Furthermore, if the average molecular weight of the synthesized epoxy curing catalyst metal chelate compound is small, the minimum weight of the epoxy curing catalyst metal chelate compound required to cure the resin is small, and therefore the ratio of the epoxy resin to the cured product is high, making it easier to maintain the original properties of the resin. Therefore, R 7 More preferably, the alcohol is an alkyl group or an alkenyl group having a carbon number of 3 to 5. Specific examples include n-propanol, 2-propanol, n-butanol, and isobutyl alcohol.

[0028] The average molecular coordination number of the aromatic sulfonic acid compound for each metal atom is preferably 0.2 to 3.0 for aluminum, 0.2 to 2.0 for zinc, and 0.2 to 4.0 for titanium. If the average molecular coordination number of the aromatic sulfonic acid compound to the metal atom is less than 0.2, sufficient curing activity may not be exhibited. In addition, it is difficult to obtain a structure with an average molecular coordination number exceeding each upper limit, and the excess may not act as a curing catalyst, resulting in high costs. The curing activity changes as the average molecular coordination number of each ligand changes, but the optimal average molecular coordination number varies depending on the type of epoxy resin, so it is not fixed.

[0029] The average total molecular coordination number of the β-ketoester compound of general formula (b), the β-diketone compound of general formula (c), and the alcohol of general formula (d) to each metal atom is preferably 0 to 2.5 when the metal atom is aluminum, 0 to 1.5 when the metal atom is zinc, and 0 to 3.5 when the metal atom is titanium. When the average total molecular coordination number of the β-ketoester compound of general formula (b), the β-diketone compound of general formula (c), and the alcohol of general formula (d) to each metal atom is above the upper limit, the proportion of the aromatic sulfonic acid compound decreases, and the curing activity may decrease. Also, R 2 is an alkyl or alkenyl group having 14 to 18 carbon atoms, the average coordination number of the β-keto ester compound of general formula (b) being 1.0 to 2.5 when the metal atom is aluminum, 1.0 to 1.5 when the metal atom is zinc, or 1.0 to 3.5 when the metal atom is titanium, since this makes it possible to obtain a liquid epoxy curing catalyst metal chelate compound which can be easily mixed into a resin, which is more preferable. Furthermore, since the β-ketoester compound of the general formula (b) is relatively expensive, it is more preferable that the average coordination number is 1.0 to 1.5 from the viewpoint of cost.

[0030] In the epoxy curing catalyst metal chelate compound of the present invention, the aromatic sulfonic acid compound must be coordinated to a metal atom in order to exhibit curing activity. From the viewpoints of ease of handling, ease of mixing with resins, ease of availability, and cost, it is preferable that the central metal atom is aluminum, the average coordination number of the aromatic sulfonic acid compound of general formula (a) is 0.3 to 1.0, and R 2 It is more preferable that the average coordination number of the β-keto ester compound in which the alkyl group or alkenyl group has 14 to 18 carbon atoms is 1.0 to 1.5. Specific examples include mono(myristyl acetoacetate) mono(p-toluenesulfonate) aluminum isopropoxide, mono(oleyl acetoacetate) mono(p-toluenesulfonate) aluminum isopropoxide, and mono(stearyl acetoacetate) mono(p-toluenesulfonate) aluminum isopropoxide.

[0031] Manufacturing method The epoxy curing catalyst metal chelate compound of the present invention can be produced, for example, by the following method when a metal alkoxide is used as the metal source. That is, a predetermined molar amount of the designed aromatic sulfonic acid compound of general formula (a), one or more selected from the β-ketoester compound of general formula (b), the β-diketone compound of general formula (c), and the alcohol of general formula (d) are dropped into the metal alkoxide as is, or as a solution in which they are dissolved in an appropriate solvent (e.g., 2-propanol, ethanol, etc.). By heating this, a monohydric alcohol that was coordinated with the raw material metal alkoxide is generated. The generated monohydric alcohol is distilled and removed under reduced pressure, and the desired epoxy curing catalyst metal chelate compound can be produced. This product can be used without purification, and if there is no problem with it being mixed into an epoxy resin or the like to be used subsequently, the product may be handled as a solution without being distilled off under reduced pressure.

[0032] The reaction is carried out at a reaction temperature of 60° C. to 200° C., and more preferably at a temperature of 100° C. to 150° C. If the reaction temperature is below 60° C., the reaction proceeds slowly, leading to undesirable conditions, whereas if the reaction temperature exceeds 200° C., the reaction may reach or exceed the boiling point of the raw materials, or thermal decomposition may occur.

[0033] Even when the metal source is other than a metal alkoxide, the desired epoxy curing catalyst metal chelate compound can be produced by reacting an aromatic sulfonic acid compound of general formula (a) in a predetermined molar amount designed relative to the metal with a β-ketoester compound of general formula (b), a β-diketone compound of general formula (c), and an alcohol of general formula (d).

[0034] Specific examples of the epoxy curing catalyst metal chelate compound of the present invention include monoacetylacetonate aluminum isopropoxy mono(benzenesulfonate) chelate, monoacetylacetonate aluminum di(benzenesulfonate) chelate, ethylacetoacetate aluminum isopropoxy mono(p-toluenesulfonate) chelate, monoethylacetoacetate aluminum mono(p-toluenesulfonate) chelate, monoethylacetoacetate aluminum isopropoxy mono(dodecylbenzenesulfonate) chelate, diisopropoxyaluminum mono(dodecylbenzenesulfonate) chelate, decylbenzenesulfonate) chelate, monooleyl acetoacetate aluminum isopropoxy mono(dodecylbenzenesulfonate), bisethyl acetoacetate aluminum mono(dodecylbenzenesulfonate) chelate, monooleyl acetoacetate aluminum mono(benzenesulfonate) chelate, monooleyl acetoacetate aluminum isopropoxy mono(m-xylene-4-sulfonate) chelate, aluminum tris(p-toluenesulfonate) chelate, aluminum tris(dodecylbenzenesulfonate) chelate, and the like.

[0035] Examples of epoxy resins for which the epoxy curing catalyst metal chelate compound of the present invention exhibits curing catalytic activity include glycidyl ether type epoxy resins (bisphenol A type, bisphenol F type, phenol novolak type, etc.), cyclic aliphatic epoxy resins (alicyclic diepoxy acetal, alicyclic diepoxy adipate, etc.), glycidyl ester type epoxy resins (diglycidyl ester of phthalic acid, diglycidyl ester of tetrahydrophthalic acid, etc.), glycidyl amine type epoxy resins (tetraglycidyl diaminodiphenylmethane, triglycidyl p-aminophenol, etc.), heterocyclic epoxy resins (hydantoin type epoxy resins such as diglycidyl hydantoin, triglycidyl isocyanurate), and resins obtained by modifying these epoxy resins with amines or polyamides, and these epoxy resins also include monomers and oligomers.

[0036] Hardeners and accelerators The epoxy curing catalyst metal chelate of the present invention can be used in combination with other commonly used curing agents and curing accelerators. For example, bifunctional phenols such as bisphenol A, hydroquinone, resorcinol, bisphenol F, tetrabromobisphenol A, and naphthalenediol, polyfunctional phenol novolac resins, and cresol novolac resins are also included.

[0037] Silane Compounds The epoxy curing catalyst metal chelate of the present invention can be used in combination with a silane compound for the purpose of reducing the curing temperature and shortening the curing time depending on the type of epoxy resin used.Specific examples include epoxy-based compounds such as 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropylmethyldiethoxysilane, amine-based silane treating agents such as N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, as well as p-styryltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-isocyanatepropyltriethoxysilane, triphenylmethoxysilane, and diphenyldimethoxysilane.

[0038] The thermosetting epoxy resin composition in the present invention is a pre-cured mixture essentially containing an epoxy resin and a curing agent.

[0039] Method for producing thermosetting epoxy resin composition The thermosetting epoxy resin composition using the epoxy curing catalyst metal chelate compound of the present invention can be produced, for example, by the following method. That is, the desired thermosetting epoxy resin composition can be produced by adding an arbitrary amount of the epoxy curing catalyst metal chelate compound of the present invention to the above-mentioned epoxy resin and stirring and mixing. The temperature during stirring and mixing may be any temperature that allows sufficient stirring and mixing and allows a generally uniform thermosetting epoxy resin composition to be obtained. Although it varies depending on the epoxy resin and the epoxy curing catalyst metal chelate compound used, it is generally preferable that the temperature be room temperature to 80°C. Although it depends on the epoxy resin and the epoxy curing catalyst metal chelate compound used, if the temperature is below room temperature, it may be difficult to homogenize the mixture, resulting in poor mixing and uneven curing. If the temperature is above 80°C, partial curing may occur during stirring and mixing. In addition, when the catalyst compound is a solid or a viscous liquid, etc., and mixing or dispersion is difficult, the catalyst compound can be dissolved in a solvent, then mixed with the resin, and the solvent can be distilled off to produce a resin composition. In this case, the solvent used is not particularly limited, and specific examples include ethanol, isopropyl alcohol, toluene, xylene, etc. Depending on the molding method, the production and curing of the thermosetting epoxy resin composition may be carried out simultaneously, so that the stirring and mixing step as described above is not necessarily required.

[0040] The amount of the epoxy curing catalyst metal chelate compound in the thermosetting epoxy resin composition may be any amount relative to the epoxy resin, but is preferably 0.1% to 20%, more preferably 1% to 10%. If the amount of the epoxy curing catalyst metal chelate is 0.1% or less, sufficient curing activity may not be obtained, and if it is 20% or more, curing activity may be obtained, but the ratio of the epoxy resin may decrease, making it difficult to maintain characteristics such as mechanical strength unique to the epoxy resin. In addition, the ratio of the catalyst cost may increase, resulting in high costs.

[0041] When the epoxy curing catalyst metal chelate compound of the present invention is used to produce a thermosetting epoxy resin composition, the stirring and mixing method can be a general method using a sand mill, a bead mill, a paint shaker, or the like.

[0042] The epoxy resin cured product in the present invention is a product obtained by curing and molding the above-mentioned thermosetting epoxy resin composition by heating or the like.

[0043] Molding method As a method for molding the thermosetting epoxy resin composition using the epoxy curing catalyst metal chelate compound of the present invention, a general method such as injection molding, compression molding, transfer molding, cast molding, lamination molding, etc. can be used.

[0044] Curing conditions The curing conditions of the thermosetting epoxy resin composition using the epoxy curing catalyst metal chelate compound of the present invention vary depending on the epoxy resin and the epoxy curing catalyst metal chelate compound used, but are generally 60 to 220 ° C., and more preferably 100 to 200 ° C. Although it varies depending on the epoxy resin and the epoxy curing catalyst metal chelate compound used, if it is less than 60 ° C., the curing may be insufficient and the desired degree of curing may not be obtained, and if it exceeds 220 ° C., it may be thermally decomposed. The curing time varies depending on the curing temperature and the epoxy resin and the epoxy curing catalyst metal chelate compound used, but is about 15 to 300 minutes, and the curing atmosphere is sufficient in air. Although it varies depending on the curing temperature and the epoxy resin and the epoxy curing catalyst metal chelate compound used, if the curing time is less than 15 minutes, the curing may be insufficient and the desired degree of curing may not be obtained, and if it is more than 300 minutes, the curing may already be sufficient, and excessive energy may be used. EXAMPLES

[0045] EXAMPLES Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples in any way. The aluminum triisopropoxide used in the production was AIPD (Kawaken Fine Chemicals), the titanium tetraisopropoxide was A-1 (Nippon Soda Co., Ltd.), and the other raw materials were special grade or first grade reagents manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[0046] Manufacturing Example 1 A four-neck flask was charged with 102.1 g (0.5 mol) of aluminum triisopropoxide, and 50.0 g (0.5 mol) of acetylacetone was added dropwise while stirring. Then, 172.2 g (1.0 mol) of p-toluenesulfonic acid was added dropwise, and the mixture was heated and refluxed at 83°C for 1 hour to remove the 2-propanol produced by the reaction. The 2-propanol produced by the reaction was then removed by distillation at a reduced pressure of 40 mmHg or less, and 223.0 g of white solid mono(acetylacetonate)bis(p-toluenesulfonate)aluminum [average structure] was obtained.

[0047] Manufacturing Example 2 A four-neck flask was charged with 102.1g (0.5mol) of aluminum triisopropoxide, and 176.3g (0.5mol) of oleyl acetoacetate was added dropwise while stirring. Next, 86.1g (0.5mol) of p-toluenesulfonic acid was added dropwise, and the mixture was heated and refluxed at 83°C for 1 hour to remove 2-propanol produced by the reaction. Thereafter, the 2-propanol produced by the reaction was distilled off at a reduced pressure of 40mmHg or less to obtain 289.7g of mono(oleylacetoacetate)mono(p-toluenesulfonate)aluminum isopropoxide [average structure] as a yellow liquid.

[0048] Production Example 3 A four-neck flask was charged with 102.1g (0.5mol) of aluminum triisopropoxide, and 176.3g (0.5mol) of oleyl acetoacetate was added dropwise while stirring. Then, 43.1g (0.25mol) of p-toluenesulfonic acid was added dropwise, and the mixture was heated and the 2-propanol produced by the reaction was refluxed at 83°C for 1 hour. Then, the 2-propanol produced by the reaction was distilled off at a reduced pressure of 40mmHg or less to obtain 254.1g of a mixture [average structure] of mono(oleylacetoacetate)mono(p-toluenesulfonate)aluminum isopropoxide and mono(oleylacetoacetate)aluminum diisopropoxide as a yellow liquid.

[0049] Production Example 4 An experiment was carried out under the same conditions as in Production Example 2, except that the oleyl acetoacetate in Production Example 2 was changed to 177.3 g (0.5 mol) of stearyl acetoacetate. As a result, 290.6 g of mono(stearyl acetoacetate)mono(p-toluenesulfonate)aluminum isopropoxide [average structure] was obtained as a yellowish brown liquid.

[0050] Production Example 5 A four-neck flask was charged with 102.1 g (0.5 mol) of aluminum triisopropoxide, and 130.1 g (1.0 mol) of ethyl acetoacetate was added dropwise while stirring. Next, 93.1 g (0.5 mol) of m-xylenesulfonic acid was added dropwise, and the mixture was heated and refluxed at 83°C for 1 hour to remove the 2-propanol produced by the reaction. The 2-propanol produced by the reaction was then removed by distillation at a reduced pressure of 40 mmHg or less to obtain 224.4 g of yellow solid bis(ethylacetoacetate)mono(m-xylenesulfonate)aluminum [average structure].

[0051] Production Example 6 The synthesis was carried out under the same conditions as in Production Example 4, except that the m-xylenesulfonic acid in Production Example 5 was changed to 100.1 g (0.5 mol) of 4-acetylbenzenesulfonic acid and the ethyl acetoacetate was changed to 354.6 g (1.0 mol) of stearyl acetoacetate, and 444.3 g of pale yellow liquid bis(stearylacetoacetonate)mono(4-acetylbenzenesulfonate)aluminum [average structure] was obtained.

[0052] Production Example 7 An experiment was carried out under the same conditions as in Production Example 4, except that the m-xylenesulfonic acid in Production Example 5 was changed to 104.1 g (0.5 mol) of 2-naphthalenesulfonic acid and the ethyl acetoacetate was changed to 352.5 g (1.0 mol) of oleyl acetoacetate. As a result, 446.1 g of pale yellow liquid bis(oleylacetoacetonate)mono(2-naphthalenebenzenesulfonate)aluminum [average structure] was obtained.

[0053] Production Example 8 An experiment was carried out under the same conditions as in Production Example 4, except that the m-xylenesulfonic acid in Production Example 5 was changed to 163.2 g (0.5 mol) of dodecylbenzenesulfonic acid and the ethyl acetoacetate was changed to 298.5 g (1.0 mol) of myristyl acetoacetate. As a result, 450.9 g of pale yellow liquid bis(myristylacetoacetonate)mono(dodecylbenzenesulfonate)aluminum [average structure] was obtained.

[0054] Production Example 9 An experiment was carried out under the same conditions as in Production Example 2, except that the p-toluenesulfonic acid in Production Example 2 was changed to 163.2 g (0.5 mol) of dodecylbenzenesulfonic acid. As a result, 362.9 g of mono(oleylacetoacetate)mono(dodecylbenzenesulfonate)aluminum isopropoxide [average structure] was obtained as a yellowish brown liquid.

[0055] Manufacturing Example 10 A prototype was produced under the same conditions as in Production Example 1, except that the p-toluenesulfonic acid in Production Example 1 was replaced with 326.4 g (1.0 mol) of dodecylbenzenesulfonic acid and the acetylacetone was replaced with 176.3 g (0.5 mol) of oleyl acetoacetate. As a result, 489.5 g of yellow liquid mono(oleylacetoacetate)bis(dodecylbenzenesulfonate)aluminum [average structure] was obtained.

[0056] Manufacturing Example 11 An experiment was carried out under the same conditions as in Production Example 2, except that the oleyl acetoacetate in Production Example 2 was changed to 177.3 g (0.5 mol) of stearyl acetoacetate and the p-toluenesulfonic acid was changed to 163.2 g (0.5 mol) of dodecylbenzenesulfonic acid. As a result, 363.9 g of mono(stearyl acetoacetate)mono(dodecylbenzenesulfonate)aluminum isopropoxide [average structure] was obtained as a yellowish brown liquid.

[0057] Manufacturing Example 12 A four-neck flask was charged with 102.1g (0.5mol) of aluminum triisopropoxide and 268.4g (1.0mol) of oleyl alcohol, and the mixture was refluxed for 1 hour, after which the resulting 2-propanol was distilled off. Then, 86.1g (0.5mol) of p-toluenesulfonic acid was added dropwise, and the mixture was heated and refluxed for 1 hour. The resulting 2-propanol was distilled off, and 348.2g of white solid mono(p-toluenesulfonate)dioleylalkoxyaluminum [average structure] was obtained.

[0058] Manufacturing Example 13 A four-neck flask was charged with 102.1 g (0.5 mol) of aluminum triisopropoxide, and 489.7 g (1.5 mol) of dodecylbenzenesulfonic acid was added dropwise with stirring, followed by heating and refluxing for 1 hour. The resulting 2-propanol was distilled off, yielding 476.6 g of tris(dodecylbenzenesulfonate)aluminum [average structure] as a pale yellow solid.

[0059] Manufacturing Example 14 A four-neck flask was charged with 142 g (0.5 mol) of titanium tetraisopropoxide, and 172 g (1.0 mol) of p-toluenesulfonic acid was added dropwise with stirring. The resulting 2-propanol was then distilled off to obtain 255 g of a viscous liquid, bis(p-toluenesulfonate)diisopropoxytitanium [average structure].

[0060] Manufacturing Example 15 142g (0.5mol) of titanium tetraisopropoxide was charged into a four-neck flask, and 100g (1.0mol) of 2,4-pentanedione was added dropwise while stirring. Next, 348g (1.0mol) of dodecylbenzenesulfonic acid was added dropwise, and the resulting 2-propanol was distilled off to obtain 470g of viscous liquid bis(acetylacetonate)bis(dodecylbenzenesulfonate)titanium [average structure].

[0061] Manufacturing Example 16 64 g (0.5 mol) of zinc dimethoxide was placed in a four-neck flask and dissolved by heating. Further, 174 g (0.5 mol) of dodecylbenzenesulfonic acid was added dropwise with stirring, and the mixture was heated and refluxed for 1 hour. The resulting methanol was distilled off to obtain 220 g of mono(dodecylbenzenesulfonate)methoxyzinc [average structure] as a brown viscous liquid.

[0062] Comparative Manufacturing Example 1 A four-neck flask was charged with 102.1 g (0.5 mol) of aluminum triisopropoxide, and 438.9 g (1.5 mol) of oleyl acetoacetate was added dropwise with stirring, followed by heating and refluxing for 1 hour. The resulting 2-propanol was distilled off, yielding 428.4 g of yellow liquid tris(oleylacetoacetate)aluminum [average structure].

[0063] Examples 1 to 16 and Comparative Examples 1 to 3 To bisphenol A type epoxy resin (product name: JER828 manufactured by Mitsubishi Chemical Corporation), 5 wt% and 10 wt% of the epoxy curing catalyst metal chelate compounds shown in Manufacturing Examples 1 to 16 as Examples 1 to 16 and the metal chelate compound of Comparative Manufacturing Example 1 as Comparative 1 were added, and the mixture was stirred at room temperature at 2000 rpm / 1 minute and 2200 rpm / 30 seconds using a planetary centrifugal mixer (ARE-310 manufactured by Thinky Corporation) to prepare the thermosetting epoxy resin compositions of Examples 1 to 16 and Comparative Example 1. At this time, the solid curing catalyst was dissolved in the resin by making it into a 10% toluene solution. In addition, for Comparative Examples 2 and 3, dodecylbenzenesulfonic acid and m-xylenediamine were added to bisphenol A type epoxy resin (product name: JER828 manufactured by Mitsubishi Chemical Corporation) at 5 wt% and 10 wt%, respectively, and mixed with stirring to prepare curable resin compositions for Comparative Examples 2 and 3. The epoxy curing catalyst metal chelate compounds used in each Example are shown in Table 1. The compounds used in the Comparative Examples are shown in Table 2.

[0064] Working Example [Table 1]

[0065] Comparative Example [Table 2]

[0066] Storage stability evaluation The change in viscosity over time of a thermosetting epoxy resin composition obtained by mixing various curing catalysts and an epoxy resin was observed and evaluated as storage stability. The viscosity of the curable resin compositions shown in Examples 1 to 16 and Comparative Examples 1 to 3, which are made using a bisphenol A type epoxy resin (product name: JER828 manufactured by Mitsubishi Chemical Corporation), was measured immediately after preparation and after one month at 25°C. A TVB-15 manufactured by Toki Sangyo Co., Ltd. was used for this viscosity measurement. The viscosity immediately after preparation and after one month (storage at 25°C) were compared to measure the change in viscosity. If the viscosity changes by 10% or more, it becomes difficult to handle as a product and the conditions of use may be limited, so storage stability was evaluated as ◎ when the viscosity change was less than 10% with 10wt% hardener added, 〇 when the viscosity change was less than 10% with 5wt% hardener added, and × when the viscosity change was 10% or more and solidification occurred with 5wt% hardener added. The evaluations are shown in Tables 3 and 4.

[0067] Curing activity evaluation The degree of cure of the epoxy resin cured product was analyzed by infrared spectroscopy (FT-IR) to evaluate the degree of cure. Bisphenol A epoxy resin (product name: JER828, manufactured by Mitsubishi Chemical Corporation) without the addition of a curing catalyst before treatment was measured by FT-IR. -1 The peak area (e 0 ) and 1500 cm -1 The absorption peak area (f 0 Next, the thermosetting epoxy resin compositions shown in Examples 1 to 16 and Comparative Examples 1 to 4 were heat-treated according to the above-mentioned curing conditions, and the 950 cm -1 The peak area (e 1 ) and 1500 cm -1 The absorption peak area (f1 ) was measured. In this measurement, an FT-IR-4100 manufactured by JASCO Corporation was used. The degree of cure was calculated from these analytical values ​​using the following formula (e). It can be determined that the higher the value, the higher the curing activity. Curing degree (%)=[1-(e 1 / F 1 ) / (e 0 / F 0 )]×100 (e) If the degree of cure is less than 80%, the mechanical strength of the cured resin decreases and it may not be able to withstand use, so the curing activity was evaluated as ◎ when the degree of cure was 80% or more with the addition of 5wt% of the curing agent, ◯ when the degree of cure was 80% or more with the addition of 10wt%, and × when the degree of cure was less than 80% with the addition of 10wt%. The evaluations are shown in Tables 3 and 4.

[0068] Storage stability evaluation and curing activity evaluation in the examples [Table 3]

[0069] Storage stability evaluation and curing activity evaluation in comparative examples [Table 4]

[0070] The storage stability evaluation of the thermosetting epoxy resin composition using the epoxy curing catalyst metal chelate compound of the present invention shown in Examples 1 to 16 and the curing activity evaluation of the epoxy resin cured product were all rated as ◯ or ⊚. In contrast, Comparative Examples 1 and 2, which do not use the catalyst of the present invention, did not show sufficient curing activity. Also, the storage stability of the amine-based curing agent shown in Comparative Example 3 was poor. [Industrial Applicability]

[0071] By using the technology of this invention, it is possible to provide a metal chelate catalyst for curing epoxy resins, which can reduce the amount of catalyst used, reduce the cost of the catalyst in the epoxy resin, and has excellent storage stability, low skin irritation, and low environmental impact. The epoxy resin can be used without restriction in fields where epoxy resins are generally used, for example, in paints, inks, adhesives, pressure sensitive adhesives, electrical insulating materials, etc., and can therefore contribute to the development of a wider range of industries.

Claims

1. An epoxy curing catalyst comprising a metal chelate compound in which an aromatic sulfonic acid compound represented by general formula (a) is coordinated to a metal atom. 【Chemistry 1】 (In the formula, n is an integer of 0 to 5, and R 1 is an aliphatic or aromatic hydrocarbon group having 1 to 12 carbon atoms.)

2. 2. The epoxy curing catalyst according to claim 1, wherein the metal atom is selected from the group consisting of aluminum, zinc and titanium.

3. The epoxy curing catalyst described in Claim 2, wherein the average molecular coordination number of the aromatic sulfonic acid compound is 0.2 to 3.0 for the aluminum, 0.2 to 2.0 for the zinc, and 0.2 to 4 for the titanium.

4. The epoxy curing catalyst described in claim 3, wherein the metal atom is aluminum.

5. A method for producing a thermosetting epoxy resin composition, comprising using the epoxy curing catalyst according to any one of claims 1 to 4 in an amount of 0.1 to 20 wt % based on the epoxy resin.

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