JP2009090252A - Mixer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep the oxygen concentration in a mixer not higher than an ignition limit even if a material to be kneaded is charged or the kneaded material is discharged when kneading the material to be kneaded, in a mixer such as a Bunbury mixer. <P>SOLUTION: A mixer body 1, which has a kneading room 2 for kneading the material to be kneaded, an inlet door 4 for throwing the material to be kneaded into the kneading room 2, and an outlet door 5 for discharging the material to be kneaded from the kneading room, has a sealing room 7 for air-tightly covering the inlet door 4, and an inert-gas introduction pipe 11, 16 for supplying an inert gas into anyone of the sealing room 7 or the kneading room 2. An inlet of the sealing room 7 has preferably a curtain 8. Then, an oxygen concentration meter 9 for measuring the oxygen concentration in the kneading room is arranged and a flow-rate control part 10 for controlling an flow rate of an inert gas to be supplied into the inert-gas introduction pipe based on an oxygen concentration signal from the oxygen concentration meter may be arranged. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a mixer such as a Banbury mixer used for kneading plastic materials such as rubber and vinyl chloride resin, in which the oxygen concentration inside the mixer is reduced to prevent ignition of the plastic material during kneading. It is.

When manufacturing rubber products such as tires, various compounding agents such as sulfur, carbon black, oil, antioxidants, and vulcanization accelerators are blended into raw rubber to form a compound, and this compound is heated and added. Kneading is performed under pressure.
Banbury mixers have been widely used for this kneading.

A Banbury mixer is a mixer in which a compound is put into a closed kneading chamber and kneaded in a plasticized state by applying a large shearing force to the compound by two mutually rotating rotating blades in a heated and pressurized state. It is well known.
In the kneading by this Banbury mixer, the temperature in the kneading chamber and the current value of the motor that rotates the rotating blade are measured, and the kneading state in the kneading chamber is grasped by this temperature and current value, and the operation management is performed.

  By the way, during this kneading operation, the kneaded product becomes hot due to its frictional heat, and there is a risk that the kneaded product will ignite by reacting with oxygen in the surrounding air. In order to avoid this danger, a method of introducing an inert gas such as nitrogen or argon into the Banbury mixer so that the oxygen concentration in the Banbury mixer is below the ignition limit of the kneaded product can be considered.

However, in reality, there is a limit to reducing the oxygen concentration below the ignition limit simply by introducing an inert gas into the Banbury mixer.
This is considered to be due to the fact that the outside air flows in by opening and closing the door accompanying the introduction of the compound or the discharge of the kneaded product, and that the compound itself is brought in with air.
Japanese Unexamined Patent Publication No. 7-309977 JP 2006-327052 A

  Therefore, the problem in the present invention is that when the material to be kneaded is kneaded in a mixer such as a Banbury mixer, the oxygen concentration in the mixer is limited to its ignition limit even if the material to be kneaded is charged and the material to be kneaded is discharged. The purpose is to be able to:

To solve this problem,
The invention according to claim 1 includes a kneading chamber for kneading the material to be kneaded, an entrance door for introducing the material to be kneaded into the kneading chamber, and an outlet door for discharging the kneaded material from the kneading chamber. A mixer characterized in that a seal chamber that covers the inlet door in an airtight manner is provided in the machine body, and an inert gas introduction pipe that supplies an inert gas to either the seal chamber or the kneading chamber is provided. .

  The invention according to claim 2 is the mixer according to claim 1, wherein a curtain is provided at the entrance of the seal chamber.

  According to a third aspect of the present invention, in the mixer according to the first or second aspect, an oxygen concentration meter for measuring the oxygen concentration in the kneading chamber is provided, and an inert gas is determined based on an oxygen concentration signal from the oxygen concentration meter. A mixer comprising a flow rate control unit for controlling a flow rate of an inert gas supplied to the introduction pipe.

  According to a fourth aspect of the present invention, in the mixer according to the first or second aspect, a count for counting a door opening time when the inlet and outlet doors are opened and closed and a number of times the inlet and outlet doors are opened and closed per unit time. And a flow rate controller for controlling the flow rate of the inert gas supplied to the inert gas introduction pipe based on a signal from the count unit.

  According to the present invention, the oxygen concentration in the kneading chamber is always kneaded even if air flows into the mixer main body from the outside due to factors such as the opening and closing of the inlet and outlet doors of the mixer main body and the introduction of the material to be kneaded. It can be below the ignition limit of the material, that is, below 10% by volume.

  Also, the oxygen concentration in the kneading chamber is measured, and based on this oxygen concentration, the flow rate of the inert gas supplied to the inert gas introduction pipe is controlled, or the door opening time and the entrance / exit when opening / closing the entrance / exit door By counting the number of times the door is opened and closed per unit time, and controlling the flow rate of the inert gas supplied to the inert gas introduction pipe based on this, the supply amount of the inert gas can be saved. And cost reduction.

FIG. 1 shows an example of a mixer according to the present invention, in which a Banbury mixer is used as the mixer body.
In FIG. 1, the code | symbol 1 shows a mixer main body. The mixing machine main body 1 includes, for example, a kneading chamber 2 for kneading a compound A in which raw rubber is mixed with sulfur, carbon black, oil, an antioxidant, a vulcanization accelerator, and the like in a heated and pressurized state, and the kneading chamber 2 , An inlet chamber 3 into which the compound A is charged, an inlet door 4 for charging the compound A into the charging chamber 3, and a kneaded material after discharging the kneaded material from the kneading chamber 3. An exit door 5 is provided.
The entrance door 4 and the exit door 5 are both hinged doors.

  Moreover, the code | symbol 6 in a figure shows a belt conveyor, and this belt conveyor 6 is for transferring the compound A to the entrance door 4 of the mixer main body 1. FIG. The belt conveyor 6 is arranged so that the end portion thereof is positioned in the vicinity of the entrance door 4, and when the entrance door 4 is opened, the composition A falls from the entrance door 4 into the charging chamber 3. It is like that.

  Further, as shown in the figure, a seal chamber 7 is provided that shields at least the vicinity of the entrance door 4 of the mixer main body 1 and the upper portion of the belt 61 of the belt conveyor 6 from outside air. The seal chamber 7 is a tunnel-like structure assembled in an airtight structure using a stainless steel plate or the like, and allows passage of the composition A transported on the belt conveyor 6 at the inlet portion, so that the outside of the air A curtain 8 is installed to prevent as much as possible from entering.

The curtain 8 is configured by attaching a sheet made of a soft vinyl chloride resin, rubber or the like in a state of hanging from an upper part of the opening of the entrance.
Depending on the operation mode of the mixer, the curtain 8 may be unnecessary, and the inlet portion may be left open. However, in this case, it is preferable to make the opening area of the inlet portion as small as possible.

  An oxygen sensor 9 for measuring the oxygen concentration in the kneading chamber 2 is attached to the kneading chamber 2 in the mixer main body 1. The oxygen concentration signal from the oxygen sensor 9 is sent to the control unit 10.

  Furthermore, the mixer main body 1 is connected to one end of a main body inert gas introduction pipe 11 for supplying an inert gas into the main body 1. An inert gas supply source 15 is connected via a flow meter 13 and a pressure regulator 14, and an inert gas such as nitrogen or argon is introduced into the main body 1.

  The seal chamber 7 is connected to one end of a seal chamber inert gas introduction pipe 16 for supplying an inert gas into the seal chamber 7. 2 An inert gas such as nitrogen or argon is introduced into the seal chamber 7 by being connected to an inert gas supply source 15 via a flow meter 18 and a pressure regulator 14.

  Further, the control signal from the control unit 10 is sent to the first flow rate regulator 12 and the second flow rate regulator 17, and the flow rate of the inert gas in each flow rate regulator 12, 17 is changed to the oxygen concentration in the main body 1. It is designed to adjust accordingly.

Next, an operation example of the mixer of this example will be described.
(Operation example 1)
The inlet door 4 and the outlet door 5 of the main body 1 are closed in advance, an inert gas is introduced into the main body 1 from the main body inert gas introduction pipe 11, and the oxygen concentration in the main body 1 is set to be equal to or lower than the ignition limit of the kneaded material. deep. The ignition limit oxygen concentration is preferably 10% by volume. In this operation example, the curtain 8 of the seal chamber 7 is not attached.

  Subsequently, the state where the supply of the inert gas from the main body inert gas introduction pipe 11 is continued is maintained. Then, the blend A is placed on the belt conveyor 6 and transferred. Thereby, the compound A reaches the terminal portion of the belt conveyor 6. At this time, the entrance door 4 opens and the compound A falls inside. Thereafter, the entrance door 4 is immediately closed.

When kneading is completed in the kneading chamber 2, the exit door 5 is opened and the kneaded material is discharged from here. When the kneaded material is completely discharged, the outlet door 5 is immediately closed.
By this operation, the oxygen concentration in the kneading chamber 2 is always below the ignition limit of the kneaded product. In this case, the introduction amount of the inert gas from the main body inert gas introduction pipe 11 needs to be relatively large.

(Operation example 2)
The inlet door 4 and the outlet door 5 of the main body 1 are closed in advance, an inert gas is introduced into the main body 1 and the seal chamber 7 from the main body inert gas introduction pipe 11, and the oxygen concentration in the main body 1 is kneaded. Keep it below the ignition limit. Also in this example, the curtain 8 of the seal chamber 7 is not attached.

Subsequently, the supply of the inert gas from the main body inert gas introduction pipe 11 is continued and the supply of the inert gas from the seal chamber inert gas introduction pipe 16 is started. Thereafter, in the same manner as in Operation Example 1, the mixture A is kneaded and the kneaded material is discharged from the outlet door 5.
By this operation, the oxygen concentration in the kneading chamber 2 is always below the ignition limit of the kneaded product. In this case, the introduction amount from the seal chamber inert introduction pipe 16 can be reduced as compared with the introduction amount of the inert gas from the main body inert gas introduction pipe 11.

(Operation example 3)
The inlet door 4 and the outlet door 5 of the main body 1 are closed in advance, an inert gas is introduced into the main body 1 from the main body inert gas introduction pipe 11, and the oxygen concentration in the main body 1 is set to be equal to or lower than the ignition limit of the kneaded material. deep. The curtain 8 of the seal chamber 7 is attached.

Subsequently, the supply of the inert gas from the main body inert gas introduction pipe 11 is continued, and the supply of the inert gas from the seal chamber inert gas introduction pipe 16 to the seal chamber 7 is started. Thereafter, in the same manner as in Operation Example 1, the mixture A is kneaded and the kneaded material is discharged from the outlet door 5.
By this operation, the oxygen concentration in the kneading chamber 2 is always below the ignition limit of the kneaded product. In this case, since the curtain 8 is attached to the seal chamber 7, there is little intrusion of outside air, and the amount of inert gas supplied can be reduced.

(Operation example 4)
The inlet door 4 and the outlet door 5 of the main body 1 are closed in advance, an inert gas is introduced into the main body 1 from the main body inert gas introduction pipe 11, and the oxygen concentration in the main body 1 is set to be equal to or lower than the ignition limit of the kneaded material. deep. The curtain 8 of the seal chamber 7 is attached.

Subsequently, the supply of the inert gas from the main body inert gas introduction pipe 11 is continued. Thereafter, in the same manner as in Operation Example 1, the mixture A is kneaded and the kneaded material is discharged from the outlet door 5.
Even in this case, since the curtain 8 is attached to the seal chamber 7, there is little intrusion of outside air, and the amount of inert gas supplied can be reduced.

(Operation example 5)
The inlet door 4 and the outlet door 5 of the main body 1 are closed in advance, an inert gas is introduced into the main body 1 from the main body inert gas introduction pipe 11, and the oxygen concentration in the main body 1 is set to be equal to or lower than the ignition limit of the kneaded material. deep. The curtain 8 of the seal chamber 7 is attached.

Subsequently, the supply of the inert gas from the main body inert gas introduction pipe 11 is continued, and the supply of the inert gas from the seal chamber inert gas introduction pipe 16 to the seal chamber 7 is started. Thereafter, in the same manner as in Operation Example 1, the mixture A is kneaded and the kneaded material is discharged from the outlet door 5. During this operation, the oxygen concentration in the kneading chamber 2 is constantly measured by the oxygen sensor 9 and before the concentration exceeds the ignition limit, a control signal is sent from the control unit 10 or to the second flow rate regulators 12 and 17. The amount of inert gas supplied from one or both of the main body inert gas introduction pipe 11 and the seal chamber inert gas introduction pipe 16 is increased.
In this case, it is not necessary to supply extra inert gas, and it can be minimized.

FIG. 2 shows another example of the mixer according to the present invention. The same components as those shown in FIG.
In the apparatus of this example, a counting unit 21 is provided that counts the opening time of the door when the entrance door 4 and the exit door 5 are opened and closed, and the number of times of opening and closing per unit time, for example, 10 minutes. The oxygen sensor 9 and the control unit 10 are not necessary, but may be present.

  The door opening time when the entrance door 4 and the exit door 5 are opened and closed and the number of times of opening and closing per unit time are counted by a signal from a control unit that instructs and controls opening and closing of the door (not shown). This is performed by a signal from an open / close sensor such as a limit switch attached to 4,5.

  The counting unit 21 determines the flow rate of the inert gas flowing through one or both of the main body inert gas introduction pipe 11 and the seal chamber inert gas introduction pipe 16 based on the door opening / closing time and the number of opening / closing times per unit time. Then, this is sent to the first or second inert gas flow rate regulator 12, 17, and the flow rate of the inert gas flowing therethrough is adjusted, so that the oxygen concentration in the main body 1 is made the ignition limit or less.

  In the apparatus of this example, since the open / closed state of the entrance door 4 and the exit door 5 which is a major cause of the outside air entering the main body 1 is referred to, it is possible to efficiently control the inert gas supply amount. Become.

Specific examples are shown below.
In the following specific example, a Banbury mixer having an internal volume of 1.0 m ³ was used. Assuming actual use of a Banbury mixer, the exit door 5 was opened after 10 seconds and then closed, and then the inlet door 4 was opened after 15 seconds and then left for 2 minutes. This was performed for 5 cycles, and the oxygen concentration in the Banbury mixer was monitored to confirm the oxygen concentration in the mixer.

(Example 1)
Without providing the seal chamber 7, nitrogen gas is supplied as an inert gas from the main body inert gas introduction pipe 11 to the Banbury mixer main body 1 at a rate of 1000 L / min, and is left until the oxygen concentration in the Banbury mixer main body 1 reaches 6%. did. Thereafter, nitrogen gas was continuously supplied at 1000 L / min, and 5 cycles were performed.
As a result, the oxygen concentration in the mixer increased to about 20% after 3 cycles, and the atmosphere in the Banbury mixer was almost replaced with air.

(Example 2)
A tunnel-like seal chamber 7 (width 1050 mm × height 600 mm × length 1800 mm) was arranged so as to cover the inlet door 4 of the Banbury mixer main body 1. Although the inlet of the seal chamber 7 is open to the atmosphere, the seal chamber 7 is sealed so that there is no gap between the Banbury mixer body 1 and the seal chamber 7.
With the entrance doors 4 and 5 closed, nitrogen gas 600 L / min was introduced from the main body inert gas introduction pipe 11 and left until the oxygen concentration in the mixer reached 6%. Thereafter, nitrogen gas was continuously supplied at 600 L / min for 5 cycles.
As a result, even after 5 cycles, the oxygen concentration in the mixer was stable at about 8%.

(Example 3)
A seal chamber inert gas introduction pipe 16 was disposed in the seal chamber 7 of Example 2. In the same manner as in Example 2, 600 L / min of nitrogen gas was introduced from the main body inert gas introduction pipe 11 with the entrance doors 4 and 5 closed, and the mixture was left until the oxygen concentration in the mixer reached 6%. Immediately thereafter, the flow rate of the nitrogen gas introduced from the main body inert gas introduction pipe 11 was set to 360 L / min, and 120 L / min of nitrogen gas was supplied from the seal chamber inert gas introduction pipe 16 to the seal chamber 7, and five cycles were performed.
As a result, the oxygen concentration in the mixer was stable at about 8% after 5 cycles.

(Example 4)
A curtain 8 made of a vinyl chloride resin having a width of 1050 mm, a height of 600 mm, and a thickness of 1 mm was attached to the entrance of the seal chamber 7 of Example 2. In the same manner as in Example 2, 600 L / min of nitrogen gas was introduced from the main body inert gas introduction pipe 11 with the entrance doors 4 and 5 closed, and the mixture was left until the oxygen concentration in the mixer reached 6%. Immediately thereafter, the flow rate of the nitrogen gas introduced from the main body inert gas introduction pipe 11 was set to 300 L / min, and nitrogen gas 60 L / min was supplied from the seal chamber inert gas introduction pipe 17 to the seal chamber 7 for 5 cycles.
As a result, the oxygen concentration in the mixer was stable at about 8% after 5 cycles.

(Example 5)
A curtain 8 made of vinyl chloride having a width of 1050 mm, a height of 600 mm, and a thickness of 1 mm was attached to the entrance of the seal chamber 7 of Example 2. In the same manner as in Example 2, 600 L / min of nitrogen gas was introduced from the main body inert gas introduction pipe 11 with the entrance doors 4 and 5 closed, and the mixture was left until the oxygen concentration in the mixer reached 6%. Immediately thereafter, the flow of nitrogen gas introduced from the main body gas inert introduction pipe 11 was set to 480 L / min for 5 cycles.
As a result, the oxygen concentration in the mixer was stable at about 8% after 5 cycles.

In the above specific example, the effect was evaluated by the oxygen concentration in the main body 1 when 5 cycles were performed. However, as the oxygen concentration increases as the number of cycles increases, an upper limit value is set and the upper limit value is reached. Can be operated continuously by supplying an inert gas from at least one of the main body inert gas introduction pipe 11 and the seal chamber inert gas introduction pipe 16 and lowering the oxygen concentration.
The upper limit of the oxygen concentration in the Banbury mixer is preferably 10%.

  Moreover, it is thought that there are many air | atmosphere approachs, when the entrance door 4 and the exit door 5 are opened. Slightly before opening, more efficient supply can be achieved by increasing the amount of inert gas supplied from at least one of the main body inert gas introduction pipe 11 and the seal chamber inert gas introduction pipe 16. .

  In addition, in the case without the sealing chamber of Example 1, the oxygen concentration in the mixer could not be maintained even when 970 L / min of nitrogen gas was introduced. However, by installing the sealing chamber of Example 2, 600 L / min. Even with a minute amount of nitrogen gas, a stable oxygen concentration lowering effect could be obtained. This amount is 60% compared to the amount in Example 1, and the amount of inert gas supplied can be greatly reduced.

Further, as shown in Examples 3, 4, and 5, the amount of nitrogen gas used is further reduced by introducing nitrogen gas into the seal chamber 7 of Example 2 and improving the shielding performance from the outside air by installing a curtain 8. can do.
From the results of Example 2, when the amount of inert gas introduced into the Banbury mixer was nitrogen gas, a sufficient effect could be obtained by introducing a flow rate of about 0.6 times / minute of the mixer capacity. Similar results were obtained with different mixer capacities.

The same effect can be obtained in a mixer for kneading plastic materials such as Henschel mixers (trade names) other than Banbury mixers and intensive mixers while applying a strong shear force in a heated and pressurized state. It is included in the machine.
In this embodiment, the seal chamber 7 is provided only at the inlet door 4 of the main body 1. However, a higher oxygen barrier effect can be obtained by providing a seal chamber at the outlet door 5 of the main body 1 and supplying an inert gas. Can do.

It is a schematic block diagram which shows an example of the mixer of this invention. It is a schematic block diagram which shows the other example of the mixer of this invention.

Explanation of symbols

1 .... Mixer body, 2 .... Kneading chamber, 4 .... Inlet door, 5 .... Outlet door, Seal chamber, 8 .... Curtain, 9 .... Oxygen sensor, 10 .... Control part, 11 .... No body Active gas introduction pipe, 12 .... first flow regulator, 16 .... seal chamber inert gas introduction pipe, 17 .... second flow regulator, 21 ... counter section

Claims (4)

  A kneading chamber for kneading the material to be kneaded, an inlet door for feeding the material to be kneaded into the kneading chamber, and a mixer main body having an outlet door for discharging the kneaded material from the kneading chamber, A mixer provided with an airtight sealing chamber and an inert gas introduction pipe for supplying an inert gas to either the sealing chamber or the kneading chamber.   The mixer according to claim 1, wherein a curtain is provided at an entrance of the seal chamber.   3. The inert gas supplied to the inert gas introduction pipe according to claim 1, wherein an oxygen concentration meter for measuring the oxygen concentration in the kneading chamber is provided and an oxygen concentration signal from the oxygen concentration meter is provided. A mixer comprising a flow rate control unit for controlling the flow rate of the liquid.   In the mixer according to claim 1 or 2, a counting unit is provided for counting a door opening time when the entrance door and the exit door are opened and closed and a number of times the entrance door and the exit door are opened and closed per unit time. A mixer having a flow rate control unit for controlling the flow rate of the inert gas supplied to the inert gas introduction pipe based on the signal.

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