Mixing apparatus and method for producing resin composition

Abstract

A mixing apparatus comprising: a container for storing materials; an inner cylinder erected within the container and opening at the lower end and upper part of the internal space of the container; an outer rotating body rotatably disposed around the central axis of the container and, by rotation, moves at least partially the materials outside the inner cylinder; and an inner rotating body disposed coaxially with the inner cylinder so as to rotate at a higher speed than the outer rotating body and, by rotation, moves the materials inside the inner cylinder upward.

Description

[Technical Field]

[0001] The present invention relates to a mixing device and a method for producing a resin composition. [Background Art]

[0002] For producing various products, a plurality of types of pre-weighed materials are sometimes mixed in a container. For this reason, various mixing devices provided with rotating stirring blades in a container are commercially available. A resin composition having a relatively high viscosity is produced by dissolving or dispersing various liquid materials and various solid (including powder) materials. In cases such as when dispersing liquids or powders with poor compatibility depending on the types of materials to be mixed, it is not easy to uniformly mix the materials, and a long stirring time may be required. For this reason, a device for mixing materials by providing, in a container, a blade that largely circulates the entire material and a blade that efficiently mixes the material locally has been proposed (see, for example, Patent Document 1). [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2019-81168 [Summary of the Invention] [Problems to be Solved by the Invention]

[0004] Depending on the materials to be mixed, even if a plurality of stirring blades are provided, the stirring efficiency may not be sufficiently improved when the materials have high viscosity or high thixotropy. Accordingly, an object of the present invention is to provide a mixing device capable of efficiently mixing a viscous material having a relatively high viscosity and a method for producing a resin composition. [Means for Solving the Problems]

[0005] A mixing apparatus according to one aspect of the present invention comprises a container for storing material, an inner cylinder erected in the container and opening at the lower end and upper part of the internal space of the container, an outer rotating body rotatably disposed about the central axis of the container and moving at least partially the material outside the inner cylinder by rotation, and an inner rotating body disposed coaxially with the inner cylinder so as to rotate at a higher speed than the outer rotating body and moving the material inside the inner cylinder upward by rotation.

[0006] In the mixing apparatus described above, the outer rotating body has a shape that moves the material on the outside of the inner cylinder downward when it rotates in the forward direction, and the inner rotating body may have a rotating shaft and a plurality of shearing blades that protrude from the outer circumference of the rotating shaft and move the material upward when it rotates in the forward direction.

[0007] The mixing apparatus described above further comprises a bearing block disposed inside the inner cylinder at a distance from the bottom surface of the container and supporting the lower end of the inner rotating body, and a bearing structure disposed at the bottom of the container inside the inner cylinder and having a plurality of support legs that support the bearing block. The container has an outer cooling channel through which refrigerant is inserted, the inner cylinder has an inner cooling channel through which the refrigerant is inserted, the bearing block has a bearing cooling channel through which the refrigerant is inserted, and the support legs may have connecting channels that communicate with the bearing cooling channel, open to the outside of the container, and introduce the refrigerant into the bearing cooling channel.

[0008] In the mixing apparatus described above, the outer rotating body may have an outer scraper extending along the inner wall surface of the container and an inner scraper inclined along the outer wall surface of the inner cylinder.

[0009] The mixing device described above is further provided with a discharge valve located directly below the inner cylinder for discharging the material from the container, and the inner rotating body may rotate in the reverse direction when the material is being discharged.

[0010] A method for producing a resin composition according to one aspect of the present invention comprises a step of mixing a liquid material and a powder material using the mixing apparatus described above. [Effects of the Invention]

[0011] According to the present invention, it is possible to efficiently mix materials having relatively high viscosity. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic cross-sectional view showing the configuration of a mixing apparatus according to one embodiment of the present invention. [Modes for carrying out the invention]

[0013] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a schematic cross-sectional view of a mixing apparatus 1 according to one embodiment of the present invention. The mixing apparatus 1 is suitably used for mixing multiple materials, particularly liquid and powder materials constituting a viscous resin composition. The mixing apparatus 1 comprises a container 10, an inner cylinder 20, an outer rotating body 30, an inner rotating body 40, a bearing structure 50, and a discharge valve 60.

[0014] The container 10 stores the material. The container 10 has a circular cross-section to prevent partial stagnation when the material to be stored is moved by the outer rotating body 30. The container 10 may have a cylindrical body 11 and a bottom 12 that has a spherical, conical, or other shape and seals the lower end of the body 11. The container 10 is preferably a somewhat elongated tank with an effective height (height for storing the material) that is larger than the effective diameter (inner diameter) so that the material to be stored can be moved downwards sequentially and overall by the outer rotating body 30. Furthermore, the container 10 preferably has an outer cooling channel 13 through which a refrigerant is inserted to suppress the temperature of the material from rising due to the heat generated by the rotation of the outer rotating body 30 and the inner rotating body 40. In addition, the container 10 may be configured so that the bottom of the bottom 12 is open and the opening of the bottom 12 is closed by a bottom flange 14 on which a bearing structure 50 and a discharge valve 60 are disposed, in order to facilitate manufacturing and maintenance. The container 10 may be configured to have a lid 15 that closes the upper end of the body 11 and holds the outer rotating body 30 and the inner rotating body 40, and may be configured to allow the internal space to be degassed when the lid 15 is closed.

[0015] The inner cylinder 20 is erected inside the container 10 and opens to the bottom and top of the internal space (effective space) of the container 10. Specifically, the inner cylinder 20 is fixed concentrically to the lower end of the container 10. The inner cylinder 20 may have an opening 21 on the side of its lower end for introducing material from the bottom of the container 10. The height of the inner cylinder 20 is preferably higher than the height of the material stored in the container 10 in order to circulate the entire material stored in the container 10. The upper end of the inner cylinder 20 is preferably open horizontally so that the material can flow out in all directions. The effective diameter of the inner cylinder 20 depends on the viscosity of the material, the amount of auxiliary material to be mixed, etc., but is preferably 1 / 10 to 1 / 3 of the effective diameter of the body 11 of the container 10, and more preferably 1 / 8 to 1 / 4. The inner cylinder 20 is preferably equipped with an internal cooling channel 22 through which a refrigerant is inserted in order to suppress the temperature rise of the material, similar to the container 10. The inner cooling channel 22 can immediately cool the material whose temperature has risen due to shearing by the inner rotating body 40 inside the inner cylinder 20, thereby effectively suppressing overheating of the material.

[0016] The outer rotating body 30 is rotatably disposed around the central axis of the container 10 and, by rotation, moves at least partially the material on the outside of the inner cylinder, thereby achieving at least one of the effects of stirring, dispersion, and vertical movement. Preferably, the outer rotating body 30 has a shape such that, by forward rotation, it moves downward to sequentially supply the material on the outside of the inner cylinder 20 into the inner cylinder 20. Preferably, the outer rotating body 30 has an outer scraper 31 that extends vertically along the inner wall surface of the container 10 and an inner scraper 32 that extends vertically along the outer wall surface of the inner cylinder 20 to prevent material stagnation. The outer scraper 31 and the inner scraper 32 may be connected by a connecting bar 33 which may have a stirring effect. The outer rotating body 30 may be configured to be driven by an outer drive motor 34 disposed on the lid 15. At least one of the outer scraper 31 and the inner scraper 32 may have an inclination such as being formed spirally so that the material can be moved downward by the rotation of the outer rotating body 30. The rotation speed of the outer rotating body 30 is set to, for example, 5 rpm to 200 rpm, preferably 10 rpm to 100 rpm, in order to move the material downward overall.

[0017] The inner rotating body 40 has a rotating shaft 41 disposed coaxially with the inner cylinder 20 so as to rotate at a higher speed than the outer rotating body 30, and a plurality of shearing blades 42 protruding from the outer circumference of the rotating shaft 41, which shear the material and move the material upward as the rotating shaft 41 rotates in the forward direction. The inner rotating body 40 may be driven by an inner drive motor 43 disposed in the lid 15. The shearing blades 42 may be directly fixed to the rotating shaft 41, or they may be fixed to a sleeve 44 fitted onto the rotating shaft 41. By using the sleeve 44, the shape, angle, and number of the shearing blades 42 can be adjusted according to the material being mixed. The shearing blades 42 may be formed in the shape of a strip extending radially from the rotating shaft 41. The shearing blades 42 may also be fixed at an angle of elevation to generate pressure that lifts the material. In this embodiment, multiple sleeves 44, each with two shear blades 42 fixed at 180° intervals around their axis, are mounted on the rotating shaft 41 in multiple stages at intervals. The elevation angle of the shear blades 42 is, for example, 20° to 60°, preferably 30° to 50°. The axial arrangement pitch of the shear blades 42 depends on the length of the inner cylinder 20, but to ensure the mixing efficiency of the materials, it is, for example, 50mm to 450mm, preferably 100mm to 300mm. The inner rotating body 40 rotates in the reverse direction when the material is discharged from the discharge valve 60, moving the material inside the inner cylinder 20 downwards. The rotational speed of the rotating shaft 41 is, for example, 300rpm to 2000rpm, preferably 600rpm to 1200rpm, so that the main material and auxiliary material can be effectively mixed by the shear blades 42. The number of times the material is circulated by the rotation of the inner rotating body 40 (the value obtained by dividing the total amount of material in the container 10 by the flow rate of material in the inner cylinder 20) is preferably 0.1 times / min to 10.0 times / min, and more preferably 0.2 times / min to 3.0 times / min, in order to appropriately balance the mixing efficiency in the inner cylinder 20 and the overall mixing speed of the material.

[0018] The bearing structure 50 includes a bearing block 51 positioned inside the inner cylinder 20, spaced apart from the bottom surface of the container 10, and supporting the lower end of the rotating shaft 41, and a plurality of support legs 52 positioned at the bottom of the container 10 inside the inner cylinder 20, and supporting the bearing block 51. By positioning the bearing block 51 spaced apart from the bottom surface of the container 10, material accumulation is less likely to occur, efficient mixing of materials is possible, and the discharge valve 60 can be provided at the very bottom to improve material discharge. The bearing block 51 may be configured to have a bushing 53 that slides against the rotating shaft 41. The bearing block 51 also has a bearing cooling passage 54 through which refrigerant is inserted, and the support legs 52 have a connecting passage 55 that communicates with the bearing cooling passage 54 and opens to the outside of the container 10, thereby introducing refrigerant into the bearing cooling passage 54. In this way, by supplying a coolant to the bearing block 51 through the support legs 52 and optimizing the cooling of the bearing block 51, which is particularly prone to generating heat due to friction, it is possible to more reliably prevent material deformation due to heat, especially unintended hardening of thermosetting resins.

[0019] The discharge valve 60 is located directly below the inner cylinder and discharges the material from the container 10 to the outside. Preferably, the discharge valve 60 has a structure in which the distance between the valve body and the bottom flange 14 is small so as not to form a buildup of material. The mixing device 1 discharges the material through the discharge valve 60 by rotating the outer rotating body 30 in the forward direction and the inner rotating body 40 in the reverse direction. In addition, even during normal operation when mixing materials, the material may be discharged through the discharge valve 60 and recirculated to the top of the container 10 to promote mixing of the materials.

[0020] The mixing device 1 can efficiently mix materials by providing an inner cylinder 20 inside the container 10 and limiting the area affected by the shearing and stirring action of the inner rotating body 40. In particular, since the mixing device 1 shears the material by rotating multiple shearing blades 42 at high speed, it can efficiently mix powders with low dispersibility, liquids with low compatibility, etc., with fluids or slurries with relatively high viscosity.

[0021] A method for producing a resin composition according to an embodiment of the present invention comprises a step of mixing a resin material and a powder material using the above-described mixing apparatus 1. By using the mixing apparatus 1 that enables uniform mixing in a short time, a resin composition can be produced relatively efficiently even when the dispersibility of the powder material is low. Specifically, the method for producing a resin composition according to the present embodiment includes: a step of feeding a liquid material into a container 10; a step of feeding a powder material into the container 10; a step of roughly mixing the materials by rotation of an outer rotating body 30 and reflux of the material discharged from a discharge valve 60; a step of uniformly mixing the materials by rotation of an inner rotating body 40; a step of stopping or reducing the speed of the inner rotating body 40 to lower the temperature of the resin composition; a step of depressurizing the inside of the container 10 for degassing; and a step of discharging the resin composition from the discharge valve 60. It should be noted that some of these steps may be performed simultaneously or in a changed order, may be performed repeatedly, or may be omitted based on common technical knowledge.

[0022] In the method for producing a resin composition using the mixing apparatus 1, a low shear rate region 1 (shear rate 0.43 sec measured at 2 rpm and 20°C using a Brookfield rotational viscometer with spindle No. 7 -1 ) has an apparent viscosity of 10 Pa·s or more and 3,000 Pa·s or less, preferably 20 Pa·s or more and 1,000 Pa·s or less, more preferably 50 Pa·s or more and 500 Pa·s or less; and a low shear rate region 2 (shear rate 4.3 sec measured at 20 rpm and 20°C using a Brookfield rotational viscometer with spindle No. 7 -1 ) has an apparent viscosity of 5 Pa·s or more and 1,000 Pa·s or less, preferably 8 Pa·s or more and 500 Pa·s or less, more preferably 10 Pa·s or more and 200 Pa·s or less; the ratio (viscosity ratio) of the low shear rate region 1 to the low shear rate region 2 is 2 or more and 10 or less, preferably 4 or more and 8 or less, more preferably 5 or more and 7 or less; and a high shear rate region (783 sec measured at 20°C using an apparent viscometer compliant with JIS K 2220 -1 ) has an apparent viscosity of 2 Pa·s or more and 50 Pa·s or less, preferably 4 Pa·s or more and 30 Pa·s or less, particularly high production efficiency can be obtained compared with conventional mixing apparatuses.

[0023] In the method for producing a resin composition using the mixing device 1, when producing a resin composition using a thermosetting resin as the resin material, the use of the mixing device 1, which is provided with an outer cooling channel 13, an inner cooling channel 22, a bearing cooling channel 54, and a connection channel 55 to prevent overheating of the material, can prevent the curing of the resin composition from being initiated by heat. Specific examples of the resin composition include, but are not particularly limited to, epoxy-based compositions, urethane-based compositions, acrylic-based compositions, plastisol-based compositions, silicone-based compositions, modified silicone-based compositions, and rubber-based compositions containing natural rubber or polybutadiene. In particular, even in the production of a one-component curable composition that has relatively high viscosity, thixotropic properties, and is curable by heat, the material can be efficiently dispersed, and a high-quality resin composition can be produced. Among these, the method is suitable for producing a plastisol composition obtained by dispersing a powder material in a liquid material containing a vinyl chloride (co)polymer, an acrylic copolymer, and a plasticizer, and can suppress temperature rise during production to enable efficient dispersion. In addition, in recent years, for the dispersion of plastic balloons, glass balloons and the like with a specific gravity of 1 or less for the purpose of weight reduction, the mixed liquid material is repeatedly circulated from the upper part of the charged powder by the in-tank circulation mechanism, so efficient stirring is achieved.

[0024] The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various changes and modifications can be made. For example, in the mixing device according to the present invention, the bearing structure may be omitted, and only the upper part of the inner rotating body may be held outside the container. In addition, in the mixing device according to the present invention, the cooling channel can also be omitted. Description of Reference Signs

[0025] 1: Mixing device 10: Container 11: Body portion 12: Bottom portion 13: Outer cooling channel 14: Bottom flange 15: Lid body 20: Inner cylinder 21: Opening 22 Inner cooling channel 30 Outer rotating body 31. Outer scraper 32. Inner scraper 33 Connection Bar 34. External drive motor 40 Internal rotating body 41 Rotation axis 42 shear blades 43 Internal drive motor 44 sleeves 50 Bearing Structure 51 Bearing block 52 Support legs 53 Bush 54 Bearing cooling channel 55 Connection channel 60 Exhaust valve

Claims

1. A container for storing the materials, An inner cylinder erected within the container, with openings at the lower end and upper part of the internal space of the container, An outer rotating body is rotatably disposed around the central axis of the container and rotates to move at least partially the material on the outside of the inner cylinder, An inner rotating body is disposed coaxially with the inner cylinder so as to rotate at a higher speed than the outer rotating body, and the rotation moves the material inside the inner cylinder upward; A bearing block is positioned inside the inner cylinder, spaced apart from the bottom surface of the container, and supports the lower end of the inner rotating body. A bearing structure is provided, with a plurality of support legs positioned inside the inner cylinder at the bottom of the container, supporting the bearing block. Equipped with, The container has an outer cooling channel through which a refrigerant is inserted, The inner cylinder has an inner cooling channel through which the refrigerant is inserted, The bearing block has a bearing cooling channel through which the refrigerant is inserted, A mixing device wherein the support legs communicate with the bearing cooling passage, open to the outside of the container, and have a connecting passage for introducing the refrigerant into the bearing cooling passage.

2. The outer rotating body has a shape that moves the material on the outside of the inner cylinder downward when it rotates in the forward direction, The mixing apparatus according to claim 1, wherein the inner rotating body comprises a rotating shaft and a plurality of shearing blades protruding from the outer circumference of the rotating shaft, which move the material upward by forward rotation.

3. The mixing apparatus according to claim 1 or 2, wherein the outer rotating body comprises an outer scraper extending along the inner wall surface of the container and an inner scraper extending along the outer wall surface of the inner cylinder.

4. The container further comprises a discharge valve disposed directly below the inner cylinder for discharging the material from the container, The mixing apparatus according to claim 1 or 2, wherein the inner rotating body rotates in the reverse direction when the material is discharged.

5. A method for producing a resin composition, comprising the step of mixing a liquid material and a powder material using the mixing apparatus described in claim 1 or 2.

Images