Polymerizable composition and resin-impregnated superconducting coil

Abstract

The present invention provides a polymerizable composition capable of providing a norbornene-based resin that has a large specific heat capacity (Cp) at 7 to 10K and can effectively suppress the temperature rise of a superconducting coil at 7 to 10K. The present invention provides a polymerizable composition for a resin-impregnated superconducting coil, which comprises a norbornene-based monomer, metal nitride particles, and a metathesis polymerization catalyst.

Description

[Technical Field]

[0001] The present invention relates to a polymerizable composition for a resin-impregnated superconducting coil, and a resin-impregnated superconducting coil obtained by using such a polymerizable composition. [Background technology]

[0002] Superconducting coils use liquid helium as a cryogen or conduction cooling in a refrigerator to maintain a temperature around 4K (-269°C), thereby creating a superconducting state and allowing large currents to flow with zero resistance, thereby generating a strong magnetic field.

[0003] On the other hand, in the cryogenic temperature range, the specific heat of many materials is small, making it easier for heat to enter from the outside. This thermal disturbance causes the temperature of the superconducting coil to rise locally, resulting in the emergence of normal conduction. When the emergence of normal conduction is re-cooled to around 4 K, the superconducting coil can maintain its superconducting state, but once normal conduction begins to propagate, a quench (transition from superconductivity to normal conduction) occurs. Joule heat generated in the quenched area can instantly generate a large amount of heat, which could lead to thermal runaway. Thermal runaway can cause problems such as the superconducting coil burning or the liquid helium refrigerant vaporizing significantly.

[0004] Here, in resin-impregnated superconducting coils, if the resin component is not completely impregnated into the superconducting coil, the occurrence of thermal runaway is not sufficiently suppressed, and current stability is not sufficiently ensured. In contrast, polymerizable compositions containing norbornene-based monomers have low viscosity and exhibit sufficient impregnation properties for superconducting coils. Therefore, the application of polymerizable compositions containing norbornene-based monomers to resin-impregnated superconducting coils has been studied.

[0005] For example, Patent Document 1 discloses a polymerizable composition containing a norbornene-based monomer, rare earth element-containing particles having a number-based mode diameter of 0.05 μm or more and less than 1.5 μm, and a metathesis polymerization catalyst. Patent Document 1 also discloses that such a polymerizable composition is suitable for use in producing a resin-impregnated superconducting coil that is highly reliable and can be cooled in a shorter time than conventional coils. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2022 / 118614 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a polymerizable composition capable of providing a norbornene-based resin that has a large specific heat capacity (Cp) at 7 to 10K and can effectively suppress the temperature rise of a superconducting coil at 7 to 10K. [Means for solving the problem]

[0008] The present inventors have conducted studies to achieve the above-mentioned object, and have found that the above-mentioned object can be achieved by a polymerizable composition comprising a composition containing a norbornene-based monomer and a metathesis polymerization catalyst, and metal nitride particles, thereby completing the present invention.

[0009] That is, according to the present invention, there are provided the following polymerizable composition and resin-impregnated superconducting coil. [1] A polymerizable composition for a resin-impregnated superconducting coil, comprising a norbornene-based monomer, metal nitride particles, and a metathesis polymerization catalyst. [2] The polymerizable composition according to [1], wherein the metal nitride particles contain a nitride of a metal of Group 13 of the periodic table. [3] The polymerizable composition according to [1] or [2], wherein the metal nitride particles contain aluminum nitride. [4] The polymerizable composition according to any one of [1] to [3], wherein the content of the metal nitride particles is 4 to 90 mass %. [5] The polymerizable composition according to any one of [1] to [4], wherein the norbornene-based monomer contains dicyclopentadiene in an amount of 50% by mass or more. [6] The polymerizable composition according to any one of [1] to [5], wherein the norbornene-based monomer includes a bicyclic compound and a tricyclic compound. [7] The polymerizable composition according to any one of [1] to [6], further comprising a silane coupling agent. [8] The polymerizable composition according to any one of [1] to [7], A polymerizable composition comprising two or more pre-mixed liquids that do not undergo a polymerization reaction by themselves, and that can form the polymerizable composition by combining the pre-mixed liquids. [9] The polymerizable composition according to any one of [1] to [8], wherein the resin-impregnated superconducting coil is a superconducting coil for generating a magnetic field in a particle accelerator.

[10] A resin-impregnated superconducting coil obtained by impregnating a superconducting coil with a norbornene-based resin obtained by bulk polymerizing the polymerizable composition according to any one of [1] to [9]. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a polymerizable composition capable of giving a norbornene-based resin that has a large specific heat capacity (Cp) at 7 to 10K and can effectively suppress the temperature rise of a superconducting coil at 7 to 10K. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1(A) is a schematic perspective view of a resin-impregnated superconducting coil according to one embodiment of the present invention, and FIG. 1(B) is a schematic cross-sectional view of the resin-impregnated superconducting coil according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] <Polymerizable composition> The polymerizable composition of the present invention is a polymerizable composition for a resin-impregnated superconducting coil, which contains a norbornene-based monomer, metal nitride particles, and a metathesis polymerization catalyst.

[0013] The present inventors considered that a temperature range of 7 to 10 K is important from the viewpoint of effectively suppressing temperature rise at cryogenic temperatures, effectively suppressing quenching, and thereby stabilizing the superconducting state. As a result of extensive research into norbornene-based resins that can effectively suppress temperature rise in superconducting coils at 7 to 10 K, the present inventors discovered that by blending metal nitride particles into a polymerizable composition, a norbornene-based resin with a large specific heat capacity (Cp) in the temperature range of 7 to 10 K can be obtained, leading to the completion of the present invention.

[0014] That is, the polymerizable composition of the present invention can provide a norbornene-based resin that has a large specific heat capacity (Cp) at 7 to 10 K and can effectively suppress the temperature rise of a superconducting coil at 7 to 10 K. Therefore, by using the polymerizable composition of the present invention, quenching can be effectively suppressed, and a resin-impregnated superconducting coil in which the superconducting state is stably maintained can be manufactured. Furthermore, since quenching usually inevitably occurs when starting operation of a resin-impregnated superconducting coil after its manufacture, repeated operations (training) are required to adjust the cryogenic temperature environment and restart the preliminary operation of the resin-impregnated superconducting coil until stable operation is achieved. By using the polymerizable composition of the present invention, the superconducting state is more likely to be stabilized, so training can be completed in a short period of time, which has the advantage of allowing stable operation of the resin-impregnated superconducting coil to be started sooner than before.

[0015] Furthermore, since the polymerizable composition of the present invention contains a norbornene-based monomer, it has low viscosity, and therefore, when applied to a superconducting coil, the polymerizable composition of the present invention exhibits sufficient impregnation properties for the superconducting coil, and therefore the polymerizable composition of the present invention can be suitably used for producing a resin-impregnated superconducting coil.

[0016] In addition, the norbornene-based resin obtained using the polymerizable composition of the present invention has excellent mechanical properties even at extremely low temperatures, while having a relatively low adhesive strength with the superconducting wire that constitutes the superconducting coil. Therefore, even if the norbornene-based resin undergoes thermal contraction during cooling, the destruction of the superconducting coil due to tensile stress caused by the thermal contraction can be suppressed. This action also effectively suppresses the occurrence of quenching, which is the cause of the destruction of the superconducting coil.

[0017] (Norbornene-based monomer) The norbornene-based monomer may be any compound having a norbornene ring structure, and is not particularly limited. Examples include bicyclic compounds such as norbornene, ethylidene norbornene, and norbornadiene; tricyclic compounds such as dicyclopentadiene; tetracyclic compounds such as tetracyclododecene; pentacyclic compounds such as tricyclopentadiene; heptacyclic compounds such as tetracyclopentadiene; and derivatives thereof having an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, an alkylidene group having 1 to 10 carbon atoms, an epoxy group, or a (meth)acrylic group. The norbornene-based monomer may be used alone or in combination of two or more. From the viewpoint of further enhancing the effects of the present invention, the tricyclic compounds are preferred as the norbornene-based monomer, and dicyclopentadiene is particularly preferred. The norbornene-based monomer used preferably contains 50% by mass or more of the tricyclic compounds, particularly dicyclopentadiene. It is also preferable to use the bicyclic compound and the tricyclic compound in combination as the norbornene-based monomer, and in this case, the mass ratio of "bicyclic compound:tricyclic compound" is preferably 1:99 to 20:80, more preferably 2:98 to 10:90.

[0018] The content of the norbornene-based monomer in the polymerizable composition of the present invention is not particularly limited, but is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, based on 100% by mass of all polymerizable monomers contained in the polymerizable composition. By setting the content of the norbornene-based monomer within the above range, the norbornene-based resin obtained using the polymerizable composition of the present invention can have improved mechanical properties at cryogenic temperatures while having a sufficiently reduced adhesive strength to the superconducting wire that constitutes the superconducting coil.

[0019] In the present invention, a monocyclic cycloolefin may further be used as a polymerizable monomer contained in the polymerizable composition.

[0020] The monocyclic cycloolefin is not particularly limited, but examples thereof include cyclobutene, cyclopentene, cyclohexene, cyclooctene, cyclododecene, cyclopentadiene, 1,4-cyclohexadiene, 1,5-cyclooctadiene, and derivatives thereof having an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, an alkylidene group having 1 to 10 carbon atoms, an epoxy group, or a (meth)acrylic group. The monocyclic cycloolefin may be used alone or in combination of two or more types.

[0021] The polymerizable composition of the present invention may contain, in addition to the norbornene-based monomer and the monocyclic cycloolefin used as needed, other polymerizable monomers polymerizable with them, such as other cycloolefin monomers.

[0022] The content of polymerizable monomers other than norbornene-based monomers in the polymerizable composition of the present invention is not particularly limited, but is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, relative to 100% by mass of all polymerizable monomers contained in the polymerizable composition, and may be 0% by mass.

[0023] The total content of polymerizable monomers including norbornene-based monomers in the polymerizable composition of the present invention is preferably 10 to 96 mass%, more preferably 15 to 92 mass%, even more preferably 20 to 85 mass%, still more preferably 25 to 70 mass%, and particularly preferably 30 to 55 mass%, based on 100 mass% of the total polymerizable composition.

[0024] (metal nitride particles) The metal nitride particles used in the present invention are not particularly limited as long as they contain a metal nitride. Examples of metal nitrides include nitrides of Group 4 metals in the long-form periodic table (the "periodic table" used herein refers to the long-form periodic table), such as TiN, ZrN, and HfN; nitrides of Group 5 metals in the periodic table, such as VN, NbN, and TaN; nitrides of Group 6 metals in the periodic table, such as CrN, MoN, and WN; nitrides of Group 13 metals in the periodic table, such as AlN, GaN, and InN; nitrides of Group 14 metals in the periodic table, such as SnN and PbN; and nitrides of Group 15 metals in the periodic table, such as BiN. Furthermore, the metal nitride may be a nitride containing two or more metal atoms and a nitrogen atom.

[0025] As the metal nitride, nitrides having a covalent crystal structure are preferred, nitrides of metals in Group 13 of the periodic table are more preferred, among which AlN, GaN, and InN having a zincblende structure or a wurtzite structure are more preferred, AlN and GaN are particularly preferred, and AlN is most preferred. That is, it is preferred that the metal nitride particles contain the above-mentioned suitable metal nitride.

[0026] The metal nitride particles may be a mixture of two or more types of particles having different compositions. The proportion of nitrides of Group 13 metals in the periodic table in the metal nitride particles used in the present invention is preferably 50% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably substantially 100% by mass.

[0027] The number-based mode diameter of the metal nitride particles used in the present invention is preferably 0.1 to 100 μm, more preferably 0.5 to 50 μm. A mode diameter within this range can further enhance the fluidity of the uncured polymerizable composition and further enhance the heat storage and heat dissipation properties of the norbornene-based resin. The number-based mode diameter is the particle diameter with the highest probability of particle existence on a number basis. The number-based mode diameter can be determined by plotting the frequency of individual particle diameters against the logarithm of particle diameter on a number basis on a particle size distribution curve. The number-based mode diameter of the metal nitride particles can be calculated, for example, by determining the particle size distribution converted into a number-based distribution from the particle size distribution measured by a light scattering method (laser diffraction / scattering method).

[0028] The shape of the metal nitride particles used in the present invention is not particularly limited, and examples thereof include spherical, bale-shaped, spheroidal, cylindrical, fibrous, and irregular shapes, and the like, and may also be a mixture of particles of a plurality of these shapes, such as a combination of spherical metal nitride particles and cylindrical metal nitride particles.

[0029] The metal nitride particles used in the present invention may be metal nitride particles having a coating layer formed on the surface thereof with a metal having high electrical and thermal conductivity, such as silver, gold, nickel, or copper.

[0030] The metal nitride particles used in the present invention may have their surfaces hydrophobized. The use of hydrophobized metal nitride particles can prevent aggregation and sedimentation of the particles in the polymerizable composition and can also ensure uniform dispersion of the particles in the norbornene-based resin obtained by bulk polymerization of the polymerizable composition. Examples of treating agents used for hydrophobization include silane coupling agents, titanate coupling agents, aluminum coupling agents, fatty acids such as stearic acid, oils and fats, surfactants, and waxes. The treating agent can also be simply blended with the metal nitride particles in the polymerizable composition.

[0031] As the treating agent, a silane coupling agent having at least one hydrocarbon group with a norbornene structure is preferably used because, even when metal nitride particles are blended into the polymerizable composition, the viscosity is low and thixotropy (viscosity at rest) is unlikely to increase. While such silane coupling agents can also function as monomers, they are treated as silane coupling agents in the present invention. Specific examples of such silane coupling agents include bicycloheptenyltrimethoxysilane, bicycloheptenyltriethoxysilane, bicycloheptenylethyltrimethoxysilane, and bicycloheptenylethyltriethoxysilane. Furthermore, other silane coupling agents, such as vinyltrimethoxysilane, that do not have a norbornene structure can also be used as the treating agent.

[0032] The treating agents may be used alone or in combination of two or more. The content of the treating agent in the polymerizable composition of the present invention is preferably 0.1 to 5 mass %, more preferably 0.3 to 3.5 mass %, and even more preferably 0.5 to 2.5 mass %.

[0033] The content of the metal nitride particles in the polymerizable composition of the present invention is preferably 4 to 90 mass%, more preferably 8 to 85 mass%, even more preferably 15 to 80 mass%, even more preferably 30 to 75 mass%, and particularly preferably 45 to 70 mass%, based on 100 mass% of the entire polymerizable composition. By setting the content of the metal nitride particles within the above range, the fluidity of the polymerizable composition when uncured can be further increased, and the temperature rise of the superconducting coil can be more effectively suppressed.

[0034] (Metathesis polymerization catalyst) The metathesis polymerization catalyst used in the present invention is not particularly limited as long as it can ring-opening polymerize norbornene-based monomers, and known metathesis polymerization catalysts can be used.

[0035] The metathesis polymerization catalyst used in the present invention is a complex formed by bonding multiple ions, atoms, polyatomic ions, and / or compounds to a transition metal atom as the central atom. The transition metal atom is an atom of Groups 5, 6, and 8 of the periodic table. The atoms of each group are not particularly limited, but examples of Group 5 atoms include tantalum, examples of Group 6 atoms include molybdenum and tungsten, and examples of Group 8 atoms include ruthenium and osmium. Among these transition metal atoms, ruthenium and osmium of Group 8 are preferred. That is, the metathesis polymerization catalyst used in the present invention is preferably a complex having ruthenium or osmium as the central atom, and more preferably a complex having ruthenium as the central atom. A ruthenium-carbene complex in which a carbene compound is coordinated to ruthenium is preferred as a complex having ruthenium as the central atom. Here, "carbene compound" is a general term for compounds containing a methylene free radical, and refers to a compound having an uncharged divalent carbon atom (carbene carbon) represented by (>C:). Ruthenium carbene complexes have excellent catalytic activity during bulk ring-opening polymerization, resulting in polymers with little odor from unreacted monomers, enabling high-quality polymers to be obtained with good productivity. Furthermore, they are relatively stable against oxygen and moisture in the air and are not easily deactivated, making them suitable for use in the atmosphere. Metathesis polymerization catalysts may be used alone or in combination.

[0036] Examples of the ruthenium carbene complex include those represented by the following general formula (1) or (2). [ka]

[0037] In the above general formulas (1) and (2), R 1 and R 2are each independently a hydrogen atom; a halogen atom; or an organic group having 1 to 20 carbon atoms which may contain a halogen atom, an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, or a silicon atom; and these groups may have a substituent, and may be bonded to each other to form a ring. 1 and R 2 Examples of groups bonded to each other to form a ring include an indenylidene group which may have a substituent, such as a phenylindenylidene group.

[0038] Specific examples of the organic group having 1 to 20 carbon atoms which may contain a halogen atom, an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom or a silicon atom include an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkenyloxy group having 2 to 20 carbon atoms, an alkynyloxy group having 2 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, an alkyl group having 1 to 20 carbon atoms, an alkyl group having 1 to 8 carbon atoms, an alkyl group having 1 to 8 carbon atoms, an alkyl group having 2 to 20 carbon atoms, an alkynyloxy group having 2 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, an alkyl group having 1 to 8 carbon atoms, an alkyl group having 1 to 8 carbon atoms, an alkyl group having 2 to 20 ...2 to 20 carbon atoms, an alkyl group having 1 to 8 carbon atoms, an alkyl group having 2 to 20 carbon atoms, an alkyl group having 2 to Examples of the organic group include an alkylthio group, a carbonyloxy group, an alkoxycarbonyl group having 1 to 20 carbon atoms, an alkylsulfonyl group having 1 to 20 carbon atoms, an alkylsulfinyl group having 1 to 20 carbon atoms, an alkylsulfonic acid group having 1 to 20 carbon atoms, an arylsulfonic acid group having 6 to 20 carbon atoms, a phosphonic acid group, an arylphosphonic acid group having 6 to 20 carbon atoms, an alkylammonium group having 1 to 20 carbon atoms, and an arylammonium group having 6 to 20 carbon atoms. These organic groups having 1 to 20 carbon atoms, which may contain a halogen atom, oxygen atom, nitrogen atom, sulfur atom, phosphorus atom, or silicon atom, may have a substituent. Examples of the substituent include an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and an aryl group having 6 to 10 carbon atoms.

[0039] X 1 and X 2 each independently represents an anionic ligand. The anionic ligand is a ligand that has a negative charge when separated from the central metal atom, and examples thereof include a halogen atom, a diketonate group, a substituted cyclopentadienyl group, an alkoxyl group, an aryloxy group, and a carboxyl group.

[0040] L 1 and L 2 represents a heteroatom-containing carbene compound or a neutral electron donor compound other than a heteroatom-containing carbene compound. Heteroatom-containing carbene compounds and neutral electron donor compounds other than a heteroatom-containing carbene compound are compounds that have a neutral charge when separated from a central metal. From the viewpoint of improving catalytic activity, heteroatom-containing carbene compounds are preferred. The heteroatom refers to an atom of Groups 15 and 16 of the periodic table, and specific examples include a nitrogen atom, an oxygen atom, a phosphorus atom, a sulfur atom, an arsenic atom, and a selenium atom. Among these, from the viewpoint of obtaining a stable carbene compound, a nitrogen atom, an oxygen atom, a phosphorus atom, and a sulfur atom are preferred, and a nitrogen atom is more preferred.

[0041] The heteroatom-containing carbene compound is preferably a compound represented by the following general formula (3) or (4), and from the viewpoint of improving catalytic activity, a compound represented by the following general formula (3) is more preferred. [ka]

[0042] In the above general formulas (3) and (4), R 3 , R 4 , R 5 and R 6 each independently represents a hydrogen atom, a halogen atom, or an organic group having 1 to 20 carbon atoms which may contain a halogen atom, oxygen atom, nitrogen atom, sulfur atom, phosphorus atom, or silicon atom. Specific examples of the organic group having 1 to 20 carbon atoms which may contain a halogen atom, oxygen atom, nitrogen atom, sulfur atom, phosphorus atom, or silicon atom are the same as those in the general formulae (1) and (2) above. Also, R 3 , R 4 , R 5 and R 6 may be bonded to each other in any combination to form a ring.

[0043] In addition, since the effect of the present invention becomes more remarkable, R 5 and R 6 is preferably a hydrogen atom. 3 and R 4 is preferably an aryl group which may have a substituent, more preferably a phenyl group having an alkyl group of 1 to 10 carbon atoms as a substituent, and even more preferably a mesityl group.

[0044] Examples of the neutral electron donor compound include oxygen atoms, water, carbonyls, ethers, nitriles, esters, phosphines, phosphinites, phosphites, sulfoxides, thioethers, amides, imines, aromatic compounds, cyclic diolefins, olefins, isocyanides, and thiocyanates.

[0045] In the above general formulas (1) and (2), R 1 , R 2 , X 1 , X 2 , L 1 and L 2 may be linked together alone and / or in any combination to form multidentate chelating ligands.

[0046] Furthermore, as the ruthenium carbene complex used in the present invention, among the compounds represented by the above general formula (1) or (2), the compound represented by the above general formula (1) is preferred because the effects of the present invention are more pronounced, and among these, the compound represented by the following general formula (5) or general formula (6) is more preferred.

[0047] General formula (5) is shown below. [ka]

[0048] In the general formula (5), Z is an oxygen atom, a sulfur atom, a selenium atom, or NR 12 , PR 12 or AsR 12 and R 12represents a hydrogen atom; a halogen atom; or an organic group having 1 to 20 carbon atoms which may contain a halogen atom, an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, or a silicon atom; however, an oxygen atom is preferred as Z, as this makes the effects of the present invention more pronounced.

[0049] In addition, R 1 , R 2 , X 1 and L 1 are the same as those in the above general formulas (1) and (2), and may be used alone or / and may be bonded to each other in any combination to form a multidentate chelating ligand, but X 1 and L 1 does not form a multidentate chelating ligand, and R 1 and R 2 are preferably bonded to each other to form a ring, are more preferably an indenylidene group which may have a substituent, and are further preferably a phenylindenylidene group. Specific examples of the organic group having 1 to 20 carbon atoms which may contain a halogen atom, oxygen atom, nitrogen atom, sulfur atom, phosphorus atom or silicon atom are the same as those in the general formulae (1) and (2) above.

[0050] In the above general formula (5), R 7 and R 8 are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, or a heteroaryl group having 6 to 20 carbon atoms, and these groups may have a substituent or may be bonded to each other to form a ring. Examples of the substituent include an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and when a ring is formed, the ring may be any of an aromatic ring, an alicyclic ring, and a heterocyclic ring, but it is preferable to form an aromatic ring, more preferably an aromatic ring having 6 to 20 carbon atoms, and even more preferably an aromatic ring having 6 to 10 carbon atoms.

[0051] In the above general formula (5), R 9 , R 10 and R 11are each independently a hydrogen atom, a halogen atom, or an organic group having 1 to 20 carbon atoms which may contain a halogen atom, an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, or a silicon atom, and these groups may have a substituent or may be bonded to each other to form a ring. Specific examples of the organic group having 1 to 20 carbon atoms which may contain a halogen atom, an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, or a silicon atom are the same as those in the general formulas (1) and (2) above.

[0052] R 9 , R 10 and R 11 is preferably a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

[0053] Specific examples of the compound represented by the general formula (5) and the method for producing the same include those described in International Publication No. 03 / 062253 (JP 2005-515260).

[0054] General formula (6) is shown below. [ka]

[0055] In the above general formula (6), m is 0 or 1. m is preferably 1, in which case Q is an oxygen atom, a nitrogen atom, a sulfur atom, a methylene group, an ethylene group or a carbonyl group, and preferably a methylene group.

[0056] In the above general formula (6), [ka] is a single bond or a double bond, preferably a single bond.

[0057] R 1 , X 1 , X 2 and L 1are the same as those in the above general formulas (1) and (2), and may be bonded to each other alone or in any combination to form a multidentate chelating ligand, but X 1 , X 2 and L 1 does not form a multidentate chelating ligand, and R 1 is preferably a hydrogen atom.

[0058] R 13 ~R 21 is a hydrogen atom, a halogen atom, or an organic group having 1 to 20 carbon atoms which may contain a halogen atom, an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, or a silicon atom; these groups may have a substituent and may be bonded to each other to form a ring. Specific examples of the organic group having 1 to 20 carbon atoms which may contain a halogen atom, an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, or a silicon atom are the same as those in the above general formulas (1) and (2).

[0059] R 13 is preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and R 14 ~R 17 is preferably a hydrogen atom, and R 18 ~R 21 is preferably a hydrogen atom or a halogen atom.

[0060] Specific examples of the compound represented by the general formula (6) and the method for producing the same include those described in International Publication No. 11 / 079799 (JP 2013-516392 A).

[0061] The content of the metathesis polymerization catalyst is preferably 0.005 mmol or more, more preferably 0.01 to 50 mmol, and even more preferably 0.015 to 20 mmol, per mol of the total amount of polymerizable monomers used in the reaction.

[0062] (optional ingredient) Furthermore, the polymerizable composition of the present invention may contain a radical generator, a diisocyanate compound, a polyfunctional (meth)acrylate compound, and other optional components, if desired.

[0063] The radical generator generates radicals upon heating, thereby inducing a crosslinking reaction in the norbornene-based resin formed by bulk polymerization. The site at which the radical generator induces the crosslinking reaction is mainly the carbon-carbon double bond contained in the norbornene-based resin, but crosslinking may also occur in saturated bond moieties. Examples of radical generators include organic peroxides, diazo compounds, and non-polar radical generators.

[0064] The amount of the radical generator in the polymerizable composition of the present invention is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, based on 100 parts by mass of the total amount of polymerizable monomers used in the reaction.

[0065] Examples of diisocyanate compounds include 4,4'-methylenediphenyl diisocyanate (MDI), toluene-2,4-diisocyanate, 4-methoxy-1,3-phenylene diisocyanate, 4-isopropyl-1,3-phenylene diisocyanate, 4-chloro-1,3-phenylene diisocyanate, 4-butoxy-1,3-phenylene diisocyanate, 2,4-diisocyanate diphenyl ether, 1,4-phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate (XDI), 1,5-naphthalene diisocyanate, benzidine diisocyanate, o-nitrobenzidine diisocyanate, and 4,4'-diisocyanate dibenzidine. Examples of suitable diisocyanate compounds include aromatic diisocyanate compounds such as benzoyl; aliphatic diisocyanate compounds such as methylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, and 1,10-decamethylene diisocyanate; alicyclic diisocyanate compounds such as 4-cyclohexylene diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,5-tetrahydronaphthalene diisocyanate, isophorone diisocyanate, hydrogenated MDI, and hydrogenated XDI; and polyurethane prepolymers obtained by reacting these diisocyanate compounds with low-molecular-weight polyols or polyamines to form isocyanate groups at the terminals. Furthermore, conventionally known compounds having polyfunctional isocyanate groups, such as isocyanurates, biurets, adducts, or polymers, can be used without particular limitation. Examples of such compounds include a dimer of 2,4-toluylene diisocyanate, triphenylmethane triisocyanate, tris-(p-isocyanatophenyl)thiophosphite, polyfunctional aromatic isocyanate compounds, polyfunctional aromatic aliphatic isocyanate compounds, polyfunctional aliphatic isocyanate compounds, fatty acid-modified polyfunctional aliphatic isocyanate compounds, polyfunctional blocked isocyanate compounds such as blocked polyfunctional aliphatic isocyanate compounds, and polyisocyanate prepolymers.Among these, polyfunctional unblocked isocyanate compounds, such as aromatic diisocyanate compounds, aliphatic diisocyanate compounds, and alicyclic diisocyanate compounds, are preferably used because of their easy availability and ease of handling. These compounds can be used alone or in combination of two or more.

[0066] A polyfunctional blocked isocyanate compound is one in which at least two isocyanate groups in the molecule are reacted with an active hydrogen-containing compound, rendering the compound inactive at room temperature. The isocyanate compound generally has a structure in which the isocyanate groups are masked with a blocking agent such as alcohols, phenols, ε-caprolactam, oximes, and active methylene compounds. Polyfunctional blocked isocyanate compounds generally do not react at room temperature, and therefore have excellent storage stability. However, heating at temperatures typically between 140 and 200°C regenerates the isocyanate groups, enabling them to exhibit excellent reactivity.

[0067] The diisocyanate compounds may be used alone or in combination of two or more. The amount of the diisocyanate compound in the polymerizable composition of the present invention is preferably 0.5 to 20 parts by mass, more preferably 1 to 15 parts by mass, and even more preferably 2 to 10 parts by mass, per 100 parts by mass of the total amount of polymerizable monomers used in the reaction.

[0068] Furthermore, from the viewpoint of further improving the mechanical properties at cryogenic temperatures of the norbornene-based resin obtained using the polymerizable composition of the present invention, a polyfunctional (meth)acrylate compound may be used. By using a polyfunctional (meth)acrylate compound together with a diisocyanate compound, the active hydrogen-reactive group of the diisocyanate compound forms a chemical bond with a hydroxyl group present in the polyfunctional (meth)acrylate compound, thereby further improving the mechanical properties at cryogenic temperatures of the norbornene-based resin. Preferred examples of the polyfunctional (meth)acrylate compound include ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, and neopentyl glycol dimethacrylate.

[0069] The polyfunctional (meth)acrylate compounds may be used alone or in combination of two or more. The amount of the polyfunctional (meth)acrylate compound in the polymerizable composition of the present invention is preferably 0.5 to 20 parts by mass, more preferably 1 to 15 parts by mass, and even more preferably 2 to 10 parts by mass, per 100 parts by mass of the total amount of polymerizable monomers used in the reaction.

[0070] Other optional components include an activator, an activity regulator, an elastomer, an antioxidant (antiaging agent), a dispersant, and the like.

[0071] The activator is a compound that acts as a cocatalyst for the metathesis polymerization catalyst described above and improves the polymerization activity of the catalyst. Examples of activators that can be used include alkylaluminum halides such as ethylaluminum dichloride and diethylaluminum chloride; alkoxyalkylaluminum halides in which some of the alkyl groups in these alkylaluminum halides are substituted with alkoxy groups; and organotin compounds. The amount of activator used is not particularly limited, but is preferably 0.1 to 100 mol, more preferably 1 to 10 mol, per mol of the total metathesis polymerization catalysts used in the polymerizable composition.

[0072] The activity regulator is used to prevent polymerization from starting during the injection process when a polymerizable composition is prepared by mixing two or more reaction stock solutions as described below and then injected into a mold to initiate polymerization.

[0073] When a compound of a transition metal of Group 5 or 6 of the periodic table is used as the metathesis polymerization catalyst, examples of the activity modifier include compounds that have the effect of reducing the metathesis polymerization catalyst, such as alcohols, haloalcohols, esters, ethers, nitriles, etc. Among these, alcohols and haloalcohols are preferred, and haloalcohols are more preferred.

[0074] Specific examples of alcohols include n-propanol, n-butanol, n-hexanol, 2-butanol, isobutyl alcohol, isopropyl alcohol, t-butyl alcohol, etc. Specific examples of haloalcohols include 1,3-dichloro-2-propanol, 2-chloroethanol, 1-chlorobutanol, etc.

[0075] Examples of activity regulators, particularly when using ruthenium carbene complexes as metathesis polymerization catalysts, include Lewis base compounds. Examples of Lewis base compounds include phosphorus-containing Lewis base compounds such as tricyclopentylphosphine, tricyclohexylphosphine, triphenylphosphine, triphenylphosphite, and n-butylphosphine; and nitrogen-containing Lewis base compounds such as n-butylamine, pyridine, 4-vinylpyridine, acetonitrile, ethylenediamine, N-benzylidenemethylamine, pyrazine, piperidine, and imidazole. Furthermore, norbornenes substituted with alkenyl groups, such as vinylnorbornene, propenylnorbornene, and isopropenylnorbornene, function not only as polymerizable monomers but also as activity regulators. The amount of these activity regulators used can be adjusted appropriately depending on the compound used.

[0076] Examples of elastomers include natural rubber, polybutadiene, polyisoprene, styrene-butadiene copolymer (SBR), styrene-butadiene-styrene copolymer (SBS), styrene-isoprene-styrene copolymer (SIS), ethylene-propylene-diene terpolymer (EPDM), ethylene-vinyl acetate copolymer (EVA), and hydrogenated versions of these. Dissolving an elastomer in the polymerizable composition allows for adjustment of its viscosity. Furthermore, adding an elastomer can improve the impact resistance of the norbornene-based resin formed by bulk polymerization of the composition. The amount of elastomer used is preferably 0.5 to 20 parts by mass, more preferably 2 to 10 parts by mass, per 100 parts by mass of the total amount of polymerizable monomers in the polymerizable composition.

[0077] Antioxidants (antiaging agents) include various antioxidants for plastics and rubbers, such as phenolic, phosphorus, and amine antioxidants. As dispersants, anionic surfactants, cationic surfactants, and nonionic surfactants can be used as desired, with nonionic surfactants being preferred.

[0078] The polymerizable composition of the present invention is prepared by appropriately mixing the above-mentioned components according to a known method. The polymerizable composition of the present invention may also be prepared by preparing two or more premixed liquids and mixing the two or more premixed liquids using a mixing device or the like immediately before bulk polymerization to produce a norbornene-based resin. Each premixed liquid will not undergo bulk polymerization on its own, but the above-mentioned components are prepared by dividing them into two or more liquids so that mixing all the liquids results in a polymerizable composition containing each component in a predetermined ratio (the total content of each component is 100% by mass). That is, the polymerizable composition of the present invention may be a polymerizable composition consisting of two or more premixed liquids that do not undergo polymerization reaction by themselves and that can be formed by combining these premixed liquids. The combination of two or more reactant liquids can be exemplified by the following two methods (a) and (b), depending on the type of metathesis polymerization catalyst used.

[0079] (a): The metathesis polymerization catalyst may be one that does not have polymerization activity by itself but exhibits polymerization activity when used in combination with an activator. In this case, a premixed liquid (Liquid A) containing a polymerizable monomer containing a norbornene-based monomer and an activator and a premixed liquid (Liquid B) containing a polymerizable monomer containing a norbornene-based monomer and a metathesis polymerization catalyst are used and mixed to obtain a polymerizable composition. Furthermore, a premixed liquid (Liquid C) containing a polymerizable monomer containing a norbornene-based monomer but not containing a metathesis polymerization catalyst or an activator may also be used in combination.

[0080] (b): When a metathesis polymerization catalyst having polymerization activity by itself is used, a polymerizable composition can be obtained by mixing a premix (i) containing a polymerizable monomer including a norbornene-based monomer with a premix (ii) containing a metathesis polymerization catalyst. In this case, the premix (ii) is typically prepared by dissolving or dispersing the metathesis polymerization catalyst in a small amount of an inert solvent. Examples of such solvents include aromatic hydrocarbons such as toluene, xylene, ethylbenzene, and trimethylbenzene; ketones such as methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and 4-hydroxy-4-methyl-2-pentanone; cyclic ethers such as tetrahydrofuran; diethyl ether, dichloromethane, dimethyl sulfoxide, and ethyl acetate.

[0081] Optional components such as a radical generator, a diisocyanate compound, and a polyfunctional (meth)acrylate compound may be contained in any of the pre-mixed liquids, or may be added in the form of a mixed liquid other than the pre-mixed liquid.

[0082] Examples of the mixing device used to mix the pre-mixed liquid include an impingement mixer that is generally used in reaction injection molding, as well as low-pressure mixers such as a dynamic mixer and a static mixer.

[0083] <Resin-impregnated superconducting coil> The resin-impregnated superconducting coil of the present invention is formed by impregnating a superconducting coil with a norbornene-based resin obtained by bulk polymerizing the polymerizable composition of the present invention. That is, the resin-impregnated superconducting coil of the present invention is a superconducting coil impregnated with a norbornene-based resin obtained by bulk polymerizing the polymerizable composition of the present invention.

[0084] 1(A) is a schematic perspective view of a resin-impregnated superconducting coil 10 according to one embodiment of the present invention, and FIG. 1(B) is a schematic cross-sectional view of the resin-impregnated superconducting coil 10 according to one embodiment of the present invention. In the following, the resin-impregnated superconducting coil of the present invention will be described using the resin-impregnated superconducting coil 10 according to one embodiment of the present invention shown in FIG. 1(A) and FIG. 1(B) as an example, but the present invention is not limited to the embodiment shown in FIG. 1(A) and FIG. 1(B).

[0085] As shown in Fig. 1(A), the resin-impregnated superconducting coil 10 according to this embodiment includes a bobbin 20 and a winding body 30 formed around the bobbin 20. Fig. 1(B) is a cross-sectional view of the resin-impregnated superconducting coil 10 taken along line Ib-Ib in Fig. 1(A). As shown in Fig. 1(B), the winding body 30 includes a superconducting wire 32 and a wire protective layer 34.

[0086] The reel 20 is formed of, for example, a glass fiber reinforced composite material, a high-strength polyethylene fiber reinforced composite material, stainless steel, aluminum, or the like, and the superconducting wire 32 is concentrically wound around the reel 20. The wire protective layer 34 is a protective layer for protecting the superconducting wire 32, and in this embodiment, the wire protective layer 34 is made of a norbornene-based resin obtained by bulk polymerization of the above-described polymerizable composition of the present invention.

[0087] Resin-impregnated superconducting coil 10 may have an insulating plate on the upper and / or lower surface of winding body 30.

[0088] The resin-impregnated superconducting coil 10 of this embodiment can be manufactured by, for example, a first manufacturing method or a second manufacturing method described below.

[0089] That is, in the first manufacturing method, the superconducting wire 32 is wound around the reel 20 while being coated with the above-described polymerizable composition of the present invention, and then the polymerizable composition is polymerized and cured to manufacture the resin-impregnated superconducting coil 10.

[0090] The superconducting wire 32 may be, for example, a superconducting material such as a niobium titanium alloy, an A15 type intermetallic compound (niobium-3-tin, niobium-3-aluminum, vanadium-3-gallium, etc.), magnesium diboride, a rare earth barium copper oxide (REBa2Cu3O7:REBCO) including yttrium barium copper oxide (YBa2Cu3O7:YBCO) or gadolinium barium copper oxide (GdBa2Cu3O7:GdBCO), or a bismuth strontium copper oxide (Bi2Sr2CaCu2O X :Bi2212, Bi2Sr2Ca2Cu3O X Examples of the shape of the superconducting wire 32 include a round wire, a rectangular wire, a twisted wire, and a tape-shaped wire. Fig. 1(B) shows an example in which the superconducting wire 32 is a tape-shaped wire.

[0091] In addition, the superconducting wire 32 may have a multilayer structure, for example, a configuration having a first stabilization layer, a substrate, an intermediate layer, a superconducting layer, a protective layer, and a second stabilization layer in this order.

[0092] The first stabilization layer can be made of a metal with a high specific heat, such as copper or aluminum, and the substrate can be made of a high-strength metal, such as a nickel-based alloy, stainless steel, or copper. The intermediate layer can have a laminated structure of multiple oxides, and the superconducting layer can be made of the above-mentioned superconducting materials. The protective layer can be made of, for example, silver, gold, or platinum, and can have the function of suppressing oxygen diffusion from the superconducting layer. The second stabilization layer can be made of a metal with a high specific heat, such as copper or aluminum.

[0093] The polymerizable composition can be applied to the superconducting wire 32, for example, by continuously conveying the superconducting wire 32 from a delivery means using rollers and passing the superconducting wire 32 through the polymerizable composition. The conveying speed of the superconducting wire 32 may be appropriately adjusted so that the polymerizable composition adheres sufficiently to the surface of the superconducting wire 32.

[0094] The polymerizable composition can be prepared by separately introducing the two or more pre-mixed liquids into an impingement mixer, bringing them into contact with each other, and mixing them. Examples of the mixer that can be used include an impingement mixer for reaction injection molding (RIM), and low-pressure mixers such as a dynamic mixer or a static mixer. The prepared polymerizable composition can be stored in a suitable tank or the like for use in passing the superconducting wire 32 through the polymerizable composition. Although the polymerizable composition may gradually thicken, from the viewpoint of uniformly applying the polymerizable composition to the superconducting wire 32, it is desirable to pass the superconducting wire 32 through the polymerizable composition within a time period shorter than the usable life of the polymerizable composition (the time from when the polymerizable composition is obtained until the polymerizable composition changes from a liquid state to a pudding-like state and becomes non-flowable, also referred to as the pot life).

[0095] The superconducting wire 32 that has passed through the polymerizable composition is then wound up on a reel 20, and the polymerizable composition is then polymerized and cured by bulk polymerization to obtain a resin-impregnated superconducting coil 10.

[0096] If the superconducting wire 32 does not have an insulating layer on its surface, it is preferable to ensure circumferential insulation between the superconducting wires 32 by winding insulating tape around the superconducting wire 32 in advance, or to insert insulating sheets between the superconducting wires 32 when winding the superconducting wire 32 around the reel 20. Examples of materials for the insulating tape or insulating sheet include polyimide and aramid fiber paper. Alternatively, paraffin, wax, grease, or the like may be applied to the surface of the superconducting wire 32 in advance.

[0097] The polymerizable composition that has been wound together with the superconducting wire 32 and that has impregnated and adhered between or on the surface of the superconducting wire 32 can be polymerized and cured by, for example, placing the composition in a mold formed of a male mold and a female mold, after optionally drying, and then heating. The heating temperature is preferably 10 to 150°C, more preferably 30 to 120°C, and even more preferably 50 to 100°C, and the heating time is preferably 20 seconds to 20 minutes, more preferably 20 seconds to 5 minutes. During heating, if desired, nitrogen gas may be sealed in the mold, and a pressure of preferably 0.1 to 1 MPa may be applied. After heating is complete, the mold is opened and demolded to obtain the resin-impregnated superconducting coil 10.

[0098] Alternatively, the following method can be employed as the second manufacturing method: In the second manufacturing method, superconducting wire 32 is wound around reel 20 without being impregnated with the polymerizable composition, and while superconducting wire 32 is wound around reel 20, the polymerizable composition is impregnated into superconducting wire 32, and the polymerizable composition is then polymerized and cured to manufacture resin-impregnated superconducting coil 10.

[0099] The superconducting wire 32 wound around the reel 20 can be impregnated with the polymerizable composition by various methods. For example, as in the first manufacturing method described above, the obtained polymerizable composition can be stored in a tank or the like, and the superconducting wire 32 wound around the reel 20 can be immersed therein and maintained for a certain period of time. In this case, the impregnation with the polymerizable composition can be performed while removing air and degassing under reduced pressure when the superconducting wire 32 is immersed, or can be performed under pressure by sealing in nitrogen gas. Alternatively, the superconducting wire 32 wound around the reel 20 can be placed in a mold formed by a male mold and a female mold, and the polymerizable composition can be injected into the mold while removing air and degassing under reduced pressure. Alternatively, after the injection of the polymerizable composition, the mold can be filled with nitrogen gas and pressurized. The pressure applied when the polymerizable composition is impregnated into the superconducting wire 32 wound around the reel 20 is preferably 0.1 to 1 MPa.

[0100] The polymerization and hardening of the polymerizable composition impregnated into the superconducting wire 32 wound around the reel 20 can be carried out in the same manner as in the first manufacturing method described above. In the second manufacturing method as well, after heating is completed, the mold is opened and demolded to obtain the resin-impregnated superconducting coil 10.

[0101] As described above, resin-impregnated superconducting coil 10 can be obtained by the first manufacturing method or the second manufacturing method. Alternatively, resin-impregnated superconducting coil 10 of this embodiment can also be manufactured by, for example, impregnating an insulating tape or an insulating sheet to be used when winding around superconducting wire 32 with the polymerizable composition of the present invention in advance to form a prepreg, and then winding this prepreg around superconducting wire 32 in advance, or inserting it between superconducting wires 32 when winding superconducting wire 32 around reel 20, and then heating superconducting wire 32 after winding to polymerize and harden the polymerizable composition.

[0102] The specifications of the resin-impregnated superconducting coil 10 of this embodiment are not particularly limited, but may be, for example, in the ranges of an inner diameter of 30 to 400 mm, an outer diameter of 100 to 1000 mm, and a number of turns of 100 to 5000.

[0103] The resin-impregnated superconducting coil 10 of this embodiment comprises a norbornene-based resin obtained by bulk polymerization of the above-described polymerizable composition of the present invention. The norbornene-based resin obtained using the polymerizable composition of the present invention has a large specific heat capacity (Cp) at 7 to 10 K and can effectively suppress the temperature rise of a superconducting coil at 7 to 10 K. Therefore, by using the polymerizable composition of the present invention, it is possible to produce a resin-impregnated superconducting coil that can effectively suppress quenching and stably maintain a superconducting state.

[0104] Furthermore, by using the polymerizable composition of the present invention, the superconducting coil can be sufficiently impregnated with the resin component. Furthermore, the norbornene-based resin obtained using the polymerizable composition of the present invention has excellent mechanical properties even at extremely low temperatures, but has the property of having relatively weak adhesive strength with the superconducting wire 32 that constitutes the resin-impregnated superconducting coil 10. Therefore, even if the norbornene-based resin undergoes thermal contraction during cooling, the resin-impregnated superconducting coil 10 can be prevented from being destroyed by tensile stress caused by the thermal contraction, thereby effectively suppressing the occurrence of quenching.

[0105] Taking advantage of these characteristics, the resin-impregnated superconducting coil 10 of this embodiment can be suitably used as a superconducting coil for generating a magnetic field in a particle accelerator. Also, the resin-impregnated superconducting coil 10 of this embodiment can be suitably used as a superconducting coil for generating a magnetic field in a nuclear magnetic resonance apparatus (NMR), a magnetic resonance imaging apparatus (MRI), a heavy particle beam therapy apparatus, or a superconducting device for a superconducting magnetic levitation railway vehicle. [Example]

[0106] The present invention will be described below based on examples, but the present invention is not limited to these examples. Note that "parts" and "%" are by mass unless otherwise specified.

[0107] <Specific heat capacity (Cp)> The specific heat capacity (Cp) of the norbornene-based resin was measured using a physical property evaluation system (product name "PPMS", manufactured by Nippon Quantum Design Co., Ltd.) as a measuring device.

[0108] Example 1 A preliminary blend liquid (i) was obtained by mixing 95 parts of dicyclopentadiene (manufactured by Maruzen Petrochemical), 5 parts of ethylidene norbornene (manufactured by ENEOS Corporation), 120 parts of AlN particles (mode diameter measured by light scattering method (laser diffraction / scattering method) on a number basis of 1 μm), 1.5 parts of coupling agent 1 (vinyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.), 3 parts of coupling agent 2 (bicycloheptenylethyltriethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.), and 3 parts of dispersant (product name "Rheodol SP-030V", isopropyl tristearoyl titanate, manufactured by Kao Corporation).

[0109] A preliminary blend solution (ii) was obtained by dissolving 0.3 parts of a ruthenium catalyst represented by formula (7) as a metathesis polymerization catalyst, 30 parts of 2,6-di-t-butyl-p-cresol (BHT, antioxidant), and 30 parts of triphenylphosphine in 39.7 parts of cyclopentanone. [ka] (In the formula, Mes represents a mesityl group.)

[0110] The mold used was a flat-plate reaction injection mold consisting of two stainless steel plates with an internal space of 245 mm long x 210 mm wide x 4 mm thick. This reaction injection mold had a structure in which a reaction liquid injection hole was located at the bottom of one of the stainless steel plates.

[0111] The pre-mixture liquids (i) and (ii) prepared above were mixed in a ratio of (i):(ii) = 600:1 (mass ratio) and degassed in a vacuum to prepare a polymerizable composition. The AlN particle content in the resulting polymerizable composition was 53%. The resulting polymerizable composition was injected into a reaction injection mold through the reaction liquid injection hole, heated in an oven heated to 40°C for 30 minutes, and then heated at 120°C for 60 minutes to obtain a polymerized and cured norbornene-based resin. The specific heat capacity (Cp) of the resulting norbornene-based resin was measured according to the method described above. The results are shown in Table 1.

[0112] <Comparative Example 1> Except for not using AlN particles, a polymerizable composition and a norbornene-based resin were obtained and their specific heat capacities (Cp) were measured in the same manner as in Example 1. The results are shown in Table 1.

[0113] <Comparative Example 2> A polymerizable composition and a norbornene-based resin were obtained and their specific heat capacities (Cp) were measured in the same manner as in Example 1, except that 700 parts of Gd2O2S particles (having a mode diameter of 1.1 μm on a number basis as measured by a light scattering method (laser diffraction / scattering method)) were used instead of 120 parts of AlN particles. The results are shown in Table 1. The content of Gd2O2S particles in the polymerizable composition was 87%.

[0114] <Comparative Example 3> A norbornene-based resin was obtained and its specific heat capacity (Cp) was measured in the same manner as in Example 1, except that 500 parts of Gd2O3 particles (the mode diameter on a number basis measured by a light scattering method (laser diffraction / scattering method) was 0.9 μm) were used instead of 120 parts of AlN particles. The results are shown in Table 1. The content of Gd2O3 particles in the polymerizable composition was 82%.

[0115] [Table 1]

[0116] As is clear from Table 1, the polymerizable composition containing a norbornene-based monomer, metal nitride particles, and a metathesis polymerization catalyst was able to provide a norbornene-based resin with a larger specific heat capacity (Cp) at 7 to 10 K compared to the polymerizable compositions of Comparative Examples 1 to 3 (Example 1). When such a norbornene-based resin is applied to a superconducting coil, it can effectively suppress the temperature rise of the superconducting coil at 7 to 10 K. Therefore, by using this polymerizable composition, it is possible to produce a resin-impregnated superconducting coil that can effectively suppress quenching and stably maintain the superconducting state. [Explanation of symbols]

[0117] 10...Resin-impregnated superconducting coil 20...Reel frame 30...Winding body 32...Superconducting wire 34...Wire protection layer

Claims

1. A polymerizable composition for a resin-impregnated superconducting coil, comprising a norbornene-based monomer, metal nitride particles, and a metathesis polymerization catalyst.

2. 2. The polymerizable composition of claim 1, wherein the metal nitride particles comprise a nitride of a Group 13 metal of the periodic table.

3. 10. The polymerizable composition of claim 1, wherein the metal nitride particles comprise aluminum nitride.

4. 4. The polymerizable composition according to claim 1, wherein the content of the metal nitride particles is 4 to 90 mass %.

5. 4. The polymerizable composition according to claim 1, wherein the norbornene-based monomer contains 50% by mass or more of dicyclopentadiene.

6. 4. The polymerizable composition according to claim 1, wherein the norbornene-based monomer comprises a bicyclic and a tricyclic compound.

7. The polymerizable composition according to any one of claims 1 to 3, further comprising a silane coupling agent.

8. The polymerizable composition according to any one of claims 1 to 3, A polymerizable composition comprising two or more pre-mixed liquids that do not undergo a polymerization reaction by themselves, and that can form the polymerizable composition by combining the pre-mixed liquids.

9. 4. The polymerizable composition according to claim 1, wherein the resin-impregnated superconducting coil is a superconducting coil for generating a magnetic field in a particle accelerator.

10. A resin-impregnated superconducting coil obtained by impregnating a superconducting coil with a norbornene-based resin obtained by bulk polymerizing the polymerizable composition according to any one of claims 1 to 3.

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