Curable epoxy composition for rotating electrical machine

Abstract

The purpose of the present invention is to provide a curable epoxy composition for a rotary electric machine, which can easily adhere to a PEEK resin and can suppress peeling during use. The epoxy composition for a rotating electrical machine according to the present disclosure is characterized by containing an epoxy compound (A), an acid anhydride-based curing agent (B), and an amine-based curing accelerator (C), being in a liquid state at 25 DEG C, having a viscosity of 3000 mPa * s or less at 25 DEG C, and having an adhesive strength to a PEEK resin of 2.5 N / cm2 or more when cured. Furthermore, it is preferable that the viscosity increase rate before and after a storage test performed at a temperature of 23 + / -5 DEG C and a humidity of 50 + / -5% for 41 days is 20000% or less.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a curable epoxy composition used in a rotating electric machine. More specifically, the present disclosure relates, in one embodiment, to a curable epoxy composition for forming a cured product used in a stator or a rotor of a rotating electric machine. Furthermore, this application claims priority to Japanese Patent Application No. 2023-108870 filed in Japan on June 30, 2023, the contents of which are incorporated herein. BACKGROUND

[0002] Epoxy resins are used as resins (encapsulation materials) that coat optical semiconductor elements in optical semiconductor devices, resins for molded coil applications in which coils such as ignition coils are impregnated / molded, resins for fiber reinforcement, resins for rotating electric machines (for example, insulating materials, adhesive resins for fixing permanent magnets, gap-filling materials, and the like), and the like (for example, refer to Patent Documents 1 and 2).

[0003] In particular, as an insulating layer of a winding of a rotating electric machine, a polyamide-imide resin having high heat resistance has been used in the past, but as a measure for achieving high voltage resistance (PDIV) for high-speed charging and the like, there is an ongoing movement to replace the insulating layer from the polyamide-imide resin to a polyether ether ketone (PEEK) resin having higher voltage resistance.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT DOCUMENTS

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-199566

[0007] Patent Document 2: Japanese Patent Application Publication No. 2021-183687

[0008] Patent Document 3: Japanese Patent Application Publication No. 2020-524190 SUMMARY

[0009] PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] However, the PEEK resin has a problem in terms of adhesion to an epoxy resin due to its properties. As in Patent Document 3, methods and the like for improving the adhesion to an epoxy resin by improving the composition of the PEEK resin have been proposed, but they are not sufficient. Therefore, when exposed to vibrations of a motor, peeling occurs between the epoxy resin and the PEEK resin, and the peeled epoxy resin repeatedly collides with the winding or the windings with the vibrations of the motor, leading to abrasion of the PEEK resin that protects the winding, and as a result, there is a problem of causing degradation of the insulation.

[0011] Therefore, the object of this disclosure is to provide a curable epoxy composition for rotating motors that can be easily bonded to PEEK resin and can suppress peeling during use.

[0012] Solution for solving the problem

[0013] The inventors of this disclosure conducted in-depth research to achieve the aforementioned objectives and discovered that the curable epoxy composition for rotating electrical machines can be easily bonded to PEEK resin, suppresses peeling during use, and comprises an epoxy compound, an anhydride-based curing agent, and an imidazole-based curing accelerator, exhibiting specific viscosity and adhesive strength. This disclosure relates to technical solutions based on these insights.

[0014] This disclosure provides a curable epoxy composition for rotating electric motors, comprising an epoxy compound (A), an anhydride-based curing agent (B), and an amine-based curing accelerator (C). The curable epoxy composition is liquid at 25°C, has a viscosity of less than 3000 mPa·s at 25°C, and exhibits a bond strength of 2.5 N / cm² to PEEK resin upon curing. 2 above.

[0015] The aforementioned curable epoxy composition for rotary motors exhibits excellent impregnation properties due to its liquid state at 25°C and viscosity below 3000 mPa·s at the same temperature, thus suppressing defects and facilitating bonding. The bond strength to PEEK resin upon curing is 2.5 N / cm. 2 In this way, sufficient adhesive strength can be achieved with PEEK resin.

[0016] Preferably, the viscosity increase rate of the above-mentioned curable epoxy composition for rotating motors before and after a storage test conducted at a temperature of 23±5°C and a humidity of 50±5% for 41 days is less than 20,000%. With the above-mentioned configuration, it exhibits excellent long-term stability and operability.

[0017] Preferably, the glass transition temperature of the curable epoxy composition for rotary motors described above is 170°C or higher during curing. With the above-described structure, sufficient heat resistance is easily achieved.

[0018] Furthermore, this disclosure provides a cured product, which is a cured product of the above-mentioned curable epoxy composition for rotating motors.

[0019] Furthermore, this disclosure provides a stator for a rotary motor, which includes the aforementioned cured material formed in a manner that covers the stator coils.

[0020] Furthermore, this disclosure provides a rotor for a rotary electric motor, the rotor having the aforementioned solidified material covering the windings of the rotor.

[0021] Invention Effects

[0022] The curable epoxy composition for rotating electrical machines disclosed herein can be easily bonded to PEEK resin and can suppress peeling during use. Detailed Implementation

[0023] [Curing epoxy composition]

[0024] One embodiment of the present disclosure discloses a curable epoxy composition (hereinafter, sometimes referred to as "curable epoxy composition") for a rotating electric motor, which is a curable (thermosetting) composition comprising at least: an epoxy compound (A), an anhydride-based curing agent (B), and an amine-based curing accelerator (C). It is liquid at 25°C, has a viscosity of 3000 mPa·s or less at 25°C, and exhibits a bond strength of 2.5 N / cm² to PEEK resin upon curing. 2 above.

[0025] The aforementioned curable epoxy composition preferably contains a polyester polyol (D). The presence of the polyester polyol (D) results in a cured epoxy composition with a high glass transition temperature, excellent flexibility, and further improved flexural strain. Consequently, the heat resistance of the cured epoxy composition is further improved. Furthermore, the aforementioned curable epoxy composition may also contain an inorganic filler (E). The presence of the inorganic filler (E) can suppress the sedimentation of any powders that may be present in the composition by imparting thixotropy to the composition, and also imparts low linear expansion to the cured product.

[0026] The aforementioned curable epoxy composition is liquid at 25°C, thus exhibiting excellent workability, including impregnation and molding properties. Furthermore, the viscosity of the aforementioned curable epoxy composition at 25°C is 3000 mPa·s or less, preferably 2000 mPa·s or less, more preferably 1500 mPa·s or less, and even more preferably 1000 mPa·s or less. If the viscosity is 3000 mPa·s or less, long-term stability is excellent, impregnation and molding workability are improved, and it is less likely to produce defects in the cured product originating from poor molding. Furthermore, as a lower limit, it is preferably 100 mPa·s or more, more preferably 200 mPa·s or more, and even more preferably 300 mPa·s or more. With a viscosity of 100 mPa·s or more, the composition does not drip after impregnation, tending to improve workability during impregnation and molding. It should be noted that the viscosity of the cured epoxy composition at 25°C can be measured, for example, using a rheometer (trade name "Modular Compact Rheometer, MCR302", manufactured by Anton Paar, rotor diameter 25 mm, sample thickness 0.1 mm).

[0027] Furthermore, the viscosity increase rate at 25°C before and after a storage test conducted at 23±5°C and 50±5% for 41 days is preferably 20,000% or less, more preferably 3,000% or less, even more preferably 5,000% or less, and particularly preferably 400% or less. With a viscosity increase rate of 20,000% or less, the curable epoxy composition can suppress viscosity increase over a long period, exhibiting excellent long-term stability and workability. Furthermore, there is no particular limitation on the lower limit, and it can be 80% or more.

[0028] The above-mentioned curable epoxy composition exhibits a bond strength of 2.5 N / cm to PEEK resin upon curing. 2 The preferred value is 2.7 N / cm. 2 The above is preferred, with 2.9 N / cm being more ideal. 2 The above indicates that the bonding strength is 2.5 N / cm. 2 The above provides sufficient adhesive strength to PEEK resin and inhibits peeling from the PEEK resin. Furthermore, there is no specific upper limit, and it can be 10 N / cm. 2The following should be noted: In this disclosure, the adhesive strength described above is a value determined by a chip shear test. This chip shear test involves pressing the joint formed by the cured product of the aforementioned curable epoxy composition with a bonding tester (trade name "4000pxy DS100", manufactured by DAGE Corporation) and calculating the load [N] at failure. The chip shear test is performed by coating the aforementioned curable epoxy composition onto PEEK resin and then stacking chips, followed by measuring the cured product (joint). The curing conditions of the cured product can be appropriately selected based on the composition of the curable epoxy composition. For example, it can be performed on cured products cured under at least one of the following conditions: a temperature of 80–180°C and a time of 60–300 minutes. Compared to conventional methods for evaluating adhesion, the chip shear test can be performed quickly and easily, and it also reduces repeatability errors for substrates with low smoothness and low-viscosity resins.

[0029] The glass transition temperature of the above-mentioned curable epoxy composition during curing is preferably 170°C or higher, more preferably 174°C or higher, even more preferably 180°C or higher, and particularly preferably 200°C or higher. If the glass transition temperature is 170°C or higher, the heat resistance is excellent, for example, even in high-temperature environments such as the operating temperature of an EV motor. The glass transition temperature of the cured product is a value measured by DSC (differential scanning calorimetry).

[0030] (Epoxy compound (A))

[0031] The epoxy compound (A) is a compound having one or more epoxy groups (ethylene oxide rings). Examples of the epoxy compound (A) include: alicyclic epoxy compounds (alicyclic epoxy resins), aromatic epoxy compounds (aromatic epoxy resins), and aliphatic epoxy compounds (aliphatic epoxy resins). Among these, alicyclic epoxy compounds are preferred as the epoxy compound (A). Only one type of epoxy compound (A) may be used, or two or more types may be used.

[0032] As the aforementioned alicyclic epoxy compounds, well-known or conventional alicyclic epoxy compounds can be used without particular limitation. Examples include: (I) compounds in which the molecule has an epoxy group (called "alicyclic epoxy group") composed of two adjacent carbon atoms and an oxygen atom constituting the alicyclic ring; (II) compounds in which an epoxy group is directly bonded to the alicyclic ring by a single bond; and (III) compounds in which the molecule has an alicyclic ring and a glycidyl ether group (glycidyl ether type epoxy compounds), etc.

[0033] As compounds having an alicyclic epoxy group in the molecule of (I) above, compounds having an epoxy cyclohexyl group can be listed, for example, compounds shown in the following formula (i).

[0034] [Chemical Formula 1]

[0035]

[0036] In formula (i) above, Y represents a single bond or a linking group (a divalent group having one or more atoms). Examples of such linking groups include: divalent hydrocarbon groups, alkenyl groups formed by partial or complete epoxidation of carbon-carbon double bonds, carbonyl groups, ether bonds, ester bonds, carbonate groups, amide groups, and groups formed by multiple linkages of these groups. It should be noted that one or more carbon atoms constituting the cyclohexane ring (epoxycyclohexyl) in formula (i) are optionally bonded to substituents such as alkyl groups.

[0037] Examples of divalent hydrocarbon groups include straight-chain or branched alkylene groups and divalent alicyclic hydrocarbon groups with 1 to 18 carbon atoms. Examples of straight-chain or branched alkylene groups with 1 to 18 carbon atoms include methylene, methylmethylene, dimethylmethylene, ethylene, propylene, and trimethylene. Examples of divalent alicyclic hydrocarbon groups include 1,2-cyclopentylene, 1,3-cyclopentylene, cyclopentylene, 1,2-cyclohexylene, 1,3-cyclohexylene, 1,4-cyclohexylene, and other divalent cycloalkylene groups (including cycloalkylidenes).

[0038] Examples of alkenyl groups (sometimes called "epoxidized alkenyl groups") in which part or all of the aforementioned carbon-carbon double bonds are epoxidized include: vinylidene, propenide, 1-butenide, 2-butenide, butadienylene group, pentenide, hexenide, heptenide, octene, and other straight-chain or branched alkenyl groups with 2 to 8 carbon atoms. In particular, alkenyl groups in which all of the carbon-carbon double bonds are epoxidized are preferred, and alkenyl groups in which all of the carbon-carbon double bonds are epoxidized with 2 to 4 carbon atoms are more preferred.

[0039] Representative examples of alicyclic epoxy compounds shown in formula (i) above include (3,4,3',4'-diepoxy)cyclohexane and compounds shown in formulas (i-1) to (i-10) below. It should be noted that in formulas (i-5) and (i-7) below, l and m represent integers from 1 to 30. In formula (i-5) below, R' is an alkylene group having 1 to 8 carbon atoms, preferably a straight-chain or branched alkylene group having 1 to 3 carbon atoms, such as methylene, ethylene, propylene, or isopropylene. In formulas (i-9) and (i-10) below, n1 to n6 represent integers from 1 to 30. In addition, as alicyclic epoxy compounds represented by formula (i) above, other examples include 2,2-bis(3,4-epoxycyclohexyl)propane, 1,2-bis(3,4-epoxycyclohexane-1-yl)ethane, 1,2-epoxy-1,2-bis(3,4-epoxycyclohexane-1-yl)ethane, bis(3,4-epoxycyclohexylmethyl) ether, etc.

[0040] [Chemical Formula 2]

[0041]

[0042] [Chemical Formula 3]

[0043]

[0044] As compounds in (II) above that have an epoxy group directly bonded to the alicyclic ring by a single bond, examples include compounds represented by the following formula (ii).

[0045] [Chemical Formula 4]

[0046]

[0047] In formula (ii), R” is a group (p-valent organic group) formed by removing p hydroxyl groups (-OH) from the structural formula of a p-hydronic alcohol, where p and n represent natural numbers. As a p-hydronic alcohol [R””OH] p Examples of compounds represented by formula (ii) include polyols such as 2,2-bis(hydroxymethyl)-1-butanol (alcohols with 1 to 15 carbon atoms). p is preferably 1 to 6, and n is preferably 1 to 30. When p is 2 or more, the n in each group within the parentheses can be the same or different. Specifically, examples of compounds represented by formula (ii) include 1,2-epoxy-4-(2-epoxyethyl)cyclohexane adducts of 2,2-bis(hydroxymethyl)-1-butanol [e.g., trade name "EHPE3150" (manufactured by DAICEL Co., Ltd.)].

[0048] As compounds containing an alicyclic ring and a glycidyl ether group within the molecule of (III) mentioned above, examples include glycidyl ethers of alicyclic alcohols (especially alicyclic polyols). More specifically, examples include: 2,2-bis[4-(2,3-epoxypropoxy)cyclohexyl]propane, 2,2-bis[3,5-dimethyl-4-(2,3-epoxypropoxy)cyclohexyl]propane, and other compounds formed by hydrogenating bisphenol A type epoxides (hydrogenated bisphenol A type epoxides); bis[o,o-(2,3-epoxypropoxy)cyclohexyl]methane, bis[o,p-(2,3-epoxypropoxy)cyclohexyl]methane, bis[p,p-(2,3-epoxypropoxy)cyclohexyl]methane, bis[o ... Compounds formed by hydrogenating bisphenol F type epoxides such as [3,5-dimethyl-4-(2,3-epoxypropoxy)cyclohexyl]methane (hydrogenated bisphenol F type epoxides); hydrogenated biphenol type epoxides; hydrogenated phenol linear phenolic type epoxides; hydrogenated cresol linear phenolic type epoxides; hydrogenated cresol linear phenolic type epoxides of bisphenol A; hydrogenated naphthalene type epoxides; hydrogenated epoxides of epoxides obtained from triphenolmethane; and hydrogenated epoxides of other epoxides having aromatic rings, etc.

[0049] Examples of the aforementioned aromatic epoxy compounds include: epi-Bis type glycidyl ether epoxy resins (bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, etc.) obtained by the condensation reaction of bisphenols [e.g., bisphenol A, bisphenol F type epoxy compounds, bisphenol F type epoxy compounds, etc.] with epihaloalcohols; and high molecular weight epi-Bis type glycidyl ether epoxy resins obtained by further adding these epi-Bis type glycidyl ether epoxy resins to the aforementioned bisphenols. Linear phenolic / alkyl glycidyl ether epoxy resins are obtained by further condensing polyols obtained by condensing phenols (e.g., phenol, cresol, xylenol, resorcinol, catechol, bisphenol A, bisphenol F, bisphenol S, etc.) with aldehydes (e.g., formaldehyde, acetaldehyde, benzaldehyde, hydroxybenzaldehyde, salicylaldehyde, etc.) with epihaloalcohols; epoxy compounds in which two phenolic skeletons are bonded at the 9-position of the fluorene ring, and the oxygen atoms after removing hydrogen atoms from the hydroxyl groups of these phenolic skeletons are directly or via alkylene oxides bonded to glycidyl groups, etc.

[0050] Examples of the aforementioned aliphatic epoxides include: glycidyl ethers of q-hydroxides (q being a natural number) that do not have a cyclic structure; glycidyl esters of mono- or polycarboxylic acids [such as acetic acid, propionic acid, butyric acid, stearic acid, adipic acid, sebacic acid, maleic acid, itaconic acid, etc.]; epoxides of oils containing double bonds, such as epoxidized linseed oil, epoxidized soybean oil, and epoxidized castor oil; and epoxides of polyolefins (including polydienes) such as epoxidized polybutadiene. It should be noted that the aforementioned non-cyclic q-ols can include, for example: monohydric alcohols such as methanol, ethanol, 1-propanol, isopropanol, and 1-butanol; dihydric alcohols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, polyethylene glycol, and polypropylene glycol; and polyols with three or more nucleotides such as glycerol, diglycerol, erythritol, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, and sorbitol. Furthermore, q-ols can also be polyether polyols, polyester polyols, polycarbonate polyols, and polyolefin polyols.

[0051] The content of the epoxy compound (A) in the above-described curable epoxy composition is preferably 10% by mass or more relative to the total amount (100% by mass) of the curable epoxy composition. In one embodiment of the above-described curable epoxy composition (e.g., without inorganic filler (E)), the content of the epoxy compound (A) is more preferably 20-90% by mass, more preferably 30-70% by mass, and even more preferably 35-60% by mass. In another embodiment of the above-described curable epoxy composition (e.g., including inorganic filler (E)), the content of the epoxy compound (A) is more preferably 10-60% by mass, more preferably 12-55% by mass, and even more preferably 14-50% by mass.

[0052] It should be noted that, in this specification, the content of each component contained in the above-described curable epoxy composition (e.g., epoxy compound (A), acid anhydride curing agent (B), etc.) can be appropriately selected from the range described above in such a way that the total content is less than 100% by mass.

[0053] (Acid anhydride-based curing agent (B))

[0054] Anhydride-based curing agent (B) is a compound that cures the curable epoxy composition by reacting with epoxy compound (A). Anhydride-based curing agent (B) can be used alone or in combination with more than one type.

[0055] As an anhydride-based curing agent (B) (anhydride class), any known or commonly used anhydride-based curing agent can be used without particular limitation. Examples include: methyltetrahydrophthalic anhydride (4-methyltetrahydrophthalic anhydride, 3-methyltetrahydrophthalic anhydride, etc.), methylhexahydrophthalic anhydride (4-methylhexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, etc.), dodecenylsuccinic anhydride, methylmethylenetetrahydrophthalic anhydride, phthalic anhydride, and methyl... Anhydrides, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylcyclohexene dicarboxylic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, nadic anhydride, methyl nadic anhydride, hydrogenated methyl nadic anhydride, 4-(4-methyl-3-pentenyl)tetrahydrophthalic anhydride, succinic anhydride, adipic anhydride, sebacic anhydride, dodecanoic anhydride, methylcyclohexene tetracarboxylic anhydride, vinyl ether-maleic anhydride copolymer, alkylstyrene-maleic anhydride copolymer, etc.

[0056] As an anhydride-based curing agent (B), from an operability point of view, anhydrides that are liquid at 25°C are preferred [e.g., methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, dodecenylsuccinic anhydride, methylmethylenetetrahydrophthalic anhydride, etc.]. On the other hand, regarding anhydrides that are solid at 25°C, for example, dissolving them in anhydrides that are liquid at 25°C to prepare a liquid mixture tends to improve operability as a curing agent in the above-mentioned curable epoxy composition.

[0057] Furthermore, from the viewpoint of further increasing the glass transition temperature of the cured product and further improving the heat resistance of the cured product, the anhydride-based curing agent (B) preferably contains nadic anhydride, methyl nadic anhydride, hydrogenated methyl nadic anhydride, or other nadic anhydrides or their derivatives, and more preferably contains methyl nadic anhydride.

[0058] The content (compound amount) of the anhydride-based curing agent (B) in the above-mentioned curable epoxy composition is not particularly limited, but is preferably 50 to 200 parts by mass relative to 100 parts by mass of the total amount of epoxy compound (A) contained in the curable epoxy composition, more preferably 80 to 150 parts by mass. More specifically, it is preferable to use it at a ratio of 0.5 to 1.5 equivalents (preferably 0.8 to 1.1 equivalents, more preferably 0.9 equivalents or more and less than 1.0 equivalents) relative to 1 equivalent of epoxy groups in the above-mentioned curable epoxy composition. If the content of the anhydride-based curing agent (B) is 50 parts by mass or more, curing can be fully carried out, and there is a tendency for the heat resistance and toughness of the cured product to be further improved. If the content of the anhydride-based curing agent (B) is 200 parts by mass or less, there is a tendency to obtain a cured product with suppressed coloring and excellent hue. Furthermore, the proportion of anhydride-based curing agent (B) in the curing agent contained in the above-mentioned curable epoxy composition is preferably more than 80% by mass relative to the total amount of curing agent (100% by mass), and may also be 85% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more.

[0059] (Amine-based curing accelerator (C))

[0060] Amine-based curing accelerators (C) are compounds that accelerate the reaction between epoxy compounds (A) and anhydride-based curing agents (B). By using amine-based curing accelerators (C) as curing accelerators, cured products with excellent heat resistance can be formed. Examples of amine-based curing accelerators (C) include imidazole-based curing accelerators and strongly basic compound-based curing accelerators. Only one type of amine-based curing accelerator (C) can be used, or two or more types can be used.

[0061] As the aforementioned imidazole-based curing accelerators, known or commonly used imidazole-based curing accelerators can be used without particular limitation, and examples include: 1-methylimidazolium, 2-methylimidazolium, 2-ethyl-4-methylimidazolium, 1-(2-hydroxypropyl)imidazolium, 2-undecylimidazolium, 2-heptadecylimidazolium, 2-phenylimidazolium, 1-benzyl-2-methylimidazolium, 1-benzyl-2-phenylimidazolium, 1-cyanoethyl-2-methylimidazolium, 1-cyanoethyl-2-ethyl-4- Imidazole compounds such as methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-undecylimidazole trimellitate, 1-cyanoethyl-2-phenylimidazole trimellitate, 2-methylimidazole trimellitate, 2-phenylimidazole trimellitate, 2,4-diamino-6-[2-methylimidazole-(1)]-ethyltriazine, and 2,4-diamino-6-[2-ethyl-4-methylimidazole-(1)]-ethyltriazine.

[0062] Furthermore, the aforementioned imidazole-based curing accelerators can also be derivatives of imidazole compounds, such as amine adducts of the aforementioned imidazole compounds (e.g., amine adducts with epoxy compounds). Examples of epoxy compounds (A) can be listed and described. Only one type of epoxy compound may be used, or two or more may be used.

[0063] As the aforementioned imidazole-based curing accelerator, from the viewpoint of further increasing the glass transition temperature and heat resistance of the cured product, it is preferable to include at least 1-methylimidazole, 2-methylimidazole, 1-(2-hydroxypropyl)imidazole, or their amine adducts (especially amine adducts with epoxy compounds, more preferably amine adducts with bisphenol-type epoxy compounds). From the viewpoint of superior long-term stability (shelf life) when mixed with anhydride-based curing agent (B), 1-(2-hydroxypropyl)imidazole, amine adducts (especially amine adducts with epoxy compounds), more preferably amine adducts, further preferably amine adducts of 2-methylimidazole with epoxy compounds, and particularly preferably amine adducts of 2-methylimidazole with bisphenol-type epoxy compounds.

[0064] The aforementioned imidazole-based curing accelerators can also be used as latent curing accelerators. By using latent curing accelerators, the long-term stability of the cured epoxy composition can be improved. Examples of latent curing accelerators include substances formed by microencapsulating imidazole-based curing accelerators (microencapsulated latent curing agents).

[0065] The aforementioned microencapsulated latent curing agents, for example, contain a core and a shell covering the surface of the core. The core contains an imidazole-based curing accelerator, and the shell contains an organic polymer and / or an inorganic compound. It should be noted that microencapsulated latent curing agents with an inorganic shell are not classified as inorganic fillers (E).

[0066] Relative to the content of the core (100 parts by mass), the content of the shell is preferably 0.01 to 100 parts by mass, more preferably 0.1 to 80 parts by mass, even more preferably 1 to 60 parts by mass, and particularly preferably 5 to 50 parts by mass. If the content of the shell is within the above range, excellent long-term stability and curing properties can be achieved.

[0067] Examples of the aforementioned organic polymers include natural polymers such as cellulose and synthetic resins. Among these, synthetic resins are preferred from the perspectives of superior long-term stability, ease of shell destruction during curing, and uniformity of the physical properties of the cured product.

[0068] Examples of the aforementioned synthetic resins include: epoxy resin, acrylic resin, polyester resin, phenolic resin, polyethylene resin, nylon resin, polystyrene resin, urea resin, polyurethane resin, mixtures thereof, and copolymers thereof.

[0069] Examples of such inorganic compounds include boron compounds such as boron oxide and boron esters; silicon dioxide; and calcium oxide. Among these, boron oxide is preferred from the perspective of superior film stability and resistance to damage upon heating.

[0070] As the aforementioned microencapsulated latent curing agent, a known or commonly used microencapsulated latent curing agent can be used, such as commercially available products under the trade names "Novacure HX-3742", "Novacure HXA-3792" (both manufactured by Asahi Kasei Corporation), and "Technicure LC-80" (manufactured by A&C Catalysts Corporation).

[0071] As the aforementioned strongly basic compound-based curing accelerator, a curing accelerator comprising a strongly basic compound with a pKa of 10 or more is preferred, more preferably with a pKa of 11 or more, even more preferably with a pKa of 11 to 16, and particularly preferably with a pKa of 11 to 14. It should be noted that the above-mentioned pKa refers to the pKa in water. As the aforementioned strongly basic compound, a nitrogen-containing cyclic compound having the above-mentioned pKa is preferred. Specifically, examples of the aforementioned strongly basic compounds include: 1,8-diazabicyclo[5.4.0]undecene-7 (DBU) and its salts (e.g., phenolates, octanoates, 2-ethylhexanoates, p-toluenesulfonates, formates, tetraphenylborates, etc.), 1,5-diazabicyclo[4.3.0]nonene-5 (DBN) and its salts (e.g., phenolates, octanoates, p-toluenesulfonates, formates, tetraphenylborates, etc.), tetramethylguanidine (TMG) and its salts, 1,4-diazabicyclo[2.2.2]octane (DABCO), 1,5,7-triazabicyclo[4.4.0]decene-5 (TBD) and its salts, and 7-methyl-1,5,7-triazabicyclo[4.4.0]decene-5 (MTBD) and its salts. Among these, DBU and its salts are further preferred as strongly basic compounds.

[0072] In addition, as an amine-based curing accelerator (C), commercially available products such as "Technicure LC-100" (manufactured by A&C Catalysts) can also be used.

[0073] The content (compound amount) of the amine curing accelerator (C) in the above-mentioned curable epoxy composition is not particularly limited. It is preferably 0.01 to 5 parts by mass, more preferably 0.03 to 3 parts by mass, and even more preferably 0.1 to 2 parts by mass, relative to 100 parts by mass of the total amount of curable compounds (e.g., epoxy compound (A), polyester polyol (D), etc., which are reactive due to the curing agent) contained in the curable epoxy composition. If the content of the amine curing accelerator (C) is 0.01 parts by mass or more, there is a tendency to further improve heat resistance and obtain a more efficient curing accelerator effect. Furthermore, when polyester polyol (D) is included, the heat resistance and flexural strain of the cured product become excellent. If the content of the amine curing accelerator (C) is 5 parts by mass or less, there is a tendency to obtain a cured product with suppressed coloring and excellent hue. Furthermore, when the amine-based curing accelerator (C) is used as a latent curing accelerator, the content of the latent curing accelerator (e.g., the total content of the core and shell) is, for example, 0.6 to 10 parts by mass, preferably 2 to 8 parts by mass, relative to 100 parts by mass of the total amount of curable compounds contained in the curable epoxy composition. Furthermore, the proportion of the amine-based curing accelerator (C) in the curing accelerator contained in the above-mentioned curable epoxy composition relative to the total amount of curing accelerator (100% by mass) is preferably 50% by mass or more, and may also be 60% by mass or more, 75% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more.

[0074] (Polyester polyol (D))

[0075] As polyester polyols (D), compounds having two or more hydroxyl groups and two or more ester bonds within their molecules can be listed. Examples of such polyester polyols include: polycaprolactone polyols and other polylactone polyols, aliphatic polyester polyols, aromatic polyester polyols, and alicyclic polyester polyols. One type of polyester polyol (D) may be used, or two or more may be used.

[0076] As the polyester polyol (D), from the viewpoint of maintaining a high glass transition temperature of the cured product and having better flexibility, it is preferable to include polylactone polyols and / or aliphatic polyester polyols. Furthermore, from the same viewpoint, as the polyester polyol (D), it is preferable to include polyester diols and / or polyester triols.

[0077] The molecular weight of the polyester polyol (D) is not particularly limited, but is preferably 250 or more, more preferably 600 or more, even more preferably 1100 or more, and particularly preferably 1700 or more. If the molecular weight is 250 or more (especially 600 or more), the strength and toughness of the cured product are easily improved, and the flexural strain is further increased. For example, the molecular weight can be 100,000 or less, or 50,000 or less, 10,000 or less, or 4,000 or less. The molecular weight of the polyester polyol (D) refers to the number-average molecular weight converted from standard polystyrene, determined by gel permeation chromatography (GPC).

[0078] The hydroxyl value of the polyester polyol (D) is not particularly limited, but is preferably 600 KOH mg / g or less, more preferably 200 KOH mg / g or less, even more preferably 100 KOH mg / g or less, and particularly preferably 80 KOH mg / g or less. If the hydroxyl value is 600 KOH mg / g or less (especially 200 KOH mg / g or less), the chain transfer reaction of the epoxy compound (A) polymerization is suppressed, the degree of polymerization of the epoxy backbone easily increases, and the glass transition temperature of the cured product can be maintained at a high level. The hydroxyl value can be determined by potentiometric titration according to JIS K0070.

[0079] When the above-mentioned curable epoxy composition contains polyester polyol (D), the content ratio of polyester polyol (D) in the curable epoxy composition is not particularly limited, but is preferably 1 to 30% by mass relative to the total amount (100% by mass), more preferably 3 to 20% by mass, and even more preferably 5 to 15% by mass. If the above-mentioned content ratio is within the above range, the heat resistance and flexural strain of the cured product become even more excellent.

[0080] (Inorganic filler (E))

[0081] As the inorganic filler (E), known or conventional inorganic fillers can be used without particular limitation, such as: silicon dioxide, alumina, zircon, calcium silicate, calcium phosphate, calcium carbonate, magnesium carbonate, silicon carbide, silicon nitride, aluminum nitride, boron nitride, aluminum hydroxide, iron oxide, zinc oxide, zirconium oxide, magnesium oxide, titanium oxide, alumina, calcium sulfate, barium sulfate, forsterite, steel, spinel, clay, kaolin, dolomite, hydroxyapatite, nepheline syenite, quartz, wollastonite, diatomite, talc, etc., in powder form or in shaped form (e.g., spherical beads). Furthermore, as the inorganic filler (E), inorganic fillers obtained by subjecting the above-mentioned inorganic fillers to known or conventional surface treatments can also be listed. Only one inorganic filler (E) can be used, or two or more can be used. Among them, from the viewpoint that the coefficient of linear expansion of the cured product is lower and the warping of the cured product is less likely to occur, silica, alumina, and aluminum nitride are preferred as inorganic fillers (E), and silica (silica filler) is more preferred.

[0082] There are no particular limitations on the silica used; for example, known or conventional silica such as molten silica, crystalline silica, and high-purity synthetic silica can be used. It should be noted that silica obtained by performing known or conventional surface treatments (e.g., surface treatment using surface treatment agents such as metal oxides, silane coupling agents, titanium coupling agents, organic acids, polyols, and organosilicones) can also be used.

[0083] Hydrophilic silica and hydrophobic silica are examples of silica. From the viewpoint that it can easily increase the viscosity of curable epoxy compositions, inhibit the sedimentation of solid components such as microencapsulated latent curing agents and improve dispersibility, and impart thixotropy to curable epoxy compositions, as well as excellent workability such as impregnation and injection molding, hydrophobic silica is preferred.

[0084] The aforementioned hydrophobic silica is silica obtained by hydrophobizing hydrophilic silica. Examples of processing agents used for hydrophobication treatment include: methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, hexamethyldisilazane, methyltrialkoxysilane, dimethyldialkoxysilane, trimethylalkoxysilane, ethyltrichlorosilane, propyltrichlorosilane, hexyltrichlorosilane, long-chain alkyltrichlorosilane, ethyltrialkoxysilane, propyltrialkoxysilane, hexyltrialkoxysilane, long-chain alkyltrialkoxysilane, methacrylate silane, fluoroalkylsilane, perfluoroalkylsilane, and other organosilicon compounds; dimethylpolysiloxane (silicone oil), methylphenylpolysiloxane, methylhydropolysiloxane, amino-modified organosilicon, and other polysiloxane organosilicon compounds, etc. Among these, hydrophobication treatment of polysiloxanes is preferred. Hydrophobication treatment can be carried out using well-known methods, such as liquid phase method, gas phase method, autoclave method, etc.

[0085] The shape of silica is not particularly limited, and examples include: powder, spherical, broken, fibrous, needle-like, and flake-like. From the viewpoint of dispersibility, spherical silica is preferred, and perfectly spherical silica (e.g., spherical silica with an aspect ratio of 1.2 or less) is particularly preferred.

[0086] The specific surface area of ​​silica is not particularly limited, but from the viewpoint of imparting thixotropic properties, impregnation properties, and excellent workability to curable epoxy compositions, a specific surface area of ​​10 μm is preferred. 2 / g or more, preferably 40m 2 / g or more, further preferably 70m 2 / g or more.

[0087] The center particle size of silica is not particularly limited, but from the viewpoint of imparting thixotropy, impregnation, and excellent workability to the cured epoxy composition, it is preferably 200 nm or less, more preferably 100 nm or less, and even more preferably 50 nm or less. The aforementioned center particle size is, for example, 3 nm or more. Furthermore, from the viewpoint of improving the low linear expansion, strength, and crack resistance of the cured product, it is preferably 0.1 to 50 μm, more preferably 0.1 to 30 μm. It should be noted that the aforementioned center particle size refers to the particle size (median diameter) at 50% of the integral value of the particle size distribution determined by laser diffraction / scattering.

[0088] When the above-mentioned curable epoxy composition contains an inorganic filler (E), the content (compound amount) of the inorganic filler (E) in the curable epoxy composition is not particularly limited, but is preferably 0.5 to 500 parts by mass relative to 100 parts by mass of the total amount of curable compound contained in the curable epoxy composition. In one embodiment, the above content is more preferably 0.5 to 50 parts by mass, and even more preferably 1 to 10 parts by mass. In this case, the composition can be easily imparted with thixotropic properties. Furthermore, in another embodiment, the above content is more preferably 100 parts by mass or more (e.g., 100 to 500 parts by mass), and even more preferably 250 parts by mass or more (e.g., 250 to 400 parts by mass). In this case, the linear expansion of the cured product can be further reduced.

[0089] When the above-mentioned curable epoxy composition contains an inorganic filler (E), the content ratio of the inorganic filler (E) in the curable epoxy composition is not particularly limited, but is preferably 0.3 to 90% by mass relative to the total amount (100% by mass) of the curable epoxy composition. In one embodiment, the above-mentioned content ratio is more preferably 0.3 to 8% by mass, and even more preferably 0.5 to 3% by mass. In this case, the composition can be easily imparted with thixotropic properties. Furthermore, in another embodiment, the above-mentioned content ratio is more preferably 50% by mass or more (e.g., 50 to 90% by mass), and even more preferably 55% by mass or more (e.g., 55 to 80% by mass). In this case, the linear expansion of the cured product can be further reduced.

[0090] The above-described curable epoxy composition may also contain curable compounds other than epoxy compound (A) and polyester polyol (D) (compounds that can react with curing agents such as anhydride-based curing agents (B)). The total content ratio of epoxy compound (A) and polyester polyol (D) in the above-described curable epoxy composition relative to the total amount (100% by mass) of all the above-described curable compounds in the above-described curable epoxy 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, and particularly preferably 95% by mass or more. It should be noted that when the above-described curable epoxy composition does not contain polyester polyol (D), the above-described content ratio refers to the content ratio of epoxy compound (A).

[0091] The proportion of epoxy compound (A) in the above-mentioned curable epoxy composition relative to the total amount (100% by mass) of curable compounds contained in the curable epoxy composition is preferably 50% by mass or more, and may also be 60% by mass or more, 70% by mass or more, or 75% by mass or more. Furthermore, the proportion of polyester polyol (D) in the above-mentioned curable epoxy composition relative to the total amount (100% by mass) of the above-mentioned curable compounds contained in the curable epoxy composition is preferably 5 to 45% by mass, more preferably 10 to 35% by mass, and even more preferably 15 to 30% by mass. If the above proportions are within the above ranges, the heat resistance and flexural strain of the cured product become even more superior.

[0092] The above-mentioned curable epoxy composition may also contain other components besides those listed above. For example, if compounds with hydroxyl groups, such as ethylene glycol, diethylene glycol, propylene glycol, and glycerin (especially polyols other than polyester polyol (D)), are included as other components, the reaction can proceed slowly. In addition, without compromising viscosity and transparency, the following commonly used additives may be used: defoamers such as silicone-based and fluorine-based agents; leveling agents; coupling agents such as silane coupling agents such as γ-epoxypropoxypropyltrimethoxysilane and 3-mercaptopropyltrimethoxysilane; surfactants; flame retardants; colorants; antioxidants; ultraviolet absorbers; ion adsorbents; colorants; phosphors (e.g., inorganic phosphor particles such as YAG-based phosphor particles and silicate-based phosphor particles); release agents; tackifiers; dispersants; rust inhibitors; corrosion inhibitors; freezing point depressants; wear-resistant additives; wetting modifiers, etc. In particular, when using 1-methylimidazole as an amine-based curing accelerator (C), from the viewpoint of reducing viscosity and achieving excellent impregnation, defoamers and leveling agents are preferred. The other components mentioned above may be used individually or in combination with more than one.

[0093] By including the aforementioned antioxidants, a cured product with even better heat resistance (especially resistance to yellowing) can be formed. As the antioxidant, known or conventional antioxidants can be used without particular limitation; examples include: phenolic antioxidants (phenolic compounds), hindered amine antioxidants (hindered amine compounds), phosphorus antioxidants (phosphorus compounds), sulfur antioxidants (sulfur compounds), etc.

[0094] Examples of phenolic antioxidants include: 2,6-di-tert-butyl-p-cresol, butylated hydroxyphenyl methyl ether, 2,6-di-tert-butyl-p-ethylphenol, stearyl-β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and other monophenols; 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 4,4'-thiobis(3-methyl-6-tert-butylphenol), 4,4'-butylenebis(3-methyl-6-tert-butylphenol), and 3,9-bis[1,1-dimethyl-2-{β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl Bisphenols such as 2,4,8,10-tetraoxaspiro[5.5]undecane; 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tetra[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane, bis[3,3'-bis-(4'-hydroxy-3'-tert-butylphenyl)butyrate]ethylene glycol ester, 1,3,5-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)-triazine-2,4,6-(1H,3H,5H)trione, tocopherol, and other high molecular weight phenols.

[0095] Examples of hindered amine antioxidants include: bis(1,2,2,6,6-pentamethyl-4-piperidinyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, methyl-1,2,2,6,6-pentamethyl-4-piperidinyl sebacate, and 4-benzoyloxy-2,2,6,6-tetramethylpiperidine.

[0096] Examples of phosphorus-based antioxidants include: triphenyl phosphite, diphenyl isodecanyl phosphite, phenyl diisodecyl phosphite, tri(nonylphenyl) phosphite, diisodecyl pentaerythritol phosphite, tris(2,4-di-tert-butylphenyl) phosphite, cyclopentanetetramethylbis(octadecyl) phosphite, cyclopentanetetramethylbis(2,4-di-tert-butylphenyl) phosphite, and cyclopentanetetramethylbis(2,4-di-tert-butyl-4-methylphenyl) phosphite. Phosphite esters such as bis[2-tert-butyl-6-methyl-4-{2-(octadecyloxycarbonyl)ethyl}phenyl]hydrogen phosphite (phosphite antioxidants); oxaphosphenanthrene oxides such as 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 10-(3,5-di-tert-butyl-4-hydroxybenzyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0097] Examples of sulfur-based antioxidants include: dodecyl mercaptan, dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, distearate-3,3'-thiodipropionate, etc.

[0098] From the viewpoint of further improving the heat resistance of the cured product, the antioxidants mentioned above preferably include phosphorus-based antioxidants, and more preferably include phosphite-based antioxidants.

[0099] When the above-mentioned curable epoxy composition contains an antioxidant, the content (amount) of the antioxidant in the curable epoxy composition is not particularly limited, but is preferably 0.1 to 5 parts by mass relative to 100 parts by mass of the total amount of epoxy compound (A) contained in the curable epoxy composition, more preferably 0.5 to 3 parts by mass. If the content of the antioxidant is 0.1 parts by mass or more, there is a tendency for the oxidation of the cured product to be effectively prevented, and the heat resistance and yellowing resistance to be further improved. If the content of the antioxidant is 5 parts by mass or less, there is a tendency for the cured product to be more easily color-controlled and have a better hue.

[0100] As the aforementioned wetting modifier, a known or commonly used wetting modifier may be used, such as commercially available products under the trade names “BYK-327”, “BYK-302”, “BYK-310”, “BYK-320”, and “BYK-330” (all manufactured by BYK Corporation).

[0101] The above-described curable epoxy composition is not particularly limited and can be prepared by stirring / mixing the above-described components under a heated state as needed. It should be noted that the above-described curable epoxy composition can be used as a single-liquid composition where the components are pre-mixed and used as is, or as a multi-liquid composition (e.g., a two-liquid composition) where two or more separately stored components are mixed before use. The stirring / mixing method is not particularly limited; for example, known or commonly used stirring / mixing units such as dissolvers, homogenizers, and various mixers; kneaders; rollers; bead mills; and self-rotating / revolutionary stirring devices can be used. Furthermore, defoaming can be performed under vacuum after stirring / mixing.

[0102] [Cured product]

[0103] By curing the above-mentioned curable epoxy composition, a cured product with excellent heat resistance can be obtained. As a curing method, known or conventional methods such as heat treatment can be used. The temperature at which curing is performed by heating (curing temperature) is not particularly limited, but is preferably 45–220°C, more preferably 50–200°C, and even more preferably 55–190°C. Furthermore, the heating time during curing (curing time) is not particularly limited, but is preferably 30–600 minutes, more preferably 45–540 minutes, and even more preferably 60–480 minutes. If the curing temperature and curing time are 45°C or higher, curing is sufficient; if they are 220°C or lower, the decomposition of the resin components can be suppressed. The curing conditions depend on various conditions; for example, they can be appropriately adjusted by shortening the curing time when the curing temperature is increased, or extending the curing time when the curing temperature is decreased. Furthermore, curing can be performed in one step or in multiple steps (two or more steps).

[0104] The flexural strain of the cured material at 23°C is preferably 2.0% or more, more preferably 3.0% or more, even more preferably 4.0% or more, and particularly preferably 4.3% or more. If the flexural strain is 2.0% or more (especially 4.0% or more), the flexibility at room temperature is improved, and the strength and toughness are excellent. The flexural strain at 23°C can be measured according to JIS K7171 (2008).

[0105] The above-described curable epoxy composition and cured product are used in parts contained in rotating electric machines (for rotating electric machine applications). The cured product exhibits excellent adhesion to PEEK resin, and is therefore preferably used in parts that preferentially use PEEK resin, particularly automotive parts (such as EV motors for automobiles). Specific applications of the cured product include: insulating materials, coating materials, and adhesive materials. Furthermore, the curing agent composition containing anhydride-based curing agent (B) and amine-based curing accelerator (C) has a long shelf life and is less prone to thickening during storage; therefore, the above-described curable epoxy composition obtained by mixing the curing agent composition with an epoxy compound (A) exhibits excellent wettability and impregnation properties on the object to be coated. Therefore, the above-described curable epoxy composition is preferably used in atmospheric pressure impregnation, depressurized pressure impregnation, pressurized impregnation, and immersion processes.

[0106] Examples of applications for the aforementioned rotating electric motors include: protection of rotor wires (winding covering, tip covering, etc.), impregnation / molding of stator coils, impregnation / molding to cover the entire stator, magnet fixing to fix a magnet inserted into a hole in the rotor core or stator core to the inner wall of the hole, and filling the gap between the hole and the magnet.

[0107] Regarding the use of the above-mentioned curable epoxy composition and the above-mentioned cured product, coil impregnation applications, such as coil (wire, winding) impregnation / molding applications in the stator and rotor of rotating electric machines, are preferred.

[0108] By using the aforementioned cured material for the aforementioned applications of rotary motors, rotary motors with rotors or stators comprising the aforementioned cured material can be obtained, for example: a rotary motor rotor comprising a rotor winding covered by the aforementioned cured material; a rotary motor stator comprising the aforementioned cured material formed in a manner covering stator coils; a rotary motor stator comprising the aforementioned cured material covering the entire stator; a rotary motor rotor or stator comprising a rotor core or stator core having a hole, a magnet inserted into the hole, and the aforementioned magnet being bonded to the inner wall of the hole; a rotary motor rotor or stator comprising a rotor core or stator core having a hole, a magnet inserted into the hole, and the aforementioned cured material filling the gap between the magnet and the inner wall of the hole, etc.

[0109] The various solutions disclosed in this specification can also be combined with any other features disclosed in this specification. The various configurations and combinations thereof in each embodiment are merely examples, and appropriate additions, omissions, substitutions, and other modifications can be made to the configuration without departing from the spirit of this disclosure. Furthermore, the inventions of this disclosure are not limited to the embodiments or the following examples, but only to the claims.

[0110] Example

[0111] The following describes one embodiment of the present disclosure in more detail based on an example.

[0112] Example 1

[0113] (Preparation of curable epoxy composition)

[0114] Using the proportions shown in Table 1 (unit: parts by mass), the epoxy compound (A) and polyester polyol (D) were uniformly mixed and defoamed using a rotary agitator (trade name "AWATORI RENTARO AR-250", manufactured by THINKY Co., Ltd.).

[0115] Next, an anhydride curing agent (B) and an amine curing accelerator (C) were added according to the proportions shown in Table 1 (unit: parts by mass). The mixture was then thoroughly mixed using a rotary mixing device (trade name "AWATORI RENTARO AR-250", manufactured by THINKY Co., Ltd.) to further defoam and produce a curable epoxy composition.

[0116] (Preparation of solidified material)

[0117] The curable epoxy composition obtained above was filled into a mold, and then heated in an oven at 80°C for 1 hour, at 130°C for 1 hour, and at 180°C for 1 hour to produce the cured product of Example 1.

[0118] Examples 2-6, Comparative Examples 1-2

[0119] (Preparation of curable epoxy composition)

[0120] The curable epoxy compositions were modified to the composition shown in Table 1. Otherwise, the curable epoxy compositions of Examples 2 to 6 and Comparative Examples 1 to 2 were prepared in the same manner as in Example 1.

[0121] (Preparation of solidified material)

[0122] The curable epoxy compositions obtained above were filled into molds and cured using an oven. For the curable epoxy compositions of Examples 2-6 and Comparative Example 2, the oven was heated continuously at 80°C for 1 hour, at 130°C for 1 hour, and at 180°C for 1 hour. For the curable epoxy composition of Comparative Example 1, the oven was heated continuously at 130°C for 2 hours and at 150°C for 1 hour. For the curable epoxy composition of Comparative Example 3, the oven was heated continuously at 100°C for 1 hour, at 150°C for 1 hour, and at 180°C for 3 hours, thereby curing them to produce the cured products of Examples 2-6 and Comparative Examples 1-3.

[0123] <Evaluation>

[0124] The following evaluation tests were performed on the curable epoxy compositions and cured products obtained in the examples and comparative examples.

[0125] (1) Bond strength

[0126] The curable epoxy composition was smoothly coated onto a glass plate with a certain film thickness (40 μm), and then transferred onto a Si chip (1.25 mm square). Using tweezers, the Si chip was evenly arranged on a PEEK resin substrate (2.5 × 1.5 cm), and thermosetting was performed under the same conditions as when the cured material was made, producing a test piece consisting of a cured product with the curable epoxy compound and a Si chip sequentially stacked on PEEK resin. The test piece was mounted on a bonding tester (trade name "4000pxy DS100", manufactured by DAGE Corporation). The load sensor mounted on the bonding tester was moved to a set height (150 μm) on the PEEK resin substrate, and the Si chip was pressed. The bond strength of the PEEK resin was measured using the load [N] at which the joint of the cured product failed.

[0127] (2) Glass transition temperature

[0128] Using a differential scanning calorimeter (trade name "Q2000", manufactured by TA Instruments), after pretreatment (heating from 30°C to 250°C at a heating rate of 10°C / min, followed by cooling from 250°C to 30°C at a cooling rate of -10°C / min), the glass transition temperature of the cured material was determined under nitrogen gas flow, a heating rate of 10°C / min, and a measurement temperature range of 30–250°C. The inflection point of the obtained temperature history curve was then taken as the glass transition temperature.

[0129] (3) Bending strain

[0130] The bending strain of the cured material was measured according to JIS K7171 (2008).

[0131] (4) Viscosity and viscosity rise rate at 25℃

[0132] The viscosity of the above-mentioned cured epoxy composition at 25°C was determined using a rheometer (trade name "Modular Compact Rheometer MCR302", manufactured by Anton Paar, rotor diameter 25 mm, sample thickness 0.1 mm).

[0133] In addition, a storage test was conducted on the above-mentioned curable epoxy composition under the conditions of temperature 23±5℃, humidity 50±5% for 41 days, and the viscosity at 25℃ after the storage test was also measured.

[0134] Furthermore, by comparing the viscosity at 25°C before and after the preservation test, the viscosity increase rate (%) before and after the preservation test was calculated. It should be noted that examples where gelation occurred after the preservation test and the viscosity could not be measured are recorded with "-".

[0135] [Table 1]

[0136]

[0137] As shown in Table 1, Examples 1-6 contain epoxy compounds, anhydride-based curing agents, and amine-based curing accelerators; their viscosity at 25°C is below 3000 mPa·s; and the bond strength of the cured product to PEEK is 2.5 N / cm. 2 The above-described curable epoxy compositions for rotating electric machines can easily bond to PEEK resin, suppress peeling from the PEEK resin during use, and are assumed to maintain insulation. On the other hand, the curable epoxy composition for rotating electric machines in Comparative Example 1 has poor adhesive strength. Furthermore, although the curable epoxy composition for rotating electric machines in Comparative Example 2 has sufficient adhesive strength after curing, its high viscosity makes it difficult to bond to PEEK resin, resulting in poor workability and long-term stability.

[0138] It should be noted that the ingredients used in the embodiments and comparative examples are as follows.

[0139] (Epoxy compound (A))

[0140] CELLOXIDE 2021P: Trade name "CELLOXIDE 2021P" (3,4-epoxycyclohexylmethyl (3,4-epoxy)cyclohexylcarbamate), manufactured by DAICEL Co., Ltd.

[0141] YD128: Trade name "YD-128" (poly[2-(chloromethyl)ethylene oxide-alt-4,4'-(propane-2,2-diyl)diol)], manufactured by Nippon Steel Chemical & Materialia Co., Ltd.

[0142] E530: Trade name "EPIFORM E-530", manufactured by SOMAR Co., Ltd.

[0143] (Polyimide compound)

[0144] Voltatex4200: Trade name "Voltatex4200", manufactured by Axalta Corporation.

[0145] (Acid anhydride-based curing agent (B))

[0146] NMA: Trade name "NMA", methyl nadic anhydride, manufactured by POLYNT.

[0147] MTHPA: Trade name "MTHPA", methyltetrahydrophthalic anhydride, manufactured by RESONAC.

[0148] (Amine-based curing accelerator (C))

[0149] 1B2MZ: 1-Benzyl-2-methylimidazole.

[0150] HPI: 1-(2-hydroxypropyl)imidazole.

[0151] U-CAT SA-102: Trade name "U-CAT SA-102", manufactured by SAN-APRO Co., Ltd., is the 2-ethylhexane salt of 1,8-diazabicyclo[5.4.0]undecene-7.

[0152] U-CAT SA-1: Trade name "U-CAT SA-1", manufactured by SAN-APRO Co., Ltd., is a phenolic salt of 1,8-diazabicyclo[5.4.0]undecene-7.

[0153] LC-80: Trade name "Technicure LC-80", an amine adduct of 2-methylimidazole and bisphenol A type epoxy compound, a latent curing accelerator, manufactured by A&C Catalysts.

[0154] LC-100: Trade name "Technicure LC-100", manufactured by A&C Catalysts.

[0155] (Polyester polyol (D))

[0156] Polyol A: Aliphatic polyester diol, molecular weight 2000, hydroxyl value 56.8 KOH mg / g.

[0157] The following describes variations of this disclosure.

[0158] [Appendix 1]

[0159] A curable epoxy composition for rotating electric motors comprises an epoxy compound (A), an anhydride-based curing agent (B), and an amine-based curing accelerator (C). The curable epoxy composition is liquid at 25°C, has a viscosity of less than 3000 mPa·s at 25°C, and exhibits a bond strength of 2.5 N / cm² to PEEK resin upon curing. 2 above.

[0160] [Appendix 2]

[0161] According to Appendix 1, the curable epoxy composition for rotating motors exhibits a viscosity increase rate of less than 20,000% before and after a storage test conducted under conditions of 23±5°C, 50±5% humidity, and 41 days.

[0162] [Appendix 3]

[0163] According to Appendix 1 or 2, the curable epoxy composition for rotating motors has a bonding strength to PEEK resin of 2.5 N / cm upon curing. 2 above.

[0164] [Appendix 4]

[0165] The curable epoxy composition for rotary motors according to any one of Appendices 1 to 3, wherein the glass transition temperature of the curable epoxy composition for rotary motors during curing is 170°C or higher.

[0166] [Appendix 5]

[0167] The curable epoxy composition for rotating electric machines according to any one of Appendices 1 to 4, wherein the curable epoxy composition for rotating electric machines comprises an alicyclic epoxy compound as the aforementioned epoxy compound (A).

[0168] [Appendix 6]

[0169] The curable epoxy composition for rotary electric machines according to any one of Appendices 1 to 5, wherein the content of the epoxy compound (A) is 10% by mass or more relative to the total amount (100% by mass) of the curable epoxy composition.

[0170] [Appendix 7]

[0171] The curable epoxy composition for rotary motors according to any one of Appendices 1 to 6, wherein the above-mentioned anhydride-based curing agent (B) is an anhydride that is liquid at 25°C.

[0172] [Appendix 8]

[0173] The curable epoxy composition for rotating electrical machines according to any one of Appendices 1 to 7, wherein the anhydride-based curing agent (B) comprises nadic anhydride or a derivative thereof.

[0174] [Appendix 9]

[0175] The curable epoxy composition for rotating electrical machines according to any one of Appendices 1 to 8, wherein the amine curing accelerator (C) comprises an imidazole curing accelerator.

[0176] [Postscript 10]

[0177] According to any one of Appendices 1 to 9, the curable epoxy composition for rotating electrical machines comprises, wherein, relative to 100 parts by mass of the total amount of curable compounds contained in the curable epoxy composition, the content of the amine curing accelerator (C) is 0.01 to 5 parts by mass.

[0178] [Postscript 11]

[0179] The curable epoxy composition for rotating motors according to any one of Appendices 1 to 10, wherein the curable epoxy composition for rotating motors further comprises polyester polyol (D).

[0180] [Postscript 12]

[0181] According to Appendix 11, the curable epoxy composition for rotating motors, wherein the molecular weight of the polyester polyol (D) is 250 to 100,000.

[0182] [Postscript 13]

[0183] According to Appendix 11 or 12, the curable epoxy composition for rotating motors wherein the hydroxyl value of the polyester polyol (D) is less than 600 KOH mg / g.

[0184] [Postscript 14]

[0185] The curable epoxy composition for rotating electrical machines according to any one of Appendices 1 to 13, wherein the curable epoxy composition for rotating electrical machines further comprises an inorganic filler (E).

[0186] [Postscript 15]

[0187] According to Appendix 14, the curable epoxy composition for rotating electrical machines contains silica as the aforementioned inorganic filler (E).

[0188] [Postscript 16]

[0189] A cured product, wherein the cured product is a cured product of a curable epoxy composition for rotating electrical machines according to any one of Appendices 1 to 15.

[0190] [Postscript 17]

[0191] A stator for a rotary motor, the stator comprising a cured material as described in Appendix 16 formed in a manner covering stator coils.

[0192] [Postscript 18]

[0193] A stator for a rotary electric motor having a solidified material according to Appendix 16 for the windings of a covered rotor.

Claims

1. A curable epoxy composition for rotating electric motors, comprising an epoxy compound (A), an anhydride-based curing agent (B), and an amine-based curing accelerator (C), wherein the curable epoxy composition is liquid at 25°C, has a viscosity of less than 3000 mPa·s at 25°C, and has a bond strength to PEEK resin of 2.5 N / cm² upon curing. 2 above.

2. The curable epoxy composition for rotating electric machines according to claim 1, wherein, The viscosity increase rate of the curable epoxy composition for rotary motors before and after storage tests conducted at a temperature of 23±5℃ and a humidity of 50±5% for 41 days was less than 20,000%.

3. The curable epoxy composition for rotating electric machines according to claim 1 or 2, wherein, The glass transition temperature of the curable epoxy composition for the rotary motor is above 170°C during curing.

4. A cured product, said cured product being a cured product of the curable epoxy composition for rotating motors according to claim 1 or 2.

5. A stator for a rotary electric motor, the stator comprising a cured material according to claim 4 formed in a manner covering stator coils.

6. A rotor for a rotary electric motor, the rotor having a cured material according to claim 4 for covering rotor windings.

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