Method for manufacturing granulated particles for regenerator particles, method for manufacturing regenerator particles, method for manufacturing regenerator, method for manufacturing refrigerator, method for manufacturing cryopump, method for manufacturing superconducting magnet, method for manufacturing nuclear magnetic resonance imaging device, method for manufacturing nuclear magnetic resonance device, method for manufacturing magnetic field application type single crystal pulling device, and method for manufacturing helium recondensation device

Abstract

To provide a method for producing granulated particles for cold storage material particles, enabling a reduction in the production cost of the cold storage material particles.SOLUTION: A method for producing granulated particles for cold storage material particles according to an embodiment includes: mixing a raw material powder comprising a rare-earth oxysulfide containing at least one rare-earth element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu or a raw material powder comprising a rare-earth oxide containing at least one rare-earth element with a binder containing 0.01 wt.% or more to 40 wt.% or less of an organic substance to prepare a raw material mixture; and then granulating the raw material mixture by tumbling granulation, stirring granulation, extrusion, spraying, or press molding, wherein the granulated particles for cold storage material particles have a carbon level of 0.001 wt.% or more and 50 wt.% or less and a relative density of 10% or more and 50% or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Embodiments of the present invention relate to a method for manufacturing granulated particles for regenerator particles, a method for manufacturing regenerator particles, a method for manufacturing a regenerator, a method for manufacturing a refrigerator, a method for manufacturing a cryopump, a method for manufacturing a superconducting magnet, a method for manufacturing a nuclear magnetic resonance imaging device, a method for manufacturing a nuclear magnetic resonance device, a method for manufacturing a magnetic field application type single crystal pulling device, and a method for manufacturing a helium recondensation device. [Background technology]

[0002] In recent years, superconducting technology has made remarkable progress, and as the fields of application of superconducting technology expand, the development of small, high-performance cryogenic refrigerators has become essential. Cryogenic refrigerators are required to be lightweight, small, and highly thermally efficient. Cryogenic refrigerators are being put to practical use in a variety of application fields.

[0003] A cryogenic refrigerator is equipped with a regenerator filled with multiple regenerator materials. For example, cold is generated by heat exchange between the regenerator materials and helium gas passing through the regenerator. For example, superconducting MRI devices and cryopumps used in semiconductor manufacturing equipment use refrigerators with refrigeration cycles such as the Gifford-McMahon (GM) system, Stirling system, or pulse tube system.

[0004] High-performance refrigerators are also essential for magnetic levitation trains, which use superconducting magnets to generate magnetic force. Furthermore, high-performance refrigerators are now being used in superconducting energy storage systems (SMES) and magnetic field-applied single crystal growing systems for producing high-quality silicon wafers. The development and practical application of pulse tube refrigerators, which are expected to be highly reliable, is also being actively pursued.

[0005] In the superconducting magnets and MRI devices mentioned above, the liquid helium used evaporates, making the replenishment of liquid helium a problem. In recent years, the helium depletion problem has become more serious, making it difficult to obtain, and affecting the industrial sector.

[0006] To reduce the consumption of liquid helium and ease the burden of maintenance such as replenishment, helium recondensing devices that recondense evaporated helium have been put into practical use and are in high demand. These helium recondensing devices also use GM refrigerators or pulse tube refrigerators that cool the helium to a temperature of 4K to liquefy it.

[0007] In a refrigerator, a working medium such as compressed helium (He) gas flows in one direction through a regenerator filled with a regenerator material, supplying its thermal energy to the regenerator material. The expanded working medium then flows in the opposite direction through the regenerator, receiving thermal energy from the regenerator material. As the heat recovery effect in this process improves, the thermal efficiency of the working medium cycle improves, making it possible to achieve lower temperatures. To ensure smooth thermal energy exchange between the helium gas and the regenerator material, it is desirable for the regenerator material to have high thermal conductivity.

[0008] The higher the specific heat per unit volume of the regenerator material, the more heat energy the regenerator material can store, improving the refrigeration capacity of the refrigerator. Therefore, it is desirable to fill the low-temperature side of the regenerator with a regenerator material that has a high specific heat at low temperatures, and the high-temperature side with a regenerator material that has a high specific heat at high temperatures.

[0009] Magnetic regenerator materials exhibit high volumetric heat capacity in specific temperature ranges depending on their composition. Therefore, by combining magnetic regenerator materials with different compositions that exhibit different volumetric heat capacity, the regenerator capacity can be increased, thereby improving the refrigeration capacity of the refrigerator.

[0010] Furthermore, the higher the thermal conductivity and heat transfer coefficient of the regenerator material filled in the regenerator, the more efficient the transfer of thermal energy becomes, and the more efficient the refrigerator becomes.

[0011] In conventional refrigerators, the high-temperature side of the regenerator is filled with metallic regenerator particles such as lead (Pb), bismuth (Bi), or tin (Sn), and the low-temperature side of the regenerator (below 20K) is filled with metallic magnetic regenerator particles such as Er3Ni, ErNi, or HoCu2, thereby achieving refrigeration at 4K.

[0012] In recent years, attempts have been made to improve the refrigeration capacity of refrigerators by replacing some of the metallic magnetic regenerator particles with ceramic magnetic regenerator particles such as Gd2O2S, Tb2O2S, Dy2O2S, Ho2O2S, and GdAlO3, which have high specific heat in the temperature range from 2K to 10K.

[0013] The ceramic magnetic regenerator particles are obtained through a multi-stage manufacturing process, including mixing raw materials and binders, granulation, debinding at several hundred degrees, sulfurization at several hundred degrees, and sintering at several thousand degrees. Therefore, if the debinding and sulfurization can be carried out at lower temperatures than conventional methods, the manufacturing cost and environmental load can be reduced. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-73661 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-213252 [Patent Document 3] International Publication No. 2018 / 025581 Summary of the Invention [Problem to be solved by the invention]

[0015] The problem to be solved by the present invention is to provide a method for producing granulated particles for use as cold storage material particles, which can reduce the production cost of cold storage material particles. [Means for solving the problem]

[0016] In one embodiment, a method for producing granulated particles for use as cold storage material particles includes mixing a raw material powder containing a rare earth oxysulfide containing at least one rare earth element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, or a raw material powder containing a rare earth oxide containing the at least one rare earth element, with a binder containing 0.01% by weight to 40% by weight of an organic substance to obtain a raw material mixture, and granulating the raw material mixture by a tumbling granulation method, a stirring granulation method, an extrusion method, a spraying method, or a press molding method, wherein the carbon concentration of the granulated particles for use as cold storage material particles is 0.001% by weight to 50% by weight, and the relative density of the granulated particles for use as cold storage material particles is 10% to 50%. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 2 is a schematic cross-sectional view of a granulated particle for use as a cold storage material particle according to the first embodiment. [Figure 2] FIG. 4 is a schematic cross-sectional view showing the main configuration of a cold storage material particle according to a second embodiment and a refrigerator according to a fourth embodiment. [Figure 3] FIG. 10 is a cross-sectional view showing a schematic configuration of a cryopump according to a fifth embodiment. [Figure 4] FIG. 10 is a perspective view showing a schematic configuration of a superconducting magnet according to a sixth embodiment. [Figure 5] FIG. 13 is a cross-sectional view showing a schematic configuration of a nuclear magnetic resonance imaging apparatus according to a seventh embodiment. [Figure 6] FIG. 13 is a cross-sectional view showing a schematic configuration of a nuclear magnetic resonance spectrometer according to an eighth embodiment. [Figure 7] FIG. 13 is a perspective view showing a schematic configuration of a magnetic field application type single crystal pulling apparatus according to a ninth embodiment. [Figure 8] FIG. 22 is a schematic diagram showing the general configuration of a helium recondensation device according to a tenth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] 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 may be omitted as appropriate.

[0019] In this specification, the term "extremely low temperature" refers to a temperature range in which the superconducting phenomenon can be industrially utilized, for example, a temperature range of 20 K or less.

[0020] (First embodiment) The granulated particles for regenerator particles of the first embodiment contain a rare earth oxysulfide containing at least one rare earth element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu), or a rare earth oxide containing the at least one rare earth element, and carbon in a concentration of 0.001% by weight or more and 50% by weight or less, and have a relative density of 10% or more and 50% or less.

[0021] FIG. 1 is a schematic cross-sectional view of a granulated particle for use as a cold storage material particle according to the first embodiment.

[0022] The granulated particles 101 for cold storage material particles of the first embodiment are granulated particles for producing cold storage material particles. For example, the granulated particles 101 for cold storage material particles of the first embodiment are subjected to a heat treatment for degreasing and a heat treatment for sintering, thereby producing the cold storage material particles. After the heat treatment for degreasing and before the heat treatment for sintering, the granulated particles 101 for cold storage material particles may be subjected to a heat treatment for sulfurization.

[0023] As shown in Fig. 1, the granulated particles 101 for cold storage material particles of the first embodiment include, for example, raw material powder 101a, a binder 101b, and voids 101c. The granulated particles 101 for cold storage material particles may contain, for example, a dispersion medium instead of the binder 101b. The granulated particles 101 for cold storage material particles may contain, for example, a gelling agent instead of the binder 101b. The raw material powder 101a may contain, for example, a sintering aid to promote sintering when producing the cold storage material particles.

[0024] The granulated particles 101 for cold storage material particles are formed by granulating raw material powder 101a. The granulated particles 101 for cold storage material particles are formed, for example, by binding a plurality of raw material powders 101a with a binder 101b.

[0025] The granulated particles 101 for cold storage material particles are, for example, gel. The granulated particles 101 for cold storage material particles are formed, for example, by gelling a plurality of raw material powders 101a using a gelling agent (gelling solution). The raw material powders 101a have, for example, lost their independent mobility and are in a solidified aggregated state.

[0026] When the granulated particles 101 for cold storage material particles are a gel, the granulated particles 101 for cold storage material particles contain, for example, raw material powder 101a and a dispersion medium. The dispersion medium contains, for example, a gelling agent. When the granulated particles 101 for cold storage material particles are a gel, the granulated particles 101 for cold storage material particles contain, for example, raw material powder 101a and a gelling agent. Note that the gelled gelling agent after the granulated particles 101 for cold storage material particles are gelled is also referred to as a gelling agent.

[0027] The raw material powder 101a contains a rare earth oxysulfide or a rare earth oxide, and the rare earth oxysulfide contained in the raw material powder 101a contains at least one rare earth element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). Furthermore, the rare earth oxide contained in the raw material powder 101a contains at least one rare earth element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).

[0028] The rare earth oxysulfide contained in the raw material powder 101a is, for example, gadolinium oxysulfide or holmium oxysulfide, or Gd2O2S, Tb2O2S, Dy2O2S, or Ho2O2S.

[0029] The rare earth oxide contained in the raw material powder 101a is, for example, gadolinium oxide or holmium oxide, Gd2O3, Tb2O3, Dy2O3, or Ho2O3.

[0030] The raw material powder 101a includes, for example, a carbonate, oxide, nitride, or carbide containing a Group 1 element.The raw material powder 101a includes, for example, a carbonate, oxide, nitride, or carbide containing a Group 2 element.

[0031] The raw material powder 101a contains, for example, a carbonate, an oxide, a nitride, or a carbide containing an additive element, which is at least one element selected from the group consisting of manganese (Mn), aluminum (Al), iron (Fe), copper (Cu), nickel (Ni), cobalt (Co), zirconium (Zr), yttrium (Y), and boron (B).

[0032] When the raw material powder 101a contains a sintering aid, the sintering aid is, for example, an oxide such as aluminum oxide (alumina), magnesium oxide, yttrium oxide, zirconium oxide, or boron oxide.

[0033] The binder 101b is an organic material, such as a resin, such as polyvinyl alcohol, polyvinyl butyral, carboxymethyl cellulose, an acrylic resin, or polyethylene glycol.

[0034] When the granulated particles 101 for cold storage material particles contain a dispersion medium, the dispersion medium is an organic substance. The dispersion medium is, for example, an alginate. The dispersion medium is, for example, sodium alginate, ammonium alginate, or potassium alginate.

[0035] The relative density of the granulated particles 101 for cold storage material particles is 10% or more and 50% or less.

[0036] For example, when the relative density of the granulated particles 101 for cold storage material particles is low, the volume ratio of the raw material powder 101a in the granulated particles 101 for cold storage material particles is relatively small. When the relative density of the granulated particles 101 for cold storage material particles is low, the volume ratio of the binder 101b, the dispersion medium, or the voids 101c in the granulated particles 101 for cold storage material particles is relatively high.

[0037] On the other hand, when the relative density of the granulated particles 101 for cold storage material particles is high, the volume ratio of the raw material powder 101a in the granulated particles 101 for cold storage material particles is relatively high. When the relative density of the granulated particles 101 for cold storage material particles is high, the volume ratio of the binder 101b, the dispersion medium, or the voids 101c in the granulated particles 101 for cold storage material particles is relatively low.

[0038] The relative density of the granulated particles 101 for use as cold storage material particles can be calculated, for example, by dividing the average compact density obtained from 50 granulated particles by the true density of the constituent materials. The average compact density of 50 particles can be calculated by dividing the weight of 50 granulated particles by the volume. The volume can be calculated by integrating the volumes of each particle, which are obtained by assuming that the circle-equivalent diameter of each particle is the diameter of the particle.

[0039] In calculating the true density of the granulated particles 101 for use as cold storage material particles, first, the crystalline phase of the raw material powder 101a constituting the granulated particles is identified by X-ray diffraction measurement. Then, the constituent ratio of the raw material powder 101a constituting the granulated particles is determined by Rietveld analysis or inductively coupled plasma atomic emission spectroscopy of the X-ray diffraction pattern. The true density of the granulated particles 101 for use as cold storage material particles can be calculated from the crystalline phase of the raw material powder 101a and the constituent ratio of the raw material powder 101a.

[0040] The particle size of the granulated particles 101 for use as cold storage material particles is, for example, 50 μm or more and 7 mm or less. The aspect ratio of the granulated particles 101 for use as cold storage material particles is, for example, 1 or more and 5 or less. The aspect ratio of the granulated particles 101 for use as cold storage material particles is the ratio of the major axis to the minor axis of the granulated particles 101 for use as cold storage material particles. The shape of the granulated particles 101 for use as cold storage material particles is, for example, spherical.

[0041] In this specification, the particle size of the granulated particles 101 for use as cold storage material particles refers to the circle-equivalent diameter. The circle-equivalent diameter is the diameter of a perfect circle corresponding to the area of ​​a figure observed in an image such as an optical microscope image or a scanning electron microscope image (SEM image). The particle size of the granulated particles 101 for use as cold storage material particles can be determined, for example, by image analysis of the optical microscope image or the SEM image.

[0042] The granulated particles 101 for cold storage material particles contain carbon. The concentration of carbon contained in the granulated particles 101 for cold storage material particles is 0.001% by weight or more and 50% by weight or less.

[0043] Carbon is contained in, for example, the binder 101b or the dispersion medium. For example, when the relative density of the granulated particles 101 for cold storage material particles is low, the carbon concentration becomes relatively high. For example, when the relative density of the granulated particles 101 for cold storage material particles is high, the carbon concentration becomes relatively low.

[0044] The granulated particles 101 for regenerator particles contain, for example, a Group 1 element. The Group 1 element is, for example, at least one element selected from the group consisting of lithium (Li), sodium (Na), and potassium (K).

[0045] The Group 1 element is contained in, for example, the raw material powder 101a, the binder 101b, or the dispersion medium, and is derived from, for example, the gelling solution used in producing the granulated particles 101 for the regenerator material particles.

[0046] The concentration of the Group 1 element contained in the granulated particles 101 for regenerator particles is, for example, 0.001 atomic % or more and 60 atomic % or less.

[0047] The granulated particles 101 for cold storage material particles contain, for example, a Group 2 element. The Group 2 element is, for example, at least one element selected from the group consisting of magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba).

[0048] The Group 2 element is contained in, for example, the raw material powder 101a, the binder 101b, or the dispersion medium, and is derived from, for example, the gelling solution used in producing the granulated particles 101 for the cold storage material particles.

[0049] The concentration of the Group 2 element contained in the granulated particles 101 for regenerator particles is, for example, 0.001 atomic % or more and 60 atomic % or less.

[0050] The granulated particles 101 for the regenerator particles contain an additive element, which is at least one element selected from the group consisting of, for example, manganese (Mn), aluminum (Al), iron (Fe), copper (Cu), nickel (Ni), cobalt (Co), zirconium (Zr), yttrium (Y), and boron (B).

[0051] The additive element is contained in, for example, the raw material powder 101a, the binder 101b, or the dispersion medium, and is derived from, for example, the gelling solution used when producing the granulated particles 101 for the regenerator material particles.

[0052] The concentration of the additive element contained in the granulated particles 101 for regenerator particles is, for example, 0.001 atomic % or more and 60 atomic % or less.

[0053] The detection of elements contained in the granulated particles 101 for regenerator particles and the measurement of the atomic concentration of the elements can be performed, for example, by dissolving the granulated particles in a liquid and using inductively coupled plasma atomic emission spectroscopy (ICP-AES). Alternatively, the detection can be performed using energy dispersive X-ray spectroscopy (EDX) or wavelength dispersive X-ray spectroscopy (WDX).

[0054] The method for producing the granulated particles for the cold storage material particles of the first embodiment is not particularly limited, but can be produced, for example, by mixing raw material powder and a binder using a ball mill or the like to prepare a raw material mixture, and then molding (granulating) the obtained raw material mixture into particles by a rolling granulation method, an agitation granulation method, an extrusion method, an atomization method (spray method), a press molding method, or the like.

[0055] In the above-mentioned granulation method, the strength of the granulated particles is improved by adding a binder to adhere the raw material powder together. Examples of binders that can be used include polyvinyl alcohol, polyvinyl butyral, carboxymethyl cellulose, acrylic resin, and polyethylene glycol. The amount of binder added is, for example, 0.01% by weight or more and 40% by weight or less. For example, by increasing the amount of binder, the breaking strength can be improved even if the relative density is low.

[0056] The raw material powder can be made of oxides or oxysulfides, and the type and ratio of the oxides or oxysulfides are adjusted to match the target composition of the regenerator particles.

[0057] The raw material powder can be a carbonate, oxide, nitride, or carbide containing a Group 1 element, Group 2 element, or additive element. The additive element is at least one element selected from the group consisting of manganese (Mn), aluminum (Al), iron (Fe), copper (Cu), nickel (Ni), cobalt (Co), zirconium (Zr), yttrium (Y), and boron (B). By using a carbonate, oxide, nitride, or carbide containing a Group 1 element, Group 2 element, or additive element as the raw material powder, granulated particles for use in regenerator particles containing the Group 1 element, Group 2 element, or additive element can be produced.

[0058] The raw material mixture may contain a sintering aid as a raw material powder, such as aluminum oxide (alumina), magnesium oxide, yttrium oxide, zirconium oxide, or boron oxide.

[0059] In tumbling granulation, the relative density of the granulated particles for use as cold storage material particles can be changed by, for example, controlling the rotation speed and diameter of the granulator during granulation. If the rotation speed is slow or the diameter of the granulator is small, the energy during tumbling decreases, resulting in a decrease in the relative density of the granulated particles for use as cold storage material particles.

[0060] In the production of granulated particles for use as cold storage material particles according to the first embodiment, a slurry may be prepared by adding raw material powder to an aqueous alginic acid solution and mixing the mixture, and then adding the resulting slurry dropwise to a gelling solution to gel the slurry. This method is a method for granulating particles by promoting gelation through a crosslinking reaction caused by polyvalent metal ions contained in the gelling solution.

[0061] The relative density of the granulated particles for cold storage material particles can be changed by changing the ratio of the raw material powder to the alginic acid aqueous solution. The weight ratio of the raw material powder to the alginic acid aqueous solution is, for example, 0.1 to 20 times.

[0062] The granulated particles for use as cold storage material particles solidify into granules due to the gelation of alginate. Therefore, the strength of the granulated particles, i.e., the gelation strength, varies depending on the amount of alginate contained in the particles or the viscosity of the alginate aqueous solution. For example, by adjusting the viscosity of the alginate aqueous solution, the raw material powder is secured in the gel, the strength of the granulated particles for use as cold storage material particles is maintained, and granulated particles for use as cold storage material particles having the desired shape can be obtained.

[0063] The slurry can be dropped into the gelling solution using, for example, a dropper, burette, pipette, syringe, dispenser, ink jet, etc. Hereinafter, this method for granulating particles is referred to as the alginate gel method.

[0064] In the alginate gel method, the particle size and aspect ratio of the granulated particles for use as cold storage material particles can be changed by adjusting the viscosity of the slurry, the diameter of the discharge port during dripping, or the distance between the tip of the discharge port and the liquid surface of the gelling solution. The diameter of the discharge port is, for example, 50 μm or more and 3000 μm or less. The distance between the tip of the discharge port and the liquid surface of the gelling solution is, for example, 0.1 mm or more and 1000 mm or less.

[0065] When a dispenser is used for discharging, any of an air pulse dispenser, a plunger dispenser, and a piezo dispenser may be used as the device.

[0066] Inkjet printers are broadly divided into continuous and on-demand types based on their ejection method, but either type may be used. Furthermore, on-demand types are further divided into three types: piezo, thermal, and valve, but any of these may be used.

[0067] Slurry dropped into a gelling solution using a dropper, burette, pipette, syringe, dispenser, inkjet, or the like is gelled by being held in the gelling solution. By gelling the slurry, granulated particles containing the raw material powder of the cold storage material are formed. The holding time of the slurry in the gelling solution is, for example, 10 minutes to 48 hours. If the gelling time is short, gelation does not proceed sufficiently, resulting in low strength of the granulated particles.

[0068] The alginic acid aqueous solution used in the alginic acid gel method is, for example, a sodium alginate aqueous solution, an ammonium alginate aqueous solution, or a potassium alginate aqueous solution. By using a sodium alginate aqueous solution or a potassium alginate aqueous solution containing a Group 1 element, sodium (Na) or potassium (K) can be contained in the granulated particles 101 for cold storage material particles. By using a mixed aqueous solution of a sodium alginate aqueous solution and a potassium alginate aqueous solution as a slurry, sodium (Na) and potassium (K) can be simultaneously contained in the granulated particles 101 for cold storage material particles.

[0069] The concentration of the alginate in the alginate aqueous solution is, for example, 0.1% by weight to 5% by weight. If the concentration of the alginate aqueous solution is lower than 0.1% by weight, a gel with sufficient strength cannot be formed, and granulated particles for use as cold storage material particles cannot be obtained.

[0070] As the gelling solution, for example, an aqueous solution of calcium lactate, an aqueous solution of calcium chloride, an aqueous solution of manganese (II) chloride, an aqueous solution of magnesium sulfate, an aqueous solution of beryllium sulfate, an aqueous solution of strontium nitrate, an aqueous solution of barium chloride, an aqueous solution of barium hydroxide, an aqueous solution of aluminum chloride, an aqueous solution of aluminum nitrate, an aqueous solution of aluminum lactate, an aqueous solution of iron (II) chloride, an aqueous solution of iron (III) chloride, an aqueous solution of copper (II) chloride, an aqueous solution of nickel (II) chloride, or an aqueous solution of cobalt (II) chloride can be used.

[0071] By using a calcium lactate aqueous solution, a calcium chloride aqueous solution, a manganese (II) chloride aqueous solution, a magnesium sulfate aqueous solution, a beryllium sulfate aqueous solution, a strontium nitrate aqueous solution, a barium chloride aqueous solution, a barium hydroxide aqueous solution, an aluminum chloride aqueous solution, an aluminum nitrate aqueous solution, an aluminum lactate aqueous solution, an iron (II) chloride aqueous solution, an iron (III) chloride aqueous solution, a copper (II) chloride aqueous solution, a nickel (II) chloride aqueous solution, or a cobalt (II) chloride aqueous solution as the gelling solution, calcium (K), manganese (Mn), magnesium (Mg), beryllium (Be), strontium (Sr), barium (Ba), aluminum (Al), iron (Fe), copper (Cu), nickel (Ni), or cobalt (Co) can be contained in the granulated particles 101 for the cold storage material particles.

[0072] Furthermore, by using an aluminum chloride aqueous solution, an aluminum nitrate aqueous solution, an aluminum lactate aqueous solution, an iron (II) chloride aqueous solution, an iron (III) chloride aqueous solution, a copper (II) chloride aqueous solution, a nickel (II) chloride aqueous solution, or a cobalt (II) chloride aqueous solution as a gelling solution, aluminum (Al), iron (Fe), copper (Cu), nickel (Ni), or cobalt (Co) can be contained in the granulated particles 101 for the cold storage material particles.

[0073] Since gelation proceeds through a crosslinking reaction caused by the polyvalent metal ions contained in the gelling solution, when an aqueous solution containing a group 1 element is used as the slurry and an aqueous solution containing an element that forms a polyvalent metal ion in the aqueous solution is used as the gelling solution, the amount of group 1 element contained in the particles and the amount of element that forms a polyvalent metal ion in the aqueous solution can be adjusted by adjusting the immersion time in the gelling solution of the particles that have been granulated by dropping them into the gelling solution.

[0074] Examples of elements that form multivalent ions in aqueous solution include calcium (Ca), manganese (Mn), magnesium (Mg), beryllium (Be), strontium (Sr), barium (Ba), aluminum (Al), iron (Fe), copper (Cu), nickel (Ni), and cobalt (Co).

[0075] At least two types of aqueous solutions containing different metal elements selected from the group consisting of calcium lactate aqueous solution, calcium chloride aqueous solution, manganese (II) chloride aqueous solution, magnesium sulfate aqueous solution, beryllium sulfate aqueous solution, strontium nitrate aqueous solution, barium chloride aqueous solution, barium hydroxide aqueous solution, aluminum chloride aqueous solution, aluminum nitrate aqueous solution, aluminum lactate aqueous solution, iron (II) chloride aqueous solution, iron (III) chloride aqueous solution, copper (II) chloride aqueous solution, nickel (II) chloride aqueous solution, and cobalt (II) chloride aqueous solution are mixed and used as a gelling solution, whereby two or more types of elements that form multivalent ions in the aqueous solution can be contained in the granulated particles 101 for the cold storage material particles.

[0076] Next, the operation and effect of the granulated particles for cold storage material particles of the first embodiment will be described.

[0077] The granulated particles for cold storage material particles are subjected to a heat treatment for degreasing and a heat treatment for sintering, thereby producing the cold storage material particles. For example, when the granulated particles for cold storage material particles contain a raw material powder of an oxide, the granulated particles for cold storage material particles may be subjected to a heat treatment for sulfurization after the heat treatment for degreasing and before the heat treatment for sintering.

[0078] By degreasing the granulated particles for use as cold storage material particles, a certain amount of organic components contained in the binder and dispersion medium can be removed. For example, if the raw material powder is an oxide, if the degreasing is insufficient, the sulfurization of the oxide will not proceed sufficiently, and the required amount of oxysulfide will not be produced.

[0079] Furthermore, if the granulated particles for cold storage material particles are not sufficiently degreased and a large amount of organic components remain, the sintering reaction is also inhibited. If the sintering reaction is inhibited, the density of the cold storage material particles after sintering will be low. If the density of the cold storage material particles is low, the strength of the cold storage material particles will be weakened and there is a risk of them breaking during use in a refrigerator. Furthermore, if the sintering reaction is inhibited, the specific heat of the cold storage material particles after sintering will be low. If the specific heat of the cold storage material particles is low, the performance of the refrigerator will be reduced.

[0080] On the other hand, if the granulated particles for use as cold storage material particles are degreased too much, the organic components necessary for ensuring strength are lost, which reduces the strength of the granulated particles after degreasing and may cause cracks or chips in the granulated particles.

[0081] The granulated particles 101 for cold storage material particles of the first embodiment have a relative density of 10% or more and 50% or less.

[0082] By setting the relative density of the granulated particles 101 for cold storage material particles to 50% or less, it is easy to remove organic components contained in the binder and dispersion medium during the degreasing heat treatment. Therefore, for example, the temperature of the degreasing heat treatment can be reduced or the time of the degreasing heat treatment can be shortened. Furthermore, for example, the temperature of the sulfurizing heat treatment can be reduced or the time of the sulfurizing heat treatment can be shortened. Furthermore, for example, the temperature of the sintering heat treatment can be reduced or the time of the sintering heat treatment can be shortened. Therefore, according to the granulated particles 101 for cold storage material particles of the first embodiment, the manufacturing cost of the cold storage material particles can be reduced by reducing the heat treatment temperature or the heat treatment time.

[0083] From the viewpoint of reducing the temperature of the heat treatment for degreasing, sulfurizing, or sintering, or from the viewpoint of reducing the time of the heat treatment for degreasing, sulfurizing, or sintering, the relative density of the granulated particles 101 for the heat storage material particles is preferably 45% or less, and more preferably 40% or less.

[0084] If the relative density of the granulated particles for cold storage material particles is less than 10%, for example, the proportion of voids in the cold storage material particles increases, and the strength of the granulated particles for cold storage material particles decreases. If the strength of the granulated particles for cold storage material particles decreases, the granulated particles for cold storage material particles become difficult to handle.

[0085] Furthermore, if the relative density of the granulated particles for cold storage material particles is less than 10%, there is a risk that an excessive amount of organic components will be removed during the heat treatment for degreasing, which will result in a decrease in the strength and specific heat of the produced cold storage material particles.

[0086] Furthermore, if the relative density of the granulated particles for cold storage material particles is less than 10%, for example, the relative density of the manufactured cold storage material particles will decrease, and the specific heat of the cold storage material particles will decrease. This is thought to be because the number of contact points between the raw material powders will decrease, and the sinterability of the cold storage material particles will decrease.

[0087] The granulated particles 101 for cold storage material particles of the first embodiment have a relative density of 10% or more, so that the strength of the granulated particles 101 for cold storage material particles is maintained and the granulated particles for cold storage material particles are easy to handle.

[0088] Furthermore, by setting the relative density of the granulated particles 101 for cold storage material particles to 10% or more, excessive removal of organic components during the heat treatment for degreasing is suppressed, and therefore, a decrease in the strength and specific heat of the manufactured cold storage material particles is suppressed.

[0089] Furthermore, by setting the relative density of the granulated particles 101 for cold storage material particles to 10% or more, the sinterability of the manufactured cold storage material particles is improved, and the specific heat of the cold storage material particles is improved.

[0090] From the viewpoint of maintaining the strength of the granulated particles 101 for cold storage material particles, the relative density of the granulated particles 101 for cold storage material particles is preferably 15% or more, and more preferably 20% or more. Furthermore, from the viewpoint of suppressing excessive removal of organic components during the heat treatment for degreasing, the relative density of the granulated particles 101 for cold storage material particles is preferably 15% or more, and more preferably 20% or more. Furthermore, from the viewpoint of improving the sinterability of the produced cold storage material particles, the relative density of the granulated particles 101 for cold storage material particles is preferably 15% or more, and more preferably 20% or more.

[0091] The granulated particles 101 for regenerator particles of the first embodiment contain carbon at a concentration of 0.001% by weight or more and 50% by weight or less.

[0092] A high carbon concentration in the granulated particles for use as cold storage material particles improves the strength of the granulated particles for use as cold storage material particles. For example, if the carbon concentration in the granulated particles for use as cold storage material particles is less than 0.001% by weight, the strength of the granulated particles for use as cold storage material particles decreases, making them difficult to handle.

[0093] On the other hand, if the carbon concentration of the granulated particles for cold storage material particles is high, the thermal conductivity of the cold storage material particles produced from the granulated particles for cold storage material particles will decrease because excess carbon will remain at the grain boundaries of the produced cold storage material particles.

[0094] The granulated particles 101 for use as cold storage material particles of the first embodiment have a carbon concentration of 0.001% by weight or more, which improves the strength of the granulated particles for use as cold storage material particles. From the viewpoint of improving the strength of the granulated particles for use as cold storage material particles, the carbon concentration of the granulated particles 101 for use as cold storage material particles is preferably 0.01% by weight or more, and more preferably 0.1% by weight or more.

[0095] The granulated particles 101 for cold storage material particles of the first embodiment have a carbon concentration of 50% by weight or less, which improves the thermal conductivity of the produced cold storage material particles. From the viewpoint of improving the thermal conductivity of the produced cold storage material particles, the carbon concentration of the granulated particles 101 for cold storage material particles is preferably 10% by weight or less, and more preferably 5% by weight or less.

[0096] The granulated particles 101 for cold storage material particles of the first embodiment preferably contain a Group 1 element at a concentration of 0.001 atomic % or more and 60 atomic % or less. By containing a Group 1 element in the above concentration range, the granulated particles 101 for cold storage material particles can improve the sinterability of the cold storage material particles to be produced. Therefore, for example, the strength and specific heat of the cold storage material particles to be produced are improved.

[0097] From the viewpoint of improving the sinterability of the produced cold storage material particles, the concentration of the Group 1 element contained in the granulated particles 101 for cold storage material particles is more preferably 0.01 atomic % or more and 30 atomic % or less, and even more preferably 0.1 atomic % or more and 10 atomic % or less.

[0098] The granulated particles 101 for cold storage material particles of the first embodiment preferably contain a Group 2 element at a concentration of 0.001 atomic % or more and 60 atomic % or less. By containing a Group 2 element in the above concentration range, the granulated particles 101 for cold storage material particles can improve the sinterability of the cold storage material particles to be produced. Therefore, for example, the strength and specific heat of the cold storage material particles to be produced are improved.

[0099] From the viewpoint of improving the sinterability of the produced cold storage material particles, the concentration of the Group 2 element contained in the granulated particles 101 for cold storage material particles is more preferably 0.01 atomic % or more and 30 atomic % or less, and even more preferably 0.1 atomic % or more and 10 atomic % or less.

[0100] The granulated particles 101 for cold storage material particles of the first embodiment preferably contain an additive element that is at least one element selected from the group consisting of manganese (Mn), aluminum (Al), iron (Fe), copper (Cu), nickel (Ni), cobalt (Co), zirconium (Zr), yttrium (Y), and boron (B) at a concentration of 0.001 atomic % or more and 60 atomic % or less. By containing an additive element in the above concentration range, the granulated particles 101 for cold storage material particles can improve the sinterability of the cold storage material particles produced. Therefore, for example, the strength and specific heat of the cold storage material particles produced are improved.

[0101] From the viewpoint of improving the sinterability of the produced cold storage material particles, the concentration of the additive element contained in the granulated particles 101 for cold storage material particles is more preferably 0.01 atomic % or more and 30 atomic % or less, and even more preferably 0.1 atomic % or more and 10 atomic % or less.

[0102] The granulated particles 101 for cold storage material particles of the first embodiment preferably contain aluminum oxide (alumina), magnesium oxide, yttrium oxide, zirconium oxide, or boron oxide. The oxides function as sintering aids. By including the oxides in the granulated particles 101 for cold storage material particles, the sinterability of the produced cold storage material particles can be improved.

[0103] As described above, according to the first embodiment, it is possible to provide granulated particles for cold storage material particles that can reduce the manufacturing cost of cold storage material particles.

[0104] (Second embodiment) The cold storage material particles of the second embodiment are obtained by sintering the granulated particles for cold storage material particles of the first embodiment.

[0105] The cold storage material particles of the second embodiment have a particle size of, for example, 50 μm or more and 5 mm or less. The aspect ratio of the cold storage material particles is, for example, 1 or more and 5 or less. The aspect ratio of the cold storage material particles is the ratio of the long axis to the short axis of the cold storage material particles. The shape of the cold storage material particles is, for example, spherical. The cold storage material particles of the second embodiment have, for example, a relative density of 90% or more. The relative density of the cold storage material particles of the second embodiment is preferably 93% or more, and more preferably 95% or more.

[0106] The cold accumulator particles of the second embodiment are obtained from the granulated particles for cold accumulator particles of the first embodiment. The cold accumulator particles of the second embodiment contain a rare earth oxysulfide or a rare earth oxide. The rare earth oxysulfide contained in the cold accumulator particles contains at least one rare earth element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). Furthermore, the rare earth oxide contained in the regenerator particles contains at least one rare earth element selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).

[0107] The maximum value of the volumetric specific heat of the regenerator particles in the second embodiment in the temperature range of 2 K to 10 K is, for example, 0.5 J / (cm 3 ·K) or more.

[0108] The cold storage material particles of the second embodiment may be, for example, a compound represented by the general formula R 2±0.1 O2S 1±0.1 (wherein R represents at least one rare earth element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu).

[0109] In the rare earth oxysulfide represented by the above general formula, the maximum volumetric specific heat and the temperature at which the maximum volumetric specific heat is exhibited vary depending on the selected rare earth element. Therefore, by appropriately adjusting the ratio of the rare earth element, the specific heat characteristics of the rare earth oxysulfide can be adjusted. The rare earth element is, for example, at least one element selected from the group consisting of Gd, Tb, Dy, Ho, and Er. The rare earth element may include, for example, two or more rare earth elements.

[0110] The cold storage material particles of the second embodiment may be, for example, a compound represented by the general formula R 1±0.1 M 1±0.1 O 3±0.1 (wherein R represents at least one element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, and M represents at least one element selected from the group consisting of Al, Cr, Mn, and Fe).

[0111] In the rare earth oxide represented by the above general formula, the maximum volumetric specific heat and the temperature at which the maximum volumetric specific heat is exhibited vary depending on the selected rare earth element. Therefore, by appropriately adjusting the ratio of the rare earth element, the specific heat characteristics of the rare earth oxide can be adjusted. The rare earth element is, for example, at least one element selected from the group consisting of Gd, Tb, Dy, Ho, and Er. The rare earth element may include, for example, two or more types of rare earth elements.

[0112] The cold storage material particles of the second embodiment contain at least one element selected from the group consisting of aluminum (Al), magnesium (Mg), iron (Fe), copper (Cu), nickel (Ni), cobalt (Co), zirconium (Zr), and yttrium (Y). The above element is, for example, an element derived from the sintering aid contained in the granulated particles 101 for cold storage material particles of the first embodiment.

[0113] The cold storage material particles of the second embodiment contain, for example, boron (B), which is derived from the sintering aid contained in the granulated particles 101 for cold storage material particles of the first embodiment.

[0114] The cold storage material particles of the second embodiment contain, as an oxide, a substance derived from the sintering aid of the granulated particles 101 for cold storage material particles of the first embodiment. The oxide is, for example, aluminum oxide (alumina), magnesium oxide, yttrium oxide, zirconium oxide, or boron oxide.

[0115] The regenerator particles of the second embodiment contain at least one element selected from the group consisting of aluminum (Al), magnesium (Mg), iron (Fe), copper (Cu), nickel (Ni), cobalt (Co), zirconium (Zr), yttrium (Y), and boron (B) in an amount of 0.01 atomic % or more and 20 atomic % or less.

[0116] The elements constituting the sintering aid do not exhibit specific heat properties, so if the amount of the elements added exceeds 20 atomic % in the cold storage material particles, the volumetric specific heat of the cold storage material particles decreases, the cold storage performance of the cold storage unit decreases, and the refrigeration capacity of the refrigerator decreases.

[0117] The cold storage material particles of the second embodiment have a volumetric specific heat of 0.5 J / (cm) in the temperature range of 2.5 K or more and 10 K or less, for example. 3 ·K) or more. The cold storage material particles of the second embodiment have a volumetric specific heat of 0.55 J / (cm ) in the temperature range of 2 K or more and 8 K or less. 3 ·K) or more. The cold storage material particles of the second embodiment have a volumetric specific heat of 0.6 J / (cm ) in the temperature range of 4 K or more and 7 K or less. 3 ·K) or more.

[0118] The cold storage material particles of the second embodiment have a maximum volumetric specific heat of 0.5 J / (cm 3 ·K) or more. Therefore, the cold storage material particles of the second embodiment have a high volumetric specific heat. Since the cold storage material particles of the second embodiment have a high volumetric specific heat, a cold storage unit equipped with the cold storage material particles of the second embodiment has high cold storage performance, and the refrigerator exhibits high refrigeration capacity.

[0119] The particle size of the cold storage material particles in the second embodiment is, for example, 50 μm or more and 5 mm or less. The particle size of the cold storage material particles is preferably 1 mm or less, and more preferably 500 μm or less. When the particle size of the cold storage material particles exceeds the above lower limit, the packing density of the cold storage material particles in the cold storage unit decreases, the pressure loss of the working medium such as helium decreases, and the refrigeration performance of the refrigerator improves. On the other hand, when the particle size of the cold storage material particles is below the above upper limit, the distance from the surface of the cold storage material particle to the center of the particle becomes shorter, and heat transfer between the working medium and the cold storage material particles becomes easier to transfer to the center of the cold storage material, and the refrigeration performance of the refrigerator improves.

[0120] The particle size of the granulated particles for use as cold storage material particles is the equivalent circle diameter. The equivalent circle diameter is the diameter of a perfect circle corresponding to the area of ​​a figure observed in an image such as an optical microscope image or a scanning electron microscope image (SEM image). The particle size of the granulated particles for use as cold storage material particles can be determined, for example, by image analysis of the optical microscope image or the SEM image.

[0121] The cold storage material particles of the second embodiment have a relative density of, for example, 90% or more. The relative density of the cold storage material particles of the second embodiment is preferably 93% or more, and more preferably 95% or more.

[0122] The relative density of the cold storage material particles in the second embodiment can be calculated by dividing the average sintered density obtained from 50 cold storage material particles by the true density of the constituent materials. The average sintered density of 50 particles is obtained by dividing the weight of 50 cold storage material particles by the volume. The volume can be calculated by integrating the volumes of each particle, which are obtained by assuming that the circle-equivalent diameter of each particle is the particle diameter.

[0123] The crystal structure of the rare earth oxysulfide contained in the regenerator particles of the second embodiment is, for example, Ce2O2S type, and its space group is P-3m. The crystal structure can be confirmed by powder X-ray diffraction measurement, observation of an electron backscatter diffraction image using a scanning electron microscope, or observation using a transmission electron microscope.

[0124] The crystal structure of the rare earth oxide contained in the regenerator particles of the second embodiment is, for example, a perovskite type, and its space group is, for example, Pnma. The space group is, for example, Pm-3m. The crystal structure and space group can be confirmed by powder X-ray diffraction measurement, observation of an electron backscatter diffraction image using a scanning electron microscope, or observation using a transmission electron microscope.

[0125] The cold storage material particles of the second embodiment are manufactured by subjecting the granulated particles 101 for cold storage material particles of the first embodiment to a heat treatment for degreasing and a heat treatment for sintering. For example, when the granulated particles for cold storage material particles contain a raw material powder of an oxide, the granulated particles for cold storage material particles may be subjected to a heat treatment for sulfurization after the heat treatment for degreasing and before the heat treatment for sintering.

[0126] The degreasing heat treatment is carried out, for example, in an air atmosphere at a temperature of 400° C. to 700° C. The degreasing heat treatment time is, for example, 30 minutes to 6 hours.

[0127] When an oxide is used as the raw material powder 101a of the granulated particles 101 for cold storage material particles to produce cold storage material particles containing oxysulfides, the granulated particles 101 for cold storage material particles are sulfurized. In this case, heat treatment is performed in a sulfurization atmosphere. The sulfurization atmosphere contains a gas containing sulfur atoms with a negative oxidation number, such as hydrogen sulfide (HS), carbon sulfide (CS), or methanethiol (CHSH). The temperature of the sulfurization heat treatment is, for example, 400°C or higher and 600°C or lower. The time of the sulfurization heat treatment is, for example, 1 hour or higher and 5 hours or lower.

[0128] The heat treatment for sintering the degreased granulated particles or the obtained oxysulfide is carried out, for example, in an inert gas atmosphere. The heat treatment temperature is, for example, 1100°C or higher and 2000°C or lower. The heat treatment temperature is, for example, 1200°C or higher and 1800°C or lower. The heat treatment time is, for example, 1 hour or higher and 48 hours or lower.

[0129] When the granulated particles 101 for regenerator particles contain a Group 1 element, a Group 2 element, or an additive element, the sintering temperature can be lowered and the sintering time can be shortened due to the sintering promotion effect. The additive element is at least one element selected from the group consisting of manganese (Mn), aluminum (Al), iron (Fe), copper (Cu), nickel (Ni), cobalt (Co), zirconium (Zr), yttrium (Y), and boron (B).

[0130] The heat treatment for sintering the granulated particles 101 for regenerator particles containing a Group 1 element, a Group 2 element, or an additive element is carried out, for example, in an inert gas atmosphere. The temperature for the sintering heat treatment is, for example, 1000°C or higher and 2000°C or lower. The temperature for the sintering heat treatment is, for example, 1100°C or higher and 1700°C or lower. The time for the sintering heat treatment is, for example, 1 hour or higher and 48 hours or lower.

[0131] The cold storage material particles of the second embodiment are manufactured by sintering the granulated particles 101 for cold storage material particles of the first embodiment. Therefore, for example, the temperature of the degreasing heat treatment or the time of the degreasing heat treatment can be reduced. Furthermore, for example, the temperature of the sulfurizing heat treatment or the time of the sulfurizing heat treatment can be reduced. Furthermore, for example, the temperature of the sintering heat treatment or the time of the sintering heat treatment can be reduced. Therefore, the manufacturing cost of the cold storage material particles of the second embodiment is reduced.

[0132] The cold storage material particles of the second embodiment are produced by sintering the granulated particles 101 for cold storage material particles of the first embodiment. Therefore, for example, organic components are sufficiently removed, the amount of residual carbon contained in the cold storage material particles is reduced, and the thermal conductivity of the cold storage material particles is improved. Therefore, the performance of a refrigerator using the cold storage material particles of the second embodiment is improved.

[0133] The aspect ratio of the cold storage material particles in the second embodiment is preferably, for example, not less than 1 and not more than 5. The aspect ratio of the cold storage material particles is more preferably, for example, not less than 1 and not more than 2. When the aspect ratio of the cold storage material particles is below the upper limit value, the voids become uniform when the cold storage material particles are filled into the cold storage unit, and the refrigeration performance of the refrigerator is improved.

[0134] As described above, according to the second embodiment, it is possible to provide cold storage material particles that can reduce the manufacturing cost.

[0135] (Third embodiment) The regenerator of the third embodiment is a regenerator filled with a plurality of regenerator particles of the second embodiment. For example, when the perimeter of the projected image of the regenerator particles of the second embodiment is L and the actual area of ​​the projected image is A, the regenerator of the third embodiment has a surface area of ​​4πA / L. 2 The ratio of the cold storage material particles having a circularity R of 0.5 or less is 5% or less.

[0136] The circularity R can be determined by image processing of the shapes of multiple cold storage material particles using an optical microscope. Cold storage material particles with a circularity R of 0.5 or less exhibit a shape with irregularities on the surface. When multiple cold storage material particles containing more than 5% of such particles are packed into a cold storage unit, the voids formed by the cold storage material particles become non-uniform within the cold storage unit, resulting in unstable packing. This can lead to a decrease in cold storage performance when the working medium flows in. Furthermore, stresses applied to the cold storage material particles during packing or operation of the refrigerator can cause the cold storage material particles to move or break, generating fine particles that clog the voids, reducing the refrigerator's refrigeration performance and long-term reliability. Preferably, the number of cold storage material particles with a circularity R of 0.5 or less is 2% or less, and even more preferably 0%.

[0137] (Fourth embodiment) The refrigerator of the fourth embodiment is a refrigerator equipped with the regenerator of the third embodiment filled with a plurality of regenerator particles of the second embodiment. Hereinafter, some of the description overlapping with the second and third embodiments will be omitted.

[0138] Fig. 2 is a schematic cross-sectional view showing the main configuration of the regenerator particles of the second embodiment and the refrigerator of the fourth embodiment. Fig. 2 is a schematic cross-sectional view showing the main configuration of a GM refrigerator, which is an example of the refrigerator of the fourth embodiment, including the regenerator of the third embodiment filled with a plurality of regenerator particles of the second embodiment. The refrigerator of the fourth embodiment is a two-stage regenerator-type cryogenic refrigerator 100 used for cooling superconducting equipment, etc. The regenerator filled with a plurality of regenerator particles of the second embodiment may be a Stirling type refrigerator, a pulse tube type refrigerator, or the like, in addition to the GM refrigerator described above.

[0139] The regenerative type cryogenic refrigerator 100 (refrigerator) includes a first cylinder 111, a second cylinder 112, a vacuum container 113, a first regenerator 114, a second regenerator 115 (regenerators), a first seal ring 116, a second seal ring 117, a first regenerator material 118, a second regenerator material 119 (regenerator particles), a first expansion chamber 120, a second expansion chamber 121, a first cooling stage 122, a second cooling stage 123, and a compressor 124.

[0140] The regenerative cryogenic refrigerator 100 has a vacuum vessel 113 in which a large-diameter first cylinder 111 and a small-diameter second cylinder 112 coaxially connected to the first cylinder 111 are installed. A first regenerator 114 is arranged in the first cylinder 111 so as to be able to reciprocate. A second regenerator 115, which is an example of the regenerator of the third embodiment, is arranged in the second cylinder 112 so as to be able to reciprocate.

[0141] A first seal ring 116 is disposed between the first cylinder 111 and the first regenerator 114. A second seal ring 117 is disposed between the second cylinder 112 and the second regenerator 115.

[0142] The first regenerator 114 is filled with a first regenerator material 118 such as a Cu mesh. The second regenerator 115 is filled with a plurality of regenerator particles of the second embodiment as a second regenerator material 119.

[0143] The second regenerator 115 may be divided by a metal mesh material and may have a plurality of regenerator packed layers. When the second regenerator 115 is divided into a plurality of packed layers, at least one packed layer is filled with a regenerator particle group consisting of a plurality of the regenerator particles of the second embodiment, and is combined with at least one type of regenerator particle group selected from, for example, lead regenerator particle group, bismuth regenerator particle group, tin regenerator particle group, holmium copper regenerator particle group, erbium nickel regenerator particle group, erbium cobalt regenerator particle group, and gadolinium aluminum oxide regenerator particle group.

[0144] The combination of the regenerator particles is such that the particle group with the higher peak specific heat temperature is the first regenerator particle group, and the particle group with the lower peak specific heat temperature is the second regenerator particle group, and the combinations are made so that the peak specific heat temperatures decrease sequentially.

[0145] In the case of a two-layer type, a combination of using holmium copper cold accumulator particles as the first cold accumulator particle group and the cold accumulator particle group according to the second embodiment as the second cold accumulator particle group can be exemplified. Also, in the case of a three-layer type, a combination of using at least one cold accumulator particle group selected from lead cold accumulator particle group, bismuth cold accumulator particle group, and tin cold accumulator particle group as the first cold accumulator particle group, holmium copper cold accumulator particle group as the second cold accumulator particle group, and the cold accumulator particle group according to the second embodiment as the third cold accumulator particle group can be exemplified.

[0146] The holmium copper regenerator particles are preferably, for example, HoCu2 or HoCu, and the erbium nickel regenerator particles are preferably, for example, ErNi or Er3Ni.

[0147] The first regenerator 114 and the second regenerator 115 each have a passage for the working medium provided in the gap between the first regenerator material 118 and the second regenerator material 119. The working medium is helium gas.

[0148] A first expansion chamber 120 is provided between the first regenerator 114 and the second regenerator 115. A second expansion chamber 121 is provided between the second regenerator 115 and the front end wall of the second cylinder 112. A first cooling stage 122 is provided at the bottom of the first expansion chamber 120. A second cooling stage 123, which has a lower temperature than the first cooling stage 122, is formed at the bottom of the second expansion chamber 121.

[0149] The two-stage regenerative cryogenic refrigerator 100 described above is supplied with a high-pressure working medium from a compressor 124. The supplied working medium passes between first regenerator materials 118 filled in the first regenerator 114 and reaches the first expansion chamber 120. Then, it passes between second regenerator materials 119 filled in the second regenerator 115 and reaches the second expansion chamber 121.

[0150] At this time, the working medium is cooled by supplying thermal energy to the first cold storage material 118 and the second cold storage material 119. The working medium that has passed between the first cold storage material 118 and the second cold storage material 119 expands in the first expansion chamber 120 and the second expansion chamber 121 to generate cold. Then, the first cooling stage 122 and the second cooling stage 123 are cooled.

[0151] The expanded working medium flows in the opposite direction between the first and second cold storage materials 118 and 119. The working medium is discharged after receiving thermal energy from the first and second cold storage materials 118 and 119. The regenerative cryogenic refrigerator 100 is configured to improve the thermal efficiency of the working medium cycle as the heat recovery effect improves during this process, thereby achieving even lower temperatures.

[0152] The cold storage unit included in the refrigerator of the fourth embodiment has a second cold storage unit 115 filled with a plurality of cold storage particles of the second embodiment as second cold storage material 119. At least a part of the second cold storage material 119 is the cold storage particle of the second embodiment.

[0153] In the second embodiment, when the perimeter of each projected image of the plurality of cold storage material particles is L and the actual area of ​​the projected image is A, the ratio of the perimeter to the actual area of ​​the projected image is 4πA / L 2It is preferable that the circularity R of 0.5 or less is 5% or less.

[0154] To improve the refrigeration capacity of a refrigerator, it is desirable to improve the specific heat per unit volume of the regenerator material and to improve its thermal conductivity and heat transfer coefficient. The refrigerator of the fourth embodiment is equipped with a regenerator material or regenerator particles that maintains the volumetric specific heat and improves its thermal conductivity and heat transfer coefficient.

[0155] By using the refrigerator of the fourth embodiment in a magnetic levitation train, the long-term reliability of the magnetic levitation train can be improved.

[0156] As described above, according to the fourth embodiment, a refrigerator with excellent characteristics can be realized by using regenerator particles with excellent characteristics.

[0157] (Fifth embodiment) The cryopump of the fifth embodiment includes the refrigerator of the fourth embodiment. Hereinafter, some of the description that overlaps with the fourth embodiment will be omitted.

[0158] 3 is a cross-sectional view showing a schematic configuration of a cryopump according to the fifth embodiment. The cryopump according to the fifth embodiment is a cryopump 500 including the regenerative cryogenic refrigerator 100 according to the fourth embodiment.

[0159] The cryopump 500 includes a cryopanel 501 that condenses or adsorbs gas molecules, a regenerative cryogenic refrigerator 100 that cools the cryopanel 501 to a predetermined cryogenic temperature, a shield 503 installed between the cryopanel 501 and the regenerative cryogenic refrigerator 100, a baffle 504 installed at the intake port, and a ring 505 that changes the pumping speed of argon, nitrogen, hydrogen, etc.

[0160] According to the fifth embodiment, a cryopump with excellent characteristics can be realized by using a refrigerator with excellent characteristics. Furthermore, by using the cryopump of the fifth embodiment in semiconductor manufacturing equipment, the long-term reliability of the semiconductor manufacturing equipment can be improved and the number of maintenance cycles for the semiconductor manufacturing equipment can be reduced. As a result, this contributes to improving the quality of the semiconductors manufactured and reducing manufacturing costs.

[0161] (Sixth embodiment) The superconducting magnet of the sixth embodiment includes the refrigerator of the fourth embodiment. Hereinafter, some of the description overlapping with the fourth embodiment will be omitted.

[0162] 4 is a perspective view showing a schematic configuration of a superconducting magnet according to the sixth embodiment. The superconducting magnet according to the sixth embodiment is, for example, a superconducting magnet 600 for a magnetic levitation train, which includes the regenerative cryogenic refrigerator 100 according to the fourth embodiment.

[0163] The superconducting magnet 600 for a magnetic levitation train includes a superconducting coil 601, a liquid helium tank 602 for cooling the superconducting coil 601, a liquid nitrogen tank 603 for preventing the evaporation of the liquid helium, a laminated insulation material 605, a power lead 606, a persistent current switch 607, and a regenerative cryogenic refrigerator 100.

[0164] According to the fifth embodiment, a superconducting magnet with excellent characteristics can be realized by using a refrigerator with excellent characteristics.

[0165] (Seventh embodiment) The nuclear magnetic resonance imaging apparatus of the seventh embodiment includes the refrigerator of the fourth embodiment. Hereinafter, some of the description overlapping with the fourth embodiment will be omitted.

[0166] 5 is a cross-sectional view showing a schematic configuration of a nuclear magnetic resonance imaging apparatus according to the seventh embodiment. The nuclear magnetic resonance imaging (MRI) apparatus according to the seventh embodiment is a nuclear magnetic resonance imaging apparatus 700 equipped with the regenerative cryogenic refrigerator 100 according to the fourth embodiment.

[0167] The nuclear magnetic resonance imaging apparatus 700 includes a superconducting static magnetic field coil 701 that applies a spatially uniform and temporally stable static magnetic field to the human body, a correction coil (not shown) that corrects non-uniformity of the generated magnetic field, a gradient magnetic field coil 702 that applies a magnetic field gradient to the measurement region, a radio frequency wave transmitting / receiving probe 703, a cryostat 705, and a radiation heat insulating shield 706. A regenerative cryogenic refrigerator 100 is used to cool the superconducting static magnetic field coil 701.

[0168] According to the seventh embodiment, a nuclear magnetic resonance imaging apparatus with excellent characteristics can be realized by using a refrigerator with excellent characteristics.

[0169] (Eighth embodiment) The nuclear magnetic resonance apparatus of the eighth embodiment includes the refrigerator of the fourth embodiment. Hereinafter, some of the description overlapping with the fourth embodiment will be omitted.

[0170] 6 is a cross-sectional view showing a schematic configuration of a nuclear magnetic resonance (NMR) apparatus according to the seventh embodiment. The NMR apparatus according to the seventh embodiment is a nuclear magnetic resonance apparatus 800 equipped with the regenerative cryogenic refrigerator 100 according to the third embodiment.

[0171] The nuclear magnetic resonance apparatus 800 includes a superconducting static magnetic field coil 802 that applies a magnetic field to a sample such as an organic substance placed in a sample tube 801, a high-frequency oscillator 803 that applies radio waves to the sample tube 801 in the magnetic field, and an amplifier 804 that amplifies an induced current generated in a coil (not shown) around the sample tube 801. The apparatus also includes a regenerative cryogenic refrigerator 100 that cools the superconducting static magnetic field coil 802.

[0172] According to the eighth embodiment, a nuclear magnetic resonance apparatus with excellent characteristics can be realized by using a refrigerator with excellent characteristics.

[0173] (Ninth embodiment) The magnetic field application type single crystal pulling apparatus of the ninth embodiment includes the refrigerator of the fourth embodiment. Hereinafter, some of the description overlapping with the fourth embodiment will be omitted.

[0174] 7 is a perspective view showing a schematic configuration of a magnetic field application type single crystal pulling apparatus according to the ninth embodiment. The magnetic field application type single crystal pulling apparatus according to the ninth embodiment is a magnetic field application type single crystal pulling apparatus 900 equipped with the regenerative cryogenic refrigerator 100 according to the fourth embodiment.

[0175] The magnetic field application type single crystal pulling apparatus 900 includes a single crystal pulling section 901 having a crucible for melting raw material, a heater, a single crystal pulling mechanism, etc., a superconducting coil 902 for applying a static magnetic field to the raw material melt, a lifting mechanism 903 for the single crystal pulling section 901, a current lead 905, a heat shield plate 906, and a helium container 907. A regenerative cryogenic refrigerator 100 is used to cool the superconducting coil 902.

[0176] According to the ninth embodiment, a magnetic field application type single crystal pulling apparatus with excellent characteristics can be realized by using a refrigerator with excellent characteristics.

[0177] (Tenth embodiment) The helium recondensing device of the tenth embodiment includes the refrigerator of the fourth embodiment. Hereinafter, some of the description overlapping with the fourth embodiment will be omitted.

[0178] 8 is a schematic diagram showing the general configuration of a helium recondensation apparatus according to a tenth embodiment. The helium recondensation apparatus according to the tenth embodiment is a helium recondensation apparatus 1000 equipped with the regenerative cryogenic refrigerator 100 according to the fourth embodiment.

[0179] The helium recondensation device 1000 includes a regenerative cryogenic refrigerator 100 , an evaporation pipe 1001 , and a liquefaction pipe 1002 .

[0180] The helium recondensation device 1000 can recondense helium gas that evaporates from a liquid helium device provided in a device that uses liquid helium, such as a superconducting magnet, a nuclear magnetic resonance (NMR) device, a nuclear magnetic resonance imaging (MRI) device, a physical property measurement system (PPMS), or a magnetic property measurement system, to produce liquid helium.

[0181] Helium gas is introduced into the helium recondenser 1000 from a liquid helium device (not shown) through evaporation piping 1001. The helium gas is cooled to 4 K, which is below the liquefaction temperature of helium, by the regenerative cryogenic refrigerator 100. The condensed and liquefied liquid helium returns to the liquid helium device through liquefaction piping 1002.

[0182] According to the tenth embodiment, a refrigerator with excellent characteristics is used, thereby realizing a helium recondensing device with excellent characteristics. [Example]

[0183] Hereinafter, examples and comparative examples relating to the granulated particles for cold storage material particles of the first embodiment and the cold storage material particles of the second embodiment, and their evaluation results will be described.

[0184] Example 1 Gd2O3 powder was mixed and pulverized in a ball mill for 24 hours to prepare a raw material mixture. The resulting raw material mixture was then dried and granulated using a rolling granulator to prepare granulated particles for use as cold storage material particles with particle sizes of 0.4mm to 0.6mm. Polyvinyl alcohol was used as the binder, and added at 1.2% by weight of the raw material powder. The carbon concentration of the granulated particles for use as cold storage material particles was 0.99% by weight. The relative density of the granulated particles for use as cold storage material particles was 34%.

[0185] To evaluate the strength of the granulated particles for use as cold storage particles, the granulated particles were packed into a cylindrical container with a diameter of 15 mm and a height of 5 mm. At this time, a sufficient amount of granulated particles for use as cold storage particles was packed so that the granulated particles for use as cold storage particles were fixed in the cylindrical container and did not move freely. The container was subjected to an amplitude of 2 mm and a maximum acceleration of 200 m / s. 2 Simple harmonic motion of 1×10 3 As a result, the proportion of broken granulated particles for the cold storage material particles was less than 0.1% by weight.

[0186] The granulated particles for use as cold storage material particles were degreased at 600°C for 2 hours in an air atmosphere. After degreasing, the granulated particles for use as cold storage material particles had a carbon concentration of 0.51% by weight and a relative density of 40%. The granulated particles for use as cold storage material particles were subjected to a heat treatment at 600°C for 2 hours in an atmosphere containing hydrogen sulfide (H2S) to sulfurize the granulated particles. Thereafter, the granulated particles for use as cold storage material particles were sintered by a heat treatment at 1300°C for 12 hours in an inert gas atmosphere to produce cold storage material particles.

[0187] The main component of the regenerator particles of Example 1 is gadolinium oxysulfide.

[0188] In the following examples and comparative examples, the mixing time of the raw material powders, the conditions of the degreasing heat treatment, the conditions of the sulfurizing heat treatment, the conditions of the sintering heat treatment, etc. are adjusted to be appropriate conditions.

[0189] Example 2 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 1, except that a mixture of Gd2O3 powder and Na2CO3 powder was used as the raw material powder.

[0190] Example 3 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 2, except that K2CO3 powder was used instead of Na2CO3 powder.

[0191] Example 4 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 2, except that CaCO3 powder was used instead of Na2CO3 powder.

[0192] Example 5 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 2, except that MgCO3 powder was used instead of Na2CO3 powder.

[0193] Example 6 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 2, except that SrCO3 powder was used instead of Na2CO3 powder.

[0194] Example 7 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 2, except that CaCO3 powder was used in addition to Na2CO3 powder.

[0195] Example 8 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 7, except that MgCO3 powder was used instead of CaCO3 powder.

[0196] Example 9 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 7, except that SrCO3 powder was used instead of CaCO3 powder.

[0197] Example 10 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 1, except that Ho2O3 powder was used instead of Gd2O3 powder.

[0198] Example 11 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 2, except that K2CO3 powder was used in addition to Na2CO3 powder.

[0199] Example 12 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 2, except that K2CO3 powder and CaCO3 powder were used in addition to Na2CO3 powder.

[0200] (Examples 13 to 15) Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 2, except that the weight of the Na2CO3 powder was changed.

[0201] (Examples 16 to 18) Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 7, except that the weight of the CaCO3 powder was changed.

[0202] Example 19 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 2, except that part of the Gd2O3 powder was changed to Ho2O3.

[0203] Example 20 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 1, except that Gd2O2S powder was used instead of Gd2O3 powder and no sulfurization was performed.

[0204] Example 21 Gd2O3 powder was added to a sodium alginate solution and mixed for 24 hours to create a slurry. The weight ratio of the raw powder to the alginate solution was 0.5. The slurry was then added dropwise to a calcium lactate solution, which was used as a gelling solution. A syringe was used to add the slurry.

[0205] The syringe diameter was 510 μm, and the distance from the tip of the syringe to the liquid surface of the calcium lactate aqueous solution was 100 mm. The slurry dropped by the syringe was kept in the gelling solution for 5 hours.

[0206] The gelled granulated particles for use as cold storage material particles were then washed with pure water. After washing, the granulated particles for use as cold storage material particles were dried. The sodium concentration of the granulated particles for use as cold storage material particles was 0.83 atomic %, and the carbon concentration was 0.5 weight %. The relative density of the granulated particles for use as cold storage material particles was 27%. After drying, the granulated particles for use as cold storage material particles were degreased, sulfurized, and sintered.

[0207] The granulated particles for use as cold storage material particles were degreased at 500°C for 2 hours in an air atmosphere. After degreasing, the sodium concentration of the granulated particles for use as cold storage material particles was 1.0 atomic %, the carbon concentration was 0.25 wt %, and the relative density was 30%. After degreasing, the granulated particles for use as cold storage material particles were sulfurized by heat treatment at 600°C for 2 hours in an atmosphere containing hydrogen sulfide (H2S). The granulated particles for use as cold storage material particles were sintered by heat treatment at 1300°C for 12 hours in an inert gas atmosphere to produce cold storage material particles.

[0208] The main component of the regenerator particles of Example 21 was gadolinium oxysulfide. The sodium concentration in the regenerator particles of Example 21 was 1.1 atomic %.

[0209] Examples 22 to 24 Granulated particles for ice accumulator particles and ice accumulator particles were produced in the same manner as in Example 21, except that the relative density of the granulated particles for ice accumulator particles was changed by changing the ratio of raw material powder to sodium alginate aqueous solution, and sodium and calcium were removed by changing the washing time and number of times.

[0210] (Examples 25 to 26) Granulated particles for ice accumulator particles and ice accumulator particles were produced in the same manner as in Example 21, except that the concentration of the sodium alginate aqueous solution was changed to change the concentration of carbon contained in the granulated particles for ice accumulator particles, and the washing time was adjusted.

[0211] Example 27 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 21, except that an aqueous magnesium chloride solution was used instead of an aqueous calcium lactate solution.

[0212] Example 28 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 21, except that an aqueous strontium chloride solution was used instead of the aqueous calcium lactate solution.

[0213] Example 29 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 21, except that an air pulse dispenser was used instead of a syringe as the method for dropping the slurry. The nozzle diameter was 510 μm, and the distance from the tip of the nozzle to the liquid surface of the calcium lactate aqueous solution was 100 mm.

[0214] Example 30 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 21, except that a piezoelectric dispenser was used instead of a syringe to drop the slurry. The nozzle diameter was 510 μm, and the distance from the tip of the nozzle to the liquid surface of the calcium lactate aqueous solution was 100 mm.

[0215] Example 31 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 21, except that a continuous ink jet was used instead of a syringe as a method for dropping the slurry.

[0216] Examples 32 to 37 The granulated particles for cold storage material particles and the cold storage material particles of Examples 32 to 37 differ in particle size or aspect ratio from the granulated particles for cold storage material particles and the cold storage material particles of Example 21. When producing the granulated particles for cold storage material particles of Examples 32 to 37, the diameter of the syringe and the distance from the tip of the syringe to the surface of the gelling solution were changed compared to when producing the granulated particles for cold storage material particles of Example 21.

[0217] Example 38 Granulated particles for ice accumulator particles and ice accumulator particles were produced in the same manner as in Example 21, except that the relative density was set to 11% by changing the ratio of raw material powder to sodium alginate aqueous solution, and only calcium was removed by changing the soaking time, washing time and number of times.

[0218] Example 39 Granulated particles for ice accumulator particles and ice accumulator particles were produced in the same manner as in Example 21, except that the relative density was set to 11% by changing the ratio of raw material powder to sodium alginate aqueous solution, and only sodium was removed by changing the soaking time, washing time and number of times.

[0219] Example 40 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 22, except that Al2O3 powder was also used as the raw material powder. The Al2O3 powder was added so that the Al content in the cold storage material particles was 15 atomic %.

[0220] Example 41 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 38, except that Al2O3 powder was also used as the raw material powder. The Al2O3 powder was added so that the Al content in the cold storage material particles was 15 atomic %.

[0221] Example 42 Granulated particles for cold storage material particles and cold storage material particles were manufactured in the same manner as in Example 21, except that the relative density was set to 11% by changing the ratio of the raw material powder and the sodium alginate aqueous solution, and Al2O3 powder was also used as the raw material powder. The Al2O3 powder was added so that the Al contained in the cold storage material particles was 15 atomic %.

[0222] Example 43 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 21, except that the ratio of the raw material powder to the sodium alginate aqueous solution was changed to make the relative density 11%, and that an aluminum chloride aqueous solution was used instead of a calcium lactate aqueous solution. Al was added so that the amount contained in the cold storage material particles was 0.01 atomic %.

[0223] Example 44 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 21, except that the ratio of the raw material powder to the sodium alginate aqueous solution was changed to make the relative density 11%, and that an aluminum chloride aqueous solution was used in addition to the calcium lactate aqueous solution. Al was added so that the amount contained in the cold storage material particles was 0.01 atomic %.

[0224] Example 45 Granulated particles for cold storage material particles and cold storage material particles were produced in the same manner as in Example 21, except that the ratio of the raw material powder to the sodium alginate aqueous solution was changed to make the relative density 11%, and that an aluminum chloride aqueous solution was used in addition to the calcium lactate aqueous solution. Al was added so that the amount contained in the cold storage material particles was 20 atomic %. Example 46 Granulated particles for cold storage material particles and cold storage material particles were manufactured in the same manner as in Example 1, except that GdO powder and AlO powder were used as raw material powders and heat treatment was not performed in an atmosphere containing hydrogen sulfide (H2S). The main component of the cold storage material particles was GdAlO3.

[0225] Example 47 Granulated particles for cold storage material particles and cold storage material particles were manufactured in the same manner as in Example 2, except that GdO powder and AlO powder were used as raw material powders and heat treatment was not performed in an atmosphere containing hydrogen sulfide (H2S). The main component was GdAlO3.

[0226] Example 48 Granulated particles for cold storage material particles and cold storage material particles were manufactured in the same manner as in Example 21, except that GdO powder and AlO powder were used as raw material powders and heat treatment was not performed in an atmosphere containing hydrogen sulfide (H2S). The main component was GdAlO3.

[0227] (Comparative Example 1) The granulated particles for cold storage material particles of Comparative Example 1 differ from the granulated particles for cold storage material particles of Example 21 in that the relative density is as low as 9%. When producing the granulated particles for cold storage material particles of Comparative Example 1 and the cold storage material particles, the amount of raw material powder was reduced compared to when producing the granulated particles for cold storage material particles of Example 21.

[0228] (Comparative Example 2) The granulated particles for cold storage material particles of Comparative Example 2 differ from the granulated particles for cold storage material particles of Example 21 in that the relative density is as high as 51%. When producing the granulated particles for cold storage material particles of Comparative Example 2, the weight of the raw material powder was increased compared to when producing the granulated particles for cold storage material particles of Example 21.

[0229] (Comparative Example 3) The granulated particles for cold storage material particles of Comparative Example 3 differ from the granulated particles for cold storage material particles of Example 21 in that the carbon concentration is as low as 0.0004 wt%. When producing the granulated particles for cold storage material particles of Comparative Example 3, the concentration of the sodium alginate aqueous solution was reduced compared to when producing the granulated particles for cold storage material particles of Example 21.

[0230] Comparative Example 4 The granulated particles for cold storage material particles of Comparative Example 4 differ from the granulated particles for cold storage material particles of Example 21 in that the carbon concentration is as high as 51% by weight. When producing the granulated particles for cold storage material particles of Comparative Example 4, the concentration of the sodium alginate aqueous solution was increased compared to when producing the granulated particles for cold storage material particles of Example 21.

[0231] (Comparative Example 5) The granulated particles for cold storage material particles and the cold storage material particles of Comparative Example 5 differ from those of Example 41 in that the Al content in the cold storage material particles is as high as 65 atomic %. When producing the granulated particles for cold storage material particles and the cold storage material particles of Comparative Example 5, the weight of Al2O3 powder was increased compared to when producing the granulated particles for cold storage material particles and the cold storage material particles of Example 41.

[0232] The strength of the granulated particles for cold storage material particles and the relative density and specific heat of the cold storage material particles were measured for the granulated particles for cold storage material particles and the cold storage material particles according to each of the Examples and Comparative Examples. The results are shown in Tables 1, 2, and 3. In Table 1, the granulated particles for cold storage material particles are referred to as "granulated particles," and the cold storage material particles produced from the granulated particles for cold storage material particles are referred to as "cold storage material particles."

[0233] [Table 1]

[0234] [Table 2]

[0235] [Table 3]

[0236] When the relative density of the granulated particles for use as cold storage material particles is less than 10%, as in Comparative Example 1, the granulated particles cannot be recovered as spherical particles. This is thought to be because when the relative density is less than 10%, the granulated particles for use as cold storage material particles contain a large proportion of voids, which significantly reduces the strength of the granulated particles for use as cold storage material particles.

[0237] When the relative density of the granulated particles for cold storage material particles exceeded 50% as in Comparative Example 2, the relative density of the produced cold storage material particles decreased significantly, and the specific heat also decreased significantly. This is thought to be because when the relative density of the granulated particles for cold storage material particles exceeded 50%, the organic components contained in the granulated particles for cold storage material particles could not be sufficiently removed, impairing the sinterability of the cold storage material particles.

[0238] The results of Comparative Example 3 show that when the carbon concentration of the granulated particles for cold storage material particles is less than 0.001% by weight, the strength of the granulated particles for cold storage material particles decreases, and therefore the granulated particles for cold storage material particles are easily broken during handling, resulting in a significant decrease in yield.

[0239] The results of Comparative Example 4 show that when the carbon concentration of the granulated particles for the cold storage material particles exceeds 50 wt%, the relative density of the sintered cold storage material particles drops significantly, and the specific heat also drops significantly. This is thought to be because the organic components contained in the granulated particles could not be sufficiently removed, leaving a large amount of carbon remaining, which impaired the sinterability of the cold storage material particles.

[0240] From Examples 22 to 24, it can be seen that when no Group 1 element or Group 2 element is contained, the relative density of the cold storage material particles is improved and the specific heat is also improved when the relative density is 15% or more and 50% or less, compared to when the relative density is 10% or more and 15% or less. This is thought to be because when the relative density is too low, the number of contact points between the raw material powders decreases, and the sinterability of the cold storage material particles decreases.

[0241] From Examples 38 and 39, it can be seen that when a Group 1 element or a Group 2 element is contained, the relative density of the regenerator particles is improved and the specific heat is also improved even if the relative density is 10% or more and 15% or less. This is thought to be due to the sintering promoting effect of the Group 1 element and the Group 2 element.

[0242] As shown in Examples 40 to 45, even when the relative density is 10% or more and 15% or less, the inclusion of a sintering aid improves the relative density of the sintered particles. This is thought to be due to the sintering-promoting effect of the sintering aid. When the relative density is less than 10%, the relative density of the regenerator particles decreases even when a sintering aid is included, and the specific heat also decreases.

[0243] From the results of Comparative Example 5, it can be seen that when the atomic concentration of the added element derived from the sintering aid is large, exceeding 60 atomic %, the specific heat of the regenerator particles decreases.

[0244] As shown in Examples 46 to 48, by not performing heat treatment in a hydrogen sulfide atmosphere, even if the main component of the regenerator particles is GdAlO3, as long as the relative density of the granulated particles for the regenerator particles is 10% or more and 50% or less, it can be seen that the same effect as when the main component is gadolinium oxysulfide is exhibited.

[0245] From the above examples, the effects achieved by the granulated particles for cold storage material particles of the first embodiment and the cold storage material particles of the second embodiment were confirmed.

[0246] Although the dispenser has been described as an air pulse dispenser or a piezo dispenser, a plunger dispenser may also be used.

[0247] Although the description has been given taking a continuous type inkjet as an example of the inkjet, an on-demand type inkjet may also be used.

[0248] 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]

[0249] 100 Regenerative cryogenic refrigerator (refrigerator) 101 Granulated particles for cold storage material particles 115 Second regenerator (regenerator) 119 Second cold storage material (cold storage material particles) 500 Cryopump 600 Superconducting Magnet 700 Nuclear Magnetic Resonance Imaging Device 800 Nuclear Magnetic Resonance Spectrometer 900 Magnetic Field Application Type Single Crystal Pulling Apparatus 1000 Helium Recondenser

Claims

1. A raw material powder containing a rare earth oxysulfide containing at least one rare earth element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, or a raw material powder containing a rare earth oxide containing the at least one rare earth element, is mixed with a binder containing 0.01 wt % to 40 wt % of an organic substance to obtain a raw material mixture; A method for producing granulated particles for use as cold storage material particles, in which the raw material mixture is granulated by a rolling granulation method, an agitation granulation method, an extrusion method, a spraying method, or a press molding method, The carbon concentration of the granulated particles for the cold storage material particles is 0.001% by weight or more and 50% by weight or less, The method for producing granulated particles for use as cold storage material particles, wherein the granulated particles for use as cold storage material particles have a relative density of 10% or more and 50% or less.

2. A raw material powder containing a rare earth oxysulfide containing at least one rare earth element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, or a raw material powder containing a rare earth oxide containing the at least one rare earth element, is mixed with a dispersion medium containing an organic substance to prepare a slurry; A method for producing granulated particles for use as cold storage material particles, comprising dropping the slurry into a gelling solution to cause gelation and granulation, a weight ratio of the raw material powder to the dispersion medium is 0.1 times or more and 20 times or less; The carbon concentration of the granulated particles for the cold storage material particles is 0.001% by weight or more and 50% by weight or less, The method for producing granulated particles for use as cold storage material particles, wherein the granulated particles for use as cold storage material particles have a relative density of 10% or more and 50% or less.

3. 3. The method for producing granulated particles for use as cold storage material particles according to claim 1, wherein the particle size is 50 μm or more and 7 mm or less.

4. 3. The method for producing granulated particles for use as cold storage material particles according to claim 1, wherein the aspect ratio is 1 or more and 5 or less.

5. 3. The method for producing granulated particles for use as regenerator particles according to claim 1, further comprising a Group 1 element in a concentration of 0.001 atomic % to 60 atomic %.

6. 6. The method for producing granulated particles for use as regenerator particles according to claim 5, wherein the first group element is at least one element selected from the group consisting of Li, Na, and K.

7. 3. The method for producing granulated particles for use as regenerator particles according to claim 1, further comprising a Group II element in a concentration of 0.001 atomic % to 60 atomic %.

8. 8. The method for producing granulated particles for use as regenerator particles according to claim 7, wherein the Group II element is at least one element selected from the group consisting of Mg, Ca, Sr, and Ba.

9. 3. The method for producing granulated particles for use in regenerator particles according to claim 1 or 2, further comprising an additive element having a concentration of 0.001 atomic % or more and 60 atomic % or less, the additive element being at least one element selected from the group consisting of Mn, Al, Fe, Cu, Ni, Co, Zr, Y, and B.

10. The method for producing granulated particles for use as cold storage material particles according to claim 2, which is a gel.

11. A method for producing cold storage particles, which is obtained by sintering granulated particles for cold storage particles produced by the method for producing granulated particles for cold storage particles according to claim 1 or 2.

12. The maximum volumetric specific heat in the temperature range of 2K to 10K is 0.5J / (cm ３ The method for producing regenerator particles according to claim 11, wherein the temperature is 0.5-1.5°C.

13. The method for producing cold storage material particles according to claim 11, wherein the particle size is 50 μm or more and 5 mm or less.

14. The method for producing regenerator particles according to claim 11, wherein the aspect ratio is 1 or more and 5 or less.

15. A method for manufacturing a regenerator, comprising filling a plurality of regenerator particles manufactured by the method for manufacturing regenerator particles according to claim 11.

16. A method for manufacturing a refrigerator, comprising: a regenerator manufactured by the method for manufacturing a regenerator according to claim 15.

17. A method for manufacturing a cryopump, comprising: a refrigerator manufactured by the method for manufacturing a refrigerator according to claim 16.

18. A method for manufacturing a superconducting magnet, comprising: a refrigerator manufactured by the method for manufacturing a refrigerator according to claim 16.

19. A method for manufacturing a nuclear magnetic resonance imaging apparatus, comprising a refrigerator manufactured by the method for manufacturing a refrigerator according to claim 16.

20. A method for manufacturing a nuclear magnetic resonance apparatus, comprising: a refrigerator manufactured by the method for manufacturing a refrigerator according to claim 16.

21. A method for manufacturing a magnetic field application type single crystal pulling apparatus, comprising a refrigerator manufactured by the method for manufacturing a refrigerator according to claim 16.

22. A method for manufacturing a helium recondensing device, comprising: a refrigerator manufactured by the method for manufacturing a refrigerator according to claim 16.

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