JP5820174B2 - Rubber composition kneading equipment and kneading method - Google Patents

Description

  The present invention relates to a kneading facility and a kneading method for a rubber composition in which silica and a silane coupling agent are blended with a raw rubber.

  Silica is used as a filler for reinforcing rubber. Silica tends to aggregate particles due to hydrogen bonding of silanol groups which are surface functional groups. Therefore, when silica is blended in the rubber composition, a silane coupling agent is added to improve the dispersion of the silica, the silica and the coupling agent are reacted to improve the dispersibility and suppress reagglomeration, thereby reducing the tire's weight. Improved fuel economy and wettability.

  In order to knead a rubber composition containing such a silica and a silane coupling agent, a closed mixer (hereinafter referred to as “closed mixer”) having a pair of rotors is widely used. The coupling reaction between the silica and the silane coupling agent requires a kneading temperature of 120 ° C. to 160 ° C., and various proposals have been made regarding optimum reaction temperature and reaction time. On the other hand, when the kneading temperature is 170 ° C. or higher, the viscosity of the rubber increases due to the occurrence of a gelling reaction.

  In order to fully demonstrate the fuel economy and wet performance of the rubber composition to which silica is added, it is necessary to secure the reaction time and heat history of the coupling reaction, and the kneading time is adjusted by adjusting the rotor speed. The process of discharging the rubber composition from the mixer and cooling it, and then charging it again into the mixer is repeated a plurality of times so that the temperature of the rubber composition does not rise excessively. Therefore, it is necessary to knead in a closed mixer for a long time in order to secure the reaction time and heat history of the coupling reaction, and since the production amount of the rubber composition per predetermined time is small, the original performance of the rubber composition is demonstrated. It is an issue to further improve the efficiency of the kneading process.

  In order to cope with this problem, techniques disclosed in Patent Documents 1 and 2 below are known. In patent document 1, after kneading the rubber composition which mix | blended the silica and the silane coupling agent with a mixer, this kneaded rubber composition is moved to a reaction control apparatus, and 130 ~ It is kept at a temperature of 170 ° C. for 2 to 20 minutes. The reaction control device is constituted by a screw extruder having a temperature control function.

  In Patent Document 2 below, a rubber composition containing silica and a silane coupling agent is kneaded with a mixer at a temperature of 160 ° C. or lower, then conveyed onto a pair of kneading rolls, and shearing given by these kneading rolls. The sheet is formed by passing between kneading rolls while maintaining the temperature of 140 ° C. to 160 ° C. by self-heating the rubber by force. The sheet is returned onto the kneading roll while being cooled on the conveyor, and is again passed between the kneading rolls.

  Further, Patent Document 3 discloses a process for producing a rubber composition by dividing it into two stages, that is, basic mixing and finished mixing. Specifically, a ram type closed mixer is used for the basic mixing, and a ramless closed mixer is disposed below the ram closed mixer.

JP 2004-352831 A JP 2007-8112 A JP-A-1-125208

  However, each of the above prior arts has the following problems. That is, in Patent Document 1, the coupling reaction is performed using a screw extruder, but the time and heat history spent for the reaction are not sufficient in the extruder. Further, in Patent Document 2, a roll is used, but since the time for which the shearing force acts on the rubber composition is limited to a very short time passing through the pair of roll gaps, the roll gap is passed several times. Even if it makes it, a silica may reagglomerate.

  In Patent Document 3, hermetic mixers are arranged at the top and bottom, and the mixer installed in the lower part needs a larger size than the mixer in the upper part, and requires a large installation area. In addition, the rubber material is transferred from the upper mixer to the lower mixer by gravity, and there is a concern of material clogging at the inlet of the lower mixer.

  The present invention has been made in view of the above circumstances, and the problem is that the reaction time and heat history of the silane coupling agent are ensured, and the performance of the rubber composition in which silica is blended is sufficiently exhibited. An object of the present invention is to provide a rubber composition kneading equipment and a kneading method capable of suppressing the installation area and equipment introduction cost while efficiently performing the composition kneading step and having excellent productivity.

In order to solve the above problems, the rubber composition kneading equipment according to the present invention comprises:
A kneading facility for a rubber composition in which silica and a silane coupling agent are blended with a raw rubber,
At least an inlet for charging raw rubber, silica, and a silane coupling agent (hereinafter referred to as a rubber composition), a rotor for kneading the charged rubber composition, and a discharge for discharging the kneaded rubber composition. An enclosed mixer with an outlet,
A receiving container for receiving the rubber composition discharged from the closed mixer;
A transfer device for transferring the rubber composition from the receiving container;
An inlet into which the rubber composition from the transfer device is charged; a rotor for kneading the charged rubber composition; and a pressure lid that closes a space above the rotor when the rubber composition is kneaded. When, with a discharge port for discharging the rubber composition is kneaded, and a kneader to promote the coupling reaction,
A sheet-like rubber molding apparatus for charging the rubber composition discharged from the kneader and molding a sheet-like rubber; and
The transfer device, the kneader, and the rubber molding device are installed on the same floor together with the receiving container.

  The operation and effect of the rubber composition kneading equipment with this configuration will be described. This facility includes a closed mixer, a receiving container, a transfer device, a kneader, and a sheet-like rubber molding device. The hermetic mixer includes a rotor, and kneads the charged rubber composition and discharges it from the discharge port. The closed mixer, which is the first stage processing step, mainly performs kneading of the rubber composition. The kneaded rubber composition is once received in a receiving container and transferred to a charging port of a kneader by a transfer device. The kneader is kneaded again, but the kneader is processed under conditions that promote the coupling reaction. After the coupling reaction is sufficiently performed, the sheet material is formed in the next step.

  After the rubber composition is sent from the closed mixer to the kneader, the rubber composition to be subjected to the next treatment can be charged in the closed mixer. That is, at the same time as the kneading of the rubber composition in the closed mixer, the kneader can promote the coupling reaction of the rubber composition that has already been treated in the closed mixer. Therefore, as a whole, it is possible to increase the kneading processing capacity of the rubber composition per predetermined time. Moreover, the receiving container, the transfer device, the kneader, and the rubber molding device are arranged to be installed on the same floor, and do not require a large arrangement space in the vertical direction. Therefore, while ensuring the reaction time and heat history of the silane coupling agent and fully exhibiting the performance of the rubber composition containing silica, it is excellent in productivity by efficiently performing the kneading process of the rubber composition. An object of the present invention is to provide a rubber composition kneading equipment and a kneading method capable of suppressing the installation area of the equipment.

  In this invention, it is preferable that the said receiving container has been arrange | positioned directly under the said closed mixer. According to this configuration, the space required in the vertical direction can be reduced by disposing it directly below. In addition, since the rubber composition is once received in the receiving container, problems such as clogging of the material can be prevented.

In order to solve the above problems, the kneading method of the rubber composition according to the present invention,
A kneading method of a rubber composition in which silica and a silane coupling agent are blended with a raw rubber,
At least raw rubber, silica and a silane coupling agent (hereinafter referred to as a rubber composition) are charged into a closed mixer, and the charged rubber composition is kneaded with a rotor and discharged;
Receiving the rubber composition discharged from the closed mixer by a receiving container;
Transferring the rubber composition from the receiving container by a transfer device;
The rubber composition from the transfer device is put into a kneader, and the charged rubber composition is kneaded with a rotor. When kneading, the space above the rotor is closed with a pressure lid to promote the coupling reaction. And a process of discharging after letting
A step of charging the rubber composition discharged from the kneader and molding a sheet-like rubber with a sheet-like rubber molding device,
The transfer device, the kneader, and the rubber molding device are installed on the same floor together with the receiving container.

  The operation and effect of the rubber composition kneading method with such a configuration is as described above, and the rubber composition kneading treatment capacity per predetermined time can be increased. Moreover, the receiving container, the transfer device, the kneader, and the rubber molding device are arranged to be installed on the same floor, and do not require a large arrangement space in the vertical direction. Therefore, while ensuring the reaction time and heat history of the silane coupling agent and fully exhibiting the performance of the rubber composition containing silica, it is excellent in productivity by efficiently performing the kneading process of the rubber composition. Further, it is possible to provide a rubber composition kneading equipment and a kneading method capable of suppressing the installation area of the equipment.

The conceptual diagram which shows the structure of the kneading equipment which concerns on 1st Embodiment. The conceptual diagram which shows the structure of the kneading equipment which concerns on 2nd Embodiment. Table showing experimental results of Examples and Comparative Examples

  A preferred embodiment of a rubber composition kneading facility according to the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram showing the configuration of the kneading equipment according to the first embodiment. The facilities are arranged over a total of 3 floors.

<Kneading equipment according to the first embodiment>
On the third floor, a carbon black measuring device 6 is installed to store and measure carbon black.

  A closed mixer 1 is installed on the second floor. The hermetic mixer 1 includes a charging port 10 for charging raw rubber, silica, silane coupling agent, oil and the like (hereinafter referred to as rubber composition including CB), and a charging port 10A for charging CB. And a rotor 11 for kneading the charged rubber composition, and a discharge port 12 for discharging the kneaded rubber composition. A belt conveyor 15 for transferring the rubber composition is provided adjacent to the charging port 10. A ram 13 that can move up and down is disposed on the upper portion of the pair of rotors 11. When the rubber composition is kneaded, the ram 13 moves downward to close the space above the rotor 11.

  The discharge port 12 is provided with an opening / closing part 14 (drop door). When kneading by the rotor 11 is performed, the opening / closing part 14 is closed, and when the kneaded rubber composition is discharged, the opening / closing part 14. Controlled to open.

  A receiving container 2 is arranged on the first floor. When the rubber composition kneaded by the closed mixer 1 is discharged from the opening / closing part 14, the receiving container 2 receives it. The discharged rubber composition falls into the receiving container 2.

  The rubber composition in the receiving container 2 is transferred to the kneader 4 by the transfer device 3. The transfer device 3 includes a conveyor 30, and the rubber composition is transferred to the upper portion of the kneader 4 by the conveyor 30.

  The kneader 4 includes an input port 40 into which the rubber composition transferred by the conveyor 30 is input, a pair of rotors 41 for kneading the input rubber composition, and a pressure lid 42 that can move up and down. ing. When the rubber composition is kneaded, the pressure lid 42 moves downward to close the space above the rotor 41. The closed mixer 1 mainly performs kneading of the charged rubber composition, whereas the kneader 4 mainly functions to promote the reaction of the silane coupling agent contained in the rubber composition.

  The rubber composition kneaded by the kneader 4 is charged into the charging port 50 of the sheet-like rubber molding device 5 by turning the entire kneader 4 in the direction of the arrow. The rubber composition discharged from the kneader 4 is also massive. The sheet-like rubber molding apparatus 5 includes a slot 50 into which the transferred rubber composition is introduced, a pair of rollers 51 for forming a sheet material, and a sheet-like rubber composition molded by the rollers 51. And a discharge port 52 for discharging.

  The said receiving container 2, the transfer apparatus 3, the kneader 4, the transfer apparatus 7, and the sheet-like rubber molding apparatus 5 are installed in the same 1F floor.

<Kneading process of rubber composition>
Next, steps for kneading a rubber composition containing silica using the kneading equipment shown in FIG. 1 will be described. First, a rubber material, silica, a silane coupling agent, and the like are charged from the charging ports 10 and 10A of the hermetic mixer 1. In the hermetic mixer 1, the rubber composition is kneaded by the rotor 11. When kneading, the ram 13 is lowered and the rubber composition is kneaded. The temperature at the time of kneading is set to be 170 ° C. or lower.

  By performing kneading, a coupling reaction between silica and a silane coupling agent is performed. Such a reaction is carried out at a temperature of 120 ° C. to 160 ° C. or higher, but when the temperature becomes 170 ° C. or higher, the viscosity of the rubber increases rapidly. To do. As for the discharge timing, the temperature of the rubber composition is measured by a temperature sensor installed in the opening / closing part 14 and discharged when it reaches a reference temperature.

  The discharged rubber composition falls into the receiving container 2. Thereafter, the rubber composition is transferred to the position of the charging port 40 of the kneader 4 by the conveyor 30. The rubber composition is charged from the charging port 40 and kneaded by the pair of rotors 41. The kneader 4 kneads the rubber composition. However, since the rubber composition that has been thermoplasticized in the hermetic mixer 1 is kneaded, the kneader 4 with low power and low cost can be applied. The capacity of the kneader 4 may be the same capacity as the closed mixer 1. Therefore, compared with the case where a closed mixer is applied to the lower mixer, the kneader 4 uses the characteristics of the kneader 4 which is mild in temperature rise and easy to control temperature while suppressing the installation area and the equipment cost. To ensure the reaction time and heat history of the ring agent, to fully demonstrate the performance of the rubber composition containing silica, and to perform kneading with excellent productivity by efficiently performing the kneading process of the rubber composition. Can do.

  Accordingly, as described above, the rubber composition can be kneaded while maintaining the temperature of 140 ° C. to 170 ° C. to promote the coupling reaction. That is, the kneader 4 can supplement the coupling reaction that has been insufficient with the kneading by the closed mixer 1. The kneading time is about 1 to 10 minutes.

  The rubber composition kneaded by the kneader 4 is charged from the charging port 50 of the sheet-like rubber molding device 5. The charged rubber composition is formed into a sheet by passing between the pair of rollers 51.

  The rubber material or the like charged into the hermetic mixer 1 is continuously processed and discharged by the kneader 4 and the sheet-like rubber molding device 5. Further, when the rubber composition is discharged from the hermetic mixer 1, the rubber material to be processed next can be input from the input ports 10 and 10A. That is, since the kneading (coupling reaction) of the rubber composition is performed with the kneader 4, the kneading process of the next rubber composition can be performed in parallel with the closed mixer 1. The kneading step can be performed efficiently while ensuring sufficient time.

  Moreover, as shown in FIG. 1, the receiving container 2, the transfer apparatus 3, the kneader 4, the transfer apparatus 7, and the sheet-like rubber molding apparatus 5 are arranged on the same floor, and the installation area and the installation floor are more than conventional. Each device can be installed in a suppressed state.

<Kneading equipment according to the second embodiment>
Next, the kneading equipment according to the second embodiment will be described with reference to FIG. The difference from the first embodiment of FIG. 1 is that, in the first embodiment, the hermetic mixer 1, the kneader 4, the sheet-like rubber molding device 5 and the like are installed on different floors. In form, they are installed on the same floor.

  Since the rubber composition discharged from the closed mixer 1 is in the form of a lump, if it is left as it is for a long time, the silane coupling reaction may partially proceed. As a result, the generation and re-aggregation of the gel progresses and the rubber physical properties are deteriorated. Further, when the rubber temperature is lowered, the plasticity is increased and kneading with the kneader 4 having a small power cannot be performed. It is preferable to keep the rubber temperature at 120 ° C. or more for a conveyance time to the kneader 4 within 60 seconds.

  Therefore, by arranging the receiving container 2 immediately below the hermetic mixer 1, it becomes easy to cope with the above-mentioned point. Even with this configuration, the same operations and effects as those of the first embodiment can be achieved.

  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.

<Experimental result>
Next, an experiment was conducted to confirm the effect of the present invention. FIG. 3 is a table showing experimental results regarding Examples 1, 2, and 3 and Comparative Examples 1 and 2.

(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: (CnH2n + 1O) 3Si-CmH2m-S-CO-CkH2k + 1 coupling agent (n = 2, m = 3, k = 7), "NXT" manufactured by Momentive Performance Materials
・ Oil: Japan Energy Co., Ltd. “Process X-140”

<Comparative Example 1>
(First step) ... Add carbon black, silica, silane coupling agent, oil, etc. to the raw rubber, knead in a closed mixer, discharge at 150 ° C, mold into a sheet, release Apply agent and cool. The rubber composition discharged from the hermetic mixer is formed into a sheet using a roll or a sheet-like rubber molding extruder.
(Second step) ... After the first step, the rubber composition is kneaded again with a closed mixer, discharged at 150 ° C, molded into a sheet, coated with a release agent and cooled. The method of forming into a sheet is the same as in the first step.
(Third step) ... After the second step, the rubber composition is kneaded with a chemical such as a vulcanizing agent in a closed mixer, discharged at 100 ° C, molded into a sheet, and a release agent is applied. Cool down. The method of forming into a sheet is the same as in the first step.

<Comparative Example 2>
During the kneading in the first step of Comparative Example 1, the kneading time was extended at 150 ° C. for 3 minutes to ensure the reaction time with the silane coupling agent.

<Example 1>
After kneading in the first step of Comparative Example 1, the mixture was put into a kneader and kneaded at 150 ° C. for 1 minute to carry out the third step.

<Example 2>
After kneading in the first step of Comparative Example 1, the mixture was put into a kneader and kneaded at 150 ° C. for 3 minutes to carry out the third step.

<Example 3>
After kneading in the first step of Comparative Example 1, the mixture was put into a kneader and kneaded at 150 ° C. for 3 minutes, and then the second step and the third step were performed.

  There are three evaluation items in the experimental results: productivity (kneading time), Mooney viscosity (ML1 + 4 at 100 ° C.), and loss resistance (tan δ). The Mooney viscosity was measured in accordance with JIS K6300 by measuring Mooney viscosity ML (1 + 4) at 100 ° C. The smaller the index, the lower the viscosity and the better the workability. For tan δ, a dynamic viscoelasticity measuring device (manufactured by Ueshima Seisakusho Co., Ltd.) was used, and loss factor tan δ was measured under the conditions of frequency 50 Hz, dynamic strain 1.0%, and temperature 50 ° C. according to JIS K6394. Comparative example 1 is indicated by an index of 100, and the smaller the value, the lower tan δ and the better the fuel economy.

  In addition, about the kneading | mixing time, since Examples 1-3 use the kneading | mixing process by a kneader and it can be implemented in parallel with a 1st process and a kneader, it calculates except the kneading | mixing time of a 1st process. Yes.

  As can be seen from FIG. 3, in Examples 1 and 2, the kneading time is shorter than in Comparative Examples 1 and 2, and the productivity is improved. In Example 1, Mooney viscosity and low exothermic property are almost the same as those in Comparative Example 1, and there is no problem in the characteristics of the rubber composition. The productivity of Example 2 is slightly improved compared to Comparative Example 1. In addition, the low heat generation property is reduced by 6 points, and the characteristics are improved.

  In Example 3, although the productivity was not improved, the Mooney viscosity was almost the same, and the low heat build-up was reduced by 8 points, and the characteristics were improved.

<Another embodiment>
As the kneader 4, a non-pressure type kneader may be used, or a pressure type kneader may be used.

DESCRIPTION OF SYMBOLS 1 Sealing type mixer 2 Receiving container 3 Transfer device 4 Kneader 5 Sheet-like rubber molding device 6 Weighing device 10 Input port 11 Rotor 12 Discharge port 30 Conveyor 40 Input port 41 Rotor 42 Pressure lid 50 Input port 51 Roller 52 Discharge port

Claims (8)

A kneading facility for a rubber composition in which silica and a silane coupling agent are blended with a raw rubber,
At least an inlet for charging raw rubber, silica and a silane coupling agent (hereinafter referred to as a rubber composition), a rotor for kneading the charged rubber composition, and a kneaded rubber composition are discharged. A closed mixer equipped with a discharge port;
A receiving container for receiving the rubber composition discharged from the closed mixer;
A transfer device for transferring the rubber composition from the receiving container;
An inlet into which the rubber composition from the transfer device is charged; a rotor for kneading the charged rubber composition; and a pressure lid that closes a space above the rotor when the rubber composition is kneaded. When, with a discharge port for discharging the rubber composition is kneaded, and a kneader to promote the coupling reaction,
A sheet-like rubber molding apparatus for charging the rubber composition discharged from the kneader and molding a sheet-like rubber; and
The rubber composition kneading equipment, wherein the transfer device, the kneader, and the rubber molding device are installed on the same floor together with the receiving container. 2. The rubber composition kneading facility according to claim 1, wherein the receiving container is disposed immediately below the hermetic mixer. A kneading method of a rubber composition in which silica and a silane coupling agent are blended with a raw rubber,
At least raw rubber, silica and a silane coupling agent (hereinafter referred to as a rubber composition) are charged into a closed mixer, the rubber composition is kneaded with a rotor, and discharged;
Receiving the rubber composition discharged from the closed mixer by a receiving container;
Transferring the rubber composition from the receiving container by a transfer device;
The rubber composition from the transfer device is put into a kneader, and the charged rubber composition is kneaded with a rotor. When kneading, the space above the rotor is closed with a pressure lid to promote the coupling reaction. And a process of discharging after letting
A step of charging the rubber composition discharged from the kneader and molding a sheet-like rubber with a sheet-like rubber molding device,
The rubber composition kneading method, wherein the transfer device, the kneader, and the rubber molding device are installed on the same floor together with the receiving container. The rubber component includes a modified styrene butadiene rubber modified with amine and alkoxylane,
The method for kneading a rubber composition according to claim 3, wherein the silane coupling agent contains bis- (3-triethoxysilylpropyl) disulfide or protected mercaptosilane. The rubber composition kneading equipment according to claim 1 or 2, wherein a capacity of the kneader is equal to a capacity of the hermetic mixer. The rubber composition kneaded by the kneader is fed into the inlet of the sheet-like rubber molding device by turning the attitude of the entire kneader. Facility. The method for kneading a rubber composition according to claim 3 or 4, wherein a capacity of the kneader is equivalent to a capacity of the closed mixer. The method for kneading a rubber composition according to claim 3, 4 or 7, wherein the rubber composition kneaded by the kneader is charged into an inlet of the sheet-like rubber molding device by turning the attitude of the entire kneader. .