Superconducting coil and superconducting device

Abstract

To provide a superconducting coil in which occurrence of quench is suppressed.SOLUTION: A superconducting coil includes a winding frame, a superconducting wire material which is wound around the winding frame and has a first region and a second region facing the first region in a coil diameter direction, and a resin layer which is positioned between the first region and the second region, and includes particles, an epoxy resin surrounding the particles, and a region including silane including a phenylamino group existing between the particles and the epoxy resin. An average particle diameter of the particles is 1 μm or more and 5 μm or less, and a volume ratio of the particles in the resin layer is 50% or more and 66% or less.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a superconducting coil, a superconducting device, and a liquid epoxy resin composition. [Background technology]

[0002] For example, nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) systems use superconducting coils to generate strong magnetic fields. Superconducting coils are formed by winding superconducting wire around a bobbin.

[0003] When a quench occurs, in which a portion of the superconducting wire loses its superconducting state and transitions to a normal conducting state, for example, the current flowing through the superconducting coil fluctuates, causing the magnetic field generated by the superconducting coil to become unstable. Furthermore, for example, Joule heat generated in the quenched portion may lead to thermal runaway, in which a large amount of heat is generated instantaneously. Thermal runaway may result in the superconducting coil burning out.

[0004] The causes of quenching are thought to be stress caused by differences in the thermal expansion coefficients of the components of the superconducting coil when it is cooled, or stress caused by deformation of the coil due to electromagnetic force. These stresses cause cracks in the impregnated resin that makes up the superconducting coil, separation between components, and movement of the coil, and the heat generated by these phenomena is thought to be the cause of quenching. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 5-311047 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a superconducting coil in which the occurrence of quenching is suppressed. [Means for solving the problem]

[0007] A superconducting coil according to an embodiment comprises a reel, a superconducting wire wound around the reel and having a first region and a second region facing the first region in the radial direction of the coil, and a resin layer located between the first region and the second region and including particles, an epoxy resin surrounding the particles, and a region containing silane containing a phenylamino group present between the particles and the epoxy resin, wherein the average particle size of the particles is 1 μm or more and 5 μm or less, and the volume fraction of the particles in the resin layer is 50% or more and 66% or less. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic perspective view of a superconducting coil according to a first embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view of the superconducting coil of the first embodiment. [Figure 3] 1 is a schematic cross-sectional view of a superconducting wire according to a first embodiment. [Figure 4] FIG. 2 is an enlarged schematic cross-sectional view of a portion of a winding portion of the superconducting coil of the first embodiment. [Figure 5] FIG. 2 is an enlarged schematic cross-sectional view of a resin layer of the superconducting coil of the first embodiment. [Figure 6] FIG. 10 is a block diagram of a superconducting device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the same or similar components will be designated by the same reference numerals, and the description of components that have already been described will be omitted as appropriate.

[0010] (First embodiment) A superconducting coil according to a first embodiment includes a bobbin, a superconducting wire wound around the bobbin and having a first region and a second region radially opposed to the first region, and a resin layer located between the first and second regions and including particles, an epoxy resin surrounding the particles, and a region between the particles and the epoxy resin containing silane containing a phenylamino group. The particles have an average particle size of 1 μm to 5 μm, and the volume fraction of the particles in the resin layer is 50% to 66%.

[0011] Fig. 1 is a schematic perspective view of a superconducting coil according to a first embodiment, Fig. 2 is a schematic cross-sectional view of the superconducting coil according to the first embodiment, and Fig. 3 is a schematic cross-sectional view of a superconducting wire according to the first embodiment.

[0012] The superconducting coil 100 of the first embodiment is used as a coil for generating a magnetic field in superconducting equipment such as a nuclear magnetic resonance apparatus, a magnetic resonance imaging diagnostic apparatus, a heavy particle beam therapy apparatus, or a superconducting magnetic levitation train.

[0013] The superconducting coil 100 includes a bobbin 10, an inner insulating layer 11a, an upper insulating layer 11b, a lower insulating layer 11c, and a winding portion 12. The winding portion 12 includes a superconducting wire 20 and a resin layer 30.

[0014] Superconducting wire 20 is, for example, linear. Superconducting wire 20 is wound around bobbin 10 in a solenoid shape around winding center C. The coil radial direction is a first direction, the coil circumferential direction is a second direction, and the direction of winding center C is a third direction.

[0015] Resin layer 30 has a function of fixing superconducting wire 20. Resin layer 30 has a function of preventing superconducting wire 20 from being damaged by vibration during use of superconducting equipment or by friction between superconducting wires 20. Resin layer 30 also has a function of insulating superconducting wires 20 from each other.

[0016] The inner insulating layer 11a, the upper insulating layer 11b, and the lower insulating layer 11c are made of, for example, fiber-reinforced plastic and have the function of insulating the winding portion 12 from the bobbin 10 and the outside.

[0017] For example, a low-temperature superconducting material having a critical temperature Tc of 8 K or more and 40 K or less is used for the superconducting wire 20. The low-temperature superconducting material used for the superconducting wire 20 is, for example, a niobium-titanium alloy-based material, a niobium-tin compound-based material, a niobium-aluminum compound-based material, or a magnesium diboride-based material.

[0018] 3 shows an example in which the superconducting wire 20 is made of a niobium-titanium alloy-based superconducting material. The superconducting wire 20 has a structure in which a plurality of niobium-titanium filaments 20x are arranged in a copper matrix 20y.

[0019] FIG. 4 is an enlarged schematic cross-sectional view of a part of the winding portion of the superconducting coil of the first embodiment.

[0020] 4 shows first region 20a and second region 20b that are parts of superconducting wire 20. Second region 20b faces first region 20a in the coil radial direction. Second region 20b faces first region 20a in the first direction. Resin layer 30 exists between first region 20a and second region 20b.

[0021] FIG. 5 is an enlarged schematic cross-sectional view of a resin layer of the superconducting coil of the first embodiment.

[0022] The resin layer 30 includes silica particles 31, an epoxy resin 32, and a coating region 33. The silica particles 31 are an example of a particle. The coating region 33 is an example of a region.

[0023] The silica particles 31 are so-called fillers. The silica particles 31 may have, for example, a spherical, spheroidal, cylindrical, or irregular shape, but are not particularly limited thereto. Fig. 5 illustrates an example where the silica particles 31 have a spherical shape.

[0024] The average particle size of the silica particles 31 is 1 μm or more and 5 μm or less. The average particle size of the silica particles 31 can be determined, for example, by measuring the major axis of a plurality of silica particles 31 in an image (SEM image) acquired by a scanning electron microscope (SEM) and then determining the average particle size from the measured major axis.

[0025] The material of the silica particles 31 is, for example, fused silica or crystalline silica.

[0026] The volume ratio of the silica particles 31 in the resin layer 30 is 50% or more and 66% or less. The volume ratio of the silica particles 31 in the resin layer 30 is represented, for example, by obtaining an SEM image of a cross section of the resin layer 30 and representing the occupancy rate of the silica particles 31 in the cross section. The occupancy rate of the silica particles 31 can be determined, for example, by image analysis of the SEM image.

[0027] The epoxy resin 32 surrounds the silica particles 31. The epoxy resin 32 is, for example, at least one resin selected from the group consisting of bisphenol A type epoxy resin, bisphenol F type epoxy resin, alicyclic epoxy resin, and novolac type epoxy resin.

[0028] The coating region 33 exists between the silica particle 31 and the epoxy resin 32. The coating region 33 surrounds, for example, the silica particle 31. The coating region 33 is, for example, a monolayer.

[0029] The coating region 33 is formed by, for example, surface treatment of the silica particles 31 using a silane coupling agent. The silane coupling agent used for the surface treatment of the silica particles 31 contains, for example, a phenylamino group. The silica particles 31 are particles that have been surface-treated with, for example, a silane coupling agent containing a phenylamino group and an alkoxy group.

[0030] The coating region 33 includes a silane containing a phenylamino group, such as at least one compound selected from the group consisting of N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyldimethoxysilane, N-phenyl-3-aminopropyldiethoxysilane, N-phenyl-8-aminooctyltrimethoxysilane, N-phenyl-8-aminooctyltriethoxysilane, N-phenyl-8-aminooctyldimethoxysilane, and N-phenyl-8-aminooctyldiethoxysilane.

[0031] Whether or not the coating region 33 contains silane containing a phenylamino group can be determined by, for example, pyrolysis-gas chromatography / mass spectrometry.

[0032] The coating region 33 contains nitrogen. The nitrogen atom concentration in the coating region 33 is higher than, for example, the nitrogen atom concentration in the epoxy resin 32. The nitrogen atom concentration in the coating region 33 is, for example, five times or more the nitrogen atom concentration in the epoxy resin 32. The nitrogen contained in the coating region 33 is derived from, for example, a silane coupling agent used in the surface treatment of the silica particles 31.

[0033] The magnitude relationship and concentration difference between the nitrogen atom concentration in the coating region 33 and the nitrogen atom concentration in the epoxy resin 32 can be determined, for example, by energy dispersive X-ray spectroscopy (EDX) using transmission electron microscopy (TEM).

[0034] The resin layer 30 has an absorption peak in the range of 580 nm to 630 nm in absorption spectrum measurement by ultraviolet visible absorption spectroscopy (UV-Vis). The absorption peak in the range of 580 nm to 630 nm is thought to be derived from the phenylamino group contained in the coating region 33.

[0035] Next, a method for manufacturing the superconducting coil 100 of the first embodiment will be described.

[0036] First, a reel 10, a superconducting wire 20, and a two-component mixed epoxy resin composition are prepared. The two-component mixed epoxy resin composition is composed of a liquid epoxy resin composition A and a liquid B containing a curing agent.

[0037] The liquid epoxy resin composition of the first embodiment comprises a liquid epoxy resin base and silica particles surface-treated with a phenylamino-containing silane coupling agent. The silica particles contained in the liquid epoxy resin composition have an average particle size of 1 μm or more and 5 μm or less, and the silica particles are contained in an amount of 260 parts by weight or more and 520 parts by weight or less per 100 parts by weight of the liquid epoxy resin base.

[0038] For example, silica particles with an average particle size of 1 μm to 5 μm are surface-treated in advance with a silane coupling agent containing a phenylamino group, such as N-phenyl-3-aminopropyltrimethoxysilane.

[0039] Next, the surface-treated silica particles are mixed with the liquid epoxy resin base. For example, the silica particles are mixed in an amount of 260 to 520 parts by weight per 100 parts by weight of the liquid epoxy resin base. By mixing the liquid epoxy resin base and the silica particles, liquid epoxy resin composition A is produced.

[0040] Next, the superconducting wire 20 is wound around the bobbin 10. When the superconducting wire 20 is wound, a two-component mixed epoxy resin composition is applied between the superconducting wires 20.

[0041] Before application of the two-component epoxy resin composition, a curing agent B liquid is added to a liquid epoxy resin composition A liquid. The curing agent is, for example, an amine-based curing agent. For example, 30 to 50 parts by weight of the curing agent are added to 100 parts by weight of the liquid epoxy resin base. However, the amount of the amine curing agent added must be such that the active hydrogen equivalent contained in the amine curing agent is in the range of 0.8 to 1.2 times the epoxy equivalent of the epoxy resin base.

[0042] During the period from the preparation of the liquid epoxy resin composition until the application of the liquid epoxy resin composition, the maximum temperature of the liquid epoxy resin composition is kept at 60°C or less.

[0043] Thereafter, the two-component mixed liquid epoxy resin composition is cured, thereby manufacturing the superconducting coil 100.

[0044] When preparing a liquid epoxy resin composition, it is also possible to simultaneously mix silica particles and a silane coupling agent into the liquid epoxy resin and then perform surface treatment on the silica particles in the liquid epoxy resin.

[0045] Resin layer 30 may be formed, for example, by a method in which superconducting wire 20 is wound and fixed, and then a liquid epoxy resin composition is poured into and impregnated into the superconducting wire 20 in a vacuum.

[0046] The operation and effects of the superconducting coil 100 of the first embodiment will be described below.

[0047] During use of a superconducting device having a superconducting coil, a quench may occur in which a part of the superconducting wire of the superconducting coil loses its superconducting state and transitions to a normal conducting state. In particular, in the case of a superconducting coil in which a low-temperature superconducting material with a low critical temperature Tc is used for the superconducting wire 20 as in the first embodiment, a phenomenon called a training quench may occur.

[0048] A training quench is an unstable phenomenon that occurs when the current flowing through the superconducting wire is lower than the allowable current value. It is necessary to suppress this unstable phenomenon and ensure that the rated current can be stably passed through the superconducting coil. By ensuring that the rated current can be stably passed through the superconducting coil, the operation of the superconducting coil becomes stable.

[0049] Possible causes of training quenches include stress caused by differences in the thermal expansion coefficients of the components of the superconducting coil when it is cooled, or stress caused by deformation of the coil due to electromagnetic force. These stresses cause cracks in the resin that makes up the superconducting coil, and the heat generated by these cracks is thought to be the cause of training quenches.

[0050] One of the causes of stress that occurs when a superconducting coil is cooled is the difference in thermal expansion coefficient between the superconducting wire and the resin layer. In the superconducting coil 100 of the first embodiment, in order to reduce the difference in thermal expansion coefficient between the superconducting wire 20 and the resin layer 30, the resin layer 30 contains silica, which has a small thermal expansion coefficient, as a filler.

[0051] In the superconducting coil 100 of the first embodiment, the volume fraction of silica particles 31 in the resin layer 30 is 50% or more and 66% or less. By setting the volume fraction of silica particles 31 to 50% or more and 66% or less, the thermal expansion coefficient of the superconducting wire 20 and the thermal expansion coefficient of the resin layer 30 become approximately the same. Therefore, stress generated when the superconducting coil 100 is cooled is reduced, and the occurrence of cracks in the resin is suppressed. Therefore, the occurrence of quenching in the superconducting coil 100 is suppressed.

[0052] When manufacturing the superconducting coil 100 of the first embodiment, a two-component mixed liquid epoxy resin composition is prepared to form the resin layer 30. Silica particles are mixed in a ratio of 260 parts by weight to 520 parts by weight per 100 parts by weight of the liquid epoxy resin. This allows the volume ratio of silica particles 31 in the manufactured resin layer 30 to be 50% to 66%.

[0053] When manufacturing a superconducting coil, increasing the density of silica particles contained in a two-component mixed liquid epoxy resin composition that forms a resin layer increases the viscosity of the liquid epoxy resin composition. In particular, decreasing the average particle size of the silica particles increases the viscosity of the liquid epoxy resin composition. If the viscosity of the liquid epoxy resin composition increases, for example, the silica particles 31 may not be uniformly dispersed in the liquid epoxy resin, which can be a problem.

[0054] In the superconducting coil 100 of the first embodiment, when preparing the liquid epoxy resin composition that forms the resin layer 30, the silica particles are surface-treated with a silane coupling agent containing a phenylamino group. By surface-treating the silica particles with the silane coupling agent containing a phenylamino group, the viscosity of the liquid epoxy resin composition is reduced. Therefore, for example, it is possible to uniformly disperse the silica particles 31 in the liquid epoxy resin.

[0055] It is believed that the phenyl group in the silane coupling agent causes an interaction with the phenyl group constituting the epoxy resin, improving the compatibility between the liquid epoxy resin and the silica particles.

[0056] The viscosity of the liquid epoxy resin composition decreases as the average particle size of the silica particles increases, and therefore, from the viewpoint of forming the resin layer 30, it is preferable that the average particle size of the silica particles is large.

[0057] The inventors' investigations have revealed that there is a correlation between the risk of quenching of the superconducting coil and the particle size of the silica particles in the resin layer 30. That is, it has been revealed that the larger the particle size of the silica particles, the higher the risk of quenching of the superconducting coil. In particular, when the average particle size of the silica particles exceeds 5 μm, the risk of quenching of the superconducting coil increases.

[0058] It is believed that as the particle size of silica particles increases, the silica particles become more likely to peel off from the epoxy resin. As the particle size of silica particles increases, the surface area of ​​the adhesive interface between the epoxy resin and silica particles relative to the volume of the silica particles, i.e., the specific surface area, decreases, making it more likely that the silica particles and epoxy resin will peel off. It is believed that peeling of silica particles from the epoxy resin increases the risk of quenching of superconducting coils.

[0059] In superconducting coil 100 of the first embodiment, silica particles 31 have an average particle size of 5 μm or less. This reduces the risk of quenching in superconducting coil 100. In other words, the occurrence of quenching in superconducting coil 100 is suppressed.

[0060] Furthermore, by subjecting the silica particles 31 to surface treatment with a silane coupling agent containing a phenylamino group, it is possible to maintain low viscosity of the liquid epoxy resin composition even if, for example, the average particle size of the silica particles 31 is 1 μm and the weight parts of the silica particles 31 are 520 weight parts.

[0061] From the viewpoint of reducing the risk of quenching of superconducting coil 100, the average particle size of silica particles 31 is preferably 4 μm or less, and more preferably 3 μm or less.

[0062] From the viewpoint of suppressing the viscosity of the liquid epoxy resin composition, the average particle size of the silica particles 31 is preferably 1.5 μm or more.

[0063] The liquid epoxy resin composition of the first embodiment contains a liquid epoxy resin and silica particles that have been surface-treated with a silane coupling agent containing a phenylamino group. By containing silica particles that have been surface-treated with a silane coupling agent containing a phenylamino group, the liquid epoxy resin composition of the first embodiment can maintain low viscosity at temperatures of 60°C or less. Therefore, it is not necessary to raise the temperature above 60°C when weighing or stirring the liquid epoxy resin composition.

[0064] For example, increasing the temperature of liquid epoxy resin composition A promotes ring-opening of the epoxy groups in the liquid epoxy resin before the liquid epoxy resin is applied. Therefore, when the liquid epoxy resin between the superconducting wires 20 solidifies, there may be excess amino groups that should react with the epoxy base of the amine curing agent, resulting in the formation of uncured areas in the resin layer 30. If uncured areas form in the resin layer 30, the movement of the wires cannot be suppressed, and heat is generated due to friction, increasing the risk of quenching.

[0065] Liquid epoxy resin composition A of the first embodiment can maintain low viscosity in a temperature range of 60° C. or less. Therefore, by producing a superconducting coil 100 using the liquid epoxy resin composition of the first embodiment, the occurrence of quenching of the superconducting coil 100 can be suppressed.

[0066] Furthermore, the liquid epoxy resin composition of the first embodiment can maintain low viscosity even at room temperature, which makes it easy to automate, for example, the mixing of the liquid epoxy resin composition with a curing agent and the application of the mixture to a superconducting wire.

[0067] As described above, according to the first embodiment, the occurrence of cracks in the resin layer is suppressed, and therefore a superconducting coil in which the occurrence of quenching is suppressed can be realized.

[0068] (Second embodiment) The superconducting device of the second embodiment is a superconducting device equipped with the superconducting coil of the first embodiment. Hereinafter, some of the description overlapping with the first embodiment will be omitted.

[0069] 6 is a block diagram of a superconducting device according to a second embodiment. The superconducting device according to the second embodiment is a heavy ion beam therapy device 300. The heavy ion beam therapy device 300 is an example of a superconducting device.

[0070] The heavy ion beam therapy device 300 includes an injection system 50 , a synchrotron accelerator 52 , a beam transport system 54 , an irradiation system 56 , and a control system 58 .

[0071] The injection system 50 has a function of generating, for example, carbon ions to be used in therapy and pre-accelerating the ions to be injected into the synchrotron accelerator 52. The injection system 50 has, for example, an ion generation source and a linear accelerator.

[0072] The synchrotron accelerator 52 has a function of accelerating the carbon ion beam injected from the injection system 50 to an energy level suitable for treatment. The synchrotron accelerator 52 uses the superconducting coil of the first embodiment.

[0073] The beam transport system 54 has a function of transporting the carbon ion beam injected from the synchrotron accelerator 52 to the irradiation system 56. The beam transport system 54 has, for example, a bending electromagnet.

[0074] The irradiation system 56 has a function of irradiating a patient, who is an irradiation target, with the carbon ion beam injected from the beam transport system 54. The irradiation system 56 has, for example, a rotating gantry that enables the carbon ion beam to be irradiated from any direction. The superconducting coil of the first embodiment is used in the rotating gantry.

[0075] The control system 58 controls the injection system 50, the synchrotron accelerator 52, the beam transport system 54, and the irradiation system 56. The control system 58 is, for example, a computer.

[0076] In the heavy ion beam therapy device 300 of the second embodiment, the superconducting coil of the first embodiment is used in the synchrotron accelerator 52 and the rotating gantry, so that the occurrence of quenching is suppressed and high reliability is achieved.

[0077] In the second embodiment, a heavy ion beam therapy device 300 has been described as an example of a superconducting device, but the superconducting device may also be a nuclear magnetic resonance device, a magnetic resonance imaging diagnostic device, or a superconducting magnetic levitation railway vehicle.

[0078] In the first embodiment, a low-temperature superconducting material is used for the superconducting wire 20, but a high-temperature superconducting material can also be used for the superconducting wire 20.

[0079] In the first embodiment, silica particles are used as an example of particles contained in the resin layer 30, but the particles contained in the resin layer 30 are not limited to silica particles. For example, alumina particles can also be used as particles contained in the resin layer 30.

[0080] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments may be embodied in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. For example, components of one embodiment may be replaced or changed with components of another embodiment. These embodiments and modifications thereof are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0081] 10 Reel frame 20 Superconducting wire 20a First Area 20b Second Region 30 resin layer 31 Silica particles 32 Epoxy Resin 33 Covered Area 110 Reel frame 100 Superconducting coil 300 Heavy ion beam therapy device

Claims

1. A reel; a superconducting wire wound around the bobbin and having a first region and a second region facing the first region in a coil radial direction; a resin layer located between the first region and the second region, the resin layer including particles, an epoxy resin surrounding the particles, and a region including a silane containing a phenylamino group present between the particles and the epoxy resin; Equipped with The average particle size of the particles is 1 μm or more and 5 μm or less, A superconducting coil, wherein the volume ratio of the particles in the resin layer is 50% or more and 66% or less.

2. 2. The superconducting coil of claim 1, wherein the region contains at least one compound selected from the group consisting of N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyldimethoxysilane, N-phenyl-3-aminopropyldiethoxysilane, N-phenyl-8-aminooctyltrimethoxysilane, N-phenyl-8-aminooctyltriethoxysilane, N-phenyl-8-aminooctyldimethoxysilane, and N-phenyl-8-aminooctyldiethoxysilane.

3. 3. The superconducting coil according to claim 1, wherein the particles are silica particles.

4. A reel; a superconducting wire wound around the bobbin and having a first region and a second region facing the first region; a resin layer located between the first region and the second region, the resin layer including particles, an epoxy resin surrounding the particles, and a region present between the particles and the epoxy resin; Equipped with The average particle size of the particles is 1 μm or more and 5 μm or less, a volume ratio of the particles in the resin layer is 50% or more and 66% or less; A superconducting coil, wherein the nitrogen atomic concentration in the region is higher than the nitrogen atomic concentration in the epoxy resin.

5. 5. The superconducting coil according to claim 4, wherein the nitrogen atom concentration in said region is at least five times the nitrogen atom concentration in said epoxy resin.

6. 6. The superconducting coil according to claim 4, wherein the particles are silica particles.

7. A reel; a superconducting wire wound around the bobbin and having a first region and a second region facing the first region; a resin layer located between the first region and the second region, the resin layer including particles surface-treated with a silane coupling agent containing a phenylamino group, and an epoxy resin surrounding the particles; Equipped with The average particle size of the particles is 1 μm or more and 5 μm or less, A superconducting coil, wherein the volume ratio of the particles in the resin layer is 50% or more and 66% or less.

8. 8. The superconducting coil according to claim 7, wherein the silane coupling agent contains at least one compound selected from the group consisting of N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyldimethoxysilane, N-phenyl-3-aminopropyldiethoxysilane, N-phenyl-8-aminooctyltrimethoxysilane, N-phenyl-8-aminooctyltriethoxysilane, N-phenyl-8-aminooctyldimethoxysilane, and N-phenyl-8-aminooctyldiethoxysilane.

9. 9. The superconducting coil according to claim 7, wherein the particles are silica particles.

10. A reel; a superconducting wire wound around the bobbin and having a first region and a second region facing the first region; a resin layer located between the first region and the second region, the resin layer including particles and an epoxy resin surrounding the particles; Equipped with The average particle size of the particles is 1 μm or more and 5 μm or less, a volume ratio of the particles in the resin layer is 50% or more and 66% or less; The resin layer has an absorption peak in the region of 580 nm or more and 630 nm or less when measured by ultraviolet-visible spectroscopy.

11. 11. The superconducting coil according to claim 10, wherein the particles are silica particles.

12. A superconducting device comprising the superconducting coil according to any one of claims 1 to 11.

13. The composition comprises a liquid epoxy resin base and particles that have been surface-treated with a silane coupling agent containing a phenylamino group, The average particle size of the particles is 1 μm or more and 5 μm or less, A liquid epoxy resin composition, wherein the particles are contained in an amount of 260 parts by weight or more and 520 parts by weight or less per 100 parts by weight of the liquid epoxy resin base.

14. The liquid epoxy resin composition according to claim 13, wherein the silane coupling agent comprises at least one compound selected from the group consisting of N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyldimethoxysilane, N-phenyl-3-aminopropyldiethoxysilane, N-phenyl-8-aminooctyltrimethoxysilane, N-phenyl-8-aminooctyltriethoxysilane, N-phenyl-8-aminooctyldimethoxysilane, and N-phenyl-8-aminooctyldiethoxysilane.

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