Method for producing spherical glass particles and apparatus for producing spherical glass particles

Abstract

To provide a method for producing spherical glass particles that is capable of suppressing the occurrence of clogging in a dispersion nozzle and the generation of coarse spherical glass particles.SOLUTION: There is provided a method for producing spherical glass particles which have non-spherical glass particles as the main raw material, the method comprising a dispersion step S41 for disintegrating, via a disperser 3, aggregated particles which include aggregated non-spherical glass particles, and a spheroidizing step S42 for further disintegrating, via a dispersion nozzle 50, the aggregated particles disintegrated in the dispersion step S41 and then spheroidizing, by heating, non-spherical glass particles ejected from the dispersion nozzle 50, wherein the disperser 3 is provided with a first disperser 30 which coarsely disintegrates the aggregated particles and a second disperser 40 which is positioned downstream of the first disperser 30 in the moving direction of the aggregated particles and which finely disintegrates the aggregated particles coarsely disintegrated via the first disperser 30.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method and an apparatus for producing spherical glass particles. [Background technology]

[0002] Conventionally, resin compositions containing glass particles in a curable resin are known. One example of a resin composition containing glass particles in a curable resin is a dental composition. In the glass particles of such a resin composition, glass particles formed into small spherical particles are desired, which can provide good physical properties.

[0003] Therefore, in the past, as described in Patent Document 1, agglomerated particles including agglomerated non-spherical glass particles were passed through a dispersion nozzle to break up the agglomerated particles, and the non-spherical glass particles were sprayed from the dispersion nozzle, and the non-spherical glass particles sprayed from the dispersion nozzle were heated to spheroidize the non-spherical glass particles, thereby producing spherical glass particles. In this case, the dispersion nozzle was formed as a collision type dispersion nozzle that breaks up the agglomerated particles by causing them to collide with a collision member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2023 / 074234 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, when spherical glass particles are produced by disintegrating aggregated particles with a dispersion nozzle and heating them, the aggregation of non-spherical glass particles becomes significant as the particle size of the spherical glass particles to be obtained becomes smaller. In particular, when the spherical glass particles to be produced have a small Dmax of 2 μm or less, the aggregation becomes significant. Here, the maximum particle diameter Dmax refers to the value measured by a laser diffraction device, and represents the particle diameter at which the cumulative amount is maximum when the cumulative amount is accumulated from the smallest particle in the cumulative particle size distribution curve measured by the laser diffraction method. In addition, the average particle diameter D50 described later refers to the value measured by a laser diffraction device, and represents the particle diameter at which the cumulative amount is 50% when the cumulative amount is accumulated from the smallest particle in the cumulative particle size distribution curve measured by the laser diffraction method.

[0006] As a result, the dispersion nozzle may become clogged with agglomerated particles colliding with the collision member, or a plurality of non-spherical glass particles may be heated in a state in which they are adhered to each other, resulting in the production of coarse spherical glass particles. [Means for solving the problem]

[0007] The inventors of the present invention have found, through extensive research, that the reason why the aggregation of the non-spherical glass particles becomes significant is because the aggregation force of the non-spherical glass particles disintegrated by the dispersion nozzle is large. That is, when producing spherical glass particles, the inventors have found that the above-mentioned problem can be solved by disintegrating the aggregated particles in advance by a plurality of dispersers before disintegrating them by the dispersion nozzle, thereby preventing clogging of the dispersion nozzle and generation of coarse spherical glass particles. The method and apparatus for producing spherical glass particles of the present invention have the following features.

[0008] The method for producing spherical glass particles is a method for producing spherical glass particles using non-spherical glass particles as a main raw material, and includes a dispersion step of disintegrating agglomerated particles containing the agglomerated non-spherical glass particles using a disperser, and a spheronization step of further disintegrating the agglomerated particles disintegrated in the dispersion step using a dispersion nozzle, and then heating the non-spherical glass particles sprayed from the dispersion nozzle to spheroidize them, wherein the disperser has a first disperser that roughly disintegrates the agglomerated particles, and a second disperser that is located downstream of the first disperser in the direction of movement of the agglomerated particles and finely disintegrates the agglomerated particles roughly disintegrated by the first disperser.

[0009] As a result, the agglomerated particles to be disintegrated by the dispersion nozzle are effectively disintegrated in advance by the first disperser and the second disperser, so that even if the spherical glass particles to be produced are small in particle size, with a Dmax of 2 μm or less, it is possible to prevent the dispersion nozzle from being clogged or coarse spherical glass particles from being produced.

[0010] The dispersion nozzle is an orifice type disperser having an orifice in a flow path through which the aggregated particles move.

[0011] This makes it possible to prevent the dispersion nozzle from being blocked by aggregated particles passing through the dispersion nozzle.

[0012] The method further includes a crushing step, which is performed before the dispersing step, of wet-crushing the raw glass to generate the non-spherical glass particles.

[0013] If the agglomerated particles to be disintegrated in the dispersion step are wet-milled in a step prior to the dispersion step, they are likely to agglomerate significantly in the drying step following the wet-milling. However, by disintegrating the agglomerated particles using the first and second dispersers in the dispersion step, the agglomerated particles can be effectively disintegrated.

[0014] The raw glass also contains at least one component of B2O3 and R2O (R represents lithium (Li), sodium (Na), and potassium (K)).

[0015] In this case, during the wet grinding process, the B (B is boron) and R components in the glass are dissolved from the raw glass by the solvent (water, alcohol, etc.), and adhere to the surface of the non-spherical glass particles produced, making them sticky. The non-spherical glass particles with sticky surfaces tend to aggregate significantly, but the agglomerated particles containing the agglomerated non-spherical glass particles can be effectively disintegrated by crushing them using the first and second dispersers in the dispersion process.

[0016] The total content of B2O3 and R2O in the raw glass is 5 mass % or more.

[0017] In this case, the stickiness that occurs on the surfaces of the non-spherical glass particles tends to increase, and the non-spherical glass particles with sticky surfaces tend to aggregate significantly. However, the aggregated particles including the aggregated non-spherical glass particles can be effectively disintegrated by disintegrating them using the first and second dispersers in the dispersion step.

[0018] Moreover, the first disperser is a rotary type disperser having a rotating first disk, and the second disperser is a rotary type disperser having a rotating second disk.

[0019] This allows the first disperser and the second disperser to effectively break down aggregated particles by the rotating first disk and the second disk, respectively.

[0020] In addition, a carrier fluid flows into the first disperser from the outside, and the flow path through which the carrier fluid flows from the first disperser to the second disperser extends in a tangential direction from the first disperser to the outer periphery of the first disk, in the opposite direction to the rotation direction of the first disk, and the flow path through which the carrier fluid flows from the second disperser to the dispersion nozzle extends in a tangential direction from the second disperser to the outer periphery of the second disk, in the opposite direction to the rotation direction of the second disk.

[0021] With this configuration, the large aggregated particles in the first and second dispersers remain in the first and second dispersers along the rotation of the first and second disks. Meanwhile, the aggregated particles that have been sufficiently disintegrated and reduced in size in the first disperser move in the flow path from the first disperser to the second disperser along the flow of the carrier fluid, and the aggregated particles that have been sufficiently disintegrated and reduced in size in the second disperser move in the flow path from the second disperser to the dispersion nozzle along the flow of the carrier fluid. This allows only the aggregated particles that have been sufficiently disintegrated and reduced in size in the disperser to be transported to the dispersion nozzle.

[0022] The first disperser is a pin-type disperser in which cylindrical pins protrude from the plate surface of the first disc, which is formed in a circular shape, and the second disperser is a block-type disperser in which rectangular blocks protrude from the plate surface of the second disc, which is formed in a circular shape.

[0023] As a result, the second disperser has a greater disintegrating power than the first disperser, and the agglomerated particles can be roughly disintegrated by the first disperser and then finely disintegrated by the second disperser, thereby effectively disintegrating the agglomerated particles.

[0024] The apparatus for manufacturing spherical glass particles includes a storage section for storing agglomerated particles including agglomerated non-spherical glass particles, a feeder connected to the storage section for transporting the agglomerated particles stored in the storage section, a disperser connected to the feeder for disintegrating the agglomerated particles transported by the feeder, a dispersion nozzle connected to the disperser for further disintegrating the agglomerated particles disintegrated by the disperser and then spraying the agglomerated particles, and a burner nozzle for heating the non-spherical glass particles sprayed from the dispersion nozzle. The disperser includes a first disperser for roughly disintegrating the agglomerated particles, and a second disperser located downstream of the first disperser in the direction of movement of the agglomerated particles for finely disintegrating the agglomerated particles roughly disintegrated by the first disperser.

[0025] As a result, the agglomerated particles to be disintegrated by the dispersion nozzle are effectively disintegrated in advance by the first disperser and the second disperser, so that even if the spherical glass particles to be produced are small in particle size, with a Dmax of 2 μm or less, it is possible to prevent the dispersion nozzle from being clogged or coarse spherical glass particles from being produced.

[0026] The dispersion nozzle is an orifice type disperser having an orifice in a flow path through which the aggregated particles move.

[0027] This makes it possible to prevent the dispersion nozzle from being blocked by aggregated particles passing through the dispersion nozzle.

[0028] Moreover, the first disperser is a rotary type disperser having a rotating first disk, and the second disperser is a rotary type disperser having a rotating second disk.

[0029] This allows the first disperser and the second disperser to effectively break down aggregated particles by the rotating first disk and the second disk, respectively.

[0030] The first disperser is a pin-type disperser in which cylindrical pins protrude from the plate surface of the first disc, which is formed in a circular shape, and the second disperser is a block-type disperser in which rectangular blocks protrude from the plate surface of the second disc, which is formed in a circular shape.

[0031] As a result, the second disperser has a greater disintegrating power than the first disperser, and the agglomerated particles can be roughly disintegrated by the first disperser and then finely disintegrated by the second disperser, thereby effectively disintegrating the agglomerated particles. Effect of the Invention

[0032] According to the present invention, even if the spherical glass particles to be produced are small in particle size with a Dmax of 2 μm or less, it is possible to prevent clogging of the dispersion nozzle and generation of coarse spherical glass particles. [Brief description of the drawings]

[0033] [Figure 1] FIG. 2 is a diagram showing a flow of a method for producing spherical glass particles. [Diagram 2] FIG. 2 is a schematic diagram showing a manufacturing apparatus for spherical glass particles. [Diagram 3] FIG. 2(a) is a perspective view showing a first rotating disk and a first fixed disk of a first dispersing machine, and (b) is a perspective view showing the first rotating disk and the first fixed disk covered by a housing. [Figure 4] FIG. 2 is a partial cross-sectional side view showing a first rotating disk and a first fixed disk of the first disperser. [Diagram 5] FIG. 2(a) is a perspective view showing a second rotating disk and a second fixed disk of a second dispersing machine, and (b) is a perspective view showing the second rotating disk and the second fixed disk covered by a housing. [Figure 6] FIG. 4 is a partial cross-sectional side view showing a second rotating disk and a second fixed disk of the second disperser. [Figure 7] FIG. 2 is a plan view showing a disperser, a first transport path, a second transport path, and a third transport path. [Figure 8] FIG. 2 is a side cross-sectional view showing the burner. [Figure 9] FIG. 2 is a front view showing the tip of the burner. [Figure 10] FIG. 2 is a diagram showing a flow of a dispersion and spheroidization step in the method for producing spherical glass particles. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] Next, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0035] [Outline of manufacturing method for spherical glass particles] A method for producing spherical glass particles, including a method for producing spherical glass particles according to the present invention, will now be described.

[0036] As shown in FIG. 1, the method for producing spherical glass particles includes a melting step S01, a coarse pulverizing step S02, a wet pulverizing step S03, a dispersion and spheroidizing step S04, and a classification step S05.

[0037] In the melting step S01, a glass raw material is melted to generate a molten glass liquid, and the generated molten glass liquid is used to form a raw glass material into any shape, such as a plate, a film, an ingot, or a fiber.

[0038] The coarse crushing step S02 is carried out after the melting step S01, and is a step in which the raw glass formed in the melting step S01 is coarsely crushed by a ball mill, a jet mill, a media stirring mill, a vibration mill, etc. to obtain non-spherical glass particles. The non-spherical glass particles are glass particles in a crushed form, and have a shape with corners and / or points.

[0039] The wet grinding step S03 is carried out after the coarse grinding step S02, and is a step in which the non-spherical glass particles obtained in the coarse grinding step S02 are finely ground by wet grinding to obtain non-spherical glass particles having a smaller diameter. Wet grinding is a grinding method in which a powder is mixed with a solvent and ground in a slurried state. Wet grinding makes it easier to finely grind non-spherical glass particles than dry grinding, and also makes it possible to narrow the width of the particle size distribution.

[0040] Since the method for producing spherical glass particles uses fine non-spherical glass particles as a raw material to produce spherical glass particles having a fine diameter, it is preferable to finely pulverize the raw glass in the coarse pulverization step S02 and the wet pulverization step S03. Note that in the coarse pulverization step S02 and the wet pulverization step S03, the non-spherical glass particles unintentionally aggregate to obtain aggregated particles.

[0041] The dispersion and spheroidization step S04 is carried out after the wet-pulverization step S03. The dispersion and spheroidization step S04 is a step of crushing the agglomerated particles obtained in the wet-pulverization step S03 and heating the crushed non-spherical glass particles to obtain spherical glass particles.

[0042] In particular, since the non-spherical glass particles obtained by wet grinding in the wet grinding step S03 tend to aggregate, in the dispersion-spheroidization step S04, the aggregated particles are roughly crushed by a first dispersing machine, and then finely crushed by a second dispersing machine, thereby enabling effective disintegration.

[0043] The classification step S05 is carried out after the dispersion-spheroidization step S04, and is a step of collecting and classifying the spherical glass particles obtained in the dispersion-spheroidization step S04. The collection of the spherical glass particles can be carried out by a combination of wet collection and dry collection, or can be carried out only by wet collection. This is because it is difficult to collect spherical glass particles with a Dmax of 2 μm or less with high efficiency by dry collection alone.

[0044] The dispersion and spheroidization step S04 includes a dispersion step S41 and a spheroidization step S42. Sublimates generated when the spherical glass particles are heated in the spheroidization step S42 adhere to the surfaces of the spherical glass particles, but by performing wet collection, it is possible to remove the sublimates adhered to the surfaces of the spherical glass particles, and spherical glass particles with good surface conditions can be obtained. In this case, since the wet collection is performed immediately after the spherical glass particles are generated, it is possible to remove the sublimates from the surfaces of the spherical glass particles before they adhere to the surfaces of the spherical glass particles, and the removal rate of the sublimates can be increased.

[0045] The classification step S05 is a step performed after the spherical glass particles are collected, and is a step for removing coarse particles of spherical glass particles having a size larger than a required particle size from the collected spherical glass particles. In the classification step S05, for example, spherical glass particles having a Dmax exceeding 2 μm can be removed.

[0046] The spherical glass particles thus produced may be surface-treated with a silane coupling agent, if necessary, to improve the wettability at the interface with the resin and the dispersibility when blended into the resin. Examples of the silane coupling agent include aminosilane, epoxysilane, methacrylsilane, ureidosilane, isocyanatesilane, etc.

[0047] [Spherical glass particle manufacturing equipment] Next, a manufacturing apparatus for spherical glass particles used in carrying out the wet grinding step S03 and the dispersion-spheroidizing step S04 constituting the manufacturing method for spherical glass particles will be described. The manufacturing apparatus 1 for spherical glass particles shown in Fig. 2 includes a storage section 10, a feeder 20, a dispersing machine 3, a burner 5, a carrier fluid supply source 81, an oxygen supply source 82, and a fuel supply source 83.

[0048] (Storage section) The storage unit 10 is a tank for storing non-spherical glass particles, which are the main raw material of the spherical glass particles. The non-spherical glass particles are obtained by coarsely crushing the raw glass formed in the melting step S01 with a crusher 91 in a coarse crushing step S02, and then finely crushing the raw glass with a wet crusher 92 in a wet crushing step S03.

[0049] The non-spherical glass particles are aggregated inside the storage section 10. The aggregation of the non-spherical glass particles is not intentional, but occurs due to interactions between the non-spherical glass particles. The non-spherical glass particles stored in the storage section 10 are subject to wet pulverization in a previous process, and therefore aggregation becomes prominent.

[0050] In the following description, aggregates containing secondary particles formed by agglomeration of non-spherical glass particles, which are primary particles, are also referred to as aggregate particles. The aggregate particles may contain non-aggregated primary particles in addition to secondary particles, or may contain higher-order particles formed by further agglomeration of secondary particles. The proportion of secondary particles in the aggregate particles may be less than the proportion of primary particles in the aggregate particles.

[0051] (feeder) Feeder 20 is connected to storage section 10. Feeder 20 transports the aggregated particles stored in storage section 10 toward disperser 3. It is preferable that feeder 20 is capable of adjusting the amount of aggregated particles transported per unit time.

[0052] (dispersion machine) The disperser 3 has a first disperser 30 and a second disperser 40. The first disperser 30 is connected to the feeder 20 by a first transport path 71, and the aggregated particles transported by the feeder 20 are supplied to the first disperser 30 through the first transport path 71.

[0053] The first disperser 30 roughly disintegrates the agglomerated particles supplied from the storage section 10. The agglomerated particles roughly disintegrated by the first disperser 30 are transported to the second disperser 40, where they are finely disintegrated. The degree of agglomeration of the agglomerated particles finely disintegrated by the second disperser 40 is smaller than the degree of agglomeration of the agglomerated particles roughly disintegrated by the first disperser 30.

[0054] The second disperser 40 is located downstream of the first disperser 30 in the moving direction of the aggregated particles, and the first disperser 30 and the second disperser 40 are connected by a second conveying path 72. The second disperser 40 is connected to the burner 5 by a third conveying path 73.

[0055] The carrier fluid supply source 81 is connected to the first disperser 30 by the first air supply passage 74, and the carrier fluid sent out from the carrier fluid supply source 81 is supplied to the first disperser 30 through the first air supply passage 74. The carrier fluid supply source 81 is connected to the second disperser 40 by the second air supply passage 75, and the carrier fluid sent out from the carrier fluid supply source 81 is supplied to the second disperser 40 through the second air supply passage 75. The carrier fluid is a gas or medium having a flowability capable of transporting the aggregated particles in a suspended state, and as the carrier fluid, for example, air can be used.

[0056] (1st disperser) As shown in Figs. 2 to 4, the first disperser 30 is a rotary disperser having a rotating first rotating disk 31. The first rotating disk 31 is an example of a rotating first disk. The first disperser 30 has the first rotating disk 31, a first fixed disk 32 disposed opposite the first rotating disk 31, and a first housing 33 that covers the first rotating disk 31 and the first fixed disk 32. The first rotating disk 31 and the first fixed disk 32 are formed in a disk shape.

[0057] The first rotating disk 31 has a plurality of rotating-side pins 311 protruding from a plate surface facing the first fixed disk 32. The first fixed disk 32 has a plurality of fixed-side pins 321 protruding from a plate surface facing the first rotating disk 31. The rotating-side pins 311 and the fixed-side pins 321 are cylindrical pins. The rotating-side pins 311 and the fixed-side pins 321 are alternately arranged with a gap therebetween in the radial direction.

[0058] The first disperser 30 is a pin-type disperser in which a cylindrical rotating side pin 311 and a cylindrical fixed side pin 321 protrude from the plate surfaces of a first rotating disk 31 and a first fixed disk 32, which are formed in a disk shape.

[0059] A supply hole 332 is formed in the surface of the first housing 33 facing the first fixed disk 32, penetrating in the direction of the rotation axis. A supply hole 322 is formed in the center of the first fixed disk 32, penetrating in the direction of the rotation axis. The supply hole 332 of the first housing 33 is connected to the first conveying path 71, and the supply hole 332 of the first housing 33 and the supply hole 322 of the first fixed disk 32 are in communication with each other. In the first disperser 30, the aggregated particles supplied to the first disperser 30 through the first conveying path 71 are guided between the first rotating disk 31 and the first fixed disk 32 through the supply hole 332 and the supply hole 322.

[0060] An air supply hole 331 penetrating in the direction of the rotation axis is formed on the surface of the first housing 33 facing the first rotating disk 31. The air supply hole 331 is connected to the first air supply passage 74. In the first disperser 30, the carrier fluid supplied to the first disperser 30 through the first air supply passage 74 is guided into the first housing 33 through the air supply hole 331.

[0061] The agglomerated particles supplied from supply hole 322 between the first rotating disk 31 and the first fixed disk 32 move from the axial center to the outer periphery due to the centrifugal force caused by the rotation of the first rotating disk 31 and the flow of the carrier fluid, and are crushed by being subjected to impact when they collide with the rotating side pin 311 of the first rotating disk 31 and the fixed side pin 321 of the first fixed disk 32.

[0062] Furthermore, the agglomerated particles that reach the gap between the outer periphery of the first rotating disk 31 and the housing 33 are crushed by impact with the first rotating disk 31 and the housing 33. The agglomerated particles roughly crushed in the first disperser 30 move to the second disperser 40 through the second conveying path 72.

[0063] Furthermore, if the number of rotating side pins 311 of the first rotating disk 31 and the fixed side pins 321 of the first fixed disk 32 is too large, the load on the rotating side pins 311 and the fixed side pins 321 will become too large and they may break, and if the number is too small, the power to disintegrate the agglomerated particles will decrease, so it is preferable to appropriately adjust the number of rotating side pins 311 and fixed side pins 321 so that the agglomerated particles can be properly disintegrated.

[0064] (2nd disperser) As shown in Figures 2, 5, and 6, the second disperser 40 is a rotary disperser having a rotating second rotating disk 41. The second rotating disk 41 is an example of a rotating second disk. The second disperser 40 has the second rotating disk 41, a second fixed disk 42 arranged opposite the second rotating disk 41, and a second housing 43 that covers the second rotating disk 41 and the second fixed disk 42. The second rotating disk 41 and the second fixed disk 42 are formed in a disk shape.

[0065] The second rotating disk 41 has a plurality of rotating-side blocks 411 protruding from a plate surface on the side facing the second fixed disk 42. The second fixed disk 42 has a plurality of fixed-side blocks 421 protruding from a plate surface on the side facing the second rotating disk 41. The rotating-side blocks 411 and the fixed-side blocks 421 are prismatic blocks. The rotating-side blocks 411 and the fixed-side blocks 421 are alternately arranged with a gap therebetween in the radial direction.

[0066] Thus, the second disperser 40 is a block-type disperser in which the rectangular prism-shaped rotating-side block 411 and fixed-side block 421 protrude from the plate surfaces of the second rotating disk 41 and the second fixed disk 42, which are formed in a disk shape.

[0067] A supply hole 432 is formed in the surface of the second housing 43 facing the second fixed disk 42, penetrating in the direction of the rotation axis. A supply hole 422 is formed in the center of the second fixed disk 42, penetrating in the direction of the rotation axis. The supply hole 432 of the second housing 43 is connected to the second conveying path 72, and the supply hole 432 of the second housing 43 and the supply hole 422 of the second fixed disk 42 are in communication with each other. In the second disperser 40, the aggregated particles supplied to the second disperser 40 through the second conveying path 72 are guided between the second rotating disk 41 and the second fixed disk 42 through the supply hole 432 and the supply hole 422.

[0068] An air supply hole 431 penetrating in the direction of the rotation axis is formed on the surface of the second housing 43 facing the second rotating disk 41. The air supply hole 431 is connected to the second air supply passage 75. In the second disperser 40, the carrier fluid supplied to the second disperser 40 through the second air supply passage 75 is guided into the second housing 43 through the air supply hole 431.

[0069] The agglomerated particles supplied from the first disperser 30 to the second disperser 40 through the second conveying path 72 are broken down by being subjected to impact upon colliding with the rotating side block 411 of the second rotating disk 41 and the fixed side block 421 of the second fixed disk 42 due to the rotation of the second rotating disk 41 and the flow of the carrier fluid.

[0070] Furthermore, the agglomerated particles located between the outer periphery of the second rotating disk 41 and the housing 43 are crushed by impact with the second rotating disk 41 and the housing 43. The agglomerated particles finely crushed in the second disperser 40 move to the burner 5 through the third transport path 73.

[0071] In addition, the rotating side block 411 and the fixed side block 421 in the second disperser 40 are formed thicker than the rotating side pin 311 and the fixed side pin 321 in the first disperser 30, and have greater rigidity, and the disintegrating force of the second disperser 40 is configured to be greater than the disintegrating force of the first disperser 30.

[0072] 7, the second conveying path 72 connecting the first disperser 30 and the second disperser 40 extends from the first disperser 30 in a tangential direction at the outer periphery of the first rotating disk 31, toward the opposite side to the rotation direction of the first rotating disk 31. The carrier fluid supplied into the first disperser 30 flows through the second conveying path 72 from the first disperser 30 toward the second disperser 40. The second conveying path 72 is an example of a flow path through which the carrier fluid flows from the first disperser 30 to the second disperser 40.

[0073] In this case, in the first disperser 30, the agglomerated particles located between the outer periphery of the first rotating disk 31 and the housing 33 are subjected to a force along the rotation direction of the first rotating disk 31 and a force along the flow of the carrier fluid. The agglomerated particles that have not been sufficiently roughly disintegrated in the first disperser 30 and have become large particles are heavy, so they move along the rotation direction of the first rotating disk 31 rather than along the flow of the carrier fluid.

[0074] On the other hand, the agglomerated particles that have been sufficiently roughly crushed into small particles in the first disperser 30 have a small weight, so they move through the second conveying path 72 along the flow of the carrier fluid, not along the rotation direction of the first rotating disk 31, and are transported to the second disperser 40.

[0075] Further, the third conveying path 73 connecting the second disperser 40 and the burner 5 extends from the second disperser 40 in a tangential direction at the outer periphery of the second rotating disk 41, toward the opposite side to the rotation direction of the second rotating disk 41. The carrier fluid supplied into the second disperser 40 flows through the third conveying path 73 from the second disperser 40 toward the burner 5. The third conveying path 73 is an example of a flow path through which the carrier fluid flows from the second disperser 40 toward the dispersion nozzle 51 of the burner 5.

[0076] In this case, in the second disperser 40, the agglomerated particles located between the outer periphery of the second rotating disk 41 and the housing 43 are subjected to a force along the rotation direction of the second rotating disk 41 and a force along the flow of the carrier fluid. The agglomerated particles that are not sufficiently finely disintegrated in the second disperser 40 and have become large particles are heavy, so they move along the rotation direction of the second rotating disk 41 rather than along the flow of the carrier fluid.

[0077] On the other hand, the agglomerated particles that have been sufficiently finely broken down into small particles in the second disperser 40 have a small weight, so they move through the third transport path 73 along the flow of the carrier fluid rather than along the rotation direction of the second rotating disk 41, and are transported to the burner 5.

[0078] In this way, the large aggregated particles in the first disperser 30 and the second disperser 40 remain in the first disperser 30 and the second disperser 40 along with the rotation of the first rotating disk 31 and the second rotating disk 41. On the other hand, the aggregated particles that have been sufficiently roughly disintegrated and reduced in size in the first disperser 30 move from the first disperser 30 to the second disperser 40 in the second conveying path 72 along the flow of the carrier fluid, and the aggregated particles that have been sufficiently finely disintegrated and reduced in size in the second disperser 40 move from the second disperser 40 to the burner 5 in the third conveying path 73 along the flow of the carrier fluid.

[0079] In the disperser 3, the first rotating disk 31 of the first disperser 30 and the second rotating disk 41 of the second disperser 40 rotate, generating airflows in the first housing 33 and the second housing 43, which may cause turbulence in the first conveying path 71, the second conveying path 72, and the third conveying path 73. If the turbulence generated in the first conveying path 71, the second conveying path 72, and the third conveying path 73, through which the carrier fluid and aggregated particles flow, becomes large, backflow or blockage may occur, so it is preferable to appropriately adjust the rotation speed of the first rotating disk 31 and the second rotating disk 41 and the flow rate of the carrier fluid so as not to cause backflow or blockage.

[0080] In the disperser 3, the distance between the rotating side block 411 and the fixed side block 421 in the second disperser 40 is set to be smaller than the distance between the rotating side pin 311 and the fixed side pin 321 in the first disperser 30, and the dispersing force of the second disperser 40 is configured to be greater than the dispersing force of the first disperser 30.

[0081] This makes it possible to smoothly roughly disintegrate large agglomerated particles into relatively small agglomerated particles using the first disperser 30, and then finely disintegrate the relatively small agglomerated particles into even smaller particles using the second disperser 40.

[0082] In addition, by crushing large agglomerated particles using the first disperser 30, which has a large gap between the rotating side pins 311 and the fixed side pins 321, and then crushing the agglomerated particles that have become somewhat smaller using the second disperser 40, which has a small gap between the rotating side block 411 and the fixed side block 421, it is possible to prevent blockages caused by agglomerated particles in the first disperser 30 and the second disperser 40.

[0083] Furthermore, the spacing between the rotating side pin 311 and the fixed side pin 321 in the first disperser 30, and the spacing between the rotating side block 411 and the fixed side block 421 in the second disperser 40 can be adjusted appropriately so as to avoid overloading the rotating side pin 311 and the fixed side pin 321, and the rotating side block 411 and the fixed side block 421.

[0084] Furthermore, if the first disperser 30 and the second disperser 40 are both configured as pin-type dispersers, the disperser 3 may not be able to disintegrate the aggregated particles, and if the first disperser 30 and the second disperser 40 are both configured as block-type dispersers, the disperser 3 may be overloaded and may become clogged. Therefore, in order to obtain a sufficient force for disintegrating the aggregated particles and to prevent the occurrence of clogging in the disperser 3, it is preferable to configure the first disperser 3 as a pin-type disperser and the second disperser 40 as a block-type disperser.

[0085] (burner) As shown in Figures 8 and 9, the burner 5 is connected to the disperser 3 and has a dispersion nozzle 50 that further disintegrates the agglomerated particles disintegrated by the disperser 3 and then sprays them, and a burner nozzle 60 that heats the non-spherical glass particles sprayed from the dispersion nozzle 50.

[0086] (Dispersion Nozzle) The dispersion nozzle 50 has a conduit 51 and an orifice 52. The conduit 51 is formed in a tubular shape and has a base end 511 connected to the third transport path 73 and a tip end 512 in which an injection port 512a is formed. The conduit 51 is a flow path through which the aggregated particles transported from the third transport path 73 along the flow of the carrier fluid move. The base end 511 of the conduit 51 is located upstream in the movement direction of the aggregated particles, and the tip end 512 of the conduit 51 is located downstream in the movement direction of the aggregated particles. The dispersion nozzle 50 is an orifice type disperser having an orifice 52 in the conduit 51, which is a flow path through which the aggregated particles move.

[0087] Orifice 52 is formed by a protrusion protruding from the inner surface on the tip 512 side of conduit 51, and the opening area of ​​the portion of conduit 51 where orifice 52 is formed is smaller than the opening area of ​​the portion of conduit 51 where orifice 52 is not formed.

[0088] The flow velocity of the carrier fluid flowing through conduit 51 increases as it passes through orifice 52, and a separating force and a shearing force due to the acceleration of the airflow act on the agglomerated particles moving through conduit 51. As a result, most of the agglomerated particles moving through conduit 51 are disintegrated until they become non-spherical glass particles, which are primary particles. The non-spherical glass particles that have passed through orifice 52 are ejected from ejection port 512a.

[0089] (Burner nozzle) Burner nozzle 60 has a first outer peripheral wall 62 and a second outer peripheral wall 63 formed in a cylindrical shape, a first partition wall 64 and a second partition wall 65 formed in a disk shape, and a plurality of rectifier tubes 67 formed in a tubular shape.

[0090] The inner diameter of the first outer peripheral wall 62 is formed larger than the outer diameter of the second outer peripheral wall 63. The first outer peripheral wall 62 has a connection port 621 connected to an oxygen supply source 82. The second outer peripheral wall 63 has a connection port 631 connected to a fuel supply source 83.

[0091] The first partition 64 is joined to the base end of the first outer peripheral wall 62. The first partition 64 closes the base end of the first outer peripheral wall 62. The second partition 65 is joined to the base end of the second outer peripheral wall 63. The second partition 65 closes the base end of the second outer peripheral wall 63. The first outer peripheral wall 62 houses the second outer peripheral wall 63, which houses the dispersion nozzle 50. The second outer peripheral wall 63 penetrates the first partition 64, and the conduit 51 of the dispersion nozzle 50 penetrates the second partition 65.

[0092] The burner nozzle 60 has an oxygen supply chamber R1 to which oxygen is supplied from an oxygen supply source 82, and a fuel supply chamber R2 to which fuel is supplied from a fuel supply source 83. The oxygen supply chamber R1 is a space partitioned by a first outer peripheral wall 62, a second outer peripheral wall 63, and a first partition wall 64. An oxygen jet port 622 that communicates the oxygen supply chamber R1 with the outside is opened at the tip of the first outer peripheral wall 62. Oxygen is supplied to the oxygen supply chamber R1 from the oxygen supply source 82 via a connection port 621. The oxygen supplied to the oxygen supply chamber R1 flows out from the oxygen jet port 622 to the outside.

[0093] The fuel supply chamber R2 is a space partitioned by the second outer peripheral wall 63, the conduit 51, and the second partition wall 65. A fuel injection port 632 that communicates the fuel supply chamber R2 with the outside is opened at the tip of the second outer peripheral wall 63. Gaseous fuel is supplied to the fuel supply chamber R2 from the fuel supply source 83 via a connection port 631. The fuel supplied to the fuel supply chamber R2 is injected from the fuel injection port 632 to the outside.

[0094] The plurality of flow straightening tubes 67 are located at the tip portion of the second outer peripheral wall 63. The plurality of flow straightening tubes 67 are arranged in an annular shape between the second outer peripheral wall 63 and the distribution nozzle 50 to form a bundle. The plurality of flow straightening tubes 67 straighten the flow of gaseous fuel circulating inside the second outer peripheral wall 63.

[0095] In the burner nozzle 60, fuel is injected from the fuel injection port 632 while oxygen flows out from the oxygen injection port 622, and the fuel injected from the fuel injection port 632 is ignited, thereby enabling a flame to be injected from the fuel injection port 632.

[0096] The non-spherical glass particles sprayed from the distribution nozzle 50 are heated by spraying a flame from the fuel spray port 632 of the burner nozzle 60. The non-spherical glass particles sprayed from the distribution nozzle 50 are heated by the flame from the burner nozzle 60 and are spheroidized to become spherical glass particles.

[0097] In the burner 5, the connection port 631 that supplies fuel from the fuel supply source 83 to the fuel supply chamber R2 is located upstream of the orifice 52 of the dispersion nozzle 50 in the direction of movement of the agglomerated particles. This makes it easier for heat to be transferred to the agglomerated particles moving within the conduit 51 of the dispersion nozzle 50, thereby making it possible to prevent the generation of insufficiently spherical glass particles when non-spherical glass particles are heated to produce spherical glass particles.

[0098] [Dispersion spheroidization process] Next, the dispersion and spheroidization step S04 in the manufacturing method of spherical glass particles will be described in detail. As shown in Fig. 10, the dispersion and spheroidization step S04 includes a dispersion step S41 and a spheroidization step S42.

[0099] The dispersion step S41 is a step in which the agglomerated particles stored in the storage section 10 are transported to the disperser 3 by the feeder 20, and the transported agglomerated particles are disintegrated by the disperser 3.

[0100] In the dispersion step S41, the aggregated particles are roughly disintegrated by the first disperser 30 and then finely disintegrated by the second disperser 40. The aggregated particles roughly disintegrated by the first disperser 30 are transported to the second disperser 40 through the second transport path 72, and the aggregated particles finely disintegrated by the second disperser 40 are transported to the dispersion nozzle 50 of the burner 5 through the third transport path 73.

[0101] The agglomerated particles disintegrated in the dispersion step S41 are wet-pulverized in the wet-pulverization step S03 prior to the dispersion-spheronization step S04, and therefore tend to become significantly agglomerated. However, by disintegrating the agglomerated particles using the first disperser 30 and the second disperser 40 in the dispersion step S41, it is possible to disintegrate the agglomerated particles effectively.

[0102] In particular, since the first disperser 30 is a rotary disperser having a rotating first rotating disk 31, and the second disperser 40 is a rotary disperser having a rotating second rotating disk 41, the first disperser 30 and the second disperser 40 are capable of effectively breaking down agglomerated particles by the rotating first rotating disk 31 and the second rotating disk 41, respectively.

[0103] The first disperser 30 is a pin-type disperser in which cylindrical pins protrude from the first rotating disk 31, and the second disperser 40 is a block-type disperser in which prismatic blocks protrude from the second rotating disk 41, and the second disperser 40 has a greater dispersing force than the first disperser 30. Therefore, the agglomerated particles can be effectively disintegrated by roughly disintegrating the agglomerated particles with the first disperser 30, which is a pin-type disperser, and then finely disintegrating the agglomerated particles with the second disperser 40, which is a block-type disperser.

[0104] Furthermore, carrier fluid flows into the first disperser 30 from the outside, and a second conveying path 72 through which the carrier fluid flows from the first disperser 30 to the second disperser 40 extends in a tangential direction from the first disperser 30 to the outer periphery of the first rotating disk 31, in the opposite direction to the rotation direction of the first rotating disk 31, and a third conveying path 73 through which the carrier fluid flows from the second disperser 40 to the dispersion nozzle 50 extends in a tangential direction from the second disperser 40 to the outer periphery of the second rotating disk 41, in the opposite direction to the rotation direction of the second rotating disk 41.

[0105] With this configuration, the large aggregated particles in the first disperser 30 and the second disperser 40 remain in the first disperser 30 and the second disperser 40 along the rotation of the first rotating disk 31 and the second rotating disk 41. On the other hand, the aggregated particles that have been sufficiently disintegrated and reduced in size in the first disperser 30 move from the first disperser 30 to the second disperser 40 in the second conveying path 72 along the flow of the carrier fluid, and the aggregated particles that have been sufficiently disintegrated and reduced in size in the second disperser 40 move from the second disperser 40 to the dispersion nozzle 50 in the third conveying path 73 along the flow of the carrier fluid. This makes it possible to convey only the aggregated particles that have been sufficiently disintegrated and reduced in the disperser 3 to the dispersion nozzle 50 of the burner 5.

[0106] After the agglomerated particles are disintegrated by the disperser 3 in the dispersion step S41, in the spheroidization step S42, the agglomerated particles disintegrated in the dispersion step S41 are further disintegrated by the dispersion nozzle 50, and the non-spheroidized glass particles sprayed from the dispersion nozzle 50 are heated by the burner nozzle 60 to be spheroidized.

[0107] In the spheroidizing step S42, most of the agglomerated particles are disintegrated by the dispersion nozzle 50 until they become non-spherical glass particles, which are primary particles. In the spheroidizing step S42, it is preferable to disintegrate all of the agglomerated particles until they become non-spherical glass particles, but it is not necessary to disintegrate all of the agglomerated particles until they become non-spherical glass particles. In addition, in the spheroidizing step S42, a flame sprayed from a burner nozzle 60 is applied to the non-spheroidized glass particles sprayed from the dispersion nozzle 50, thereby spheroidizing the non-spheroidized glass particles.

[0108] In this case, the agglomerated particles to be disintegrated by the dispersion nozzle 50 have been effectively disintegrated in advance by the first disperser 30 and the second disperser 40, so that even if the spherical glass particles to be produced are small in diameter, Dmax 2 μm or less, it is possible to prevent the dispersion nozzle 50 from being blocked or coarse spherical glass particles from being produced.

[0109] In particular, since the dispersion nozzle 50 is an orifice-type disperser and does not have a collision member against which the agglomerated particles collide, it is possible to prevent the dispersion nozzle 50 from being blocked by the agglomerated particles passing through the dispersion nozzle 50.

[0110] [Spherical glass particles] Next, the spherical glass particles produced by the above-mentioned method for producing spherical glass particles will be described.

[0111] The spherical glass particles have a fire-polished surface because they are heated in the spheroidizing step S42. The fire-polished surface may constitute only a part of the surface of the spherical glass particles, but it is preferable that the fire-polished surface constitutes the entire surface of the spherical glass particles. Whether or not the spherical glass particles have a fire-polished surface can be determined by observing the surface of the spherical glass particles with an optical microscope.

[0112] The spherical glass particles can be rephrased as solid or non-porous glass particles. The spherical glass particles preferably have a smooth surface that does not include corners, points, voids, cracks, etc. The fire-polished surface can be rephrased as a convex curved surface, a spherical convex surface, or a curved surface. The fire-polished surface is preferably a smooth surface that does not include corners, points, voids, cracks, etc.

[0113] If the surface of the spherical glass particles is a fire-polished surface, the specific surface area tends to be small. The smaller the specific surface area of ​​the spherical glass particles, the lower the viscosity of the dental composition obtained by mixing the resin and the spherical glass particles. As a result, the dental material obtained by hardening the dental composition is less likely to contain bubbles, and the decrease in strength of the dental material is suppressed.

[0114] The sphericity, which indicates the degree of sphericity of the spherical glass particles, is preferably "0.5 to 1". The sphericity is preferably "0.7 or more", more preferably "0.8 or more", and even more preferably "0.85 or more". In this embodiment, spherical glass particles with a sphericity of "0.5 or more" are referred to as spherical.

[0115] The sphericity can be calculated by substituting the particle area (S) and the average circumference (d) of at least 10 million particles measured using an image analyzer such as the Camsizer XT manufactured by Verder Scientific into the following formula (1). Sphericity = 4π S / d 2 (1)

[0116] More specifically, when calculating sphericity, a particle is photographed as it is transported through the air by compressed air. The photographed image is then analyzed to obtain the area and circumference of the particle. Finally, the obtained values ​​are substituted into the above formula (1) to calculate sphericity. In the above measurement, the photographed particle becomes a two-dimensional flat circle, so it can be said that the circularity is actually being evaluated. However, measuring the shapes of 10 million or more particles is synonymous with measuring the circularity of the particles at all angles. For this reason, the above circularity is statistically equivalent to sphericity. If the photographed particle is a perfect sphere, the sphericity will be "1".

[0117] Because spherical glass particles are spherical, their specific surface area tends to be smaller than that of crushed glass particles. However, as the diameter of the spherical glass particles becomes smaller, the specific surface area of ​​the spherical glass particles per unit volume becomes larger. Therefore, dental compositions in which spherical glass particles with a small particle size are mixed with resin tend to have high viscosity. For this reason, dental materials obtained by hardening the dental composition may contain bubbles. In this case, the strength of the dental material may decrease, or the dental material may peel off from the cavity due to a decrease in adhesion between the dental material and the cavity. Specifically, this problem becomes apparent when the viscosity of the dental composition exceeds 1500 mPa·s.

[0118] Therefore, to avoid this problem, the spherical glass particles are designed to have a specific surface area of ​​25 m 2 / g or less is preferable, and 2 / g or less is preferable, and "17m 2 / g or less is more preferable. There is no particular lower limit to the specific surface area, but in reality it is no more than 0.1 m 2 / g or more." Here, the specific surface area is the specific surface area measured by the BET method.

[0119] For example, a dental material for repairing teeth is produced by curing a dental composition obtained by mixing a resin and spherical glass particles by photocuring or the like, and from the viewpoint of preventing the spherical glass particles from falling out of the surface of the dental material and forming recesses on the surface of the dental material, it is preferable that the Dmax of the spherical glass particles is 2 μm or less. In addition, it is preferable that the refractive index of the spherical glass particles is "1.48 to 1.62".

[0120] The spherical glass particles contain, as a glass composition, 20-80 mass% SiO2, 1-30 mass% Al2O3, 0-20 mass% B2O3, 0-40 mass% BaO+CaO, 0-20 mass% ZnO, and 0-25 mass% F. Preferably, the spherical glass particles contain, as a glass composition, 40-80 mass% SiO2, 1-30 mass% Al2O3, 2-20 mass% B2O3, 0-25 mass% CaO, 0-10 mass% ZnO, 0-10 mass% Li2O, 0-30 mass% Na2O, 0-30 mass% K2O, 0-20 mass% Nb2O5, 0-20 mass% WO3, 0.1-30 mass% Nb2O5+WO3, 0-15 mass% TiO2, and 0-10 mass% F. In order to make the spherical glass particles have the above composition, it is preferable that the non-spherical glass particles and the raw glass have the above composition.

[0121] The raw glass may have a composition containing at least one of B2O3 and R2O (R represents lithium (Li), sodium (Na) and potassium (K)). In this case, the total content of B2O3 and R2O in the raw glass may be 5 mass% or more.

[0122] In this case, if the raw glass contains at least one of B2O3 and R2O, the B and R components may be dissolved from the raw glass by the solvent during wet grinding in the wet grinding step S03, and may adhere to the surfaces of the produced non-spherical glass particles, causing stickiness. In particular, if the content of B2O3 and R2O in the raw glass is 5 mass% or more in total, the stickiness generated on the surfaces of the non-spherical glass particles tends to increase.

[0123] Non-spherical glass particles tend to aggregate significantly due to the sticky surface, but the aggregated particles containing the aggregated non-spherical glass particles can be effectively disintegrated by the first disperser 30 and the second disperser 40 in the subsequent dispersion step S41.

[0124] Next, each component contained in the spherical glass particles will be described.

[0125] SiO2 is a component that forms the glass skeleton. It is also a component that improves chemical durability and devitrification resistance. The content of SiO2 is preferably 20 to 80 mass%, 50 to 80 mass%, 50 to 75 mass%, and particularly preferably 50 to 65 mass%. If the amount of SiO2 is too small, the chemical durability is likely to decrease, and the glass is likely to devitrify, which may make production difficult. On the other hand, if the amount of SiO2 is too large, the melting property is likely to decrease. In addition, the glass is unlikely to soften during molding, which may make production difficult.

[0126] Al2O3 is a vitrification stabilizing component. It is also a component that improves chemical durability and devitrification resistance. The content of Al2O3 is preferably 1 to 30 mass%, 2.5 to 25 mass%, and particularly preferably 5 to 20 mass%. If the content of Al2O3 is too high, the melting property is likely to decrease. In addition, the glass may become difficult to soften during molding, which may make production difficult. On the other hand, if the content of Al2O3 is too low, the chemical durability and devitrification resistance are likely to decrease.

[0127] B2O3 is a component that forms the glass skeleton. It is also a component that improves chemical durability and devitrification resistance. The B2O3 content is preferably 0 to 20 mass%, 3 to 19 mass%, and particularly preferably 3.5 to 17 mass%. If the B2O3 content is too low, the chemical durability is likely to decrease. Furthermore, the glass is likely to devitrify, which may make manufacturing difficult. On the other hand, if the B2O3 content is too high, the meltability is likely to decrease. Furthermore, the glass is unlikely to soften during molding, which may make manufacturing difficult.

[0128] BaO and CaO are alkaline earth elements, and are components that stabilize vitrification as intermediate substances. The total content of these components is preferably 0 to 40 mass%, 0 to 35 mass%, 0 to 30 mass%, and particularly preferably 0 to 28 mass%. The content of BaO or CaO is preferably 0 to 25 mass%, 0 to 20 mass%, and particularly preferably 0 to 14 mass%. If the content of BaO or CaO is too high, the chemical durability is likely to decrease, and the glass is likely to devitrify, which may make production difficult.

[0129] ZnO is a component that reduces the viscosity of glass and suppresses devitrification. The ZnO content is preferably 0 to 20 mass%, 0.1 to 9 mass%, 0.4 to 7 mass%, and particularly preferably 0.6 to 5 mass%. If the ZnO content is too high, the chemical durability is likely to decrease, and the glass is likely to devitrify, which may make production difficult.

[0130] Li2O is a component that reduces the viscosity of glass. The content of Li2O is preferably 0 to 10 mass%, 0 to 9 mass%, 0 to 7 mass%, and particularly preferably 0 to 5 mass%. If the content of Li2O is too much, the chemical durability is likely to decrease, and the glass is likely to devitrify, which may make production difficult.

[0131] Na2O is a component that reduces the viscosity of glass. The Na2O content is preferably 0 to 30 mass%, 0 to 25 mass%, 0 to 20 mass%, and particularly preferably 0 to 15 mass%. If the Na2O content is too high, the chemical durability is likely to decrease, and the glass is likely to devitrify, which may make production difficult.

[0132] K2O is a component that reduces the viscosity of glass. The content of K2O is preferably 0 to 30 mass%, 0.1 to 25 mass%, 0.5 to 20 mass%, and particularly preferably 1 to 15 mass%. If the content of K2O is too much, the chemical durability is likely to decrease, and the glass is likely to devitrify, which may make production difficult.

[0133] Nb2O5 is a component that can adjust the refractive index and Abbe number. The content of Nb2O5 is preferably 0 to 20 mass%, 0 to 15 mass%, 0 to 10 mass%, and particularly preferably 0 to 5 mass%. If the content of Nb2O5 is too high, the glass is likely to become devitrified.

[0134] WO3 is a component that can adjust the refractive index and Abbe number, and also reduces the viscosity of the glass. The content of WO3 is preferably 0 to 20 mass%, 0.1 to 15 mass%, 0.5 to 10 mass%, and particularly preferably 1 to 5 mass%. If the amount of WO3 is too much, the glass is likely to devitrify.

[0135] The total amount of Nb2O5 and WO3 is preferably 0.1 to 30 mass%, 0.1 to 25 mass%, 1 to 20 mass%, and particularly preferably 1 to 10 mass%. By limiting the ranges of these components as above, it becomes easier to adjust the refractive index and Abbe number, and coloring becomes less likely. It also becomes easier to suppress devitrification of the glass. Furthermore, it becomes easier to obtain glass with high chemical durability.

[0136] TiO2 is a component that can adjust the refractive index and Abbe number, and also reduces the viscosity of the glass. The content of TiO2 is preferably 0 to 15 mass%, 0 to 12 mass%, 0 to 10 mass%, and particularly preferably 0 to 5 mass%. If the amount of TiO2 is too small, it becomes difficult to obtain the desired optical properties. In addition, chemical durability is likely to decrease. On the other hand, if the amount of TiO2 is too large, it becomes difficult to obtain the desired optical properties. In addition, coloring of the glass is likely to occur, and light transmittance is likely to decrease.

[0137] The total content of Nb2O5, WO3 and TiO2 is preferably 0.1 to 30 mass%, 0.1 to 25 mass%, 1 to 20 mass%, and particularly preferably 1 to 15 mass%. By limiting the ranges of these components as above, it becomes easier to adjust the refractive index and Abbe number, and it becomes easier to suppress devitrification of the glass. Furthermore, it becomes easier to obtain glass with high chemical durability.

[0138] F is a component capable of increasing transmittance, particularly transmittance in the ultraviolet region. The content of F is preferably 0 to 25 mass%, 0 to 10 mass%, 0 to 7.5 mass%, 0 to 5 mass%, particularly 0 to 3 mass%. If the amount of F is too large, chemical durability is likely to decrease. In addition, F is highly volatile, and the components sublimated in the spheroidizing step S42 may adhere to the surface of the spherical glass particles, causing deterioration of the surface properties. However, the sublimated components adhering to the surface of the spherical glass particles can be removed by wet collecting the spherical glass particles produced in the spheroidizing step S42.

[0139] In addition to the above components, the spherical glass particles may contain MgO and SrO. MgO and SrO, like BaO and CaO, are components that stabilize vitrification as intermediate substances. The total content of these components is preferably 0 to 50 mass%, 0 to 50 mass%, 0 to 40 mass%, and particularly preferably 0 to 30 mass%. If the content of these components is too high, the chemical durability is likely to decrease, and the glass is likely to devitrify, which may make production difficult.

[0140] [Dental composition] Next, a dental composition containing spherical glass particles will be described. The dental composition is an example of a resin composition that uses spherical glass particles as a filler.

[0141] The dental composition is obtained by mixing the resin and the spherical glass particles in a mixer. When the application is a temporary tooth, the compounding ratio of the resin and the spherical glass particles is preferably "95:5" to "25:75" by mass%, more preferably "90:10" to "40:60", even more preferably "85:15" to "50:50", and particularly preferably "80:20" to "60:40". In addition, in the case of a dental restorative material (so-called dental composite resin), which is an application requiring long-term reliability and higher strength, hardness, and abrasion resistance than a temporary tooth, the compounding ratio of the resin and the spherical glass particles is preferably "50:50" to "10:90" by mass%, more preferably "45:55" to "15:85", and even more preferably "40:60" to "20:80".

[0142] If the content of the spherical glass particles is too low, the mechanical strength of the dental composition tends to be poor. On the other hand, if the content of the spherical glass particles is too high, the viscosity of the dental composition becomes too high, the flowability decreases, and molding becomes difficult. Examples of the mixer include a three-roll mill and a rotary mixer.

[0143] The resin may be a curable resin such as a photocurable resin or a thermosetting resin, and may be appropriately selected depending on the molding method to be used. For example, when a stereolithography method is used, a liquid photocurable resin may be selected, and when a powder sintering method is used, a powdered thermosetting resin may be selected.

[0144] Examples of photocurable resins include polyamide-based resins, polyamideimide-based resins, polyacetal-based resins, (meth)acrylic-based resins, melamine resins, (meth)acrylic-styrene copolymers, polycarbonate-based resins, styrene-based resins, polyvinyl chloride-based resins, benzoguanamine-melamine formaldehyde, silicone-based resins, fluorine-based resins, polyester-based resins, crosslinked (meth)acrylic-based resins, crosslinked polystyrene-based resins, crosslinked polyurethane-based resins, and epoxy-based resins.

[0145] Examples of thermosetting resins include epoxy resins, thermosetting modified polyphenylene ether resins, thermosetting polyimide resins, urea resins, allyl resins, silicon resins, benzoxazine resins, phenol resins, unsaturated polyester resins, bismaleimide triazine resins, alkyd resins, furan resins, melamine resins, polyurethane resins, and aniline resins.

[0146] [Example] Next, examples of the spherical glass particles produced by the method for producing spherical glass particles according to the present invention will be described. Note that the following examples are intended to illustrate the present invention and do not limit the present invention in any way.

[0147] In this example, Example, Comparative Example 1, and Comparative Example 2 were prepared as shown in Table 1. Note that, as the raw glass, borosilicate glass containing 55 mass% SiO2, 10 mass% Al2O3, 10 mass% B2O3, 5 mass% BaO, 5 mass% CaO, 10 mass% ZnO, and 5 mass% F was used in all of Example, Comparative Example 1, and Comparative Example 2.

[0148] In the example, raw glass is wet-pulverized in the wet-pulverizing step S03, and in the dispersion-spheroidizing step S04, agglomerated particles are disintegrated using a first disperser 30, a second disperser 40, and a dispersion nozzle 50, which is an orifice-type disperser, and then the non-spherical glass particles are heated by a burner nozzle 60 to obtain spherical glass particles.

[0149] In Comparative Example 1, the raw glass was wet-pulverized in the wet-pulverization step S03, and the agglomerated particles were disintegrated using a first disperser 30 and then disintegrated using a collision-type disperser, and the non-spherical glass particles were then heated using a burner nozzle 60 to obtain spherical glass particles.

[0150] In Comparative Example 2, the raw glass was wet-pulverized in the wet-pulverization step S03, and the agglomerated particles were disintegrated using the first disperser 30 and then disintegrated using a dispersion nozzle 50, which is an orifice-type disperser. Then, the non-spherical glass particles were heated using a burner nozzle 60 to obtain spherical glass particles.

[0151] [Table 1]

[0152] In the example, the particle size Dmax before spheroidization was 1.7 μm, and the particle size Dmax after spheroidization was 1.9 μm, both of which were values ​​of 2 μm or less. In addition, the "spheroidization rate of up to 2 μm", which indicates the ratio of spherical glass particles to glass particles having a particle size of 2 μm or less, of the obtained glass particles, was 97%. Here, the spheroidization rate in this embodiment is a value indicating the ratio of spherical glass particles to an arbitrary number of glass particles when an image is obtained using a scanning electron microscope (SEM) and an arbitrary number of glass particles of 2 μm or less are selected. The spherical glass particles refer to particles having the above-mentioned sphericity of 0.5 to 1. In addition, the arbitrary number described above is, for example, a positive integer of 100 or more.

[0153] This shows that the agglomerated particles are well disintegrated by the first disperser 30, the second disperser 40, and the dispersion nozzle 50 in the dispersion and spheroidization step S04, and most of the agglomerated particles are disintegrated to the point of becoming non-spherical glass particles, which are primary particles. It also shows that the generation of coarse spherical glass particles, which occurs when multiple non-spherical glass particles are heated in a state where they are adhered to each other, in the spheroidization step S42, is suppressed.

[0154] In addition, when the examples were produced, no clogging occurred in the dispersion nozzle 50, which is an orifice-type disperser. In other words, it is understood that in the production of the examples, it is possible to produce spherical glass particles with a Dmax of 2 μm or less while suppressing both the generation of coarse spherical glass particles and the occurrence of clogging of the dispersion nozzle 50.

[0155] In Comparative Example 1, the particle size Dmax before spheroidization was 1.7 μm and the particle size Dmax after spheroidization was 1.8 μm, both of which were values ​​of 2 μm or less. The "spheroidization rate of up to 2 μm" was 99%.

[0156] This indicates that most of the aggregated particles are successfully disintegrated by the first disperser 30 and the collision type disperser to form non-spherical glass particles, which are primary particles, and also indicates that the generation of coarse spherical glass particles is suppressed in the spheroidization step S42.

[0157] In addition, when Comparative Example 1 was produced, clogging occurred in the collision type disperser. This is thought to be because, when agglomerated particles that were not sufficiently disintegrated in the first disperser 30 pass through the collision type disperser, the agglomerated particles that collided with the collision member were not adequately disintegrated and remained there, causing clogging. In other words, it can be seen that, in the production of Comparative Example 1, the generation of coarse spherical glass particles was suppressed, but the occurrence of clogging of the dispersion nozzle 50 was not suppressed.

[0158] In Comparative Example 2, the particle size Dmax before spheroidization was 1.7 μm, and the particle size Dmax after spheroidization was 3.3 μm, so that the particle size Dmax before spheroidization was a value of 2 μm or less, but the particle size Dmax after spheroidization was a value exceeding 2 μm. In addition, the "spheroidization rate of up to 2 μm" was 67%.

[0159] This indicates that the agglomerated particles are not adequately disintegrated by the first disperser 30 and the dispersing nozzle 50, which is an orifice-type disperser, and that when the non-spherical glass particles are spheroidized, multiple non-spherical glass particles are heated in a state where they are adhered to each other, resulting in the production of coarse spherical glass particles.

[0160] Furthermore, when Comparative Example 2 was produced, no clogging occurred in the dispersion nozzle 50, which is an orifice-type disperser. In other words, it can be seen that, although no clogging occurred in the dispersion nozzle 50 when Comparative Example 2 was produced, the generation of coarse spherical glass particles was not suppressed.

[0161] Thus, in the preparation of the examples, it was confirmed that even when producing spherical glass particles with a small particle size having a Dmax of 2 μm or less, it is possible to prevent clogging of the dispersion nozzle and the generation of coarse spherical glass particles.

[0162] Although an embodiment of the present invention has been described above, the present invention is not limited to these embodiments, which are merely illustrative, and can of course be embodied in various other forms without departing from the spirit of the present invention. The scope of the present invention is defined by the claims, and includes the equivalent meanings of the claims and all modifications within the scope of the claims. [Explanation of symbols]

[0163] 1. Spherical glass particle manufacturing equipment 3 Dispersion machine 5 Burner 10 Storage section 20 Feeder 30 1st disperser 31 First rotating disk 32 First fixed disk 40 2nd disperser 41 Second rotating disk 42 Second fixed disk 50 Dispersion Nozzle 52 Orifice 60 Burner Nozzle 71 First conveyor route 72 Second Transport Route 73 Third Transport Route 311 Rotating side pin 321 Fixed side pin 411 Rotating block 421 Fixed side block S03 Wet grinding process S04 Dispersion spheroidization process S41 Dispersion process S42 Spheroidization process

Claims

1. A method for producing spherical glass particles using non-spherical glass particles as a main raw material, comprising the steps of: a dispersing step of disintegrating aggregated particles including the aggregated non-spherical glass particles by a dispersing machine; a spheroidizing step in which the aggregated particles disintegrated in the dispersion step are further disintegrated by a dispersion nozzle, and then the non-spherical glass particles sprayed from the dispersion nozzle are heated to spheroidize the non-spherical glass particles, The dispersing machine is A first disperser for roughly disintegrating the aggregated particles; a second disperser located downstream of the first disperser in the moving direction of the agglomerated particles, the second disperser finely disintegrating the agglomerated particles roughly disintegrated by the first disperser; A method for producing spherical glass particles having the above structure.

2. 2. The method for producing spherical glass particles according to claim 1, wherein the dispersion nozzle is an orifice-type disperser having an orifice in a flow path through which the aggregated particles move.

3. 3. The method for producing spherical glass particles according to claim 1, further comprising a crushing step of wet-crushing a raw glass material to produce the non-spherical glass particles, prior to the dispersing step.

4. The raw glass is B ２ O ３ and R ２ 4. The method for producing spherical glass particles according to claim 3, further comprising the step of: adding at least one of the following components to the glass particles: O (R represents lithium (Li), sodium (Na) and potassium (K)).

5. In the raw glass, B ２ O ３ and R ２ The content of O is B ２ O ３ and R ２ The method for producing spherical glass particles according to claim 4, wherein the total amount of oxygen and the oxygen is 5% by mass or more.

6. The first dispersing machine is a rotary dispersing machine having a rotating first disk, 3. The method for producing spherical glass particles according to claim 1, wherein the second dispersing machine is a rotary dispersing machine having a rotating second disk.

7. A carrier fluid is introduced into the first disperser from the outside, a flow path through which the carrier fluid flows from the first disperser to the second disperser extends from the first disperser in a tangential direction at an outer periphery of the first disk and in a direction opposite to a rotation direction of the first disk, The method for producing spherical glass particles as described in claim 6, wherein the flow path through which the carrier fluid flows from the second disperser to the dispersion nozzle extends from the second disperser in a tangential direction at the outer periphery of the second disk, in a direction opposite to the direction of rotation of the second disk.

8. The first dispersing machine is a pin-type dispersing machine in which a cylindrical pin protrudes from a plate surface of the first disk formed in a disk shape, 7. The method for producing spherical glass particles according to claim 6, wherein the second dispersing machine is a block-type dispersing machine having a prismatic block protruding from a plate surface of the second disk formed in a circular shape.

9. a storage section for storing agglomerated particles including agglomerated non-spherical glass particles; a feeder connected to the storage section and configured to transport the aggregated particles stored in the storage section; a disperser connected to the feeder and configured to disintegrate the agglomerated particles conveyed by the feeder; a burner having a dispersion nozzle connected to the disperser for dispersing the agglomerated particles disintegrated by the disperser after further disintegrating the agglomerated particles, and a burner nozzle for heating the non-spherical glass particles sprayed from the dispersion nozzle; Equipped with The dispersing machine is A first disperser for roughly disintegrating the aggregated particles; a second disperser located downstream of the first disperser in the direction of movement of the agglomerated particles, the second disperser finely disintegrating the agglomerated particles roughly disintegrated by the first disperser.

10. 10. The apparatus for producing spherical glass particles according to claim 9, wherein the dispersion nozzle is an orifice-type disperser having an orifice in a flow path through which the aggregated particles move.

11. The first dispersing machine is a rotary dispersing machine having a rotating first disk, 11. The apparatus for producing spherical glass particles according to claim 9, wherein the second dispersing machine is a rotary dispersing machine having a rotating second disk.

12. The first dispersing machine is a pin-type dispersing machine in which a cylindrical pin protrudes from a plate surface of the first disk formed in a disk shape, 12. The apparatus for producing spherical glass particles according to claim 11, wherein the second disperser is a block-type disperser in which a prismatic block protrudes from a plate surface of the second disk formed in a circular shape.

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