Rubber Processing Method

Abstract

To provide a rubber processing method capable of effectively preventing quality abnormality and poor kneading.SOLUTION: After kneading an unvulcanized rubber R1 with a compounding ingredient X in a closed-type rubber kneader 1, a rubber processing method processes an unvulcanized rubber R2 kneaded by the closed-type rubber kneader 1 into a sheet-shape by a rolling mill 21. In the rubber processing method, the method measures a temperature of a rubber sheet R3 discharged from the rolling mill 21 in a width direction of the rubber sheet R3. On the basis of temperature information obtained from the rubber sheet R3, the method adjusts a processing condition and / or a material condition in the closed-type rubber kneader 1.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a rubber processing method in which unvulcanized rubber is kneaded together with compounding ingredients in an internal rubber kneader, and the kneaded unvulcanized rubber is then processed into a sheet shape by a rolling mill. More specifically, the present invention relates to a rubber processing method which makes it possible to effectively prevent quality abnormalities and poor kneading. [Background technology]

[0002] When manufacturing rubber products such as tires and rubber hoses, unvulcanized rubber, which is made by kneading raw rubber with non-vulcanization compounding agents such as carbon black and oil, is kneaded together with vulcanization compounding agents such as sulfur in an internal rubber kneading machine.

[0003] However, if the temperature of the unvulcanized rubber in the internal rubber mixer is too high, vulcanization may proceed unintentionally or localized burning may occur, resulting in a deterioration in the quality of the rubber composition.On the other hand, if the temperature of the unvulcanized rubber in the internal rubber mixer is too low, there is a problem that poor kneading occurs, particularly with hard rubber, and the vulcanization compounding agents are not uniformly dispersed.

[0004] For this reason, for example, a thermocouple is installed at the position of the drop door inside an internal rubber mixer, and the thermocouple is used to measure the temperature of the unvulcanized rubber being mixed inside the internal rubber mixer, and quality abnormalities and poor mixing are judged based on the measured temperature (see, for example, Patent Document 1).

[0005] However, since the thermocouple installed in the closed rubber mixer is affected by the temperature of the part where it is installed (e.g., the drop door) or by the frictional heat of the hard rubber, it is not always possible to accurately detect the temperature of the unvulcanized rubber being mixed in the closed rubber mixer. Therefore, the current situation is that the judgment method using the temperature of the unvulcanized rubber in the closed rubber mixer measured by the thermocouple as an index cannot reliably detect quality abnormalities or poor mixing. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2019-43055 A Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a method for processing rubber which makes it possible to effectively prevent quality abnormalities and poor kneading. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the rubber processing method of the present invention comprises kneading unvulcanized rubber together with compounding agents in an internal rubber kneader, and then processing the unvulcanized rubber kneaded by the internal rubber kneader into a sheet by a roll mill, characterized in that the temperature of the rubber sheet discharged from the roll mill is measured along the width direction of the rubber sheet, and processing conditions and / or material conditions in the internal rubber kneader are adjusted based on temperature information obtained from the rubber sheet. Effect of the Invention

[0009] In the present invention, in a rubber processing method in which unvulcanized rubber is kneaded with compounding ingredients in an internal rubber kneader, and the unvulcanized rubber kneaded by the internal rubber kneader is then processed into a sheet shape by a roll mill, the temperature of the rubber sheet discharged from the roll mill is measured along the width direction of the rubber sheet, and the kneaded state of the unvulcanized rubber can be grasped in detail based on the temperature information obtained from the rubber sheet. Then, the processing conditions and / or material conditions in the internal rubber kneader are adjusted based on such temperature information, so that not only quality abnormalities caused by an excessively high temperature of the unvulcanized rubber in the internal rubber kneader, but also poor kneading caused by an excessively low temperature of the unvulcanized rubber in the internal rubber kneader can be prevented.

[0010] In the present invention, the processing conditions in the internal rubber mixer that are adjusted based on the temperature information preferably include at least one of the rotor rotation speed, the number of times the ram is moved up and down, the processing time, the set temperature, and the integrated power consumption. By adjusting such processing conditions, the kneading state of the unvulcanized rubber can be optimized.

[0011] In addition, the material conditions in the closed rubber mixer that are adjusted based on the temperature information preferably include the temperature at the time of inputting the unvulcanized rubber. By adjusting such material conditions, the kneading state of the unvulcanized rubber can be optimized.

[0012] When adjusting the processing conditions or material conditions in the internal rubber mixer based on the temperature information, it is preferable to take into account the driving state of the roll rolling machine as a judgment condition. For example, when the roll rolling machine stops, the heat of the rubber sheet moves to the roll side, and the influence of this appears in the temperature information of the rubber sheet. Therefore, by taking into account the driving state of the roll rolling machine as a judgment condition, more accurate feedback can be performed.

[0013] In a preferred rubber processing method, the temperature information includes the average temperature in the width direction of the rubber sheet and the temperature distribution in the width direction of the rubber sheet, and when the average temperature is higher than a first threshold value set in advance, the processing time by the closed-type rubber mixer is shortened, and when the average temperature is lower than the first threshold value set in advance and there is at least one minimum value in the temperature distribution that is lower than a second threshold value set in advance, the processing time by the closed-type rubber mixer is extended. This makes it possible to optimize the kneading state of the unvulcanized rubber. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a cross-sectional view showing an example of an internal rubber kneader used in the present invention. [Diagram 2] FIG. 1 is a cross-sectional view showing an example of a rolling mill used in the present invention. [Diagram 3] 3 is a plan view showing a rubber sheet discharged from the rolling mill of FIG. 2. [Figure 4]1 is a graph showing the relationship between the average temperature in the width direction of a rubber sheet and time. [Diagram 5] 4 is a graph showing a temperature distribution in a width direction of a rubber sheet. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The configuration of the present invention will be described in detail below with reference to the accompanying drawings. Fig. 1 shows an example of an internal rubber kneader used in the present invention, Fig. 2 shows an example of a rolling mill used in the present invention, and Fig. 3 shows a rubber sheet discharged from the rolling mill of Fig. 2.

[0016] As shown in FIG. 1, the closed rubber mixer 1 includes a cylindrical casing 2 extending in the vertical direction and a chamber 3 connected to the lower part of the casing 2. An inlet 5 with an inlet door 4 is provided in the vertical middle of the casing 2. Unvulcanized rubber R1 and compounding agent X are fed through the inlet 5. More specifically, the unvulcanized rubber R1 is unvulcanized rubber obtained by kneading raw rubber with non-vulcanization compounding agents such as carbon black and oil, and the compounding agent X is a vulcanization compounding agent such as sulfur. A ram 6 for closing the chamber 3 is slidably disposed in the casing 2 along the longitudinal direction of the casing 2. When the unvulcanized rubber R1 and compounding agent X are fed into the casing 2, the ram 6 is disposed in an upper standby position, and after the unvulcanized rubber R1 and compounding agent X are fed into the casing 2, the ram 6 moves downward from the standby position to a position for blocking the upper part of the chamber 3.

[0017] Meanwhile, a pair of rotors 7, 7 are arranged in parallel in the chamber 3. Each rotor 7 has a rotor shaft 7a arranged in the horizontal direction and an agitating blade 7b protruding from the outer circumferential surface of the rotor shaft 7a. The pair of rotors 7, 7 are driven to rotate in opposite directions based on the control of the control device 8. A discharge port 10 equipped with a drop door 9 is provided at the bottom of the chamber 3. Unvulcanized rubber R2, which is a mixture of unvulcanized rubber R1 and compounding agent X, is discharged from the discharge port 10 and is sent to the next process. A temperature sensor 11 protruding into the chamber 3 is embedded in the drop door 9, and the measurement result of the temperature sensor 11 is supplied to the control device 8.

[0018] As shown in FIG. 2, the rolling mill 21 includes a cylindrical casing 22 extending in the horizontal direction, a screw shaft 23 extending in the longitudinal direction of the casing 22 and housed in the casing 22, and a pair of rolls 24, 24 disposed at the front end side of the casing 22. An inlet 25 is provided at the top of the rear end side of the casing 22, and a discharge outlet 26 is formed at the front end of the casing 22. The unvulcanized rubber R2 fed into the inlet 25 moves to the front end side of the casing 22 with the rotation of the screw shaft 23, and is extruded from the discharge outlet 26. The unvulcanized rubber R2 extruded from the discharge outlet 26 passes through the gap between the pair of rolls 24, 24, and is processed into a rubber sheet R3 having a thickness determined by the gap. The rubber sheet R3 is formed to a constant width by a guide member (not shown).

[0019] A non-contact temperature measuring device 31 is disposed on the transport path of the rubber sheet R3. The temperature measuring device 31 measures the temperature of the rubber sheet R3 discharged from the rolling mill 21 along the width direction of the rubber sheet R3. That is, as shown in FIG. 3, the temperature of the rubber sheet R3 is continuously collected along a measurement line L across the entire width of the rubber sheet R3. For example, an infrared thermograph can be used as the temperature measuring device 31. The infrared thermograph continuously captures temperature information in the width direction of the rubber sheet R3 as an image or video as the rubber sheet R3 is transported. Information to be referred to is extracted from the temperature information captured in this way. Of course, other devices can be used as the temperature measuring device 31.

[0020] Next, a rubber processing method using the above-mentioned device will be described. First, as shown in Fig. 1, unvulcanized rubber R1 is put into the closed rubber mixer 1 together with compounding agent X, and the pair of rotors 7, 7 are rotated with the chamber 3 closed by the ram 6, thereby kneading the unvulcanized rubber R1 together with the compounding agent X. From the start of kneading to the end of kneading, the ram 6 can be moved up and down as necessary. In other words, a process of kneading with the ram 6 positioned at the lower position is regarded as one stage, and multiple stages can be repeated.

[0021] The unvulcanized rubber R2 thus obtained is fed to a roll mill 21 as shown in Fig. 2 and Fig. 3. The roll mill 21 processes the unvulcanized rubber R2 fed from an inlet 25 into a sheet. At that time, the temperature of the rubber sheet R3 discharged from the roll mill 21 is continuously measured along the width direction of the rubber sheet R3 by a temperature measuring device 31. Then, the processing conditions and / or material conditions in the internal rubber mixer 1 are adjusted based on the temperature information obtained from the rubber sheet R3. In other words, the temperature information obtained from the rubber sheet R3 is used as feedback for the processing conditions and / or material conditions in the internal rubber mixer 1.

[0022] According to the above-mentioned rubber processing method, after kneading the unvulcanized rubber R1 together with the compounding agent X in the closed rubber kneader 1, the unvulcanized rubber R2 kneaded by the closed rubber kneader 1 is processed into a sheet shape by the roll mill 21. By measuring the temperature of the rubber sheet R3 discharged from the roll mill 1 along the width direction of the rubber sheet R3, the kneaded state of the unvulcanized rubber R1 can be grasped in detail based on the temperature information obtained from the rubber sheet R3. Then, since the processing conditions and / or material conditions in the closed rubber kneader 1 are adjusted based on such temperature information, not only the quality abnormality caused by the temperature of the unvulcanized rubber R2 in the closed rubber kneader 1 being too high, but also the kneading failure caused by the temperature of the unvulcanized rubber R2 in the closed rubber kneader 1 being too low can be prevented.

[0023] In the above-mentioned rubber processing method, the processing conditions in the internal rubber mixer 1, which are adjusted based on the temperature information obtained from the rubber sheet R3, preferably include at least one of the rotor rotation speed, the number of ram up-down movements, the processing time, the set temperature, and the integrated power consumption. By adjusting such processing conditions, the kneading state of the unvulcanized rubber R2 can be optimized.

[0024] More specifically, the average temperature in the width direction of the rubber sheet R3 and the temperature distribution in the width direction of the rubber sheet R3 can be used as the temperature information. For example, when the temperature distribution in the width direction at any position in the longitudinal direction of the rubber sheet R3 is measured and the average temperature is obtained, the relationship between the average temperature in the width direction of the rubber sheet R3 and time is, for example, as shown in FIG. 4. Here, when the average temperature in the width direction of the rubber sheet R3 is higher than a first threshold value T1 set in advance, the processing time by the closed rubber kneading machine 1 is shortened. In other words, when the average temperature in the width direction of the rubber sheet R3 is higher than the first threshold value T1, it is determined that there is a risk of unintentional vulcanization progressing or local burning occurring, resulting in a deterioration in the quality of the rubber composition, and the processing time by the closed rubber kneading machine 1 is shortened. The first threshold value T1 can be arbitrarily selected using the average temperature in the width direction of the rubber sheet R3 when no quality abnormality occurs as an index. In addition, if necessary, it is also possible to set a threshold value for specifying the lower limit of the average temperature in the width direction of the rubber sheet R3.

[0025] On the other hand, the temperature distribution in the width direction of the rubber sheet R3 is, for example, as shown in FIG. 5. Here, when the average temperature in the width direction of the rubber sheet R3 is lower than the first threshold value T1 set in advance, and at least one minimum value lower than the second threshold value T2 set in advance exists in the temperature distribution in the width direction of the rubber sheet R3 (particularly, when at least one minimum value lower than the second threshold value T2 is detected multiple times in the same batch), the processing time by the closed-type rubber mixer 1 is extended. For example, in FIG. 3, if a lump of compounding agent X exists in a part of the rubber sheet R3, the temperature of that part is locally lowered, and a minimum value lower than the second threshold value T2 is detected in the temperature distribution in FIG. 5. Therefore, when the average temperature in the width direction of the rubber sheet R3 is lower than the first threshold value T1, no quality abnormality problem occurs due to high temperature, but when at least one minimum value lower than the second threshold value T2 set in advance exists in the temperature distribution in the width direction of the rubber sheet R3, it is determined that a lump of compounding agent X exists due to poor mixing, and the processing time by the closed-type rubber mixer 1 is extended. The second threshold value T2 can be arbitrarily selected using the local temperature of the rubber sheet R3 when a lump of compounding agent X is formed due to poor kneading as an index, and can be set, for example, to 80% or less of the average temperature of the rubber sheet R3.

[0026] Instead of shortening the processing time by the closed-type rubber kneading machine 1, it is possible to reduce the rotor rotation speed, reduce the number of times the ram moves up and down, lower the set temperature, or reduce the integrated power. Similarly, instead of extending the processing time by the closed-type rubber kneading machine 1, it is possible to increase the rotor rotation speed, increase the number of times the ram moves up and down, raise the set temperature, or increase the integrated power. In particular, when the processing time by the closed-type rubber kneading machine 1 is adjusted, the kneading state of the unvulcanized rubber R2 can be easily optimized.

[0027] Moreover, the material conditions in the closed rubber mixer 1, which are adjusted based on the temperature information obtained from the rubber sheet R3, preferably include the temperature at the time of feeding the unvulcanized rubber R1 that does not contain the vulcanization-based compounding agent X. For example, by increasing the temperature at the time of feeding the unvulcanized rubber R1, the compounding agent X is uniformly dispersed. Therefore, if there is at least one minimum value lower than the second threshold value T2 set in advance in the temperature distribution in the width direction of the rubber sheet R3, it is also possible to change the material conditions in the closed rubber mixer 1 and increase the temperature at the time of feeding the unvulcanized rubber R1.

[0028] In addition, when adjusting the processing conditions or material conditions in the internal rubber mixer 1 based on the temperature information obtained from the rubber sheet R3, it is advisable to take into account the driving state of the roll mill 21 as a judgment condition. For example, when the roll mill 21 stops, the heat of the rubber sheet R3 moves to the roll 24 side, and the influence of this appears in the temperature information of the rubber sheet R3, so that more accurate feedback can be performed by taking the driving state of the roll mill 1 into account as a judgment condition. For example, when the roll mill 21 stops, the temperature information on the part where the rubber sheet R3 was in contact with the roll 24 at the time of the stoppage can be excluded from the feedback. [Explanation of symbols]

[0029] 1. Internal rubber mixer 2 Casing 3. Chamber 4. Loading door 5 Inlet 6. Ram 7 Rotor 8 Control device 9. Drop Door 10 Outlet 11 Temperature Sensor 21 Rolling mill 22 Casing 23 Screw shaft 24 rolls 25 Inlet 26 Outlet 31 Temperature measuring device R1, R2 Unvulcanized rubber R3 Rubber sheet X Combination Agent

Claims

1. A rubber processing method in which unvulcanized rubber is kneaded together with compounding agents in an internal rubber kneader, and the unvulcanized rubber kneaded in the internal rubber kneader is then processed into a sheet by a roll mill, the method comprising measuring the temperature of the rubber sheet discharged from the roll mill along the width direction of the rubber sheet, and adjusting processing conditions and / or material conditions in the internal rubber kneader based on temperature information obtained from the rubber sheet.

2. 2. The rubber processing method according to claim 1, wherein the processing conditions in the internal rubber mixer that are adjusted based on the temperature information include at least one of rotor rotation speed, number of ram up and down movements, processing time, set temperature, and integrated power consumption.

3. 3. The rubber processing method according to claim 1, wherein the material conditions in the internal rubber mixer that are adjusted based on the temperature information include a temperature at the time of introduction of the unvulcanized rubber.

4. The rubber processing method according to any one of claims 1 to 3, characterized in that when adjusting the processing conditions or material conditions in the internal rubber kneader based on the temperature information, the driving state of the roll mill is taken into consideration as a judgment condition.

5. The rubber processing method according to any one of claims 1 to 4, characterized in that the temperature information includes an average temperature in the width direction of the rubber sheet and a temperature distribution in the width direction of the rubber sheet, and when the average temperature is higher than a predetermined first threshold, the processing time by the internal rubber kneader is shortened, and when the average temperature is lower than a predetermined first threshold and there is at least one minimum value in the temperature distribution that is lower than a predetermined second threshold, the processing time by the internal rubber kneader is extended.

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