Kneader

Abstract

Provided is a kneader (1) that suppresses a deterioration in the physical properties of a kneaded material, and that has a high sealing performance on a shaft part of a rotor. A kneader (1) comprises: a chamber (2) that defines a kneading space (15); rotors (3) that each include a first rotor shaft portion (12) and a second rotor shaft portion (13); first bearing portions (4) that rotatably support the first rotor shaft portions (12); second bearing portions (5) that rotatably support the second rotor shaft portions (13); and sealing materials (6a, 6b) that prevent leakage of a working fluid in a position closer to a motor than the chamber (2). The first bearing portions (4) and / or the second bearing portions (5) consist of non-lubricated bearings.

Description

Kneading machine

[0001] The present invention relates to a kneader that kneads materials in the presence of a working fluid in a supercritical or subcritical state.

[0002] Patent Document 1 discloses a kneading machine for kneading materials, which includes a kneading rotor and a pair of bearings. The bearings rotatably support both axial ends of the kneading rotor. Each of the pair of bearings uses a lubricating oil made from a non-petroleum resource.

[0003] The kneading may be carried out in the presence of a working fluid in a supercritical or subcritical state. In this case, the kneader used requires a chamber with high airtightness. In particular, high sealing performance is required for the shaft of the kneading rotor.

[0004] Furthermore, in the kneader of Patent Document 1, there is a risk that the lubricating oil, which is a non-petroleum resource, may be mixed into the materials and deteriorate the physical properties of the kneaded product.

[0005] Japanese Patent Application Laid-Open No. 2009-234077

[0006] An object of the present invention is to provide a kneader that can suppress deterioration in the physical properties of the kneaded material and that can provide high sealing performance for the rotor shaft.

[0007] Provided is a kneader that kneads materials in the presence of a working fluid in a supercritical or subcritical state, the kneader comprising a chamber, a rotor, a first bearing, a second bearing, and a seal. The chamber defines a kneading space in which the materials are kneaded. The rotor includes a first rotor shaft, a rotor body, and a second rotor shaft, which are aligned in the rotor axial direction. The first rotor shaft is at one end in the rotor axial direction and connected to a motor. The second rotor shaft is at the other end in the rotor axial direction. The rotor body is located between the first rotor shaft and the second rotor shaft and rotates in the kneading space to perform the kneading. The first bearing rotatably supports the first rotor shaft. The second bearing rotatably supports the second rotor shaft. The seal is positioned closer to the motor than the chamber so as to prevent leakage of the working fluid from the chamber toward the motor. At least one of the first bearing and the second bearing is composed of a non-lubricated bearing that does not contain lubricant oil.

[0008] Fig. 1 is a flow sheet showing a kneading device according to each embodiment of the present invention. Fig. 2 is a cross-sectional view of a kneader according to a first embodiment of the present invention. Fig. 3 is a cross-sectional view of a kneader according to a modified example of the first embodiment. Fig. 4 is a cross-sectional view of a kneader according to a second embodiment of the present invention. Fig. 5 is a cross-sectional view of a kneader according to a third embodiment of the present invention.

[0009] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0010] FIG. 1 shows a kneading apparatus 20 including a kneader 1 according to a first embodiment of the present invention. The kneader 1 kneads materials in the presence of a working fluid in a supercritical or subcritical state. The material in each embodiment is rubber, but it may also be resin, food, or the like. The kneading apparatus 20 performs the kneading in a batch manner.

[0011] The supercritical state is a state in which the temperature is equal to or higher than the critical temperature Tc of the working fluid and the pressure is equal to or higher than the critical pressure Pc of the working fluid. The subcritical state is a state close to the supercritical state. Examples of conditions for the temperature T and pressure P of the subcritical state are shown below. The units of the temperature T and the critical temperature Tc in each example are Celsius. [Condition Example 1] The temperature T is equal to or higher than the critical temperature Tc and the pressure P is less than the critical pressure Pc (T≧Tc and P<Pc). [Condition Example 2] The temperature T is less than the critical temperature Tc and the pressure P is less than the critical pressure Pc (T<Tc and P<Pc), the temperature T is sufficiently higher than room temperature, and the pressure P is sufficiently higher than normal pressure (atmospheric pressure). [Example Condition 3] The ratio of temperature T to critical temperature Tc is greater than 0.5 and less than 1.0 (0.5<T / Tc<1.0), and the ratio of pressure P to critical pressure Pc is less than 0.5 (0.5<P / Pc). [Example Condition 4] The ratio of temperature T to critical temperature Tc is less than 0.5 (0.5<T / Tc), and the ratio of pressure P to critical pressure Pc is greater than 0.5 and less than 1.0 (0.5<P / Pc<1.0). [Example Condition 5] When critical temperature Tc is 0° C. or less, the ratio of pressure P to critical pressure Pc is less than 0.5 (0.5<P / Pc).

[0012] Examples of materials constituting the working fluid include carbon dioxide, nitrogen, hydrogen, xenon, ethane, ammonia, methanol, and water. Of these, carbon dioxide and nitrogen are suitable for kneading rubber.

[0013] In this embodiment, carbon dioxide (CO ２ ) is used as the working fluid, and carbon dioxide in a supercritical state (supercritical CO ２ The kneading machine according to the present invention can also be applied to kneading in the presence of other working fluids in a supercritical state or in the presence of a working fluid in a subcritical state.

[0014] The kneading device 20 includes a production section 21 and a kneading section 22 .

[0015] The production unit 21 is a supercritical CO ２ The production section 21 includes a tank 31, a first heat exchanger 32, a pump 33, and a second heat exchanger 34.

[0016] The tank 31 contains CO ２ The first heat exchanger 32 stores the CO gas supplied from the tank 31. ２ Cool the gas to obtain liquid CO ２ Liquid CO ２ To do so.

[0017] The pump 33 pumps liquid CO ２ Pressurize the CO ２ The power required to pressurize the gas is less than that of the pump 33. ２ The pump 33 requires only a small amount of power to pressurize the pressurized liquid CO. ２ is pumped downstream.

[0018] The second heat exchanger 34 is a heat exchanger for ２ is heated in a container to produce liquid CO ２ is vaporized, thereby ２ supercritical CO ２ To do so.

[0019] The kneading section 22 is a supercritical CO ２ The materials are kneaded in the presence of the mixing unit 22. The mixing unit 22 includes the mixer 1, an adjusting valve 42, and a separation filter 43.

[0020] In the flow path connecting the production section 21 and the kneading section 22, supercritical CO ２ Materials and additives are added to the supercritical CO ２ The materials and additives added thereto are introduced into the kneader 1 .

[0021] The kneader 1 contains supercritical CO ２ The material and the additive are kneaded in the presence of supercritical CO. ２ By dissolving the hydroxybenzoate in the hydroxybenzoate, the hydroxybenzoate is quickly kneaded.

[0022] When the material is a polymer material such as rubber or resin, the additive is an additive, kneaded rubber, a plant-derived material containing cellulose nanofiber, etc. When the material is a food, the additive is a food additive, etc. The addition of the additive is optional.

[0023] When the kneading in the kneader 1 is completed, the kneaded mixture of the material and the additives and the supercritical CO ２ The kneaded mixture and the supercritical CO ２ is discharged separately from the mixer 1. The adjusting valve 42 controls the amount of supercritical CO2 discharged from the mixer 1. ２ In this embodiment, the adjusting valve 42 adjusts the flow rate of the supercritical CO 2 discharged from the inside of the kneader 1. ２ The pressure is reduced to CO ２ The separation filter 43 separates CO ２ The additive remaining in the gas is ２ Separate from the gas.

[0024] The kneading device 20 further includes a return flow path 23. The return flow path 23 is used to return the CO separated from the kneaded product produced by kneading the materials. ２ The gas is allowed to flow through the return flow path 23, and the CO ２ The gas is guided to the upstream side of the first heat exchanger 32. Specifically, the return flow path 23 has an upstream end and a downstream end, and the upstream end is connected to the separation filter 43 of the kneading section 22, and the downstream end is connected to a flow path connecting the tank 31 and the first heat exchanger 32.

[0025] The return flow path 23 is for discharging the CO separated from the kneaded material in the kneading section 22. ２ The gas can be returned to the production section 21 through the return flow path 23, thereby reducing the CO 2 separated from the kneaded product. ２ Allows the gas to be recycled.

[0026] The overall configuration of the kneading device 20 shown in Fig. 1 is common to the second and subsequent embodiments described later. However, the specific configuration of the kneading device including the kneader according to the present invention is not limited to that shown in Fig. 1.

[0027] As shown in FIG. 2, the kneader 1 according to the first embodiment includes a chamber 2, a pair of rotors 3, a pair of lubricated bearings 4, a pair of non-lubricated bearings 5, a pair of first sealing members 6a, a pair of second sealing members 6b, and a pair of bearing supports 7.

[0028] The chamber 2 defines a kneading space 15, and kneading of the materials is carried out within the kneading space 15. The kneader 1 further includes a pair of supply / discharge ports 16 for mutual communication between the kneading space 15 and the outside of the kneader 1. In this embodiment, the pair of supply / discharge ports 16 are fixed to portions near the boundaries between the chamber 2 and the pair of bearing support portions 7, which will be described in detail later. The supply / discharge ports 16 allow supercritical CO 2 to be supplied into the kneading space 15 through the supply / discharge ports 16. ２ The supply and discharge port 16 allows the supercritical CO 2 in the kneading space 15 to be supplied. ２ is allowed to be discharged to the outside of the chamber 2.

[0029] The chamber 2 includes a chamber main body 2a, a pair of threaded portion accommodating portions 2b, and a lid member 8. The chamber main body 2a has a substantially cylindrical side wall surrounding the kneading space 15 and an end wall partially closing one of its ends in the rotor axial direction, and a pair of through holes is formed in the end wall to allow the pair of rotors 3 to pass through the end wall, respectively. The rotor axial direction is parallel to the pair of rotors 3, and corresponds to the up-and-down direction on the paper surface of FIG. 2. The pair of threaded portion accommodating portions 2b are aligned in a direction perpendicular to the rotor axial direction and are connected to the end wall of the chamber main body 2a so as to communicate with the kneading space 15 through the pair of through holes, respectively. The other end of the chamber main body 2a in the rotor axial direction (the lower end in FIG. 2) is entirely open to form an opening that exposes the kneading space 15, and the lid member 8 is detachably attached to the chamber main body 2a so as to close the opening.

[0030] The pair of bearing support portions 7 are each cylindrical, and are connected to the pair of thread portion accommodating portions 2b of the chamber 2 so as to extend from the pair of thread portion accommodating portions 2b to the side opposite the lid member 8. In other words, the lid member 8 is attached to the chamber main body 2a on the opposite side of the chamber main body 2a from the pair of bearing support portions 7.

[0031] The pair of rotors 3 extend in the rotor axial direction in a parallel orientation to each other, and are rotatably supported by the cover member 8 of the chamber 2 and the pair of bearing supports 7. The rotation of each of the pair of rotors 3 causes the supercritical CO ２ The material in the kneading space 15 is kneaded in the presence of the

[0032] Each of the pair of rotors 3 includes a rotor body 11, a first rotor shaft 12, a second rotor shaft 13, a first screw portion 14A, and a second screw portion 14B, which are arranged on a straight line extending in the rotor axial direction. The rotor body 11 is disposed in the kneading space 15. The rotor body 11 has helical teeth (not shown). The teeth have a shape that enables the rotor body 11 to knead the material by rotating in the kneading space 15.

[0033] The first rotor shaft 12 and the second rotor shaft 13 are located on both sides of the rotor body 11 in the rotor axial direction. The first rotor shaft 12 is one end of the rotor 3 in the rotor axial direction, and the second rotor shaft 13 is the other end of the rotor 3 in the rotor axial direction. The first and second rotor shafts 12, 13 each extend in the rotor axial direction. The first rotor shaft 12 is rotatably supported by the bearing support portion 7 via the lubricated bearing 4. The second rotor shaft 13 is rotatably supported by the chamber 2, specifically the lid member 8, via the unlubricated bearing 5. A motor (not shown) for rotating the rotor 3 is connected to the end of the first rotor shaft 12.

[0034] The first threaded portion 14A is interposed between the rotor body 11 and the first rotor shaft 12, and is accommodated with an appropriate gap in the corresponding threaded portion accommodating portion 2b of the pair of threaded portion accommodating portions 2b. The second threaded portion 14B is interposed between the rotor body 11 and the second rotor shaft 13, and a portion of the second threaded portion 14B is accommodated with an appropriate gap in a threaded portion accommodating recess 8b formed on the inner surface of the cover member 8. Each of the first and second threaded portions 14 has an outer peripheral surface on which a thread is formed. The helical direction of the thread of the first threaded portion 14A is a direction that can push back, toward the rotor body 11, the kneaded material that attempts to move toward the first rotor shaft 12 as the rotor 3 rotates. The spiral direction of the threads of the second screw portion 14B is opposite to the spiral direction of the threads of the first screw portion 14A, and is a direction that can push back, toward the rotor body 11, the kneaded material that attempts to move toward the second rotor shaft 13 as the rotor 3 rotates. Therefore, the first screw portion 14A can suppress the movement of the kneaded material to the lubricated bearing 4, and the second screw portion 14B can suppress the movement of the kneaded material to the unlubricated bearing 5.

[0035] The lubricated bearing 4 is a bearing lubricated with lubricating oil and constitutes a first bearing portion that rotatably supports the first rotor shaft 12. Specifically, the lubricated bearing 4 is disposed inside the bearing support portion 7 and rotatably supports the first rotor shaft 12 while being supported by the bearing support portion 7. The lubricated bearing 4 is, for example, a rolling bearing.

[0036] The dry bearing 5 is a bearing that does not contain lubricating oil, i.e., a bearing that is not lubricated by lubricating oil, and constitutes a second bearing portion that rotatably supports the second rotor shaft 13. The dry bearing 5 is disposed inside the cover member 8 and rotatably supports the end of the second rotor shaft 13 while being held by the cover member 8. Therefore, the second rotor shaft 13 is restrained inside the cover member 8 without passing through the cover member 8. The dry bearing 5 is, for example, a metal bushing.

[0037] The kneader 1 according to this embodiment further includes a pair of protective members 9. Each of the pair of protective members 9 is cylindrical and disposed around the first rotor shaft 12 so as to cover the entire outer circumferential surface of the first rotor shaft 12 at a position closer to the rotor body 11 than the lubricating bearing 4. That is, the protective member 9 is interposed between the outer circumferential surface of the first rotor shaft 12 and the inner circumferential surfaces of the pair of bearing supports 7. The protective member 9 can rotate together with the first rotor shaft 12 as the rotor 3 rotates. Meanwhile, the first rotor shaft 12 is configured to be separable from a portion of the rotor 3 adjacent to the first rotor shaft 12 (the first threaded portion 14A in this embodiment). This separation allows the protective member 9 to be extracted from between the bearing support 7 and the first rotor shaft 12 into the chamber 2 in the rotor axial direction, and also allows the protective member 9 to be inserted from the chamber 2 into between the bearing support 7 and the first rotor shaft 12 in the rotor axial direction.

[0038] The pair of first seals 6a and the pair of second seals 6b are respectively disposed inside the pair of bearing support portions 7 and are configured to prevent (suppress) leakage of fluid through gaps within the bearing support portions 7. Therefore, the first and second seals 6a, 6b prevent leakage of working fluid from the chamber 2 toward the motor, i.e., in the direction from the second rotor shaft 13 toward the first rotor shaft 12, at positions closer to the motor than the chamber 2. The first and second seals 6a, 6b also prevent leakage of fluid (e.g., lubricating oil) toward the chamber 2 from a side closer to the motor than the seals 6a, 6b. The first and second seals 6a, 6b are disposed in the bearing support portions 7 closer to the chamber 2 than the lubricated bearing 4, i.e., between the lubricated bearing 4 and the chamber 2.

[0039] The first seal 6a is annular and is interposed between the outer peripheral surface of the first rotor shaft 12 and the inner peripheral surface of the sliding member 9. The first seal 6a is, for example, a one-sided pressure seal with a built-in spring. The first seal 6a is fitted into an annular groove formed on the inner peripheral surface of the protective member 9. The kneader 1 may include a plurality of first seals 6a aligned in the rotor axial direction.

[0040] The second seal 6b is annular and is interposed between the outer circumferential surface of the protective member 9 and the inner circumferential surface of the bearing support portion 7. The second seal 6b is, for example, an O-ring. The second seal 6b is fitted into an annular groove formed in the outer circumferential surface of the protective member 9.

[0041] The outer peripheral surface of the protective member 9 comes into contact with the second seal material 6b instead of the outer peripheral surface of the first rotor shaft 12, thereby protecting the outer peripheral surface of the first rotor shaft 12. As the rotor 3 rotates, the outer peripheral surface of the protective member 9 may slide against the second seal material 6b in the rotational direction, and this sliding may promote wear and tear on the outer peripheral surface of the protective member 9 and reduce the sealing performance of the second seal material 6b. However, the protective member 9 can be removed from the first rotor shaft 12 and replaced with a new protective member 9. This makes it possible to significantly reduce the replacement frequency of the first rotor shaft 12 compared to when the outer peripheral surface of the first rotor shaft 12 comes into contact with the second seal material 6b.

[0042] The second seal material 6b is arranged on the opposite side of the chamber 2 with respect to the supply / discharge port 16 in the rotor axial direction. More specifically, the second seal material 6b is arranged between the supply / discharge port 16 and the lubricating bearing 4. The kneader 1 may include a plurality of second seal materials 6b arranged in the rotor axial direction.

[0043] The first and second seals 6a, 6b are disposed between the lubricated bearing 4, which is lubricated with lubricating oil, and the chamber 2, thereby preventing the lubricating oil from leaking into the kneading space 15 of the chamber 2, thereby preventing the lubricating oil from deteriorating the physical properties of the kneaded material. Furthermore, the first and second seals 6a, 6b can be easily replaced with the protective member 9 removed from between the bearing support portion 7 and the first rotor shaft 12.

[0044] On the other hand, the non-lubricated bearing 5 functioning as the second bearing does not contain lubricating oil, and therefore no sealing material is required between the non-lubricated bearing 5 and the chamber 2. This makes it possible to reduce the number of parts, including the sealing material, of the kneader 1. In addition, the use of the non-lubricated bearing 5 prevents lubricating oil from deteriorating the physical properties of the material kneaded in the kneading space 15.

[0045] FIG. 3 shows a modified example of the kneader 1 according to the first embodiment. In this modified example, the protective member 9 shown in FIG. 2 is omitted from each of the pair of bearing support portions 7. Also, instead of the first and second seals 6a and 6b shown in FIG. 2, only a single annular third seal 6c is disposed. The third seal 6c is in close contact with the outer circumferential surface of the first rotor shaft 12 and the inner circumferential surface of the bearing support portion 7 at a position between the supply / discharge port 15 and the lubricating bearing 4. Like the first and second seals 6a and 6b, the third seal 6c can also seal between the chamber 2 and the lubricating bearing 4. Alternatively, the kneader 1 may include a plurality of third seals 6c arranged in the rotor axial direction between the supply / discharge port 15 and the first bearing 4.

[0046] In the kneader 1 described above, the first and second seals 6a and 6b shown in Fig. 2 and the third seal 6c shown in Fig. 3 are all arranged between the chamber 2 and the motor to prevent leakage of the working fluid from the chamber 2 to the motor, thereby improving the sealing performance around the first rotor shaft 12. In order to be connected to the motor, the first rotor shaft 12 needs to be arranged to penetrate a member that contains the working fluid between the chamber 2 and the motor, which is the bearing support 7 in the kneader 1 shown in Figs. 2 and 3. However, each of the first and second seals 6a and 6b and the third seal 6c can effectively prevent leakage of the working fluid from the chamber 2 to the motor between the first rotor shaft 12 and the bearing support 7.

[0047] Furthermore, since the non-lubricated bearing 5 constituting the second bearing portion does not contain lubricating oil, deterioration of the physical properties of the kneaded material is suppressed. Although the lubricating oil may be mixed into the kneaded material and thereby deteriorate the physical properties of the kneaded material, the fact that the second bearing portion is constituted by the non-lubricated bearing 5 reduces the possibility that the lubricating oil will be mixed into the kneaded material, thereby suppressing deterioration of the physical properties of the kneaded material.

[0048] Furthermore, since the non-lubricated bearing can have a simpler structure than a lubricated bearing such as a rolling bearing, the kneader 1 can have a simpler configuration than, for example, a case in which both the first bearing portion and the second bearing portion include lubricated bearings. This makes it possible, for example, to easily perform maintenance of the kneader 1.

[0049] On the other hand, the chamber 2 includes the chamber main body 2a and the cover member 8. The chamber main body 2a has an opening that exposes the kneading space 15 at an end closer to the second rotor shaft 13 in the rotor axial direction. The cover member 8 is detachably attached to the chamber main body 2a so as to close the opening, thereby enabling easy maintenance through the opening. Moreover, the non-lubricated bearing 5, which serves as the second bearing, is disposed inside the cover member 8 to support the end of the second rotor shaft 13, so that the second rotor shaft 13 can be supported without penetrating the cover member 8. This eliminates the need to dispose a seal around the second rotor shaft 13 to prevent leakage of the working fluid from the chamber 2, thereby enabling a reduction in the number of parts, including the seal, of the entire kneader 1. In other words, the kneader 1 can have a simple structure, which makes it easier to perform maintenance of the kneader 1. Furthermore, the fact that a sealant between the dry bearing 5 and the chamber 2 is not required makes it possible to shorten the distance between the lubricated bearing 4 constituting the first bearing portion and the dry bearing 5 constituting the second bearing portion, thereby suppressing eccentricity of the rotor 3. This makes it possible to suppress bearing seizure and the like caused by eccentricity of the rotor 3.

[0050] 2 and the third seal 6c shown in Fig. 3 are arranged between the lubricating bearing 4 and the chamber 2 so as to prevent leakage of fluid from the motor to the chamber 2, thereby suppressing leakage of lubricating oil from the lubricating bearing 4 into the kneading space 15 of the chamber 2. This prevents the lubricating oil from mixing with the kneaded material and suppresses the lubricating oil from deteriorating the physical properties of the kneaded material.

[0051] Furthermore, since lubricated bearings are generally less susceptible to wear than non-lubricated bearings and can have a longer lifespan, constructing the first bearing portion from the lubricated bearing 4 may potentially reduce the frequency of maintenance work on the first bearing portion.

[0052] FIG. 4 shows a kneader 101 according to a second embodiment of the present invention. The kneader 101 includes a dry bearing 51 in addition to the components of the kneader 1 shown in FIG. 3. The dry bearing 51, together with the lubricated bearing 4, is disposed inside the bearing support portion 7 to form a first bearing portion. That is, the dry bearing 51, together with the lubricated bearing 4, rotatably supports the first rotor shaft 12 at a position in the bearing support portion 7 between the third seal member 6c and the chamber 2. The dry bearing 51 is therefore located between the chamber 2 and the lubricated bearing 4. The dry bearing 51 is also located between the supply / discharge port 15 and the lubricated bearing 4 in the rotor axial direction.

[0053] 3, the kneader 101 does not include the protective member 9 shown in Fig. 2, and the only sealing material in each bearing support portion 7 is the annular third sealing material 6c. The third sealing material 6c is located between the lubricated bearing 4 and the unlubricated bearing 51 in the rotor axial direction. Alternatively, the kneader 101 may include a plurality of third sealing materials 6c lined up in the rotor axial direction between the lubricated bearing 4 and the unlubricated bearing 51.

[0054] The non-lubricated bearing 51 is disposed closer to the chamber 2 than the lubricated bearing 4 and constitutes the first bearing portion that rotatably supports the first rotor shaft 12 together with the lubricated bearing 4, thereby suppressing eccentricity of the rotor 3 and suppressing bearing seizure and the like caused by the eccentricity. Furthermore, because the non-lubricated bearing 51 is located closer to the chamber 2 than the third seal material 6c, the distance between the non-lubricated bearing 51 and the second bearing portion (non-lubricated bearing 5 in FIG. 4 ) can be shortened, thereby more effectively suppressing eccentricity of the rotor 3. Moreover, because the non-lubricated bearing 51 does not contain lubricating oil, it is possible to suppress the deterioration of the physical properties of the kneaded material in the kneading space 15 of the chamber 2 due to lubricating oil, even though the non-lubricated bearing 51 is located closer to the chamber 2 than the third seal material 6c.

[0055] 5 shows a mixer 201 according to a third embodiment of the present invention. In the mixer 201, the first bearing portion in each of the pair of bearing supports 7 includes only a non-lubricated bearing 51, and does not include a lubricated bearing, such as the lubricated bearing 4 shown in FIG.

[0056] Like the kneader 101 according to the second embodiment, the kneader 201 does not include the protective member 9 shown in FIG. 2 and only includes an annular third seal 6c as a seal. The third seal 6c is arranged on the opposite side of the non-lubricated bearing 51 from the chamber 2, that is, on the side closer to the motor than the non-lubricated bearing 51. The kneader 201 may also include a plurality of third seals 6c arranged in the rotor axial direction between the non-lubricated bearing 51 and the motor. The third seals 6c may also be arranged in a position closer to the chamber 2 than the non-lubricated bearing 51.

[0057] The first bearing portion of the kneader 201 may further include, in addition to the unlubricated bearing 51, an unlubricated bearing disposed between the supply / discharge port 15 and the unlubricated bearing 51, or between the unlubricated bearing 51 and the third seal material 6c. Increasing the number of bearings supporting the shaft portion of the rotor 3 makes it possible to more effectively suppress eccentricity of the rotor 3, and thereby makes it possible to more effectively suppress bearing seizure and the like caused by the eccentricity.

[0058] Although the embodiments of the present invention have been described above, they are merely illustrative examples and do not limit the present invention, and the specific configurations and other aspects can be appropriately modified in design. Furthermore, the actions and effects described in the embodiments of the invention are merely a list of the most preferred actions and effects resulting from the present invention, and the actions and effects of the present invention are not limited to those described in the embodiments of the present invention.

[0059] 2 to 5 may have the same or different configurations of the first and second bearing portions and sealing materials provided for each of the pair of rotors 3. For example, when the motor is connected to only the first rotor shaft 12 of one of the pair of rotors 3, the first bearing portion supporting the first rotor shaft 12 connected to the motor may include only the lubricated bearing 4, while the first bearing portion supporting the first rotor shaft 12 not connected to the motor may include only a non-lubricated bearing.

[0060] When the first bearing portion is configured by a non-lubricated bearing, for example, the non-lubricated bearing 51 shown in Fig. 4, the second bearing portion may include a lubricated bearing. In this case, it is preferable that a sealant be disposed between the lubricated bearing included in the second bearing portion and the chamber 2.

[0061] The present invention is not limited to a kneader having a pair of rotors 3, but can also be applied to a kneader having only a single rotor.

[0062] As described above, a kneading machine is provided that can suppress deterioration in the physical properties of the kneaded material and has high sealing performance for the rotor shaft. The kneading machine kneads materials in the presence of a working fluid in a supercritical or subcritical state. The kneading machine includes a chamber, a rotor, a first bearing, a second bearing, and a seal. The chamber defines a kneading space in which the materials are kneaded. The rotor includes a first rotor shaft, a rotor body, and a second rotor shaft, which are aligned in the rotor axial direction. The first rotor shaft is at one end in the rotor axial direction and is connected to a motor. The second rotor shaft is at the other end in the rotor axial direction. The rotor body is located between the first rotor shaft and the second rotor shaft and rotates in the kneading space to perform the kneading. The first bearing rotatably supports the first rotor shaft. The second bearing rotatably supports the second rotor shaft. The seal is disposed at a position closer to the motor than the chamber so as to prevent leakage of the working fluid from the chamber toward the motor. At least one of the first bearing portion and the second bearing portion is configured as a non-lubricated bearing that does not contain lubricant oil. The kneader has high sealing performance and can suppress deterioration of the physical properties of the material kneaded in the kneading space.

[0063] In the kneader, each of the first bearing unit and the second bearing unit may include the non-lubricated bearing, which makes it possible to more reliably prevent lubricating oil from deteriorating the physical properties of the material.

[0064] The chamber may include a chamber body having an opening for opening the kneading space at one of both ends in the rotor axial direction closer to the second rotor shaft, and a cover member attached to the chamber body so as to close the opening. In this case, it is preferable that the second bearing portion is constituted by the non-lubricated bearing, and the non-lubricated bearing is fixed to the cover member. This makes it possible to suppress deterioration of the physical properties of the material kneaded in the kneading space by lubricating oil while ensuring high airtightness of the kneading space.

[0065] The first bearing portion may include a lubricated bearing lubricated with lubricating oil. In this case, the sealing material is disposed between the lubricated bearing and the chamber so as to prevent leakage of fluid from the lubricated bearing to the chamber, thereby making it possible to suppress leakage of lubricating oil from the lubricated bearing to the kneading space in the chamber using the sealing material, regardless of whether the lubricated bearing is in use.

[0066] Alternatively, the first bearing portion may include the non-lubricated bearing, and the non-lubricated bearing may be disposed between the sealing material and the chamber. Such an arrangement of the non-lubricated bearing makes it possible to reduce the distance between the non-lubricated bearing and the second bearing portion and to suppress eccentricity of the rotor, while suppressing deterioration of the physical properties of the kneaded material due to lubricating oil.

Claims

1. A kneader for kneading materials in the presence of a working fluid in a supercritical or subcritical state, comprising: a chamber defining a kneading space in which the material is kneaded; a rotor including a first rotor shaft portion, a rotor body, and a second rotor shaft portion aligned in the rotor axial direction, the first rotor shaft portion being one end in the rotor axial direction and connected to a motor, the second rotor shaft portion being the other end in the rotor axial direction, the rotor body being located between the first rotor shaft portion and the second rotor shaft portion and rotating within the kneading space to perform the kneading; a first bearing portion rotatably supporting the first rotor shaft portion; a second bearing portion rotatably supporting the second rotor shaft portion; and a sealing material positioned closer to the motor than the chamber so as to prevent leakage of the working fluid from the chamber toward the motor, wherein at least one of the first bearing portion and the second bearing portion is constituted by an unlubricated bearing that does not contain lubricating oil.

2. A kneader according to claim 1, wherein each of said first bearing portion and said second bearing portion includes said unlubricated bearing.

3. A kneading machine as described in claim 1, wherein the chamber includes a chamber body having an opening that opens the kneading space at one of both ends in the rotor axial direction that is closer to the second rotor shaft, and a cover member attached to the chamber body so as to cover the opening, and the second bearing portion is constituted by the non-lubricated bearing, and the non-lubricated bearing is fixed to the cover member.

4. A kneader as claimed in claim 1, wherein the first bearing portion includes a lubricated bearing lubricated by lubricating oil, and the seal material is positioned between the lubricated bearing and the chamber so as to prevent leakage of fluid from the lubricated bearing to the chamber.

5. A kneader according to claim 1, wherein the first bearing portion includes the non-lubricated bearing, the non-lubricated bearing being disposed between the seal material and the chamber.

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