Method for producing fullerene-derivative-containing resin composition, fullerene-derivative-containing resin composition obtained from the same, resin paint, resin coating, and enamel wire

Abstract

To provide a material that suppresses a decrease in the life of an insulation material against surge voltage, that is, a material that provides a long dielectric breakdown lifetime.SOLUTION: A method for producing a fullerene-derivative-containing resin composition containing a fullerene derivative and a resin that has an affinity for a polar solvent, the method comprising the following steps (I) and (II): (I) a step of dispersing a fullerene derivative in a polar solvent; and (II) a step of mixing the polar solvent in which the fullerene derivative is dispersed with a resin that has an affinity for the polar solvent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a fullerene derivative-containing resin composition, and to the fullerene derivative-containing resin composition, resin paint, resin coating film, and enameled wire obtained thereby, in order to provide a material that suppresses the reduction in the lifespan of insulating materials due to surge voltages, i.e., a material that adds a long dielectric breakdown lifespan. [Background technology]

[0002] In recent years, electric vehicles using motors as their drive source have been developed. Motor manufacturers have announced prototypes of inverter-equipped in-wheel motors. Electric motors are an attractive power source that can generate high torque over a wide range of revolutions, from low to high. However, currently, motors used in electric vehicles are only capable of generating high torque at low revolutions, and are dependent on conventional technologies such as transmissions and engines (hybrid vehicles) to handle high revolutions. Therefore, in order to develop fully-fledged electric vehicles, it is considered essential to commercialize motors that can generate high torque over a wide range of revolutions.

[0003] A problem with high-speed, high-torque motors is that surge voltages generated by inverter control devices reduce the lifespan of the motor windings. Surge voltages are about twice the input voltage, and their frequency is thought to be proportional to the frequency.

[0004] To achieve high torque and high rotation speeds, it is necessary to increase the frequency by about 10 times compared to the current level. In other words, the life of the motor winding insulation against surge voltages must be increased by more than 10 times.

[0005] Assuming that the current warranty period for automobile motors is 10 years, the warranty period for a 10-times higher frequency would be one year, which is not realistic. In order to increase the frequency to about 10 times the current level, the lifespan of the motor winding insulation against surge voltages would need to be increased by more than 10 times.

[0006] Motor deterioration due to surge voltages is thought to be caused by corona discharges that occur between the motor windings. The partial discharge inception voltage (V), which is the voltage at which discharge begins between the windings, is expressed by Dakin's formula below. [Formula] V=α(t / ε) 0.46 α: Constant (α=720 when t is in mils) ε: relative permittivity of the insulating layer t: thickness of the insulating layer

[0007] Heat resistance is also an important characteristic required for insulating materials for high-speed, high-torque motors. In other words, heat-resistant materials are selected to meet the cooling requirements of motors operating at high speeds and torque.

[0008] Fullerenes are spherical carbon compounds with a diameter of approximately 1 nm, and are heat-resistant and have excellent electron-accepting properties, so they are expected to mitigate the accumulation of electric charges inside insulators. However, despite attempts to utilize them, fullerenes and fullerene derivatives have strong cohesion properties and poor compatibility with synthetic resins, making it difficult to uniformly disperse fullerenes in synthetic resins at nanometer levels.

[0009] Non-patent document 1 describes the use of C 60 Fullerene and C 60 The voltage at which electrical trees are generated using cross-linked polyethylene insulation with nano-dispersed C-PCBM and C-PCBM has been measured. 60 Fullerene and C 60 -The cross-linked polyethylene insulation material with nano-dispersed PCBM at 1mmol / kg (approximately 0.1% by weight) has a higher AC voltage resistance than the cross-linked polyethylene insulation material without additives. 60 15% for fullerenes, C 60 - PCBM is said to have improved by 26%.

[0010] Patent Document 1 also discloses an electrical insulating varnish produced by adding and dispersing silica sol dispersed in a mixed solvent of a resin solvent and alcohol, naphtha, or the like, in an amount of 5 to 100 parts by weight, calculated as silica, per 100 parts by weight of insulating resin. The varnish is impregnated into the coil of an electrical device, solidified, and produced an inverter surge-resistant coil. The time to breakdown is more than six times longer than when no additives are used. [Prior art documents] [Non-patent literature]

[0011] [Non-Patent Document 1] Markus Jarvid, Anette Johansson, Renee Kroon, Jonas M.Bjuggren, Harald Wutzel, Villgot Englund, Stanislaw Gubanski, Mats R. Andersson, and Christian Muller, "A New Application Area for Fullerenes: Voltage Stabilizers for Power Cable Insulation", Advanced Materials 2015, 27, 897-902 [Non-patent document 2] E. Markus Jarvid, Anette B. Johansson, Jorgen HM Blennow, Mats R. Andersson and Stanislaw M. Gubanski, "Evaluation of the Performance of Several Object Types for Electrical Treeing Experiments", IEEE Transactions on Dielectrics and Electrical Insulation, Vol.20, No.5, October 2013, 1712-1719 [Patent documents]

[0012] [Patent Document 1] Patent No. 4061981 Summary of the Invention [Problem to be solved by the invention]

[0013] Although Non-Patent Document 1 does not describe a method for uniformly nano-dispersing fullerenes in polyethylene, Non-Patent Document 2 describes a method for producing cable insulation in which a mixture of polyethylene, an antioxidant (fullerene), and a cross-linking agent is cooled and solidified with liquid nitrogen, the solidified product is finely pulverized, and the uniformly mixed fine powder is melted to obtain a nano-dispersion. However, this method cannot be used on an industrial level due to its complexity and economic reasons. Furthermore, in the above Patent Document 1, a large amount of silica sol is added, equivalent to 5 to 100 parts by weight of silica per 100 parts by weight of insulating resin, which has the drawback of increasing the stiffness of the coil, making it difficult to wind the coil tightly, and increasing the weight of the motor.

[0014] Therefore, under these circumstances, the present invention provides a material that suppresses the reduction in the lifespan of insulating materials due to surge voltages, as well as a material that suppresses the reduction in lifespan at a low content, i.e., a material that adds a long dielectric breakdown lifespan at a low content. In order to do so, the present invention provides a method for producing a fullerene derivative-containing resin composition, and the fullerene derivative-containing resin composition, resin paint, resin coating film, and enameled wire obtained thereby. [Means for solving the problem]

[0015] In order to achieve the above object, the present inventors have conducted extensive research to solve the above problems, and have found that when a fullerene derivative is dispersed in a polar solvent and then the polar solvent in which the fullerene derivative is dispersed is mixed with a resin having affinity for the polar solvent, the fullerene derivative is highly dispersed in the resulting fullerene derivative-containing resin composition.

[0016] That is, the present invention provides the following [1] to

[10] . [1] A method for producing a fullerene derivative-containing resin composition containing a fullerene derivative and a resin having affinity for polar solvents, the method comprising the following steps (I) and (II): (I) A step of dispersing a fullerene derivative in a polar solvent (II) A step of mixing the polar solvent in which the fullerene derivative is dispersed with a resin having an affinity for the polar solvent. [2] The method for producing a fullerene derivative-containing resin composition according to [1], wherein the fullerene derivative is a fullerene represented by the following general formula (1): Cn[O(CH2)xCH3]y(OH)z …(1) (n is 60 or more, x is 3 or more, y is an integer of 1 or more, z is 0 or an integer of 1 or more) [3] The method for producing a fullerene derivative-containing resin composition according to [1] or [2], wherein the polar solvent is a solvent having an amide bond. [4] The method for producing a fullerene derivative-containing resin composition according to any one of [1] to [3], wherein the polar solvent is N-methyl-2-pyrrolidone. [5] A fullerene derivative-containing resin composition obtained by the method for producing a fullerene derivative-containing resin composition according to any one of [1] to [4]. [6] A fullerene derivative-containing resin composition containing a fullerene derivative and a resin having affinity for polar solvents, characterized in that the dielectric breakdown life measured under the following measurement conditions is 10 times or more longer than that of a resin to which the fullerene derivative is not added. [Measurement conditions] Test pieces of the above resin composition, sized 50 x 50 x 0.2-0.4 mm, were measured under conditions of an AC voltage range of 10-100 kV, a voltage rise rate of 1 kV / sec, and a frequency of 60 Hz. [7] The fullerene derivative-containing resin composition according to [5] or [6], wherein the content of the fullerene derivative is 0.0001 to 5% by weight of the resin composition. [8] A resin coating composition comprising, as a main component, the fullerene derivative-containing resin composition according to any one of [5] to [7]. [9] A resin coating film obtained by solidifying the resin coating material according to [8].

[10] An enameled wire comprising a conductor and the resin coating film according to [9] provided on the outer periphery of the conductor. [Effects of the Invention]

[0017] As described above, the present invention provides a method for producing a fullerene derivative-containing resin composition containing a fullerene derivative and a resin having affinity for polar solvents, characterized in that the method comprises the steps of (I) dispersing a fullerene derivative in a polar solvent and (II) mixing the polar solvent in which the fullerene derivative is dispersed with a resin having affinity for the polar solvent. Therefore, according to this method, the fullerene derivative in the resulting resin composition is highly dispersed, making it possible to suppress a decrease in the lifespan of insulating materials against surge voltages.

[0018] In particular, when the fullerene derivative is a fullerene represented by the following general formula (1), the dispersibility of the fullerene derivative in the resin composition is further improved. Cn[O(CH2)xCH3]y(OH)z …(1) (n is 60 or more, x is 3 or more, y is an integer of 1 or more, z is 0 or an integer of 1 or more)

[0019] In particular, when the polar solvent has an amide bond, it can act as a bridge between the resin and the fullerene derivative, thereby further increasing the dispersibility of the fullerene derivative in the resin composition.

[0020] In particular, when the polar solvent is N-methyl-2-pyrrolidone, the dispersibility of the fullerene derivative in the resin composition is further improved.

[0021] Furthermore, since the fullerene derivative-containing resin composition obtained by the production method of the present invention has a long dielectric breakdown life, it is possible to impart a long dielectric breakdown life to resin paints, resin coating films, and enameled wires that use this resin composition. DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention provides a method for producing a fullerene derivative-containing resin composition (hereinafter sometimes abbreviated as "resin composition") containing a fullerene derivative and a resin having affinity for polar solvents. This production method significantly improves the dispersibility of the fullerene derivative in the resin composition. First, the fullerene derivative-containing resin composition obtained by this production method will be described.

[0023] <Fullerene derivatives> The fullerene derivative-containing resin composition contains a fullerene derivative and a resin having affinity for polar solvents. The fullerene derivative will now be described.

[0024] The above fullerene derivatives are C 60 or C 70 A part of the fullerene skeleton is chemically modified, for example, C 60 (OH)n, chlorinated fullerenes, phenol fullerenes (phenol-C 60 ), (6,6,)-phenyl C 60 Butyric acid methyl ester (C 60 -PCBM), long-chain alkylated fullerenes, long-chain alkyl-etherified fullerenes, etc. These can be used alone or in combination of two or more types.

[0025] The fullerene skeleton is a general term for a skeleton made of spherical carbon molecules. Carbon molecules that can form spherical shell molecules include nanomaterials represented by the general formula Cn (where n is an integer of 60 or more). Here, nanomaterials refer to materials having at least one dimension smaller than 100 nm.

[0026] Furthermore, as the fullerene derivative, a long-chain alkyl-etherified fullerene is preferably used. Because of its excellent affinity with the dispersion medium resin, the long-chain alkyl-etherified fullerenes do not aggregate when mixed with the resin, making it easy to obtain a resin in which the long-chain alkyl-etherified fullerenes are stably dispersed in nano-sized particles. For this reason, it can be applied to electric wires such as enameled wires, which require uniformity in the longitudinal direction.

[0027] The long-chain alkyl-etherified fullerene may be either a straight-chain or branched-chain alkyl group, so long as it contains a long-chain alkyl group having 4 or more carbon atoms. The alkyl group has 4 or more carbon atoms, but preferably has 6 or more carbon atoms in terms of improving compatibility with resins, and the upper limit of the carbon number is usually 12.

[0028] Furthermore, the fullerene derivative is preferably a fullerene represented by the following general formula (1). Cn[O(CH2)xCH3]y(OH)z …(1) (n is 60 or more, x is 3 or more, y is an integer of 1 or more, z is 0 or an integer of 1 or more)

[0029] In the above general formula (1), y+z is preferably 3 to 14, and more preferably 5 to 12, for synthesis under simple conditions. For example, when the total number of substituents, y+z, is 10, y is 1 or greater, and is preferably 5 to 9 in terms of dispersibility and amphiphilicity. Furthermore, z is 0 or an integer of 1 or greater, and is preferably 1 to 5 in terms of heat resistance and stability. Therefore, it is more preferable that the ratio of y to z (number of long-chain alkyl groups / number of hydroxyl groups) be 1 / 1 to 9 / 1, as this tends to contribute to improved heat resistance without impairing compatibility with resins or other advantages.

[0030] The content of the fullerene derivative is preferably 0.0001 to 5% by weight, more preferably 0.001 to 1% by weight, and particularly preferably 0.001 to 0.5% by weight, of the resin composition excluding the solvent. From the viewpoint of increasing the partial discharge inception voltage (making it difficult for electric charges to accumulate in the insulating material), the content is preferably 0.0001 to 0.3% by weight, more preferably 0.0005 to 0.2% by weight, and particularly preferably 0.001 to 0.1% by weight.

[0031] <Method for producing fullerene derivatives> As a method for producing the above-mentioned fullerene derivative, for example, in a first step, polycyclosulfated fullerene (CS) is synthesized from untreated fullerene and fuming sulfuric acid, and in a second step, at least one alkyl group is introduced into the fullerene skeleton via an ether bond formed by reacting the CS with a long-chain alcohol, thereby synthesizing an alkyl-etherified fullerene derivative.

[0032] In place of the above CS, other fullerene derivatives having a substituent that is easily eliminated in a nucleophilic substitution reaction of an alcohol, such as a halogenated fullerene having a fluorine, chlorine, or bromine atom as a substituent on the fullerene skeleton or a nitrated fullerene having a nitro group, may be used. However, the method of reacting the above CS with a long-chain alcohol is preferred.

[0033] Before or after the first and second steps, other steps such as pre-treatment and post-treatment for the purpose of purification may be included.

[0034] <Resin with affinity to polar solvents> First, when explaining the resin having an affinity for polar solvents, the polar solvent will be explained first.

[0035] <Polar solvent> The polar solvent may be any liquid made up of molecules with a large dipole moment, and preferably has an SP value (solubility parameter) of 10 to 13. In the present invention, the polar solvent functions as a solvent that swells and dissolves resins that have an affinity with the polar solvent.

[0036] Examples of such polar solvents include aprotic polar solvents such as N-methyl-2-pyrrolidone, N-formylmorpholine, N-acetylmorpholine, N,N'-dimethylethyleneurea, N,N-dimethylacetamide, and N,N-dimethylformamide, and protic polar solvents such as hexafluoroisopropanol, formic acid, and various alcohols (for example, lower alcohols having 1 to 6 carbon atoms such as methanol, ethanol, and 2-propanol).These may be used alone or in combination of two or more.

[0037] Among these, from the viewpoint of solubility, polar solvents having an amide bond are preferred, and aprotic polar solvents such as N-methyl-2-pyrrolidone, N-formylmorpholine, N-acetylmorpholine, N,N'-dimethylethyleneurea, N,N-dimethylacetamide, and N,N-dimethylformamide are more preferred, with N-methyl-2-pyrrolidone being particularly preferred.

[0038] In the polar solvent, when the total amount of the polar solvent is taken as 100% by weight, the content of the polar solvent having an amide bond is preferably within a range of 10 to 100% by weight.

[0039] The solvent that can be used for nano-dispersion tends to be determined by the properties of the fullerene derivative used. For example, polar phenol-C 60 It dissolves in the polar solvent 1,4-dioxane, but although it disperses well in tetrahydrofuran (THF), its molecular size is somewhat large, and it does not dissolve in toluene, which has a lower polarity.

[0040] The content of the polar solvent to be mixed per 1 g of the fullerene derivative is preferably 10 to 500 mL, more preferably 30 to 300 mL, and particularly preferably 50 to 200 mL.

[0041] <Resin with affinity to polar solvents (dispersion medium resin)> The resin having an affinity for the polar solvent may be any resin having an affinity for the polar solvent, and is preferably a polar resin. In the present invention, the fullerene derivative is dispersed in such a resin, and therefore, the resin may be referred to as a "dispersion medium resin."

[0042] Examples of such dispersion medium resins include polyamideimide resins, epoxy resins, mixtures of polyamideimide resins and epoxy resins, polyester resins, vinyl ester resins, and phenolic resins. These can be used alone or in combination of two or more. Among these, polyamideimide resins and epoxy resins are preferred from the viewpoints of affinity and heat resistance, and polyamideimide resins are more preferred.

[0043] In particular, from the viewpoint of heat resistance, it is preferable that the main component of the dispersion medium resin is a polyamideimide resin.Furthermore, it is preferable that the polar solvent has an amide bond, since this increases the affinity with the resin. In the present invention, the term "main component" refers to a component that has a significant effect on the properties of the dispersion medium resin, and the content of the component is usually 50% by weight or more, preferably 60% by weight or more, and particularly preferably 70% by weight or more of the entire dispersion medium resin.

[0044] When the main component of the dispersion medium resin is polyamide-imide resin, the other resin is preferably a versatile epoxy resin. The above-mentioned epoxy resins are classified into bisphenol type, novolac type, aliphatic type and amine type depending on the type of base resin, and each type has affinity with a wide range of solvents depending on the combination of base resin and curing agent, but bisphenol type epoxy resins are preferred because of their high affinity with polar solvents.

[0045] The content of the fullerene derivative in the dispersion medium resin is preferably 0.0001 to 5 wt %, more preferably 0.001 to 1 wt %, and particularly preferably 0.001 to 0.5 wt %. From the viewpoint of increasing the partial discharge inception voltage (making it difficult for electric charges to accumulate in the insulating material), the content is preferably 0.0001 to 0.3 wt %, more preferably 0.0005 to 0.2 wt %, and particularly preferably 0.001 to 0.1 wt %.

[0046] Furthermore, it is preferable that the dispersion medium resin has affinity not only with the polar solvent but also with the fullerene derivative. If the affinity is low, the particle size of the fullerene derivative tends to increase rapidly due to stirring and impact during storage and application, concentration during heat treatment, etc., which hinders uniformity along the length of enameled wire, etc., and even if an enameled wire shows good results in a sampling test, the initial effect may not be obtained in the assembled motor.

[0047] <Resin composition and method for producing same> The fullerene derivative-containing resin composition of the present invention contains the fullerene derivative and a resin (dispersion medium resin) having affinity for the polar solvent, and is obtained through the following steps (I) and (II). The obtained resin composition has excellent dispersibility of the fullerene derivative in the resin composition. (I) A step of dispersing a fullerene derivative in a polar solvent (II) A step of mixing the polar solvent in which the fullerene derivative is dispersed with a resin having an affinity for the polar solvent.

[0048] In the above step (I), since polar solvents have high solubility, dispersing the fullerene derivative in a polar solvent exhibits excellent dispersibility. Dispersion methods include, for example, stirring and mixing with a blade stirrer, ultrasonic treatment, a homogenizer, a ball mill, etc. Among these, ultrasonic treatment is preferred from the viewpoint of dispersibility.

[0049] In the above step (II), when the polar solvent in which the fullerene derivative obtained in the above step (I) is dispersed is mixed with a dispersion medium resin, the polar solvent penetrates into the boundary portions of the dispersion medium resin, causing the dispersion medium resin to rapidly swell. Then, by stirring, nanoparticles of the fullerene derivative with high electron capture ability are arranged in the free volume at the boundary portions of the swollen dispersion medium resin. This results in a dispersion medium resin in which the fullerene derivative with electron capture ability is uniformly dispersed in nanoparticles.

[0050] The mixing method of (II) above is not particularly limited, but examples thereof include a method in which a polar solvent in which a fullerene derivative is dispersed is added to a dispersion medium resin, and the mixture is stirred and mixed using a blade stirrer, ultrasonic treatment, a homogenizer, a ball mill, or the like, and then the solvent is removed by heat or the like; and a method in which a polar solvent in which a fullerene derivative is dispersed is mixed with a dispersion medium resin, and the mixture is melted, stirred, and mixed, and then the solvent is removed by heat or the like. Examples of the melt-kneading include a method in which a mixture of a fullerene derivative and a resin is melt-kneaded using a kneader, a Banbury mixer, a roll, or the like. Among these, ultrasonic treatment is preferred from the viewpoint of dispersibility, and ultrasonic treatment at a mixing temperature of 10 to 40°C for 0.5 to 1 hour is more preferred.

[0051] The resulting dispersion medium resin, in which the fullerene derivatives are uniformly dispersed in nanometer-scale, is believed to capture electrons and prevent the accumulation of space charge in the insulating layer, thereby significantly increasing the AC tree initiation voltage, which governs insulation performance and electrical degradation.

[0052] Furthermore, the resin composition of the present invention preferably has a dielectric breakdown life under the following measurement conditions that is 10 times or more, more preferably 15 times or more, particularly 18 times or more, and especially 20 times or more, of that of a resin containing no fullerene derivative. The upper limit is usually 10,000 hours. If a solvent is present in the resin composition during measurement, the solvent is removed before measurement. The above-mentioned resin containing no fullerene derivative refers to a resin composition containing the fullerene derivative of the present invention that is the subject of measurement, from which the fullerene derivative has been removed (a system to which no fullerene derivative has been added). [Measurement conditions] Test pieces of the above resin composition, sized 50 x 50 x 0.2-0.4 mm, were measured under conditions of an AC voltage range of 10-100 kV, a voltage rise rate of 1 kV / sec, and a frequency of 60 Hz.

[0053] The resin composition of the present invention can achieve a long dielectric breakdown life, which suggests that the fullerene derivative, which is a nanomaterial, is in a dispersed state, i.e., is in a "nano-dispersed" state. This nano-dispersed state also includes cases where the nanomaterial is at the molecular level.

[0054] In addition to the fullerene derivative and dispersion medium resin, the resin composition according to the present invention may contain additives such as polar solvents, solvents other than polar solvents, plasticizers, dispersants, antioxidants, heat stabilizers, ultraviolet absorbers, weather resistance stabilizers, dripping inhibitors, mold release agents, lubricants, flame retardants, colorants, antibacterial agents, and antistatic agents, as well as optional components such as glass fibers, carbon fibers, high-melting-point organic fibers, carbon black, silica, calcium carbonate, clay, talc, shirasu balloons, and glass balloons.

[0055] The polar solvent will eventually be removed when the product is manufactured, so the content of the polar solvent is not particularly limited.

[0056] The content of the optional components is not limited as long as it is an amount that does not impair the effects of the present invention.

[0057] <Resin paint> The resin coating material of the present invention mainly comprises the fullerene derivative-containing resin composition obtained above, i.e., a dispersion medium resin in which the fullerene derivative is nano-dispersed. By using a dispersion medium resin in which the fullerene derivative is nano-dispersed as the main component, a resin coating material in which the fullerene derivative is nano-dispersed can be obtained. Here, the term "main component" refers to a component that has a significant effect on the properties of the material, and the content of the component is usually 50% by weight or more of the entire material, preferably 60% by weight or more, particularly preferably 70% by weight or more, and most preferably 100% by weight.

[0058] The content of the fullerene derivative in the resin coating (excluding the solvent) is preferably 0.0001 to 5 wt %, more preferably 0.001 to 1 wt %, and particularly preferably 0.001 to 0.5 wt %. Within this range, the resin coating film obtained by solidifying the resin coating has excellent life against surge voltage. In particular, if the content is 0.001 wt % or more, the life against surge voltage of the resin coating film can be made 20 times or more longer than that of a resin coating film containing no fullerene derivative. Furthermore, from the viewpoint of increasing the partial discharge inception voltage (making it difficult for electric charge to accumulate in the insulating material), the content is preferably 0.0001 to 0.3 wt %, more preferably 0.0005 to 0.2 wt %, and particularly preferably 0.001 to 0.1 wt %.

[0059] By adjusting the viscosity and other properties of the dispersion medium resin in which the fullerene derivative is nano-dispersed depending on the application, a resin coating material in which the fullerene derivative is nano-dispersed can be obtained.

[0060] <Resin coating> In the present invention, the resin coating film produced by solidifying the resin coating material in which the fullerene derivative is nano-dispersed has partial discharge resistance and heat resistance. The solidification method is not particularly limited, but examples include desolvation, defoaming, photocuring, and heat curing, and among these, desolvation and defoaming by heating are preferred.

[0061] A more preferred method for producing a resin coating film is to pour the resin coating material into a molding die or the like, and then heat (80 to 200°C, 24 to 48 hours) using a reduced pressure dryer (0.1 Pa or less) to defoam and remove the solvent. The resulting resin coating film has heat resistance and partial discharge resistance.

[0062] Since the electron-accepting ability of a fullerene derivative is proportional to the surface area of ​​the fullerene skeleton, it is believed that the fullerene derivative nanoparticles in the resin coating film do not aggregate but remain present in the resin coating film, thereby improving the electron-accepting ability per mole. Therefore, even when the resin coating material is kneaded during the production of enameled wire, the fullerene derivative nanoparticles dispersed in the coating material do not aggregate and remain stable along the length of the enameled wire.

[0063] <Enameled wire> The enameled wire of the present invention has excellent heat resistance and partial discharge resistance because the resin coating film having heat resistance and partial discharge resistance is provided on the outer periphery of the conductor.

[0064] In the case of enameled wire, the conductor is continuously immersed in a resin paint containing nano-dispersed fullerene derivatives, and excess resin paint is removed to make the thickness of the resin paint uniform. After that, the wire is heated in a tunnel heater and the solvent is removed, thereby continuously producing enameled wire that is heat-resistant and resistant to partial discharge.

[0065] The resin coating film formed by solidifying the resin paint has a lifespan against surge voltages that is 20 times longer than conventional products. Therefore, by using an enameled wire with the resin coating film of the present invention applied to the outer periphery of the conductor, it is possible to realize electric vehicles using high-torque / high-speed motors without incurring a reduction in the motor's lifespan due to surge voltages generated by inverter control devices. [Example]

[0066] The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited to these examples as long as it does not depart from the gist of the present invention.

[0067] Example 1 [Synthesis of fullerene derivatives] The fullerene derivative used in the resin composition was synthesized by the following method.

[0068] <Preparation of long-chain alkyl-etherified fullerene derivatives> The raw material fullerene (C 60 ) (trade name: nanom purple ST) was purchased from Frontier Carbon Co., Ltd. and used.

[0069] The synthesis of polycyclosulfated fullerene (CS) in the first step was carried out as follows according to Reference Example 1 in the examples of JP-A No. 2005-251505.

[0070] Fullerene (C 60 5 g of the product was reacted with 75 mL of 60 wt % fuming sulfuric acid at 60°C under a nitrogen atmosphere for 3 days with stirring. Next, the resulting reaction mixture was added dropwise to 500 mL of diethyl ether in an ice bath to obtain a precipitate. The resulting precipitate was separated by centrifugation, washed with a total of approximately 1000 mL of anhydrous diethyl ether in several portions, and then washed with approximately 300 mL of a diethyl ether / acetonitrile = 2 / 1 mixed solvent and dried in vacuo to obtain sample (CS).

[0071] The infrared absorption spectrum (IR spectrum) of the obtained sample (CS) was in good agreement with the infrared absorption spectrum (IR spectrum) in FIG. 1 of JP-A-2005-251505, and it was confirmed to be polycyclosulfated fullerene (CS).

[0072] Next, in the second step, hexyl etherified hydroxylated fullerene (HexC 60 ) was synthesized as follows. 2 g of the polycyclosulfated fullerene (CS) obtained above was reacted with 20 mL of hexanol under a nitrogen atmosphere at 80°C for 2 days with stirring. The reaction mixture was centrifuged with approximately 910 mL of methanol to remove the precipitated product and unreacted hexanol. The reaction mixture was then washed with water until the pH reached 6.5, removing the sulfuric acid, and hexyl etherified hydroxylated fullerene (HexC 60 ) 0.95g was obtained.

[0073] Hexyl etherified hydroxylated fullerene (HexC 60 ) was identified by infrared absorption spectroscopy (IR spectrum), and elemental analysis was performed to determine the structural formula as C 60 The fullerene was determined to be [O(CH2)5CH3]4(OH)5, and hexyl etherified hydroxylated fullerene (HexC 60 ) was confirmed.

[0074] [Resin composition and film production thereof] Hexyl etherified hydroxylated fullerene derivatives (HexC 601.57 mg of PEG-14 was added to 1,000 g of N-methyl-2-pyrrolidone (SP value: 11.2) and sonicated to prepare a 0.000157 wt% solution. 30.79 g of this solution was added to 30.79 g of polyamideimide resin (Toyobo Co., Ltd., Pyromax HR-11 (concentration: 15 wt%)), and the resin solution was sonicated to dissolve it.

[0075] This resin solution was poured into a 120 x 120 x 10 mm hollowed-out Teflon (registered trademark) plate, and degassed and desolvated at 140°C using a vacuum dryer to obtain a hexyl etherified hydroxylated fullerene derivative (HexC 60 A film with a thickness of 0.328 mm was prepared, containing 0.0083 mmol / kg (0.001 wt %) of the hydroxybenzoate with respect to the polyamide-imide resin.

[0076] [Film dielectric breakdown life] A film sample cut to a size of 50 mm x 50 mm was subjected to breakdown voltage measurement (also called "voltage resistance measurement") using an AC high voltage generator (Tokyo Transformer Co., Ltd., "100 kV 20 kVA") under the following conditions: electrode in electrical insulating oil, voltage rise rate: 1 kV / sec, current: AC, frequency: 60 Hz.

[0077] From the breakdown voltage measurement, the dielectric breakdown life was calculated in the following order. (1) The breakdown voltage of the sample is measured. (2) Measure the time until breakdown when a voltage (at multiple points) lower than the breakdown voltage is applied. (3) Determine the relationship between the applied voltage and the breakdown time. (4) The breakdown time was calculated using 30 kV as the threshold voltage, and this was taken as the lifespan.

[0078] [Partial discharge inception voltage of film] The partial discharge inception voltage was measured using a discharge detector "B010" manufactured by Fujikura Diamond Electric Wire Co., Ltd., an upper electrode being a sphere of 20 mm diameter, and a lower electrode being a cylinder of 25 mm diameter.

[0079] The measurement conditions were as follows: voltage increase rate 2kV / 12sec (10kV / min) ⇒ hold for 5sec (2kV) ⇒ voltage decrease rate 2kV / 12sec (10kV / min), frequency: 60Hz. The voltage (threshold) at a charge of 100 pC was taken as the partial discharge inception voltage.

[0080] From these measurement results, the dielectric breakdown life was 20 hours and the partial discharge inception voltage was 3.89 kV / mm. The measurement results are shown in Table 1 below.

[0081] <Example 2> In the same manner as in Example 1, a hexyl etherified hydroxylated fullerene derivative (HexC 60 A film with a thickness of 0.293 mm was prepared, containing 0.083 mmol / kg (0.01 wt %) of the hydroxybenzoate with respect to the polyamide-imide resin.

[0082] Next, the dielectric breakdown life and partial discharge inception voltage were measured, and the results were that the dielectric breakdown life was 33 hours and the partial discharge inception voltage was 3.65 kV / mm. The measurement results are shown in Table 1 below.

[0083] Example 3 In the same manner as in Example 1, a hexyl etherified hydroxylated fullerene derivative (HexC 60 A film with a thickness of 0.319 mm was prepared, containing 0.827 mmol / kg (0.1 wt %) of methyl methyl acrylate with respect to the polyamide-imide resin.

[0084] Next, the dielectric breakdown life and partial discharge inception voltage were measured, and the dielectric breakdown life was 56 hours and the partial discharge inception voltage was 4.40 kV / mm. The measurement results are shown in Table 1 below.

[0085] Example 4 In the same manner as in Example 1, a hexyl etherified hydroxylated fullerene derivative (HexC 60 A film with a thickness of 0.317 mm was prepared, containing 4.136 mmol / kg (0.5 wt %) of methyl methyl acrylate with respect to the polyamide-imide resin.

[0086] Next, the dielectric breakdown life and partial discharge inception voltage were measured, and the results were that the dielectric breakdown life was 375 hours and the partial discharge inception voltage was 3.51 kV / mm. The measurement results are shown in Table 1 below.

[0087] <Example 5> A hexyl etherified fullerene derivative (HBC) without a hydroxyl group was prepared from bromide fullerene and anhydrous hexanol according to JP 2014-172865 A. 60 ) was synthesized.

[0088] From infrared absorption spectroscopy (IR spectroscopy) and elemental analysis, the structural formula was determined to be C 60 [O(CH2)5CH3] 12 and a hexyl etherified fullerene derivative (HBC) without a hydroxyl group was identified. 60 ) was confirmed.

[0089] In the same manner as in Example 1, a hexyl etherified fullerene derivative (HBC) having no hydroxyl group was obtained. 60 A film with a thickness of 0.357 mm was prepared, containing 0.518 mmol / kg (0.1 wt %) of the hydroxybenzoate with respect to the polyamide-imide resin.

[0090] Next, the dielectric breakdown life and partial discharge inception voltage were measured, and the results were that the dielectric breakdown life was 15 hours and the partial discharge inception voltage was 3.82 kV / mm. The measurement results are shown in Table 1 below.

[0091] Example 6 In the same manner as in Example 1, cyclosulfated fullerene (CS) and octanol were converted into octyl etherified hydroxylated fullerene derivative (OctC 60 ) was synthesized.

[0092] From infrared absorption spectroscopy (IR spectroscopy) and elemental analysis, the structural formula was determined to be C 60 The hydroxylated fullerene derivative (OctC) was determined to be [O(CH2)5CH3]4(OH)2. 60 ) was confirmed.

[0093] In the same manner as in Example 1, an octyl etherified hydroxylated fullerene derivative (OctC 60 A film with a thickness of 0.256 mm was prepared, containing 0.787 mmol / kg (0.1 wt %) of the hydroxybenzoate with respect to the polyamide-imide resin.

[0094] Next, the dielectric breakdown life and partial discharge inception voltage were measured, and the results were that the dielectric breakdown life was 60 hours and the partial discharge inception voltage was 3.94 kV / mm. The measurement results are shown in Table 1 below.

[0095] Example 7 Phenyl C 61 A 0.317 mm thick film containing methyl butyrate-esterified fullerene derivative (PCBM) at a concentration of 1.098 mmol / kg (0.1 wt%) relative to the polyamide-imide resin was prepared.

[0096] Next, the dielectric breakdown life and partial discharge inception voltage were measured, and the results were that the dielectric breakdown life was 17 hours and the partial discharge inception voltage was 3.72 kV / mm. The measurement results are shown in Table 1 below. PCBM (trade name nanom spectra E102) was purchased from Frontier Carbon Co., Ltd.

[0097] <Comparative Example 1> In the same manner as in Example 1, 30.79 g of N-methyl-2-pyrrolidone was added to 30.79 g of polyamideimide resin (Pyromax HR-11 (concentration 15 wt%) manufactured by Toyobo Co., Ltd.), and the resin solution was dissolved by ultrasonic treatment. The resin solution was poured into a 120 x 120 x 10 mm cutout Teflon (registered trademark) plate, and degassed and desolvated at 140°C using a vacuum dryer to produce a film with a thickness of 0.295 mm.

[0098] Next, the dielectric breakdown life and partial discharge inception voltage were measured, and the results were that the dielectric breakdown life was 0.88 hours and the partial discharge inception voltage was 3.61 kV / mm. The measurement results are shown in Table 1 below.

[0099] [Table 1]

[0100] From the results in Table 1 above, it can be seen that Examples 1 to 7 all have a dielectric breakdown life of 10 hours or more, and are excellent in dielectric breakdown life. Furthermore, when the dielectric breakdown life of Comparative Example 1, which is made only of a resin without adding a fullerene derivative, is set to "1", it can be seen that Examples 1 to 7 all show a high multiplier, and that the dielectric breakdown life is significantly improved compared to Comparative Example 1.

[0101] Furthermore, it is clear that in Examples 1 to 3 and 5 to 7, even though a small amount of fullerene derivative was added (0.1% by weight or less), the dielectric breakdown life was excellent and the partial discharge inception voltage could also be increased.

[0102] Example 8 [Epoxy resin composition and sheet preparation thereof] Hexyl etherified hydroxylated fullerene derivatives (HexC 60 25.2 mg of the hexyl etherified fullerene derivative was added to 28 g of N-methyl-2-pyrrolidone (SP value: 11.2) and sonicated to prepare a solution. This solution was added to 28.01 g of epoxy resin base (Mitsubishi Chemical Corporation, jER828). The resin solution was sonicated and degassed and desolvated at 160°C using a vacuum dryer to prepare a composite of the hexyl etherified fullerene derivative and epoxy resin base. 22.41 g of curing agent (Hitachi Chemical Company, HN-2200) and 0.28 g of curing accelerator 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole (Tokyo Chemical Industry Co., Ltd.) were added to the composite, and the resin solution was sonicated and degassed at 50°C to obtain a resin composition. The content of the hexyl etherified fullerene derivative is 0.05% by weight relative to the resin composition (solid content), and the content of the hexyl etherified fullerene derivative in the cured product after heat curing, which will be described next, is also 0.05% by weight.

[0103] This resin composition was poured into a Teflon frame and cured by heating at 70°C for 15 hours to produce an epoxy resin sheet (cured product) with an average thickness of 1.348 mm.

[0104] [Sheet dielectric breakdown life] A sheet sample cut to a size of 50 mm x 50 mm was subjected to breakdown voltage measurement using an AC high voltage generator (Tokyo Transformer Co., Ltd., "100 kV 20 kVA") under the following conditions: electrode in electrical insulating oil, voltage rise rate: 1 kV / sec, current: AC, frequency: 60 Hz. The dielectric breakdown life was calculated based on the breakdown voltage measurement results in the order described in (1) to (4) of [Dielectric breakdown life of film] in Example 1, except that 15 kV was used as the threshold.

[0105] [Partial discharge inception voltage of sheet] The partial discharge inception voltage was measured under the same conditions as those shown in [Measurement of partial discharge inception voltage of film] in Example 1, except that the voltage rise rate was 0.05 kV / sec.

[0106] From these measurement results, the dielectric breakdown life in the withstand voltage measurement is 4.08 × 10 4 The partial discharge inception voltage was 1.96 kV / mm. The measurement results are shown in Table 2 below.

[0107] Example 9 Hexyl etherified hydroxylated fullerene (HexC 60 An epoxy resin sheet having an average thickness of 1.312 mm and containing 50.4 mg of PEG-100 (0.1% by weight based on the resin composition) was prepared.

[0108] As a result of measuring the dielectric breakdown life and partial discharge inception voltage, the dielectric breakdown life in the withstand voltage measurement was 7.39 × 10 6 The measurement results were 2.11 kV / mm and partial discharge inception voltage. Table 2 below shows the measurement results.

[0109] <Comparative Example 2> In Example 8, hexyl etherified hydroxylated fullerene (HexC60 An epoxy resin sheet having an average thickness of 1.318 mm was prepared in the same manner, except that the sintered body was not used.

[0110] As a result of measuring the dielectric breakdown life and partial discharge inception voltage, the dielectric breakdown life in the withstand voltage measurement was 4.86 hours, and the partial discharge inception voltage was 1.93 kV / mm. The measurement results are shown in Table 2 below.

[0111] [Table 2]

[0112] From the results in Table 2 above, it can be seen that the epoxy resin sheets of Examples 8 and 9 are both extremely long and excellent in dielectric breakdown life. Furthermore, when the dielectric breakdown life of Comparative Example 2, which is made only of resin without adding a fullerene derivative, is set to "1", it can be seen that Examples 1 to 7 all show a very high multiplier, and that the dielectric breakdown life is significantly improved compared to Comparative Example 2.

[0113] Example 10 [Preparation of enameled wire coating liquid] Hexyl etherified hydroxylated fullerene (HexC) from the same lot as in Example 1 60 4.64 mg (0.05 wt % content of the resin composition) of PEG-14 was added to 10 g of N-methyl-2-pyrrolidone and ultrasonically treated to prepare an additive solution. This solution was added to 61.55 g of polyamideimide resin (Pyromax HR-11 (concentration 15 wt %) manufactured by Toyobo Co., Ltd.), and the resin solution was ultrasonically treated to prepare a coating liquid.

[0114] [Making enameled wire] An untreated copper wire (Daido Hunt: #20, diameter 0.9 mm) was immersed in the coating solution and passed through a die (hole diameter: 1.2 mm). An enameled wire with a uniform coating film of approximately 30 to 40 μm was then produced using a dryer at 230°C.

[0115] [Enameled wire dielectric breakdown life] The withstand voltage (dielectric breakdown life) of twisted pair enameled wire twisted eight times in accordance with JIS C3216-5 was measured using a withstand voltage and insulation resistance tester (Kikusui Electronics Co., Ltd., TOS5302 (frequency 60 Hz)). The dielectric breakdown life was calculated based on the breakdown voltage measurement results in the order described in (1) to (4) of [Dielectric breakdown life of film] in Example 1, except that 50 kV was used as the threshold.

[0116] As a result of measuring the dielectric breakdown life, the dielectric breakdown life in the withstand voltage measurement was 66 hours. The measurement results are shown in Table 3 below.

[0117] Example 11 Hexyl etherified hydroxylated fullerene (HexC 60 9.28 mg of this compound (0.1 wt % of the resin composition) was added to 10 g of N-methyl-2-pyrrolidone and ultrasonically treated to prepare an additive solution. This solution was added to 61.55 g of polyamideimide resin (Pyromax HR-11, manufactured by Toyobo Co., Ltd., concentration 15 wt %), and the resin solution was ultrasonically treated to prepare a coating solution. Enameled wires with a uniform coating film of approximately 30 to 40 μm were fabricated using this coating solution.

[0118] Measurements of dielectric breakdown life and partial discharge inception voltage showed that the dielectric breakdown life in the withstand voltage measurement was 102 hours and the partial discharge inception voltage was 0.54 kV / mm. The partial discharge inception voltage was measured under the same conditions as those shown in Example 8 (Partial discharge inception voltage of sheet).

[0119] Example 12 Hexyl etherified hydroxylated fullerene (HexC 6046.4 mg of this compound (0.5 wt % of the resin composition) was added to 10 g of N-methyl-2-pyrrolidone and ultrasonically treated to prepare an additive solution. This solution was added to 61.55 g of polyamideimide resin (Pyromax HR-11, manufactured by Toyobo Co., Ltd., concentration 15 wt %), and the resin solution was ultrasonically treated to prepare a coating solution. Enameled wire with a uniform coating film of approximately 30 to 40 μm was produced using this coating solution.

[0120] As a result of measuring the dielectric breakdown life, the dielectric breakdown life in the withstand voltage measurement was 444 hours. The measurement results are shown in Table 3 below.

[0121] Example 13 In the same manner as in Example 10, octyl etherified hydroxylated fullerene (OctC 60 9.28 mg of this compound (0.1 wt % of the resin composition) was added to 10 g of N-methyl-2-pyrrolidone and ultrasonically treated to prepare an additive solution. This solution was added to 61.55 g of polyamideimide resin (Pyromax HR-11, manufactured by Toyobo Co., Ltd., concentration 15 wt %), and the resin solution was ultrasonically treated to prepare a coating solution. Enameled wires with a uniform coating film of approximately 30 to 40 μm were fabricated using this coating solution.

[0122] As a result of measuring the dielectric breakdown life, the dielectric breakdown life measured by the withstand voltage measurement was 3,389 hours. The measurement results are shown in Table 3 below.

[0123] Example 14 Phenyl C 61 9.28 mg of butyric acid methyl esterified fullerene derivative (PCBM) (0.1 wt% content relative to the resin composition) was added to 10 g of N-methyl-2-pyrrolidone and ultrasonically treated to prepare an additive solution. This solution was added to 61.55 g of polyamide-imide resin (Toyobo Co., Ltd., Pyromax HR-11 (concentration 15 wt%)), and the resin solution was ultrasonically treated to prepare a coating solution. Enameled wire with a uniform coating film of approximately 30 to 40 μm was prepared using this coating solution.

[0124] As a result of measuring the dielectric breakdown life, the dielectric breakdown life measured by the withstand voltage measurement was 1.41 hours. The measurement results are shown in Table 3 below.

[0125] <Comparative Example 3> In Example 10, hexyl etherified hydroxylated fullerene (HexC 60 In the same manner, except that the ferrite core was not used, an enameled wire with a uniform coating thickness of approximately 30 to 40 μm was produced.

[0126] As a result of measuring the dielectric breakdown life and partial discharge inception voltage, the dielectric breakdown life in the withstand voltage measurement was 0.48 hours and the partial discharge inception voltage was 0.45 kV / mm. The measurement results are shown in Table 3 below.

[0127] [Table 3]

[0128] The results in Table 3 above show that the dielectric breakdown life of the enameled wires in Examples 10 to 14 was 50 hours or more, demonstrating their excellent dielectric breakdown life. Furthermore, when the dielectric breakdown life of an enameled wire made from a resin composition containing no fullerene derivative (Comparative Example 3) was set at "1," Examples 10 to 14 all showed high multipliers, demonstrating that the dielectric breakdown life of the enameled wires was significantly improved compared to Comparative Example 3.

[0129] Furthermore, it is clear that in Example 11, the enameled wire contains a small amount of fullerene derivative (0.1% by weight), but the partial discharge inception voltage can be increased compared to Comparative Example 3, which does not contain any fullerene derivative.

[0130] Although the above examples show specific embodiments of the present invention, the examples are merely illustrative and should not be construed as limiting. Various modifications that are obvious to those skilled in the art are intended to fall within the scope of the present invention. [Industrial Applicability]

[0131] The resin composition, resin paint, resin coating film, and enameled wire obtained by the production method of the present invention can suppress the reduction in the life of insulating materials against surge voltages, and can therefore be advantageously used in any of automotive materials, electrical and electronic equipment materials, and industrial machinery materials.

Claims

1. A method for producing a fullerene derivative-containing resin composition containing a fullerene derivative and a resin having affinity for polar solvents, the method comprising the following steps (I) and (II): (I) Step of dispersing a fullerene derivative in a polar solvent (II) A step of mixing the polar solvent in which the fullerene derivative is dispersed with a resin having an affinity for the polar solvent.

2. 2. The method for producing a fullerene derivative-containing resin composition according to claim 1, wherein the fullerene derivative is a fullerene represented by the following general formula (1): Cn[O(CH 2 )xCH 3 ]y(OH)z …(1) (n is 60 or more, x is 3 or more, y is an integer of 1 or more, and z is 0 or an integer of 1 or more)

3. 3. The method for producing a fullerene derivative-containing resin composition according to claim 1, wherein the polar solvent is a solvent having an amide bond.

4. 4. The method for producing a fullerene derivative-containing resin composition according to claim 1, wherein the polar solvent is N-methyl-2-pyrrolidone.

5. A fullerene derivative-containing resin composition obtained by the method for producing a fullerene derivative-containing resin composition according to any one of claims 1 to 4.

6. A fullerene derivative-containing resin composition containing a fullerene derivative and a resin having affinity for polar solvents, characterized in that the dielectric breakdown life measured under the following measurement conditions is 10 times or more longer than that of a resin to which the fullerene derivative is not added. [Measurement conditions] A test piece of the above resin composition measuring 50 x 50 x 0.2 to 0.4 mm was measured under the conditions of an AC voltage range of 10 to 100 kV, a voltage rise rate of 1 kV / sec, and a frequency of 60 Hz.

7. 7. The fullerene derivative-containing resin composition according to claim 5, wherein the content of the fullerene derivative is 0.0001 to 5% by weight of the resin composition.

8. A resin coating composition comprising the fullerene derivative-containing resin composition according to any one of claims 5 to 7 as a main component.

9. A resin coating film obtained by solidifying the resin coating material according to claim 8.

10. An enameled wire comprising a conductor and the resin coating film according to claim 9 provided on the outer periphery of the conductor.

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