JP5404236B2 - Kneading device and kneading molding device - Google Patents

Description

  The present invention relates to a kneading apparatus and a kneading and forming apparatus, and more particularly to a melt kneading apparatus and a melt kneading and forming apparatus used for kneading polymer materials.

  2. Description of the Related Art Conventionally, as a device for kneading a polymer material, a melt kneading device that applies a shearing force to a melted polymer material while controlling its temperature is known. According to the melt-kneading apparatus, a polymer material is uniformly kneaded and a material to be kneaded having high dispersibility can be obtained.

  As an example of such a kneading apparatus, Patent Document 1 describes a kneading apparatus that includes two screws that are reduced in diameter at the tip and operate in directions facing each other. According to the kneading apparatus described in Patent Document 1, pressure is applied to the polymer material with a screw whose tip is reduced in diameter, and a shearing force is applied to the polymer material at a portion where the screws mesh with each other. As a result, the dispersibility of the material to be kneaded with the molten polymer material can be enhanced.

However, when a high shear force is applied to the molten polymer material, the polymer material itself generates heat due to shear heat generation. In addition, when a shearing force is applied at a high pressure, the kneadability of the polymer material is enhanced while shearing heat generation is increased.
For this reason, the conventional kneading apparatus such as the kneading apparatus described in Patent Document 1 has a problem that the polymer material excessively generates heat due to shearing heat generation and deteriorates or decomposes.

US Pat. No. 6,129,450

  In order to solve the problem of degradation or decomposition due to heat generation of the polymer material, it is conceivable to provide temperature control means such as water cooling or air cooling in the kneading cylinder in which the screw is arranged. However, in the circulation-type kneading apparatus described in Patent Document 1, when the polymer material is rapidly cooled using the temperature control means, it takes time to adjust the temperature during processing by the kneading cylinder. There was a problem of poor productivity.

  Moreover, in the kneading apparatus described in Patent Document 1, since shearing heat is generated particularly at the portion where the screw is engaged, the temperature of the molten polymer material is uneven. When the temperature of the molten polymer material is cooled by water cooling or air cooling, there is a problem that the apparatus configuration for temperature control becomes very complicated and the manufacturing cost of the kneading apparatus itself increases.

  For this reason, it has been difficult to suitably suppress shearing heat generated in the polymer material by means of cooling the polymer material by water cooling or air cooling.

  The present invention has been made in view of the above-described circumstances, and its purpose is to produce a kneaded material with good dispersibility by imparting a high shearing force while suppressing deterioration and decomposition of the polymer material. It is to provide a kneading apparatus that can be used.

In order to solve the above problems, the present invention proposes the following means.
The kneading apparatus of the present invention includes at least one cylinder to which a polymer material is supplied, a screw that is disposed in each cylinder and is rotated to convey the polymer material in one direction, and each cylinder. The polymer material is provided so as to open downstream in the transport direction of the polymer material, and is provided between a discharge path for discharging the polymer material, the discharge path and the cylinder, and the polymer material is disposed in the cylinder. A return path that returns the polymer material to the upstream side in the conveyance direction, and the cross-sectional area of each of the discharge path and the return path is set such that the cross-sectional area of the discharge path> the cross-sectional area of the return path It is characterized by being.

  Further, the kneading apparatus of the present invention may include a plurality of sets of the screw and the cylinder, the discharge path further includes a merging portion that merges with each other, and the return path may be communicated with the plurality of cylinders. .

  In addition, the kneading apparatus of the present invention may further include a material transport unit that communicates with the discharge path and melts the polymer material and transports the polymer material into the discharge path.

The kneading and forming apparatus of the present invention is characterized by comprising the kneading apparatus of the present invention and a molding unit for forming the material to be kneaded into a predetermined shape in the kneading apparatus.
According to this invention, since the molding unit is provided in the kneading apparatus, the steps of kneading and molding can be performed continuously, so that the production lead time can be shortened. Moreover, since mixing of air into the kneaded material to be kneaded can be suppressed, mixing of air bubbles into the molded product can be suppressed.

According to the kneading apparatus of the present invention, it is possible to produce a material to be kneaded with good dispersibility by applying a high shearing force while suppressing deterioration and decomposition of the polymer material.
Moreover, according to the kneading and molding apparatus of the present invention, it is possible to reduce production lead time when molding the material to be kneaded and to suppress the mixing of bubbles into the molded product.

(A) is a top view which shows the structure of the kneading apparatus of 1st Embodiment of this invention in a partial cross section, (B) is sectional drawing which expands and shows a part of structure of the kneading apparatus. It is a top view which shows the structure of the kneading apparatus of 2nd Embodiment of this invention in a partial cross section. It is a top view which shows the structure of the kneading apparatus of 3rd Embodiment of this invention in a partial cross section. It is a side view which shows the structure of the kneading apparatus. It is a front view which shows the structure of the kneading apparatus of 4th Embodiment of this invention. It is a side view which shows the modification of the kneading apparatus.

(First embodiment)
Hereinafter, the kneading apparatus of the first embodiment of the present invention will be described with reference to FIGS. 1 (A) and 1 (B).
FIG. 1A is a schematic configuration diagram of the kneading apparatus of the present embodiment, and is a plan view of a part of the kneading apparatus 100 as a cross-sectional view. FIG. 1B is an enlarged cross-sectional view showing a part of the configuration of the kneading apparatus 100. As shown in FIG. 1 (A) and FIG. 1 (B), the kneading apparatus 100 is disposed in the cylinder 3 to which the polymer material M is supplied, and is rotationally driven by the drive unit 1 by being disposed in the cylinder 3. And a screw 2 for conveying the polymer material M in one direction (direction a to b in the figure).

  Hereinafter, in the present specification, the direction in which the polymer material M is conveyed will be described with the a side in the cylinder 3 being the upstream side and the b side being the downstream side.

  The screw 2 is provided so as to extend spirally along the outer peripheral surface of the screw 2 to form a ridge 12. A continuous groove is formed between the ridges 12, and a space C for conveying the polymer material M is formed between the screw 2 and the cylinder 3.

  The cylinder 3 is provided with a band heater 4 fixed to the outer peripheral surface. The band heater 4 includes a heating element that generates heat when power is supplied, for example, and heats the cylinder 3 and the space C.

  An extrusion tip 8 is fixed downstream of the cylinder 3. The extrusion tip 8 is provided with a discharge path 6 that is open and formed so that one end communicates with the space C. In this embodiment, the discharge path 6 has a circular shape with a radial cross section having a diameter S1. A loading / unloading valve 5 for carrying the polymer material M into the discharge path 6 and discharging the kneaded material to be kneaded from the discharge path 6 is attached to the discharge path 6. Further, the carry-in / out valve 5 is integrally configured with a thermocouple (not shown) for detecting the temperature inside the discharge path 6.

  A cylindrical flow pipe 7 is provided between the discharge path 6 and the cylinder 3. One end 7 a of the flow pipe 7 is connected to the discharge path 6, and the other end 7 b of the flow pipe 7 is connected to the cylinder 3 so as to communicate with the space C of the cylinder 3. The inside of the flow pipe 7 has a circular shape with a radial cross section having an inner diameter of S2, and becomes a return path 9 for returning the polymer material M to the upstream side in the transport direction of the polymer material M in the cylinder 3. Yes.

  As shown in FIG. 1B, the respective diameters of the discharge path 6 and the return path 9 satisfy S1> S2, that is, the cross-sectional area in the radial direction of the discharge path 6> the cross section in the radial direction of the return path 9. It is an area.

The operation of the kneading apparatus of the present embodiment having the configuration described above will be described with reference to FIGS. 1 (A) and 1 (B).
In the kneading apparatus 100, the polymer material M is supplied to the cylinder 3 through the loading / unloading valve 5. When the drive unit 1 is driven, the screw 2 is rotated around the axis. In a portion where the spiral ridge 12 formed on the outer peripheral surface of the screw 2 and the polymer material M are in contact with each other, the rotational motion of the screw 2 is converted into thrust in the axial direction of the screw 2. Then, the polymer material M is conveyed to the tip of the screw 2 (direction b shown in FIG. 1A). Here, the polymer material M is heated and melted by the band heater 4.

  The polymer material M is pushed out of the cylinder 3 by the thrust of the screw 2 and moves into the discharge path 6. Further, the polymer material M is pressed and moved from the discharge path 6 to the return path 9.

  Here, as shown in FIG. 1B, at the boundary portion L0 between the discharge path 6 and the return path 9, the polymer material M in the discharge path 6 having the diameter S1 has a diameter S2 smaller than the diameter S1. Into the return path 9 having At this time, adiabatic compression occurs in the polymer material M, and the pressure applied to the polymer material M becomes a pressure P1 higher than the pressure P0 in the discharge path 6.

  In the molten polymer material M, even when the temperature is equal, the apparent viscosity decreases when the applied pressure is high. Therefore, the fluidity of the polymer material M at the pressure P1 inside the return path 9 having the diameter S2 is higher than the fluidity at the pressure P0.

  Although the degree of the apparent viscosity change with respect to the pressure change varies depending on the type of the polymer material M, the polymer material M applied with the pressure P1 higher than the pressure P0 is in the discharge path 6 in the vicinity of the central axis of the return path 9. It circulates at a flow velocity V1 that is faster than the flow velocity V0. On the other hand, in the vicinity of the wall surface of the return path 9, the flow rate of the polymer material M is slower than the flow rate V1 due to the resistance between the polymer material M and the wall surface of the return path 9. For this reason, as indicated by reference numerals L1 to L3 in FIG. 1B, a difference occurs in the moving distance of the polymer material M between the vicinity of the central axis of the feedback path 9 and the vicinity of the wall surface of the feedback path 9, and the central axis Shear stress is generated in the direction.

  Accordingly, the polymer material M that has flowed in at the boundary portion L0 is curved at the boundary surface as indicated by, for example, L3 while passing through the feedback path 9, and the polymer material near the central axis of the feedback path 9 M first flows back to the cylinder 3. Thus, the polymer material M circulating through the space C, the discharge path 6 and the return path 9 is dispersed and uniformly kneaded due to the difference in the time for which the polymer material M is refluxed.

  By the way, when the polymer material M flows into the return path 9, heat is generated by adiabatic compression, and when the polymer material M passes through the return path 9, shear heat is generated by receiving shear stress. To do. Here, these heat generations occur during the period from when the polymer material M flows into the return path 9 until it flows out of the return path 9. Further, when the polymer material M flows out from the return path 9, it flows into the space C wider than the return path 9 having the diameter S <b> 2 and the shear stress generated between the inner wall surface of the return path 9. Disappears. For this reason, the temperature of the polymer material M in the space C is lower than when the polymer material M is in the return path 9.

  In the kneading apparatus 100, the polymer material M circulating through the space C, the discharge path 6, and the return path 9 is dispersed and uniformly kneaded, and a material to be kneaded in which the polymer material M is uniformly kneaded is produced. The material to be kneaded is carried out of the kneading apparatus 100 through the carry-in / out valve 5 and subsequently used for an appropriate processing step.

  As described above, according to the kneading apparatus 100 according to the present embodiment, the polymer material M is kneaded by the shear stress generated between the inner wall surface of the return path 9 and the shearing heat generated in the polymer material M is returned. Heat is dissipated when it flows from the path 9 to the space C. For this reason, even if the polymer material M is circulated and kneaded in the kneading apparatus 100, the accumulation of shear heat is suppressed in the polymer material M. Therefore, it is possible to produce a material to be kneaded with good dispersibility by imparting a high shearing force while suppressing deterioration and decomposition of the polymer material.

(Second Embodiment)
Next, the kneading apparatus of 2nd Embodiment of this invention is demonstrated with reference to FIG. In each embodiment described below, portions having the same configuration as those of the kneading apparatus 100 of the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

  FIG. 2 is a diagram showing a schematic configuration of the kneading apparatus of the present embodiment, and is a plan view in which a part of the kneading apparatus is viewed in cross section. As shown in FIG. 2, the kneading apparatus 200 of the present embodiment is different in configuration from the kneading apparatus 100 of the first embodiment in that it includes two sets of screws 2 and cylinders 3.

  Further, belts 1a and 1b are interposed between the drive unit 1 and the screw 2. The rotational force of the drive unit 1 is transmitted to the screw 2a by the belt 1a, and the rotational operation of the screw 2a is screwed by the belt 1b. 2b.

  Further, an extrusion tip portion 18 is provided instead of the extrusion tip portion 8. The extrusion tip 18 has discharge paths 16a and 16b instead of the discharge path 6, and one end thereof is opened on the downstream side of the cylinders 3a and 3b. In this embodiment, the other end of each of the discharge paths 16a and 16b is a merged part 16c.

  Further, in place of the flow pipe 7, a flow pipe 17 provided between the merging portion 16c and the cylinders 3a and 3b is provided. In the lumen of the flow pipe 17, the discharge paths 16a and 16b and the spaces Ca and Cb are provided. And a return path 19 that communicates with each other.

  The merge portion 16c has a cross-sectional area equal to the sum of the cross-sectional areas in the radial direction of the discharge paths 16a and 16b and communicates with the post-merging pipe line 16d. The post-merging pipe line 16d functions as a part of the discharge path and has a cross-sectional area equal to the sum of the cross-sectional areas in the radial direction of the discharge paths 16a and 16b and communicates with the return path 19. In the return path 19, the opening area on the side of the post-merging pipe line 16d is smaller than the sum of the cross-sectional areas of the discharge paths 16a and 16b.

  The return path 19 is branched to the cylinders 3a and 3b. The sum of the cross-sectional areas of the return path 19 from the branch (branch portion 19a) to the cylinders 3a and 3b is the post-merging pipe. It is equal to the cross-sectional area on the side of the path 16d.

  Thus, in the kneading apparatus 200 of the present embodiment, the merging portion 16c in which the discharge paths 16a and 16b are assembled is connected to the return path 19 via the post-merging pipe line 16d. The cross-sectional areas of the post-merging pipe line 16d and the return path 19 satisfy the cross-sectional area of the post-merging pipe line 16d> the cross-sectional area of the return path 19. Further, the relationship of the sum of the cross-sectional areas in the radial direction of the discharge paths 16a and 16> the sum of the cross-sectional areas in the radial direction of the return path 19 is also satisfied. Accordingly, the polymer material M is kneaded by the shear stress generated between the inner wall surface of the return path 19 and the shearing heat generated in the polymer material M from the return path 19 to the space Ca similarly to the kneading apparatus 100 of the first embodiment. The heat is dissipated when it flows out to Cb. For this reason, even if the polymer material M is circulated and kneaded in the kneading apparatus 200, shear heat generation is suppressed from being accumulated in the polymer material M. Therefore, it is possible to produce a material to be kneaded with good dispersibility by imparting a high shearing force while suppressing deterioration and decomposition of the polymer material. Moreover, in this embodiment, the joining part 19 is provided and it has the kneading | mixing effect by the joining of the polymeric material M. FIG.

(Third embodiment)
Next, a kneading apparatus according to a third embodiment of the present invention will be described with reference to FIGS.
FIG. 3 is a schematic configuration diagram of the kneading apparatus of the present embodiment, and is a plan view showing a part of the kneading apparatus in a sectional view. FIG. 4 is a side view of the kneading apparatus.
As shown in FIG. 3 and FIG. 4, the kneading apparatus 300 of the present embodiment is different in configuration from the kneading apparatus 200 of the second embodiment in that it includes a material transport unit 35.
The material transport unit 35 is disposed in the cylinder 23 to which the polymer material M is supplied, and is rotationally driven by the driving unit 11 via the belt 11a, thereby causing the polymer material M to move in one direction (cylinder 3a). 3b side).

  The screw 22 has a spiral ridge portion 12 like the screw 2, and a space Cc for conveying the polymer material M is generated between the screw 22 and the cylinder 23.

  The cylinder 23 is provided with a hopper 34 for storing material and supplying it to the space Cc. The cylinder 23 has a built-in heater 24. For example, the heater 24 has a heating element that generates heat when electric power is supplied to heat the cylinder 23 and the space Cc.

  An extrusion tip portion 28 provided in place of the extrusion tip portion 18 is fixed on the downstream side of the cylinder 23. In the extrusion tip portion 28, a valve 26c is provided in the junction portion 16c, and the valve 26c is operated so that the communication state of the input path 31 between the cylinder 23 and the discharge paths 26a and 26b becomes an open state or a closed state. . Further, as shown in FIG. 4, the valve 26c is configured such that the flow path can be selected so as to connect the discharge port 33 opened to the outside of the kneading apparatus 300 and the discharge paths 26a and 26b.

  In this embodiment, the temperature of the polymer material M is measured by a thermocouple 25 provided in the flow pipe 17.

  In the kneading apparatus 300 of this embodiment, the pellets of the polymer material M stocked in the hopper 34 in the material transport unit 35 are sent into the space Cc by their own weight. The polymer material M sent to the space Cc is melted by a heater built in the cylinder 23. The melted polymer material M is conveyed toward the extrusion tip portion 28 by the rotation operation of the screw 22, and each of the discharge route 26 a, 26 b, the merging portion 16 c, the post-merging conduit 16 d, and the return route 19 from the charging path 31. Through the spaces Ca and Cb.

  Subsequently, the introduction path 31 is closed by the valve 26c, and the polymer material M is kneaded in the same manner as the kneading apparatus 200 of the second embodiment. When the kneading step of the polymer material M is completed, the discharge paths 26a and 26b and the discharge port 33 are communicated with each other by the valve 26c, and the material to be kneaded with the polymer material M is discharged through the discharge port 33. This material to be kneaded is used in an appropriate post-process.

Also in the present embodiment, like the kneading apparatus 200 of the second embodiment, the merging portion 16c in which the discharge paths 26a and 26b are gathered and the return path 19 are connected via the post-merging pipe line 16d. The cross-sectional areas of the post-merging pipe line 16 d and the return path 19 satisfy the cross-sectional area of the post-merging pipe line 16 d> the return path 19.
Therefore, like the kneading apparatus 200 of the second embodiment, the polymer material M is kneaded by the shear stress generated between the inner wall surface of the return path 19 and the shear heat generated in the polymer material M is generated from the return path 19 to the space Ca. The heat is dissipated when it flows out to Cb.

  For this reason, even if the polymer material M is circulated and kneaded in the kneading apparatus 200, shear heat generation is suppressed from being accumulated in the polymer material M. Therefore, it is possible to produce a material to be kneaded with good dispersibility by imparting a high shearing force while suppressing deterioration and decomposition of the polymer material.

  In addition, the polymer material M is melted by the heater 24 in the material transport unit 35, and the respective paths are filled with the polymer material M in order from the charging path 31. For this reason, it is suppressed that a bubble remains in each path | route.

(Fourth embodiment)
Next, a kneading and forming apparatus according to a fourth embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a side view of the kneading and forming apparatus of the present embodiment. FIG. 6 is a side view showing a modification of the kneading and forming apparatus of the present embodiment.

As shown in FIG. 5, the kneading and forming apparatus 400 of the present embodiment is different from the kneading apparatus 300 of the third embodiment in that the forming die 41 communicated with the discharge port 33 and the high amount discharged to the outside through the forming die 41. A take-up machine 42 is further provided for pulling the material to be kneaded of the molecular material M vertically below the mold 41. A molding part 43 is constituted by the molding die 41 and the take-up machine 42.
The take-up machine 42 has a pulley 42a that changes the direction of the material to be kneaded and a main body 42b that winds up the material to be kneaded.

  In the present embodiment, the material to be kneaded of the polymer material M discharged from the discharge port 33 is sent to the molding die 41. In the molding die 41, the material to be kneaded is shaped into a predetermined shape such as a tube shape, for example, following a predetermined mold shape, and then the molded material to be kneaded is discharged from the molding die 41. Further, the material to be kneaded discharged from the mold 41 is taken up by the take-up machine 42, and a molded product that is cooled and solidified by air is produced.

  As described above, according to the kneading and forming apparatus 400 of this embodiment, since the material to be kneaded discharged from the discharge port 33 can be continuously formed to produce a molded product, the production lead time of the molded product can be reduced. It can be shortened.

  Further, since the material to be kneaded discharged from the molding die 41 can be taken vertically downward in the molding part 43, the influence of the bending of the molded product in the process in which the material to be kneaded is cooled and solidified by air is reduced. The molding accuracy of the molded product can be kept high.

(Modification)
Below, the modification of the kneading-molding apparatus of this embodiment is demonstrated with reference to FIG. FIG. 6 is a side view of a kneading and forming apparatus 500 of this modification.
As shown in FIG. 6, the kneading and forming apparatus 500 of this modification includes a forming unit 51 instead of the forming unit 43. Unlike the molding part 43, the molding part 51 is a molding part that can be suitably applied to injection molding.

  Also in this modified example, since the material to be kneaded discharged from the discharge port 33 can be continuously formed to produce a molded product, as in the fourth embodiment described above, the production lead time of the molded product can be increased. It can be shortened.

As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.
For example, in each embodiment of the present invention, an example is shown in which the diameter of the return path is configured to be smaller than the diameter of the discharge path. If there is a small-diameter portion whose cross-sectional area is smaller than the cross-sectional area of the discharge path, the effect of the present invention can be achieved.

  In the first embodiment of the present invention, an example in which the discharge path 6 and the return path 9 have a circular cross section in the radial direction is shown. However, the present invention is not limited thereto, and the relationship of the cross-sectional area of the discharge path> the cross-sectional area of the return path. Other shapes can be adopted as long as the above is satisfied. For example, the shape of the radial cross section of the discharge path and the return path may be polygonal, or the shape of the radial cross section of the discharge path and the return path may be different from each other.

  In the second embodiment of the present invention, the post-merging pipe line 16d is configured to be a part of the discharge path. However, the present invention is not limited to this, and the merging portion 16c is the discharge path. A configuration that is a part of the return path, and in which the cross-sectional area of the post-merging pipe line 16d is smaller than the sum of the cross-sectional areas of the discharge paths 16a and 16b and the cross-sectional area of the merging portion 16c may be employed.

Further, the constituent elements shown in the above-described embodiments and modifications can be combined as appropriate.
For example, the material conveyance part 35 demonstrated in 3rd Embodiment can be combined suitably also with the kneading apparatus 100 of 1st Embodiment. In other words, the material carrying part 35 can be provided instead of the carry-in / out valve 5. In this case, the material conveying unit 35 is configured to communicate with the discharge path 6 at the extrusion tip 8, and the polymer material M can be filled into the space C inside the cylinder 3 through the discharge path 6 and the return path 9. .

2, 2a, 2b Screw 3, 3a, 3b Cylinder 6, 16a, 16b, 26a, 26b Discharge path 9, 19 Return path 16c Merging part 35 Material conveying part 43, 51 Molding part

Claims (4)

At least one cylinder to which a polymer material is supplied;
A screw that is disposed in each cylinder and is driven to rotate to convey the polymer material in one direction;
A discharge path that is provided so as to open to the downstream side in the conveying direction of the polymer material of each cylinder, and discharges the polymer material;
A return path that is provided between the discharge path and the cylinder and returns the polymer material to the upstream side in the transport direction of the polymer material in the cylinder;
With
The cross-sectional area of each of the discharge path and the return path in the radial direction is the cross-sectional area of the discharge path> the cross-sectional area of the return path,
Kneading device. A plurality of sets of the screw and the cylinder are provided,
The discharge path further includes a merge portion that merges with each other,
The return path communicates with a plurality of the cylinders;
The kneading apparatus according to claim 1.   3. The kneading apparatus according to claim 1, further comprising a material transport unit that communicates with the discharge path, melts the polymer material, and transports the polymer material into the discharge path. A kneading apparatus according to any one of claims 1 to 3,
A molding part for molding the material to be kneaded into a predetermined shape in the kneading apparatus;
A kneading and forming apparatus.

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