JP5204610B2 - Tire rubber kneading method and apparatus - Google Patents

Description

  The present invention relates to a method and an apparatus for kneading tire rubber, which can improve rubber physical properties by increasing the coupling reaction between silica and a silane coupling agent in obtaining a silica-blended tire rubber.

  In recent years, in order to improve rolling resistance and wet grip performance of pneumatic tires, it has been proposed to use silica as a rubber reinforcing agent instead of carbon black. In this case, a silane coupling agent is used with the silica to enhance the dispersibility of the silica and bond the silica and rubber.

  This is because particulate silica as a reinforcing agent has a silanol group on its surface, but this silanol group is repelled from a hydrophilic and oleophilic rubber, and is therefore difficult to mix with rubber. Moreover, since silica itself tends to aggregate with each other due to the hydrogen bond of the silanol group, the dispersibility is poor. On the other hand, the silane coupling agent is composed of an alkoxy group (OR portion) and a Y portion, as shown in FIG. For example, a polysulfide group or the like having excellent affinity with the alkenyl group is included. The alkoxy group is hydrolyzed in the presence of moisture as in (a) to form a hydroxyl group (OH group) to produce an alcohol (R—OH), and further, OH groups are dehydrated as in (c). Bond by condensation. As shown in FIG. 7B, these generated components are subjected to a dehydration condensation reaction with a silanol group on the silica surface (coupling reaction between silica and a silane coupling agent) to form a silanol on the silica surface. Decrease groups and suppress silica aggregation. On the other hand, the Y portion exhibits affinity with rubber. Thereby, while dispersibility of the silica in rubber | gum is improved, rubber | gum and a silica can be combined firmly after vulcanization.

  On the other hand, when manufacturing the rubber | gum for tires of the said silica mixing, it manufactures with the following method shown in FIG. 8 according to the case of the conventional carbon black mixing | blending. Specifically, a raw rubber and a first chemical (containing at least silica and a silane coupling agent and not containing a vulcanizing agent) are charged into a sealed rubber mixer a1 that is a Banbury mixer, and shear force is applied. By applying and kneading, the first kneaded rubber g1 is formed. This stage is called master training. Thereafter, the lump-like first kneaded rubber g1 discharged from the hermetic rubber mixer a1 is supplied to a roller head extruder b or the like to be processed into a long sheet and cooled to a vulcanization temperature or lower. The Thereafter, the cooled first kneaded rubber g1 and the second chemical (including the vulcanizing agent) are charged into the closed rubber mixer a2 and kneaded at a low temperature not higher than the vulcanization temperature. This forms the final rubber composition g2. This stage is called final training. The final rubber composition g2 is processed into a long sheet through a roller head extruder b or the like, and after being cooled and temporarily stored, for example, tire rubber such as tread rubber or sidewall rubber is used. For the final rubber extrusion process.

  Here, the reason why the silica and the vulcanizing agent are kneaded in separate steps is that a strong kneading operation is required for dispersing the silica, so that the kneading temperature greatly exceeds the vulcanization temperature. Therefore, in master kneading, strong kneading under high pressure is performed mainly for dispersion of silica, and conversely, in final kneading, weak mixing at a low temperature below the vulcanization temperature is performed mainly for dispersion of vulcanizing agent. Kneading is done.

  However, as a result of the inventor's research, when master kneading is carried out only with a sealed rubber mixer, it is difficult to uniformly disperse silica. For example, desired rubber such as low heat build-up, wet grip performance, and wear resistance performance It was found that the physical properties could not be fully exhibited. In the case of dispersing silica, it is particularly important to increase the affinity with rubber by coupling the silica with a silane coupling agent as described above, but kneading with a closed rubber mixer. In this case, since the high pressure and the shearing force are strong, the temperature of the rubber rises significantly in a short time, and it is presumed that the coupling reaction is not sufficiently performed during kneading because the temperature is not constant. .

  Therefore, as a result of further studies by the present inventors, the master kneading is separated into a primary kneading step using a closed rubber mixer and a secondary kneading step using a biaxial kneader, and this secondary kneading step. It has been found that kneading while taking a predetermined temperature and time is effective for enhancing the coupling reaction and uniformly dispersing the silica.

  The present invention relates to a method for kneading a rubber for a tire which can enhance the coupling reaction between silica and a silane coupling agent during kneading to achieve more uniform dispersion of silica and improve the rubber physical properties of the silica-containing rubber. And to provide an apparatus.

  In addition, there exists the following patent document 1 as what kneads | mixes using a biaxial kneader.

JP 2005-53190 A

In order to achieve the above object, the invention of claim 1 of the present invention includes a raw material rubber for tires, and at least a silica of 20 phr or more and a silane coupling agent having a ratio of 3 to 35% by mass with respect to the silica and a vulcanizing agent. A kneading method of a rubber for tires that kneads a first chemical that does not contain to form a first kneaded rubber,
A primary kneading step of forming a first kneaded rubber by kneading the raw rubber and the first chemical with a shearing force by a hermetic rubber mixer;
Conveying and feeding step of feeding and feeding the first kneaded rubber discharged in a lump form from the outlet of the hermetic rubber mixer to the inlet of the biaxial kneader while forming into a long body using a screw feeder When,
The input first kneaded rubber is kneaded by applying a shearing force to the biaxial kneader to form a second kneaded rubber, and the second kneaded rubber is used in the biaxial kneader. A secondary kneading step for discharging from the discharge port,
The secondary kneading step includes a secondary kneading step in which the first kneaded rubber is kneaded by applying shear while controlling the temperature at a secondary kneading temperature T2 in the range of 120 to 200 ° C., and this secondary mixing. And a cooling step of cooling the rubber after the kneading step to a temperature lower than 120 ° C.

  The invention of claim 2 is characterized in that the first kneaded rubber has a temperature T1 in the range of 120 to 200 ° C. when discharged from the discharge port of the hermetic rubber mixer.

  In the invention of claim 3, the secondary kneading step is characterized in that the process time J of the secondary kneading step is 30 seconds to 8 minutes.

  In the invention of claim 4, the secondary kneading step is such that the product J × T2 of the process time J of the secondary kneading step and the secondary kneading temperature T2 is 60 to 1600 (° C./min). It is characterized by being.

In the invention of claim 5, the raw material rubber for tires and the first chemical containing at least 20 phr of silica and a silane coupling agent having a ratio of 3 to 35% by mass with respect to the silica and not containing a vulcanizing agent are included. A tire rubber kneading apparatus for kneading to form a first kneaded rubber,
A hermetic rubber mixer that forms a first kneaded rubber by kneading the raw rubber and the first chemical by applying a shearing force;
Receiving the first kneaded rubber discharged in a lump form from the discharge port of the hermetic rubber mixer, and conveying the received first kneaded rubber to the input port of the biaxial kneader while forming a long body; A screw feeder to be charged,
A biaxial kneader that forms a second kneaded rubber by kneading the first kneaded rubber charged with a shearing force,
In addition, the biaxial kneader was kneaded with a feed zone for feeding the first kneaded rubber charged to the downstream side, and a secondary kneading zone for applying shear to the fed rubber and kneading. A cooling zone for cooling the rubber to a temperature lower than 120 ° C., and the biaxial kneader has a secondary kneading temperature T2 in the range of 120 to 200 ° C. A temperature control means for controlling is further provided.

  In the present invention, as described above, in the master kneading of the raw rubber and the first chemical (containing silica and silane coupling agent and not containing the vulcanizing agent), this master kneading is carried out by using a sealed rubber mixer. The primary kneading step used and the secondary kneading step using a biaxial kneader are separated.

  In the primary kneading step, high kneading energy is imparted by the closed rubber mixer, and the raw rubber is pulverized → plasticized → agglomerated → integrated → fluidized, and the first chemical is mixed and dispersed. In this step, the temperature of the rubber rises significantly in a short time, and since the temperature is not constant and non-uniform, the coupling reaction between silica and the silane coupling agent is not sufficiently performed.

  On the other hand, the secondary kneading step using the biaxial kneader includes a secondary kneading step of kneading the first kneaded rubber while controlling the temperature to a predetermined kneading temperature T2. In this step, the first kneaded rubber can be kneaded while taking a predetermined kneading temperature T2 and time. Therefore, it becomes possible to enhance the coupling reaction and uniformly disperse the silica, thereby improving the rubber physical properties of the silica-containing rubber.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic side view conceptually showing an example of a kneading apparatus for carrying out the tire rubber kneading method of the present invention.

  The kneading apparatus 1 of the present embodiment is a kneading apparatus for performing the above-described master kneading, and kneading the raw rubber and the first chemical with a shearing force to knead the first kneaded rubber G1. The sealed rubber mixer 2 to be formed and the lump-like first kneaded rubber G1 discharged from the sealed rubber mixer 2 are conveyed and charged to the inlet 4 of the biaxial kneader 3 while being formed into a long body. The screw feeder 5 and the biaxial kneader 3 that forms the second kneaded rubber G2 by further applying a shearing force to the charged first kneaded rubber G1 and kneading are configured.

  Here, the first chemical is composed of a chemical containing at least silica and a silane coupling agent and not containing a vulcanizing agent. In this example, the case where the first chemical is composed of silica, a silane coupling agent, and carbon black having a fine powder form and inferior dispersibility is exemplified, but besides this, for example, a softener (oil, wax), Additives usually used in the rubber industry such as anti-aging agent, stearic acid, zinc white and the like can be appropriately included.

  Silica is blended in an amount of 20 parts by mass or more with respect to 100 parts by mass of the raw rubber in order to exhibit rubber physical properties such as low heat build-up and good wet grip properties unique to this silica. Further, the silane coupling agent is blended in an amount of 3 to 35% by mass with respect to silica in order to appropriately perform a coupling reaction with silica. In addition, when there are too many compounding quantities of silica, even if it uses the kneading apparatus 1 and the kneading method of this invention, it will be difficult to disperse | distribute uniformly, Therefore The upper limit of a silica compounding quantity is 100 mass parts or less. If the amount of the silane coupling agent is less than 3% by mass, the coupling reaction becomes insufficient and the dispersibility of the silica is impaired. Conversely, if the amount exceeds 35% by mass, the silane coupling agent is more than necessary. The reaction causes the problem that the rubber becomes too hard.

The silica is not particularly limited as long as it is usually used in the rubber industry. For example, the nitrogen adsorption specific surface area (BET) is in the range of 150 to 250 m ² / g, and the dibutyl phthalate (DBP) oil absorption is What shows the colloidal characteristic of 180 ml / 100g or more is preferable at points, such as a reinforcement effect to rubber | gum and rubber processability. Silane coupling agents are also commonly used in the rubber industry, for example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylpropyl). Tetrasulfide, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane and the like can be suitably employed. The raw rubber is also usually used in the rubber industry, for example, natural rubber (NR), and diene synthetic rubber such as polyisoprene rubber (IR), polybutadiene rubber (BR), styrene butadiene rubber (SBR), etc. In particular, modified BR and modified SBR modified for silica can be more preferably employed.

  Next, the sealed rubber mixer 2 is a so-called Banbury mixer in this example, and includes a mixing chamber 7 provided with a pair of agitating rotors 6 and 6 arranged in parallel, as schematically shown in FIG. The raw rubber and the first chemical introduced into the mixing chamber 7 are kneaded by applying a shearing force, and the first kneading rubber G1 is provided from an openable / closable discharge port 8 provided at the lower end of the mixing chamber 7. Dump in bulk.

  The stirring rotor 6 has a known configuration in which a stirring blade is provided, for example, in a spiral shape around a base shaft that is rotatably supported, and is disposed in the mixing chamber 7 provided in the mixer main body 9. They are driven to rotate in the same direction or in opposite directions by a motor or the like. The mixing chamber 7 has a cross-sectional gourd shape in which two circumferential surfaces concentric with the pair of stirring rotors 6 and 6 are connected, and the constricted portion includes the raw rubber and the first chemical (generically named The lower end of the vertical hole 11 leading to the insertion port 10 for introducing the material rubber may be called raw material rubber or the like. The vertical hole 11 is provided with a floating weight 12 supported so as to be movable up and down by a cylinder or the like. The floating weight 12 pressurizes the raw rubber or the like put into the mixing chamber 7 and improves the stirring efficiency and kneading efficiency by the stirring rotor 6. The loading port 10 is provided with a carry-in conveyor 13 for carrying the raw rubber and the like next to it.

  The mixer main body 9 is provided with a drop door 14 that opens and closes the discharge port 8, and the kneaded first kneaded rubber G <b> 1 is discharged and dropped from the discharge port 8 as a lump by opening the drop door 14.

  Next, the screw feeder 5 is intended to continuously and automatically supply the lump-like first kneaded rubber G1 to a biaxial kneader 3 by forming it into a long body. Therefore, the screw feeder 5 does not require a kneading function having a shearing force, and a screw type rubber extruder having a well-known structure can be employed. In this example, a so-called biaxial taper extruder 20 is employed as the screw feeder 5. Specifically, as schematically shown in FIG. 3, the biaxial taper extruder 20 has a large inlet 20a for receiving the first kneaded rubber G1 from the hermetic rubber mixer 2 on the rear end side. And two taper screw shafts 22 horizontally supported rotatably in the casing 21.

  The taper screw shafts 22 are arranged so that the respective shaft centers approach each other toward the front end, and the blade portions 22b wound continuously around the taper shaft portions 22a of the respective taper screw shafts 22 in a spiral manner. Is formed. The direction of the spiral and the direction of rotation are different from each other between the taper screw shafts 22 and 22, so that the first kneaded rubber G <b> 1 dropped and charged can be surely caught between the taper screw shafts 22 and 22. If the caught rubber is caught between the blade portions 22b, it can be pushed forward and continuously extruded from the discharge port 23 at the front end while being formed into a long body. In addition, as the screw feeder 5, what is called a uniaxial screw type rubber extruder can also be employ | adopted.

  Next, in the biaxial kneader 3, a cup of silica and a silane coupling agent is added to the first kneaded rubber G1 received from the closed rubber mixer 2 via the screw feeder 5 while further kneading. By increasing the ring reaction, silica is more uniformly dispersed.

  For this purpose, the biaxial kneader 3 includes a feed zone Y1 for feeding the received first kneaded rubber G1 downstream, and a secondary kneading zone Y2 for imparting shear to the fed rubber and kneading. And a cooling zone Y3 for cooling the kneaded rubber to a temperature lower than 120 ° C, and the temperature of the rubber in the secondary kneading zone Y2 is set to a secondary kneading temperature T2 in the range of 120 to 200 ° C. A temperature control means 30 for controlling is provided.

  Specifically, the biaxial kneader 3 is arranged in parallel with each other in a cylinder 33 having a charging port 4 on the rear end side and a discharge port 32 on the front end side, and in a lumen H of the cylinder 33. Two stirring shafts 34, 34. The lumen H has a cross-sectional gourd shape (shown in FIG. 4B) in which two circumferential surfaces concentric with the stirring shafts 34, 34 are connected. Each of the agitation shafts 34 has a base shaft portion 36 concentric with the lumen H and a blade portion 37 formed around the same, and are rotated at the same speed and in the same direction by driving a motor.

  As shown in FIG. 4, the blade portion 37 is formed as a screw-shaped spiral blade 37 </ b> A that continuously winds around the base shaft portion 36 in the feed zone Y <b> 1. The spiral blade 37 </ b> A extends under the insertion port 4 and extends forward (downstream). As a result, the first kneading rubber G1 charged into the charging port 4 is wound between the spiral blades 37A and sent to the secondary kneading zone Y2 on the downstream side.

  In the secondary kneading zone Y2, the blade portion 37 is formed as a plurality of discontinuous paddles 37B. The paddle 37B has a substantially elliptical cross section, and the paddles 37B adjacent to each other in the axial direction are arranged with the phase angle appropriately changed, for example, 45 ° or 90 °. Accordingly, in the secondary kneading zone Y2, the rubber is subjected to compression and expansion volume changes as the paddle 37B rotates, and at the same time, a shearing force is applied between the paddles 37B and 37B to perform kneading and dispersion. . The paddle 37B disposed on one stirring shaft 34 and the paddle 37B disposed on the other stirring shaft 34 have a phase angle of 90 °, and in this example, the tip of one paddle 37B is the other Rotate to rub the paddle 37B. In addition, as the cross-sectional shape of the paddle 37B, various shapes such as a substantially triangular shape and a substantially cross shape can be adopted.

  Further, in this example, as shown in FIG. 5, the pressure wall 38 and the rubber are directed toward the upstream side at the downstream end of the secondary kneading zone Y2 so that the rubber can be pressurized in the secondary kneading zone Y2. The counterflow spiral blades 37C that are energized are arranged. The pressurizing wall 38 reduces the distance D between the base shaft portion 36 of the stirring shaft 34 and the inner peripheral surface of the cylinder 33 and prevents the rubber from moving downstream. The reverse flow spiral blade 37C has a reverse direction to the spiral of the spiral blade 37A and biases the rubber upstream. With these, the rubber in the secondary kneading zone Y2 can be appropriately pressurized. In this example, the pressurizing wall 38 is composed of upper and lower divided pieces 38a, 38a, and each divided piece 38a is moved up and down by, for example, lifting means 39 provided in the cylinder 33 to adjust the distance D. Thus, the rubber pressure in the secondary kneading zone Y2 can be freely adjusted.

  Here, when kneading in the secondary kneading zone Y2, it is important to control the temperature of the rubber to a secondary kneading temperature T2 in the range of 120 to 200 ° C., thereby enhancing the coupling reaction. Improve dispersibility and achieve more uniform dispersion. For this purpose, a temperature control means 30 is provided in the biaxial kneader 3.

  As shown in FIG. 4 (A), the temperature control means 30 includes a jacket 40 disposed in the region of the cylinder 33 and the secondary kneading zone Y2 in this example, and heat that flows through the jacket 40. By adjusting the temperature of the medium and / or the flow rate of the heat medium, the temperature of the rubber can be accurately controlled to the secondary kneading temperature T2.

  Next, in the cooling zone Y3, the rubber at the secondary kneading temperature T2 kneaded in the secondary kneading zone Y2 is cooled to a temperature lower than 120 ° C. and discharged from the discharge port 32 at the front end. Therefore, in the cooling zone Y3, the blade portion 37 is formed as a spiral blade 37D wound in the same direction as the spiral blade 37A in the feed zone Y1, and cooling means (not shown) is provided in the cooling zone Y3. Is arranged. This cooling means includes a jacket disposed in the region of the cylinder 33 and the cooling zone Y3, and cools the rubber by allowing a coolant to flow through the jacket.

  Further, in the biaxial kneader 3, for example, a roller head 41 is provided at the discharge port 32 as shown in FIG. 1 to further cool the second kneaded rubber G2, and the second kneaded rubber G2 is extruded into a sheet shape. It is preferable. In this example, on the downstream side of the biaxial kneader 3, for example, a cooling device having a plurality of cooling rollers is installed, and by passing the sheet-like second kneading rubber G2 through the cooling device, It is cooling.

  As described above, alcohol (R—OH) such as methanol is generated in the process of coupling reaction between silica and a silane coupling agent. Therefore, in this example, the methanol removal unit 42 for removing methanol and the like is provided in the cooling zone Y3. As the demethanolizer 42, various well-known structures using a catalyst, a filter, or the like can be used.

Next, a kneading method using the kneading apparatus 1 will be described. As shown in the flowchart of FIG.
(1) A primary kneading step of forming the first kneaded rubber G1 by kneading the raw rubber and the first chemical with a shearing force by the sealed rubber mixer 2;
(2) The massive first kneaded rubber G1 discharged from the closed rubber mixer 2 is conveyed to the inlet 4 of the biaxial kneader 3 while being molded into a long body using the screw feeder 5. And a transfer loading step for loading,
(3) The second kneaded rubber G2 is formed by kneading the charged first kneaded rubber G1 with the biaxial kneader 3 while applying a shearing force, and the second kneaded rubber G2 is formed. And a secondary kneading step for discharging G2 from the discharge port 32 of the biaxial kneader 3.

  In the secondary kneading step, as described above, the first kneading rubber G1 is kneaded by applying shear while controlling the temperature to the secondary kneading temperature T2 in the range of 120 to 200 ° C. Process.

  Thus, by kneading the first kneaded rubber G1 while controlling the temperature to the secondary kneading temperature T2, the coupling reaction is enhanced and the dispersibility of the silica is improved, so that more uniform dispersion can be achieved. When the secondary kneading temperature T2 is lower than 120 ° C. or higher than 200 ° C., the coupling reaction hardly occurs and the dispersibility of silica cannot be improved. Accordingly, the lower limit value of the secondary kneading temperature T2 is preferably 140 ° C. or higher, more preferably 150 ° C. or higher, and the upper limit value is preferably 180 ° C. or lower, more preferably 170 ° C. or lower. In order to enhance the coupling reaction, it is also preferable that the secondary kneading temperature T2 is stable within the above range. Therefore, the fluctuation range of the secondary kneading temperature T2 during operation can be suppressed to ± 5 ° C. or less. desirable.

  In the secondary kneading step, the process time J is preferably in the range of 30 seconds to 8 minutes, and if it is less than 30 seconds, the process time J is insufficient and the coupling reaction cannot be performed sufficiently. On the other hand, if it exceeds 8 minutes, no further coupling reaction can be expected, leading to an unnecessary excess of time, that is, a reduction in productivity. From such a viewpoint, the lower limit of the process time J is more preferably 1 minute or more, and the upper limit is more preferably 5 minutes or less. For the coupling reaction, the product J × T2 of the process time J and the secondary kneading temperature T2 is preferably in the range of 60 to 1600 (° C./min). If the product J × T2 is less than 60 (° C. · min), the coupling reaction is insufficient. Conversely, if it exceeds 1600 (° C. · min), no further coupling reaction can be expected, leading to an unnecessary excess of time. From such a viewpoint, the lower limit of the product J × T2 is more preferably 100 (° C./min) or more, and the upper limit is more preferably 1200 (° C./min) or less. When the secondary kneading temperature T2 fluctuates, a curve y of the secondary kneading temperature T2 is obtained with the process time J as the horizontal axis and the secondary kneading temperature T2 as the vertical axis, for example, and this curve y is used as the process. The value integrated at time J is adopted as the product J × T2. The secondary kneading temperature T2 can be freely controlled by the temperature control means 30 described above. The process time J can be controlled by adjusting the rotational speed of the stirring shaft 34 in the biaxial kneader 3 and adjusting the distance D by the pressure wall 38.

  In the kneading method, the temperature T1 of the first kneaded rubber G1 when discharged from the discharge port 8 of the hermetic rubber mixer 2 is preferably in the range of 120 to 200 ° C. When this temperature T1 is less than 120 ° C., it takes a long time to raise the rubber to the secondary kneading temperature T2 in the secondary kneading step, resulting in a decrease in productivity. On the other hand, when the temperature T1 is lower than 200 ° C., in order to lower the rubber temperature to the secondary kneading temperature T2, for example, it is necessary to lengthen the extrusion by the screw feeder 5 and the conveying time.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

  Using the kneading apparatus and the kneading method of the present invention, a rubber composition having the composition shown in Table 1 was formed. And the sheet-like test sample was created using each rubber composition, and the rubber physical properties after vulcanization of this test sample were compared with each other. In addition, raw tires using each rubber composition as a tread rubber were vulcanized and molded to produce trial passenger car tires (size 195 / 65R15), and the performances of the tires were compared with each other.

In Comparative Example 1 (conventional example), a rubber composition was formed by the following kneading methods (1) to (3).
(1) A raw rubber and a first chemical (silica, silane coupling agent, carbon black) were charged into a Banbury mixer (sealed rubber mixer), and these were kneaded to form a primary kneaded rubber. The kneading time was 5 minutes, and the temperature of the rubber at the time of discharging was 165 ° C. This was processed into a sheet by a roller head extruder and cooled to a temperature of 40 ° C.
(2) Put the cooled sheet-like primary kneaded rubber and the second chemical (oil, wax, anti-aging agent, stearic acid, zinc white) into a Banbury mixer (sealed rubber mixer), Were kneaded to form a secondary kneaded rubber. The kneading time was 5 minutes, and the temperature of the rubber at the time of discharging was 150 ° C. This was processed into a sheet by a roller head extruder and cooled to a temperature of 40 ° C.
(3) The cooled secondary kneaded rubber and the third chemical (vulcanizing agent (sulfur), vulcanization accelerator) are put into a Banbury mixer (sealed rubber mixer) and kneaded. Thus, the final kneaded rubber was formed. The kneading time was 3 minutes, and the temperature of the rubber at the time of discharging was 100 ° C. This was processed into a sheet by a roller head extruder and cooled to a temperature of 40 ° C.

In other comparative examples and examples, rubber compositions were formed by the following kneading methods (4) to (6).
(4)
(4-1) Raw material rubber and first chemical (silica, silane coupling agent, carbon black) are charged into a Banbury mixer (sealed rubber mixer), and these are kneaded to produce a first kneaded rubber. (Primary kneading step). The kneading time was 5 minutes, and the temperature of the rubber at the time of discharging was 165 ° C.
(4-2) The first kneaded rubber is charged into a biaxial kneader using a screw feeder without cooling (conveying charging step).
(4-3) The charged first kneaded rubber is kneaded by a biaxial kneader while controlling the temperature to the secondary kneading temperature T2, and discharged from the discharge port as a second kneaded rubber (secondary kneading step). ). The secondary kneading process time J was 2 minutes, and the secondary kneading temperature T2 was constant at 150 ° C. The second kneaded rubber to be discharged was processed into a sheet shape and cooled to a temperature of 40 ° C. This sheet-like second kneaded rubber corresponds to the sheet-like primary kneaded rubber in Comparative Example 1 (conventional example).
(5) Substantially the same as (2) above, the cooled sheet-like primary kneaded rubber (second kneaded rubber) and the second chemical (oil, wax, anti-aging agent, stearic acid, zinc) Were added to a Banbury mixer (sealed rubber mixer) and kneaded to form a secondary kneaded rubber. The kneading time was 5 minutes, and the temperature of the rubber at the time of discharging was 150 ° C. This was processed into a sheet by a roller head extruder and cooled to a temperature of 40 ° C.
(6) Substantially the same as (3) above, the cooled secondary kneaded rubber and the third chemical (vulcanizing agent (sulfur), vulcanization accelerator) are combined with a Banbury mixer (sealed rubber) The resulting mixture was kneaded to form a final kneaded rubber. The kneading time was 3 minutes, and the temperature of the rubber at the time of discharging was 100 ° C. This was processed into a sheet by a roller head extruder and cooled to a temperature of 40 ° C.

The compounding amounts of the second chemical and the third chemical are as follows, and are the same for each rubber composition.
"Second chemical"
Oil --- 26phr
Wax--2 phr
Anti-aging agent--2 phr
Stearin--3 phr
Zinc acid flower--5phr
"Third medicine"
Sulfur--2 phr
Vulcanization accelerator Cz--2phr
Vulcanization accelerator DPG--1 phr

In the rubber physical properties of the test sample,
The rubber hardness Hs is a durometer A hardness measured at 23 ° C. by durometer type A according to JIS-K6253.
・ Tensile strength TB (tensile strength) and tensile breaking strength EB (tensile stress at cutting) are described in JIS K6251 “Vulcanized rubber and thermoplastic rubber-Determination of tensile properties” and “Tensile test method for vulcanized rubber”. Value measured according to the test method:
The complex elastic modulus E * and loss tangent tan δ were measured using “Viscoelastic Spectrometer” manufactured by Iwamoto Seisakusho under the conditions shown below in accordance with JIS-K6394. It was evaluated with the index. Initial strain (10%), amplitude (± 1%), frequency (10 Hz), deformation mode (tensile), measurement temperature (70 ° C.).
The complex elastic modulus E * has a higher elasticity when the index is larger, and the loss tangent tanδ has a higher exothermic property when the index is larger.

In terms of tire performance,
・ For dry performance, tires are mounted on all wheels of a passenger car (2000cc, FF car) under the conditions of rim (15 × 6J) and internal pressure (200kPa), driving on a dry asphalt road test course, and stable operation The properties (handle responsiveness, rigidity, grip, etc.) were evaluated in five stages, with Comparative Example 1 taken as 3 by sensory evaluation of the driver. A larger index is better.
-Wet performance is determined by driving the test vehicle on a wet asphalt road surface using the above vehicle, handling stability (steering response, rigidity, grip, etc.), and Comparative Example 1 as 3 based on sensory evaluation of the driver 4 Rated by stage. A larger index is better.
・ Abrasion resistance is an index of Comparative Example 100 measured by measuring the wear amount of tread rubber when running on a dry asphalt road test course 3000 km in the circumferential groove closest to the tire equator. It was evaluated with. A larger index is better.

1 is a schematic side view conceptually showing an embodiment of a kneading apparatus of the present invention. It is sectional drawing which expands and shows a sealing-type rubber mixer. (A) is a top view in case a screw feeder is a biaxial taper extruder, (B) is the sectional drawing. (A) is a top view which shows a part of feed zone and secondary kneading zone of a biaxial kneader, (B) is the II sectional drawing. It is side part sectional drawing which shows a pressurization wall and a backflow spiral blade. It is a flowchart which shows the kneading | mixing method. (A), (B) is a conceptual diagram explaining the mechanism of dispersion | distribution of the silica in rubber | gum by a silane coupling agent. It is a conceptual diagram explaining the conventional kneading | mixing method in the rubber | gum for tires.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Kneading apparatus 2 Sealed rubber mixer 4 Input port 5 Screw feeder 3 Twin screw kneader 8 Discharge port 30 Temperature control means G1 First kneading rubber G2 Second kneading rubber Y1 Feed zone Y2 Secondary kneading zone Y3 Cooling zone

Claims (5)

First kneaded by kneading a raw material rubber for tire and a first chemical containing at least 20 phr of silica and a silane coupling agent having a ratio of 3 to 35 mass% with respect to the silica and not containing a vulcanizing agent. A method of kneading rubber for tires to form rubber,
A primary kneading step of forming a first kneaded rubber by kneading the raw rubber and the first chemical with a shearing force by a hermetic rubber mixer;
Conveying and feeding step of feeding and feeding the first kneaded rubber discharged in a lump form from the outlet of the hermetic rubber mixer to the inlet of the biaxial kneader while forming into a long body using a screw feeder When,
The input first kneaded rubber is kneaded by applying a shearing force to the biaxial kneader to form a second kneaded rubber, and the second kneaded rubber is used in the biaxial kneader. A secondary kneading step for discharging from the discharge port,
The secondary kneading step includes a secondary kneading step in which the first kneaded rubber is kneaded by applying shear while controlling the temperature at a secondary kneading temperature T2 in the range of 120 to 200 ° C., and this secondary mixing. And a cooling step of cooling the rubber after the kneading step to a temperature lower than 120 ° C.   2. The method for kneading tire rubber according to claim 1, wherein the first kneaded rubber has a temperature T1 in a range of 120 to 200 ° C. when discharged from an outlet of the hermetic rubber mixer. .   3. The method for kneading tire rubber according to claim 2, wherein the secondary kneading step has a process time J of the secondary kneading step of 30 seconds to 8 minutes.   The secondary kneading step is characterized in that a product J x T2 of a process time J of the secondary kneading step and the secondary kneading temperature T2 is 60 to 1600 (° C / min). The method for kneading rubber for tires according to any one of 1 to 3. First kneaded by kneading a raw material rubber for tire and a first chemical containing at least 20 phr of silica and a silane coupling agent having a ratio of 3 to 35 mass% with respect to the silica and not containing a vulcanizing agent. A tire rubber kneading device for forming rubber,
A hermetic rubber mixer that forms a first kneaded rubber by kneading the raw rubber and the first chemical by applying a shearing force;
Receiving the first kneaded rubber discharged in a lump form from the discharge port of the hermetic rubber mixer, and conveying the received first kneaded rubber to the input port of the biaxial kneader while forming a long body; A screw feeder to be charged,
A biaxial kneader that forms a second kneaded rubber by kneading the first kneaded rubber charged with a shearing force,
In addition, the biaxial kneader was kneaded with a feed zone for feeding the first kneaded rubber charged to the downstream side, and a secondary kneading zone for applying shear to the fed rubber and kneading. A cooling zone for cooling the rubber to a temperature lower than 120 ° C., and the biaxial kneader has a secondary kneading temperature T2 in the range of 120 to 200 ° C. A tire rubber kneading apparatus, further comprising temperature control means for controlling.

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