JP4909442B1 - Manufacturing apparatus and manufacturing method of rubber compounding composition - Google Patents

Abstract

The present invention provides an apparatus and a method for producing a rubber compounding composition that enables rubber kneading and reaction of a silane coupling agent to be efficiently performed with inexpensive and space-saving equipment.
An agitation rotor 6 for agitating a material introduced from an inlet 3 in a sealed kneading chamber 5, a control unit 11 for automatically controlling the rotation speed of the agitation rotor 6, and a temperature in the kneading chamber 5 are controlled. A temperature sensor 13 that detects and outputs information relating to the detected actual temperature to the control unit 11, and the control unit 11 has at least a rubber component, silica, and a silane coupling agent in the kneading chamber. In the above, until the set control time elapses, the rotational speed is automatically controlled by PID control for setting the measured temperature to the target temperature based on the information about the measured temperature and the set target temperature. To do.
[Selection] Figure 1

Description

  The present invention relates to an apparatus and a method for producing a rubber compounding composition, and more particularly to an apparatus and method for producing a rubber compounding composition by kneading a rubber component, silica, and a silane coupling agent.

  In recent years, silica has been used as a filler for rubber reinforcement in place of carbon black. However, since silica has a weak reinforcing property against rubber compared to carbon black, it is common to add a silane coupling agent when blending silica into a rubber component in order to enhance this reinforcing property. By adding silane coupling as a compounding agent, the silane coupling agent is immobilized on silica by a coupling reaction, and the rubber component reacts with the silane coupling agent, so that the dispersibility of silica in rubber is improved. This increases the reinforcement.

  By the way, in order to efficiently perform the reaction between the silica and the silane coupling agent, it is desirable to knead for a long time at a specific temperature. In a low temperature environment, the coupling reaction between silica and the silane coupling agent is difficult to occur. However, when the temperature is too high, a rubber crosslinking reaction occurs, and the viscosity rapidly increases and gels.

  When kneading with a mixer in the presence of a rubber component, silica, and a silane coupling agent, the temperature in the mixer rises due to heat generation due to rubber viscous flow and heat generation due to the coupling reaction. . For this reason, it raises to the temperature which gelatinizes within a short time, and there exists a problem that the time of a coupling reaction cannot be taken fully.

  Patent Document 1 proposes a method in which a kneading step for dispersion is performed in a closed Banbury mixer, and a coupling reaction after adding a silane coupling agent is performed in another unsealed mixer. .

  In Patent Document 2, after kneading with a closed Banbury mixer in the presence of a rubber component, silica, and a silane coupling agent, in a temperature state slightly lower than the temperature range suitable for the coupling reaction, There has been proposed a method in which the produced rubber composition is conveyed onto a pair of kneading rolls, and a coupling reaction is performed while causing self-heating by a shearing force applied from the kneading rolls.

JP 2004-352831 A JP 2007-8112 A

  However, according to the methods of Patent Documents 1 and 2, since both require a dedicated mixer and roll for the coupling reaction, there is a problem that the installation space is increased and the production cost is greatly increased. .

  An object of the present invention is to provide an apparatus and a method for producing a rubber compounding composition that enables rubber kneading and reaction of a silane coupling agent to be efficiently performed with inexpensive and space-saving equipment. And

In order to achieve the above object, the apparatus for producing a rubber compounding composition according to the present invention comprises:
A slot for feeding materials;
An agitation rotor for agitating the material charged from the charging port in a sealed kneading chamber;
A control unit for automatically controlling the rotation speed of the stirring rotor;
A temperature sensor that detects the temperature in the kneading chamber and outputs information on the detected actual temperature to the control unit;
The control unit includes information on the measured temperature and a set target temperature until a set control time elapses in a state where at least a rubber component, silica, and a silane coupling agent are present in the kneading chamber. The rotational speed is automatically controlled by PID control for setting the measured temperature to the target temperature based on the information regarding the rotation speed.

  More specifically, the control unit may be configured to automatically control the rotation speed of a motor for rotationally driving the stirring rotor.

In order to achieve the above object, a method for producing a rubber compounding composition according to the present invention comprises:
At least a rubber component, silica, and a silane coupling agent are mixed in a sealed kneading chamber equipped with a stirring rotor capable of automatically controlling the rotation speed by a control unit and capable of detecting and outputting the internal temperature. Steps,
Setting the control unit for the control time and the target temperature;
PID control for setting the measured temperature to the target temperature by the control unit based on the information about the measured temperature in the kneading chamber and the target temperature until the control time elapses after the completion of the two steps. And agitating the kneading chamber while automatically controlling the rotation speed.

  At this time, the target temperature is preferably set to a temperature lower than the lower limit temperature at which the rubber component gels and higher than the lower limit temperature at which the coupling reaction between the silica and the silane coupling agent occurs. The lower limit temperature at which the rubber component gels and the lower limit temperature at which the coupling reaction between the silica and the silane coupling agent occurs are determined according to the materials employed for kneading. For this reason, the kneading process can be performed under an appropriate temperature environment according to the material.

  According to the present invention, the rotation speed of the stirring rotor is automatically controlled by PID control by the control unit, so that the temperature in the kneading chamber can be kept within a certain range over a certain time. This makes it possible to stir and knead in the kneading chamber for a certain period of time while maintaining the temperature, so that it has better characteristics than the conventional configuration in which the rubber compound is discharged when the temperature reaches a certain temperature or higher. Can be produced.

  In addition, since a device for kneading silica and a rubber component and a device for causing a coupling reaction can be realized in the same device, it is possible to produce a rubber compound showing good characteristics with inexpensive and space-saving equipment. it can.

1 is a schematic structural diagram of a kneading apparatus according to the present invention. It is a flowchart which shows the flow of the rubber processing method performed with this apparatus. It is the graph which showed the change of the actual temperature in a kneading chamber and the rotation speed of a motor under PID control from a control part in this device with time.

  FIG. 1 shows a schematic diagram of a manufacturing apparatus according to the present invention (hereinafter referred to as “the present apparatus”). This apparatus 1 shown in FIG. 1 is a closed mixer, a cylinder 2 used for raising and lowering a ram 4, a charging port 3 for charging work material, a kneading chamber 5 for kneading material, and kneaded. A drop door 7 for discharging the rubber is provided. The ram 4 is arranged to adjust the pressure in the kneading chamber 5 by raising and lowering.

  The kneading chamber 5 is provided with a pair of agitation rotors 6 for agitating the material, and the agitation rotors 6 are rotationally driven around a rotary shaft 12 by a motor (not shown). The kneading chamber 5 is provided with a temperature sensor 13 for detecting the temperature in the chamber. The temperature sensor 13 may be installed inside the drop door 7, for example.

  The rotation speed of the motor that rotates the stirring rotor 6 is adjusted based on a control signal from the control unit 11. The controller 11 controls the rotational speed of the motor based on the temperature information in the kneading chamber 5 sent from the temperature sensor 13. The motor may be configured so that the rotation speed can be freely changed by the control unit 11, and is configured by an inverter motor, for example.

  More specifically, the rotational speed of the motor is proportional to the deviation between the measured temperature Tp in the kneading chamber 5 detected by the temperature sensor 13 and the target temperature Ts by the PID calculation processing unit provided inside the control unit 11. PID control based on execution of operations of (P), integration (I), and differentiation (D) is executed. That is, the PID calculation processing unit calculates a control amount in proportion to the difference (deviation e) between the measured temperature Tp in the kneading chamber 5 detected by the temperature sensor 13 and the target temperature Ts (deviation). For each controlled variable obtained by an integral (I) operation for calculating a controlled variable by an integral value obtained by integrating e in the time axis direction, and a differential (D) operation for calculating a controlled variable from the slope of the deviation e, that is, a differential value. The rotational speed of the motor is determined by the total value.

  In FIG. 2, the flow of the rubber processing method performed by this apparatus 1 is illustrated as a flowchart. When a rubber component, silica, and a silane coupling agent are introduced into the apparatus 1 (step S1), the controller 11 supplies the motor to the motor based on the target temperature Ts and the control set time tm input in step S2. PID control is started (step S3). That is, the rotational speed of the motor is determined based on the control signal from the control unit 11, and thereby the rotational speed of the stirring rotor 6 (that is, the stirring speed) is determined. Information regarding the target temperature Ts and the control set time tm may be given in advance to the control unit 11 in the stage before step S1.

  In step S1, the rubber component, silica, and the silane coupling agent may be independently charged into the apparatus 1, and after the rubber component and silica are charged, a certain stirring process is performed. A mode in which a silane coupling agent is introduced later is also acceptable.

  The control unit 11 performs PID control on the rotational speed of the motor until the elapsed time t from the control start time becomes equal to or longer than the control set time tm (No in step S4). As for the specific control contents, as described above, based on the deviation between the measured temperature Tp and the target temperature Ts in the kneading chamber 5 sent from the temperature sensor 13, the deviation integral value, and the deviation differential value, To change.

  Note that the value of the target temperature Ts is preferably set lower than the lower limit temperature at which the rubber component starts gelling by a minute temperature. This is because the control unit 11 is configured to perform PID control, but it is assumed that the target temperature Ts may be temporarily exceeded in the control process. That is, it is preferable to set the value of the target temperature Ts so that the actually measured temperature Tp in the kneading chamber 5 is temporarily allowed to slightly exceed the target temperature Ts in the control process. The target temperature Ts is set to a value higher than the lower limit temperature at which the coupling reaction between silica and the silane coupling agent occurs.

  When the control time t becomes equal to or greater than the control set time tm (Yes in step S4), the control unit 11 finishes the PID control to the motor and discharges the rubber composition from the drop door 7 (step S5). ).

  Here, the control set time tm is set to a time longer than the time tc necessary for sufficiently performing the coupling reaction between the silica and the silane coupling agent. More specifically, the time tc and the time ti are added in consideration of the time ti that is expected to rise to the temperature range suitable for the coupling reaction after the actually measured temperature Tp is started. It is preferable that the time be at least.

  FIG. 3 is a graph showing changes over time in the measured temperature Tp in the kneading chamber 5 and the rotational speed of the motor under PID control from the control unit 11 in the present apparatus 1. Note that (b) is an enlarged view of a region A portion in (a).

  According to FIG. 3, it can be seen that the measured temperature Tp in the kneading chamber 5 can be maintained at a value substantially equal to the target temperature Ts over a long period of time by changing (increasing or decreasing) the rotational speed of the motor in small increments. Therefore, by maintaining this temperature longer than the time ti, the coupling reaction with the silane coupling agent can be sufficiently performed in the kneading chamber 5. In the example of FIG. 3, PID control was performed with the target temperature Ts set to 155 ° C., and the measured temperature Tp could be maintained at 150 ° C. to 158 ° C.

  In the flowchart of FIG. 2, the PID control by the control unit 11 is always executed after the silane coupling agent is added. However, in practice, the user can select whether to perform the PID control. It doesn't matter.

  Further, the rubber component to be added contains terminal-modified diene rubber having a number average molecular weight of 150,000 to 400,000 before modification. The type of diene rubber to be terminally modified is not particularly limited, but butadiene rubber (BR. For example, high cis BR having 90% or more of cis-1,4 bond, syndiotactic-1,2-polybutadiene (SPB). Containing BR), styrene butadiene rubber (SBR), natural rubber (NR), isoprene rubber (IR), styrene isoprene copolymer rubber, butadiene isoprene copolymer rubber, and the like, more preferably BR and SBR. More preferably, it is SBR.

  As this terminal-modified diene rubber, diene rubber whose polymer terminal is modified with various modifiers can be used, and various known modification methods can be used. Specifically, as the modifier, tin compound, aminobenzophenone compound, isocyanate compound, diglycidylamine compound, cyclic imine compound, halogenated alkoxysilane compound, glycidoxypropylmethoxysilane compound, neodymium compound, alkoxysilane compound, amine Examples thereof include a combination of a compound and an alkoxysilane compound.

  Moreover, as a silane coupling agent used at the time of kneading | mixing, if it contains sulfur in a molecule | numerator, it will not specifically limit, The various silane coupling agents mix | blended with a silica in a rubber composition can be used. For example, bis (3-triethoxysilylpropyl) tetrasulfide (for example, “Si69” manufactured by Degussa), bis (3-triethoxysilylpropyl) disulfide (for example, “Si75” manufactured by Degussa), bis (2-tri Sulfide silanes such as ethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) disulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) disulfide, γ-mercaptopropyltri Mercaptosilanes such as methoxysilane, γ-mercaptopropyltriethoxysilane, mercaptopropylmethyldimethoxysilane, mercaptopropyldimethylmethoxysilane, mercaptoethyltriethoxysilane, 3-octanoylthio-1- Examples thereof include protected mercaptosilanes such as propyltriethoxysilane and 3-propionylthiopropyltrimethoxysilane. It is preferable that the compounding quantity of a silane coupling agent is 2-25 mass parts with respect to 100 mass parts of silica, More preferably, it is 5-15 mass parts.

  By using this apparatus, the temperature in the kneading chamber 5 can be maintained for a certain period of time, so that a good rubber compounding composition can be produced. Specific effects are described in more detail in the following examples.

  The results are shown in Table 1 below as Examples 1 to 3 when kneaded under PID control by the present apparatus 1 and Comparative Examples 1 to 3 when kneaded without performing PID control. Each value is shown as a relative value when the value in Comparative Example 1 is used as a reference (100). In each example and comparative example, the following materials were used.

(material)
Modified styrene butadiene rubber (modified SBR): HPR340 (modified S-SBR, amount of bonded styrene: 10% by mass, modified with amine and alkoxyl silane) manufactured by JSR Corporation.
・ Untreated silica: Tosoh Silica Industry Co., Ltd. “Nipseal AQ”
Silane coupling agent: bis- (3-triethoxysilylpropyl) disulfide, “Si-75” manufactured by Degussa
Protected mercaptosilane: (C _n H _{2n + 1} O) ₃ Si—C _m H _2m —S—CO—C _k H _{2k + 1} (n = 2, m = 3, k = 7) Momentive Performance Materials "NXT"
・ Oil: Japan Energy Co., Ltd. “Process X-140”

  In addition, when the said material is employ | adopted, the minimum temperature in which a rubber component gelatinizes is about 170 degreeC, and the minimum temperature in which the coupling reaction of a silica and a silane coupling agent produces is about 130 degreeC. That is, by performing the stirring treatment while maintaining a temperature range exceeding about 130 ° C. and below about 170 ° C., it is possible to sufficiently proceed the coupling reaction while preventing gelation of the rubber component. In particular, it is preferable to maintain a temperature range exceeding 140 ° C. and below 165 ° C., and more preferably maintaining a temperature range exceeding 145 ° C. and below 160 ° C. In the following Examples 1 to 3, the stirring process is performed while keeping the inside of the kneading chamber 5 at 150 ° C., which is within the above temperature range, by the PID control of the apparatus 1.

  In addition, about each item, a value was measured by the method shown below, and it obtained by calculating | requiring the relative value with respect to the comparative example 1. FIG.

(viscosity)
The Mooney viscosity (ML _{1 + 4} ) of the rubber compounded composition taken out from the mixer was measured using a Mooney viscometer in accordance with JIS K6300 using an L-shaped rotor, preheating time was 1 minute, rotor rotation time was 4 minutes, Was measured under the conditions of 100 ° C. and a rotation speed of 2 rpm. The smaller this index, the better the moldability.

(Pain effect)
A part of the rubber compounding composition taken out from the mixer was collected as a test piece, and the minimum shearing force was subtracted from the maximum shearing force when the strain was changed from 0.5% to 45% using a rubber processing analyzer. The value was used as the value of the pane effect. Note that, as described above, the relative value with respect to Comparative Example 1 is indicated. The smaller the Payne effect, the better the dispersibility of the silica.

(Rolling resistance)
Trial tires were produced using tread rubber obtained by vulcanizing the rubber compounded composition taken out from the mixer at 150 ° C. for 30 minutes, and the rolling resistance was evaluated. The rolling resistance test was performed according to JIS D4234. Here, the drum diameter was 1708 mm, the ambient temperature was 25 ° C., the test method was the force method, and the index was expressed as an index with the tire of Comparative Example 1 as 100. Smaller values indicate lower rolling resistance and better fuel economy.

(Tan δ)
Using a test piece of a predetermined shape obtained by vulcanizing the rubber compounded composition taken out from the mixer at 150 ° C. for 30 minutes, an initial strain of 15% and a dynamic strain of ± 2.5% using a viscoelastic spectrometer manufactured by UBM Tan δ was measured according to JISK6394 under the conditions of a frequency of 10 Hz and a temperature of 60 ° C. The measured value of Comparative Example 1 is indicated by index evaluation with 100, and the smaller the value, the better the low heat buildup.

  According to Table 1, it can be seen that Examples 1 to 3 have lower viscosities and pain effects than Comparative Examples 1 to 3, and are excellent in molding processability and silica dispersibility. It can also be seen that the longer the holding time, the lower the rolling resistance and the value of tan δ, and the lower the fuel consumption and the lower the heat generation.

  According to Comparative Examples 1 to 3, it can be seen that the higher the temperature in the kneading chamber, the lower the value of the Pain effect and the more the dispersibility of the silica. However, with regard to rolling resistance and tan δ, even if the temperature is raised, the effect is not obtained so much. Furthermore, it can be seen that the viscosity is increased and the silica is re-agglomerated. On the other hand, according to Examples 1 to 3, it can be seen that the effect of lowering all the values of viscosity, rolling resistance, and tan δ can be obtained by extending the holding time.

1: Kneading device according to the present invention 2: Cylinder 3: Loading port 4: Ram 5: Kneading chamber 6: Stirring rotor 7: Drop door 11: Control unit 12: Rotating shaft 13: Temperature sensor

Claims (4)

A slot for feeding materials;
An agitation rotor for agitating the material charged from the charging port in a sealed kneading chamber;
A control unit for automatically controlling the rotation speed of the stirring rotor;
A temperature sensor that detects the temperature in the kneading chamber and outputs information on the detected actual temperature to the control unit;
The control unit is a control set as a time exceeding the minimum time required for the coupling reaction between silica and the silane coupling agent in a state where at least the rubber component, silica, and the silane coupling agent are present in the kneading chamber. Until the time elapses, the rotational speed is automatically controlled by PID control for setting the measured temperature to the target temperature based on the information on the measured temperature and information on the set target temperature. Equipment for producing a rubber compounding composition. A method for producing a rubber compounding composition comprising:
At least a rubber component, silica, and a silane coupling agent are mixed in a sealed kneading chamber equipped with a stirring rotor capable of automatically controlling the rotation speed by a control unit and capable of detecting and outputting the internal temperature. Steps,
For the control unit , setting for control time and target temperature exceeding the minimum time required for the coupling reaction of silica and silane coupling agent, and
PID control for setting the measured temperature to the target temperature by the control unit based on the information about the measured temperature in the kneading chamber and the target temperature until the control time elapses after the completion of the two steps. And a step of stirring the kneading chamber while automatically controlling the rotation speed by the method of manufacturing a rubber compounding composition.   The rubber compounding composition according to claim 2, wherein the target temperature is lower than a lower limit temperature at which the rubber component is gelled and higher than a lower limit temperature at which a coupling reaction between silica and a silane coupling agent occurs. Manufacturing method. The rubber component includes a modified styrene butadiene rubber modified with amine and alkoxylane,
The method for producing a rubber compounding composition according to claim 3, wherein the silane coupling agent contains bis- (3-triethoxysilylpropyl) disulfide or protected mercaptosilane.

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