JP6996248B2 - Kneading method and equipment for rubber materials - Google Patents

Description

The present invention relates to a method and an apparatus for kneading a rubber material, and more particularly, a rubber capable of more evenly dispersing a powdery compounding agent in a raw material rubber without excessive compression by using a closed type kneader. It relates to a kneading method and an apparatus for materials.

When manufacturing rubber products such as tires, various rubber members are used. A closed type kneader (so-called Banbury mixer) is known as a facility for kneading a rubber material that is a material for a rubber member. The closed kneader has a specification provided with a meshing rotor in which a set of rotors is arranged so as to mesh with each other inside the kneading chamber (see, for example, Patent Document 1).

The raw rubber and the powdery compounding agent charged into the kneading chamber are kneaded by the rotating rotors while being pressed downward by the ram having the upper end opening of the kneading chamber closed. In the case of a meshing rotor, the volume of the gap between the rotors and the receiving space above the rotors varies relatively greatly depending on the phase due to the rotation of the set of rotors. Therefore, if the ram pressure is increased when the gap between the rotors is narrowed, the powdery compounding agent may be excessively compressed between the rotors. Along with this, the powdery compounding agent is firmly solidified into a lump that is hard to break, and there arises a problem that it cannot be evenly dispersed in the raw rubber. Even if it is not a meshing rotor, the same problem occurs when the volume fluctuation of the gap between the rotors and the receiving space above the rotors is relatively large due to the phase due to the rotation of the set of rotors.

Japanese Patent Application Laid-Open No. 2003-277861

An object of the present invention is to provide a method and an apparatus for kneading a rubber material, which can more evenly disperse a powdery compounding agent in a raw material rubber by using a closed kneader without excessive compression. be.

In the method for kneading a rubber material of the present invention for achieving the above object, a kneaded product containing a raw material rubber and a powdery compounding agent is mixed with a set of rotors arranged inside a kneading chamber and the above. In the method of kneading a rubber material to be kneaded using a closed type kneader equipped with a ram capable of moving up and down above the kneading chamber to close the upper end opening of the kneading chamber, the above-mentioned set. The phase data due to the rotation of the rotors of the above is input to the control unit, and the area of the gap in the top view between the set of rotors is sequentially calculated by the control unit based on the phase data. Based on the size of the area, the ram pressure acting on the ram is adjusted by the control unit, and the kneaded material charged into the kneading chamber is kneaded by the set of rotating rotors. It is characterized in that the ram pressure is increased when the area of the gap calculated sequentially is in an increasing state, and the ram pressure is decreased when the area of the gap calculated sequentially is in a decreasing state . ..

The rubber material kneading device of the present invention includes a kneading chamber in which a kneaded product containing a raw material rubber and a powdery compounding agent is charged, a set of rotors arranged inside the kneading chamber, and a set of rotors. In a rubber material kneader having a closed kneader with a ram capable of moving up and down above the kneading chamber to close the upper end opening of the kneading chamber, the set of rotors. It has a control unit that inputs phase data due to rotation and a pressure sensor that detects the ram pressure acting on the ram. The area of the gap is sequentially calculated, and based on the size of the area of the gap calculated sequentially, the ram pressure detected by the pressure sensor is adjusted by the control unit and charged into the kneading chamber. In a configuration in which the kneaded material is kneaded by the set of rotors that rotate, the ram pressure is increased when the sequentially calculated area of the gap is in an increasing state, and the sequentially calculated gap is calculated. It is characterized in that the adjustment is made to reduce the ram pressure when the area of the ram pressure is in a decreasing state .

According to the present invention, the control unit sequentially calculates the area of the gap in the top view between the set of rotors based on the phase data due to the rotation of the set of rotors, and the size of the sequentially calculated gap area is large. Based on this, the ram pressure can be adjusted appropriately. As a result, when the area of the gap is small, the ram pressure applied to the kneaded material can be reduced so that the kneaded material can pass between the rotors. Therefore, the powdery compounding agent is not excessively compressed between the narrowed rotors, and it is possible to suppress the formation of a firmly solidified mass. Along with this, it is advantageous to disperse the powdery compounding agent more evenly in the raw rubber.

It is explanatory drawing which illustrates the kneading apparatus of this invention in a vertical cross-sectional view of a closed type kneader. It is explanatory drawing which enlarges and exemplifies the inside of the kneading chamber of FIG. It is explanatory drawing which illustrates the set of rotors of FIG. 2 in the top view. It is a graph which illustrates the phase data of a set of rotors of FIG. 1 and the fluctuation of a ram pressure. It is explanatory drawing which illustrates the state which the kneaded material is kneaded by the kneading apparatus of FIG.

Hereinafter, the method and apparatus for kneading the rubber material of the present invention will be described based on the embodiment shown in the figure.

The rubber material kneading device 1 (hereinafter referred to as kneading device 1) of the present invention exemplified in FIGS. 1 to 3 kneads the kneaded material R containing the raw material rubber G and the compounding agent N. By this kneading step, the compounding agent N is evenly dispersed in the raw rubber G to produce an unvulcanized rubber material having an appropriate viscosity.

As the raw material rubber G and the compounding agent N, appropriate materials are selected according to the type (characteristics) of the rubber material to be manufactured. The raw material rubber G includes natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), 1,2-polybutadiene, chloroprene rubber, butyl rubber, styrene-butadiene rubber (SBR), and nitrile rubber (acrylic nitrile rubber, Nitrile hydride rubber), ethylene propylene diene rubber and the like can be exemplified. These may be used alone or in combination of two or more. As the compounding agent N, a filler such as silica and silane coupling agent, carbon black, and a non-vulcanized compounding agent N such as zinc oxide and stearic acid are appropriately selected and used. Oil is also used as the compounding agent N.

The kneading device 1 has a closed kneading machine 2. The closed type kneader 2 includes a kneading chamber 5 in which the kneaded material R containing the raw material rubber G and the compounding agent N is charged, a set of rotors 3 arranged inside the kneading chamber 5, and the upper end of the kneading chamber 5. It includes a ram 6 capable of closing the opening 5a, a control unit 12, and a pressure sensor 14. The phase data due to the rotation of the set of rotors 3 and the detection data by the pressure sensor 14 are input to the control unit 12. The control unit 12 controls the rotational drive of the rotor 3.

An oil charging section 7 is provided on the side of the kneading chamber 5, and a discharge door 11 that opens and closes is provided on the bottom surface. A ram chamber 6a is connected to the upper end opening 5a of the kneading chamber 5 and extends upward. The ram 6 moves up and down inside the ram chamber 6a to apply pressure (ram pressure P) to the kneaded material R in the kneading chamber 5. The ram 6 can close the upper end opening 5a of the kneading chamber 5 by moving downward. On the side of the ram chamber 6a, a charging mechanism 8 having a conveyor and the like, and a compounding agent charging section 10 in which the non-vulcanizing compounding agent N is charged from the hopper 9 are provided. The charging mechanism 8 is controlled by the control unit 12 to charge the raw rubber G into the kneading chamber 5.

The kneading device 1 of this embodiment further has a temperature sensor 13. The temperature sensor 13 is provided in the kneading chamber 5 with its tip exposed. The temperature sensor 13 sequentially detects the temperature of the kneaded material R (raw material rubber G) kneaded in the kneading chamber 5, and the detection data is input to the control unit 12.

The pressure sensor 14 installed in the ram 6 sequentially detects the pressure acting on the ram 6 when the kneaded material R (raw material rubber G) is kneaded in the kneading chamber 5, and the detection data is transmitted to the control unit 12. Entered. Since the pressure acting on the kneaded material R in the kneading chamber 5 acts on the ram 6 as a reaction, the detection data by the pressure sensor 14 becomes the pressure applied to the kneaded material R in the kneading chamber 5.

A power meter 12a is attached to the control unit 12. The instantaneous power P required to drive the rotation of the rotor 3 is sequentially detected by the power meter 12a, and the detection data is input to the control unit 12. The control unit 12 calculates the integrated electric power amount obtained by integrating the instantaneous power, and can grasp the electric energy amount (load acting on the rotor 3) required for rotationally driving the rotor 3 in an arbitrary kneading period. The rotation speed (rotation speed) of the rotor 3 is also input to the control unit 12, and the rotation speed of the rotor 3 and the ram pressure P (vertical movement of the ram 6) and the like are controlled by the control unit 12.

Each rotor 3 has a rotating shaft 4a arranged in parallel with each other and a stirring blade 4b projecting from the outer peripheral surface of the rotating shaft 4a. The rotors 3 are of a so-called meshing type, which are arranged so that the outer peripheral surfaces of the rotors 3 mesh with each other. The specifications of the outer peripheral surface of each rotor 3 (shape of the outer peripheral surface, etc.) are appropriately set according to the type of the kneaded product R and the like.

The above-mentioned phase data is data on the rotation angle (rotated position) of each rotor 3. When each rotor 3 makes one rotation (360 ° rotation), as illustrated in FIG. 4, the volume V (curve V shown by the solid line) of the receiving space 5b above the rotor 3 and the gap in the top view between the rotors 3 The area S (curve S shown by the broken line) of 5c fluctuates. The fluctuations in the volume V of the receiving space 5b and the area S of the gap 5c are repeated for each rotation of each rotor 3.

The receiving space 5b is located above between the rotors 3 and is a space in which the kneaded material R charged into the kneading chamber 5 is first arranged. As illustrated in FIG. 2, the space above the rotor 3 surrounded by the upper end opening 5a of the kneading chamber 5 and the outer peripheral surface of each rotor 3 is the receiving space 5b.

The area S of the gap 5c in the top view between the rotors 3 is the area of the top view sandwiched between the outer peripheral surfaces of the respective rotors 3 in the kneading chamber 5. In FIG. 3, the area S of the gap 5c is illustrated by the shaded area.

In this embodiment, as illustrated in FIG. 4, the volume V of the receiving space 5b becomes the minimum value Vn (minimum volume) when each rotor 3 is rotated 90 ° from a certain position, and the receiving space 5b is rotated 180 °. The volume V of is the maximum value Vx (maximum volume). The area S of the gap 5c becomes the maximum value Sx (maximum area) when each rotor 3 is rotated by 30 ° from a certain position, and becomes the minimum value Sn (minimum area) when rotated by 110 °. When the volume V of the receiving space 5b reaches the maximum value Vx due to the rotation of each rotor 3, the area S of the gap 5c is in an increasing state, and then becomes the maximum area. Such fluctuations in volume V and area S are repeated every 1/2 rotation (180 ° rotation) of each rotor 3. The fluctuations in the volume V of the receiving space 5b and the area S of the gap 5c are not limited to those illustrated in FIG. 4 because they differ depending on the specifications of the outer peripheral surface of each rotor 3. The present invention can also be applied when the volume V and the area S vary in various ways other than those illustrated in FIG.

Since the specifications (outer peripheral surface shape, etc.) of each rotor 3 are known, if the phase of each rotor 3 is known, the volume V of the receiving space 5b and the area S of the gap 5c at any time can be grasped. Therefore, in the present invention, the phase data due to the rotation of the set of rotors 3 is input to the control unit 12, and the area S of the gap 5c is sequentially calculated by the control unit 12 based on the input phase data. Further, in this embodiment, the volume V of the receiving space 5b is sequentially calculated by the control unit 12 based on the input phase data.

The means for acquiring the phase data is not particularly limited. For example, the rotation speed (rotation position) of the rotation shaft 4a of each rotor 3 can be detected by a known sensor or the like, and phase data can be obtained (calculated) based on the detection data.

Hereinafter, an example of the kneading method for the rubber material of the present invention will be described.

As illustrated in FIG. 1, when the raw rubber G and the powdery compounding agent N are put into the kneading chamber 5 and the kneaded product R is kneaded, the ram 6 is held in the standby position at the upper end of the ram chamber 6a. In this state, a predetermined amount of the raw material rubber G set in advance is charged into the kneading chamber 5 using the charging mechanism 8. A predetermined amount of the compounding agent N (filler or the like) of a preset type is charged into the kneading chamber 5 from the hopper 9 through the compounding agent charging section 10. Further, the oil is appropriately charged into the kneading chamber 5 through the oil charging unit 7.

After that, as illustrated in FIG. 5, the ram 6 is moved below the ram chamber 6a so that the upper end opening 5a is closed. In this state, each rotor 3 is rotationally driven to adjust the vertical position of the ram 6, the rotation speed of the rotor 3, and the like, and the kneaded material R is detected while detecting the temperature, ram pressure P, and electric energy of the kneaded material R. Knead. As a result, the unvulcanized rubber material having an appropriate viscosity is produced by evenly dispersing the compounding agent N in the raw rubber G. The produced unvulcanized rubber material is discharged to the outside of the closed kneader 2 through the opened discharge door 11. In the next step, the discharged rubber material is kneaded with a vulcanization-based compounding agent such as sulfur and a vulcanization accelerator in a predetermined ratio.

In the present invention, when the kneaded material R is kneaded, the phase data of a set of rotating rotors 3 is sequentially detected and input to the control unit 12. The control unit 12 sequentially calculates the area S of the gap 5c in the top view between the rotors 3 based on the input phase data. The ram pressure P detected by the pressure sensor 14 is sequentially input to the control unit 12. Therefore, based on the size of the area S of the gap 5c calculated sequentially, the kneaded material R is kneaded while adjusting the size of the ram pressure P (detected pressure detected by the pressure sensor 14) acting on the ram 6 by the control unit 12. ..

FIG. 4 illustrates the adjusted ram pressure P variation by the alternate long and short dash line P. As illustrated in FIG. 4, when the area S of the gap 5c calculated sequentially is in an increasing state (the curve S in FIG. 4 is in a state of rising to the right), the ram 6 is moved downward to increase the ram pressure P. Make adjustments. On the other hand, when the area S of the gap 5c calculated sequentially is in a decreasing state (the curve S in FIG. 4 is in a state of descending to the right), the ram 6 is moved upward to reduce the ram pressure P.

In this way, the ram pressure P is increased as the area S of the gap 5c calculated sequentially is larger, and the ram pressure P is decreased as the area S of the gap 5c calculated sequentially is smaller. As a result, when the area S of the gap 5c calculated sequentially is the maximum area Sx, the ram pressure P is maximized, and when the area S of the gap 5c calculated sequentially is the minimum area Sn, the ram pressure P is minimized.

According to the present invention, the area S of the gap 5c in the top view between the set of rotors 3 is sequentially calculated by the control unit 12 based on the phase data, and the size of the area S of the gap 5c calculated sequentially is large. Based on this, the ram pressure P can be adjusted appropriately. As a result, when the area S of the gap 5c is small, the ram pressure P applied to the kneaded material R can be reduced so that the kneaded material R can pass between the rotors 3.

Therefore, it is possible to prevent the powdery compounding agent N from being excessively compressed between the narrowed rotors 3 and to prevent the powdery compounding agent N from forming a firmly solidified mass. Along with this, it is advantageous to disperse the powdery compounding agent N more evenly in the raw material rubber G.

On the other hand, when the area S of the gap 5c is large, the ram pressure P applied to the kneaded material R can be made larger so that the kneaded material R can pass between the rotors 3. Therefore, it is advantageous to knead the powdery compounding agent N more evenly in the raw material rubber G in a shorter time without excessively compressing the powdery compounding agent N between the rotors 3.

By making the ram pressure P applied to the kneaded material R passed between the narrowed rotors 3 smaller, there is also an advantage that the load acting on the rotary driven rotor 3 can be reduced. Along with this, it is advantageous to reduce the amount of electric power required for rotationally driving the rotor 3.

Before kneading the kneaded product R on the production line, test kneading is performed to prevent the powdery compounding agent N passing between the rotors 3 from forming into a firmly solidified mass, and the ram pressure P and the gap 5c. It is good to understand the correlation with the size of the area S. When the kneaded material R is kneaded to mass-produce an unvulcanized rubber material, it is desirable that the ram pressure P is adjusted by the control unit 12 using this correlation that has been grasped.

The present invention is particularly useful when the set of rotors 3 is of the meshing type, because the fluctuation of the volume V of the gap 5c between the rotors 3 and the receiving space 5b above the rotors 3 of each other is relatively large. However, even if a set of rotors is non-meshing type, if the volume of the gap between the rotors and the receiving space above the rotors fluctuates relatively large due to the phase due to the rotation of the rotors of the set. , The present invention can be applied.

Since powdery silica has a small bulk density, it is liable to be excessively compressed in the closed kneader 2, and if it is excessively compressed, it is liable to be firmly solidified into a lump that is hard to break. Therefore, the present invention is particularly useful when the kneaded product R contains silica as the powdery compounding agent N.

The present invention can also be applied to the case where the pre-kneaded raw material rubber G and the compounding agent N are put together and kneaded. Further, the present invention can also be applied to the case where the vulcanizing compounding agent N is kneaded into the kneaded product R in which the non-vulcanizing compounding agent N is kneaded with the raw material rubber G.

Using the same equipment as the closed kneaders exemplified in FIGS. 1 to 5, the raw rubber and a predetermined amount of powdered silica were put together into the kneading chamber and kneaded. As shown in Table 1, only the presence or absence of adjustment of the ram pressure applied to the kneaded material rubber and silica is different in two ways (cases 1 and 2), and the dispersibility of silica and the load acting on the rotating rotor are different. I confirmed the size. In Case 1, as illustrated in FIG. 4, adjustments are made to increase the ram pressure when the area of the gap between the rotors in the top view is increasing, and to decrease the ram pressure when this area is decreasing. went. When this area was the maximum value, the ram pressure was set to the predetermined maximum value. In case 2, the ram pressure was not adjusted and was always maintained at a predetermined maximum value.

The dispersibility of silica was evaluated by confirming the number of silica firmly solidified and agglomerated in the raw rubber after kneading, and in Table 1, Case 1 was used as a reference index 100 for index evaluation. The smaller the index value, the smaller the number of silica lumps, indicating that the silica is evenly dispersed and the dispersibility is excellent.

In Table 1, the magnitude of the load acting on the rotor was index-evaluated with Case 1 as the reference index 100. The smaller the value of the index, the smaller the load.

From the results in Table 1, it can be seen that Case 1 is superior in dispersibility of silica as compared with Case 2. Further, it can be seen that the case 1 has a smaller load acting on the rotating rotor than the case 2, and is effective in reducing energy.

1 Kneading device 2 Sealed kneader 3 Rotor 4a Rotating shaft 4b Stirring blade 5 Kneading chamber 5a Top opening 5b Receiving space 5c Gap 6 Lamb 6a Lamb chamber 7 Oil charging part 8 Filling mechanism 9 Hopper 10 Mixing agent charging part 11 Discharge door 12 Control unit 12a Power meter 13 Temperature sensor 14 Pressure sensor G Raw material rubber N Blending agent R Kneaded product

Claims (6)

The kneaded product containing the raw rubber and the powdery compounding agent is moved up and down with a set of rotors arranged inside the kneading chamber and above the kneading chamber to open the upper end opening of the kneading chamber. In the method of kneading a rubber material to be kneaded using a closed kneader equipped with a ram that can be closed.
The phase data due to the rotation of the set of rotors is input to the control unit, and the area of the gap in the top view between the set of rotors is sequentially calculated by the control unit based on the phase data, and the sequential calculation is performed. Based on the size of the area of the gap, the ram pressure acting on the ram is adjusted by the control unit, and the kneaded material charged into the kneading chamber is kneaded by the set of rotors that rotate. Then, when the sequentially calculated area of the gap is in an increasing state, the ram pressure is increased, and when the sequentially calculated area of the gap is in a decreasing state, the ram pressure is decreased . A characteristic method of kneading rubber materials. The method for kneading a rubber material according to claim 1, wherein the set of rotors is a meshing type rotor in which the outer peripheral surfaces of the rotors are arranged so as to mesh with each other. The method for kneading a rubber material according to claim 1 or 2 , wherein the compounding agent contains at least silica. A kneading chamber in which a kneaded product containing raw rubber and a powdery compounding agent is charged, a set of rotors arranged inside the kneading chamber, and moving up and down above the kneading chamber. In a rubber material kneader having a closed kneader with a ram capable of closing the upper end opening of the kneading chamber.
It has a control unit for inputting phase data due to the rotation of the set of rotors and a pressure sensor for detecting the ram pressure acting on the ram, and the control unit has the set of rotors based on the phase data. The area of the gap in the top view of the space is sequentially calculated, and the ram pressure detected by the pressure sensor is adjusted by the control unit based on the size of the area of the gap calculated sequentially, and the said The ram pressure is increased when the sequentially calculated gap area is in an increasing state in a configuration in which the kneaded material charged into the kneading chamber is kneaded by the set of rotating rotors. A rubber material kneading device characterized in that an adjustment is made to reduce the ram pressure when the sequentially calculated area of the gap is in a decreasing state . The rubber material kneading device according to claim 4 , wherein the set of rotors is a meshing type rotor in which the outer peripheral surfaces of the rotors are arranged so as to mesh with each other. The rubber material kneading apparatus according to claim 4 or 5 , wherein at least silica is contained as the compounding agent.

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