JP2017128071A - Method of and device for kneading rubber material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of and device for kneading a rubber material capable of accelerating a chemical reaction when kneading a silica-blended rubber material, and capable of improving the specified physical properties of a rubber composition obtained by vulcanization after kneading.SOLUTION: A method of kneading a rubber material includes: detecting by a temperature sensor 11, the temperature of a silica-blended rubber material R comprising a raw material rubber G, silica, and a nonvulcanizing ingredient N including a silane coupling agent during kneading by a closed type kneader 2; controlling the rotation of a rotor 3 by a control part 12 based on the above detection data; and maintaining the silica-blended rubber material R in which a prescribed amount of the water W is added by a water supply mechanism 13 in a previously set prescribed temperature range to knead.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rubber material kneading method and apparatus, and more particularly, a specific rubber of a rubber composition that can promote a chemical reaction when kneading a silica-blended rubber material and is vulcanized after kneading. The present invention relates to a rubber material kneading method and apparatus capable of improving physical properties.

  By using silica-containing rubber for tire tread rubber and the like, tire rolling resistance and wet grip performance can be improved. Since silica is easy to aggregate particles, the dispersibility with respect to a rubber material is bad, and the dispersibility is improved by mix | blending a silane coupling agent and carrying out a coupling reaction with a silica. Since silica compounded rubber materials have such properties different from ordinary rubber materials, various kneading methods and apparatuses suitable for silica compounded rubber materials have been proposed (see, for example, Patent Document 1).

  Patent Document 1 proposes a kneading system for kneading a silica-blended rubber material by combining a closed kneader and an open structure roll kneader. In this kneading system, by using an open structure roll kneader, alcohol generated when kneading the silica-blended rubber material is diffused to the outside to promote the coupling reaction.

  On the other hand, the inventor of the present application pays attention to the process of kneading with a closed kneader, can promote the chemical reaction when kneading the silica-blended rubber material, and vulcanized after kneading. It was found that the specific rubber physical properties were improved. And based on this knowledge, it came to create this invention.

JP 2007-216471 A

  An object of the present invention is to knead a rubber material capable of promoting a chemical reaction when kneading a silica-blended rubber material and improving specific rubber physical properties of a rubber composition obtained by vulcanization after kneading. It is to provide a method and apparatus.

  The rubber material kneading method of the present invention for achieving the above object is a rubber in which a silica-containing rubber material comprising a raw rubber and a non-vulcanizing compound containing silica and a silane coupling agent is kneaded by a closed kneader. The material kneading method is characterized in that the silica-blended rubber material with a predetermined amount of water added is kneaded by the closed kneader while maintaining a predetermined temperature range set in advance.

  The rubber material kneading apparatus of the present invention is a rubber material kneading apparatus provided with a closed kneader for kneading a silica-blended rubber material comprising a raw rubber and a non-vulcanizing compound containing silica and a silane coupling agent. A temperature sensor that detects the temperature of the silica-containing rubber material being kneaded by the closed kneader, a control unit that controls the rotation of the rotor of the closed kneader, and water in the kneading chamber of the closed kneader. The silica-containing rubber material in a state where a predetermined amount of water is added by the water supply mechanism by controlling the number of rotations of the rotor based on detection data of the temperature sensor. The kneading is performed while maintaining the temperature in a predetermined temperature range set in advance.

  According to the present invention, the chemical reaction (hydrolysis reaction) in the silica-blended rubber material is promoted by kneading the silica-blended rubber material to which a predetermined amount of water has been added while maintaining the predetermined temperature range. Can do. Furthermore, specific rubber properties of the rubber composition obtained by vulcanization after kneading can be improved. Specifically, when a rubber composition obtained by vulcanization is used for a tread rubber of a tire, the rolling resistance and wet grip performance of the tire can be improved.

  The predetermined temperature range is, for example, 130 ° C. or higher and 160 ° C. or lower. By setting this temperature range, it becomes easier to promote the chemical reaction in the silica-blended rubber material being kneaded. Moreover, when the rubber composition obtained by vulcanization is used for a tread rubber of a tire, it becomes easier to further improve the rolling resistance and wet grip performance of the tire.

  The water is added to the silica-blended rubber material, for example, by spraying or dropping into the kneading chamber of the closed kneader. Alternatively, the water can be added to the silica-containing rubber material in a state where the ram constituting the closed kneader is raised from the lower end of the ram chamber of the closed kneader. This facilitates uniform mixing of water with the silica-containing rubber material, which is advantageous for suppressing variations in the quality of the rubber composition obtained by vulcanization.

  The temperature of the water is, for example, 10 ° C. or higher and 50 ° C. or lower, which is lower than the silica-containing rubber material being kneaded. By using relatively low temperature water of 10 ° C. or more and 50 ° C. or less, the rotational speed of the rotor of the closed kneader is increased in order to maintain the silica-containing rubber material in the predetermined temperature range. Therefore, the kneading time can be shortened while ensuring a certain rubber quality of the rubber composition obtained by vulcanization.

It is explanatory drawing which illustrates the kneading apparatus of the rubber material of this invention. It is AA sectional drawing of FIG. It is explanatory drawing which illustrates the state which knead | mixes the silica compound rubber material with the kneading apparatus of FIG. It is explanatory drawing which illustrates the state which has added water to the silica compounding rubber material kneaded in the kneading chamber of FIG. It is a graph which illustrates the time-dependent change of the instantaneous electric power required for the rotational drive of the rotor in the kneading process of a silica compounding rubber material, and the temperature of a silica compounding rubber material.

  Hereinafter, the kneading method and apparatus for silica-containing rubber material of the present invention will be described based on the embodiments shown in the drawings.

  A rubber material kneading apparatus 1 (hereinafter referred to as a kneading apparatus 1) of the present invention illustrated in FIGS. 1 to 2 kneads a silica-blended rubber material R. The silica-containing rubber material R is composed of a raw rubber G and a non-vulcanizing compound N containing silica and a silane coupling agent, and the non-vulcanizing compound N is uniformly dispersed in the raw rubber G by kneading. In this way, an appropriate viscosity is obtained.

  As the raw rubber G, natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), 1,2-polybutadiene, chloroprene rubber, butyl rubber, styrene-butadiene rubber (SBR), nitrile rubber (acrylonitrile rubber, Examples thereof include hydrogenated nitrile rubber) and ethylene propylene diene rubber. These are used individually by 1 type or in combination of 2 or more types.

  As the non-vulcanizing compounding agent N, in addition to silica and a silane coupling agent, a filler other than silica (for example, carbon black), zinc oxide, stearic acid and the like are used as necessary.

  As silica, the well-known silica mix | blended with the rubber composition for uses, such as a tire, can be used, Specifically, wet silica, dry silica, fumed silica, diatomaceous earth etc. can be illustrated, for example. These are used individually by 1 type or in combination of 2 or more types.

  As the silane coupling agent, known ones can be used. Specifically, for example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (3-tri Ethoxysilylpropyl) disulfide, mercaptopropyltrimethoxysilane, mercaptopropyltriethoxysilane, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl-tetrasulfide, trimethoxysilylpropyl-mercaptobenzothiazole tetrasulfide, triethoxysilyl Examples thereof include propyl-methacrylate-monosulfide and dimethoxymethylsilylpropyl-N, N-dimethylthiocarbamoyl-tetrasulfide. These are used individually by 1 type or in combination of 2 or more types.

  The kneading apparatus 1 includes a closed kneader 2 such as a Banbury mixer including a rotor 3, a temperature sensor 11, a control unit 12 that controls rotation of the rotor, and a water supply mechanism 13.

  The closed kneading machine 2 includes a kneading chamber 4a and a ram chamber 4b connected to the upper side of the kneading chamber 4a. The kneading chamber 4a includes a pair of rotors 3 and an oil charging unit 5 that are opposed to each other. Is provided. A blade 3b is projected from the rotating shaft 3a of each rotor 3, and the rotating shaft 3a arranged in parallel is driven to rotate by a driving motor. A discharge door 10 that opens and closes is provided on the bottom surface of the kneading chamber 4a.

  In the ram chamber 4b, a ram 8 that moves up and down to adjust the pressure (ram pressure) in the kneading chamber 4a is disposed. The ram chamber 4 b is further provided with a rubber charging unit 6 for charging the raw rubber G and a compounding agent charging unit 9 for charging the non-vulcanized compounding agent N from the hopper 7.

  The temperature sensor 11 is provided in the kneading chamber 4a with its tip portion exposed. The temperature sensor 11 sequentially detects the temperature of the silica-containing rubber material R kneaded in the kneading chamber 4a. Data detected by the temperature sensor 11 is input to the control unit 12.

  The water supply mechanism 13 supplies a predetermined amount of water W to the kneading chamber 4a. In this embodiment, the water supply mechanism 13 is attached to the ram 8. The water supply mechanism 13 includes a water storage portion 13a disposed inside the ram 8, and a nozzle 13b installed at a lower end portion of a flow path 13c extending downward from the water storage portion 13a. For example, water W is supplied from the nozzle 13b by opening an on-off valve installed in the flow path 13c. Depending on the specifications of the nozzle 13b, the water W can be sprayed into the kneading chamber 4a, dropped, or simply dripped down.

  The water supply mechanism 13 is not limited to the exemplified form, and various other forms can be adopted. For example, the water W can be supplied to the kneading chamber 4a through the rubber charging unit 6 and the compounding agent charging unit 9. The temperature of the water W supplied to the kneading chamber 4a is, for example, 10 ° C. or more and 50 ° C. or less.

  A wattmeter 12 a is attached to the control unit 12. Instantaneous power required for rotationally driving the rotor 3 is sequentially detected by the wattmeter 12a. Data detected by the wattmeter 12 a is input to the control unit 12. The control unit 12 calculates an integrated electric energy obtained by integrating the instantaneous electric power, and can grasp the electric energy (load acting on the rotor 3) required for the rotational driving of the rotor 3 in an arbitrary kneading period. In addition, the rotational speed of the rotor 3, the ram pressure, and the like are input to the control unit 12.

  The control unit 12 controls the number of rotations of the rotor 3, the ram pressure (the vertical movement of the ram), the operation of the water supply mechanism 13, and the like. Depending on the specifications of the silica-blended rubber material R to be kneaded, the control unit 12 has an optimum predetermined temperature range of the silica-blended rubber material R to be maintained when kneading, the timing of supplying water W from the water supply mechanism 13, The supply amount is input. The rotational speed of the rotor 3 is controlled based on the detection data from the temperature sensor 11. Basically, the temperature of the silica-blended rubber material R being kneaded increases as the rotational speed of the rotor 3 is increased (the rotational speed is increased).

  The procedure of the rubber material kneading method of the present invention will be described below.

  The rubber material kneading process includes a rubber kneading step (S1), a compounding agent intake step (S2), and a uniform dispersion step (S3) as illustrated in FIG. FIG. 5 exemplifies time-lapse data of the instantaneous power P required for rotational driving of the rotor 3 and the temperature T of the silica-containing rubber material R (raw rubber G) in the kneading process to which the present invention is applied.

  In the rubber mastication step, as shown in FIG. 1, a predetermined amount of raw rubber G set in advance is kneaded through the rubber charging unit 6 with the ram 8 held at the standby position at the upper end of the ram chamber 4b. It puts into the chamber 4a. Thereafter, the ram 8 is moved downward to the lower end of the ram chamber 4b, and the upper surface of the kneading chamber 4a is formed by the ram 8. In this state, the raw rubber G and the oil are kneaded by rotating the rotor 3 while supplying the oil into the kneading chamber 4a through the oil charging unit 5. In this step, the instantaneous power P indicating the load of the rotor 3 is relatively small. The temperature T of the raw rubber G gradually decreases.

  After the rubber mastication process is completed, the process proceeds to the compounding agent incorporation process. In the compounding agent intake step, the ram 8 is moved to the standby position at the upper end of the ram chamber 4b, and a predetermined amount of a non-vulcanized compounding agent N (silica, silane coupling agent, etc.) of a preset type is placed in the hopper. 7 is charged into the kneading chamber 4a through the compounding agent charging unit 9. Thereafter, the ram 8 is moved downward to the lower end of the ram chamber 4b, and the upper surface of the kneading chamber 4a is formed by the ram 8. In this state, the rotor 3 is rotationally driven as illustrated in FIG. 3 to knead the silica-containing rubber material R composed of the raw rubber G and the non-vulcanized compounding agent N. In order to prevent the nozzle 13b from being clogged by the raw rubber G or the non-vulcanizing compounding agent N, a clogging prevention cover or the like can be installed on the nozzle 13b.

  In the compounding agent incorporation step, the non-vulcanized compounding agent N placed on the rubber kneaded raw material rubber G is agitated greatly, and a small rubber lump is gradually formed. Then a small mass of rubber gradually grows and eventually lumps. In the compounding agent taking-in step, ram inversion is performed to invert the silica compounded rubber material R up and down by rotating the rotor 3 with the ram 8 raised to the upper end of the ram chamber 4b several times. In this step, the temperature T of the silica-containing rubber material R gradually increases.

  When the carbon uptake process ends, the process moves to a uniform dispersion process. In this step, the non-vulcanizing compounding agent N is uniformly dispersed throughout the raw rubber G. In this step, the instantaneous power P is initially large but gradually decreases and becomes constant. The temperature T of the silica compounded rubber material R being kneaded is maintained substantially constant within a predetermined temperature range. That is, in this process, the controller 12 controls the number of rotations of the rotor 3 based on the detection data of the temperature T of the silica-blended rubber material R sequentially detected by the temperature sensor 11, and the temperature T of the silica-blended rubber material R is controlled. Is maintained in a predetermined temperature range and kneaded. This predetermined temperature range is, for example, 130 ° C. or more and 160 ° C. or less.

  Control for increasing the rotational speed of the rotor 3 if the temperature T of the silica-containing rubber material R is likely to be lower than the predetermined temperature range, and decreasing the rotational speed of the rotor 3 if it is likely to be higher than the predetermined temperature range. I do. Alternatively, the temperature T of the silica-containing rubber material R can be lowered by raising the ram 8 and lowering the ram pressure, and the temperature T can be raised by lowering the ram 8 and raising the ram pressure.

  In the present invention, a predetermined amount of water W is supplied to the kneading chamber 4a and added to the silica compounded rubber material R as illustrated in FIG. . In this embodiment, the ram 8 is raised from the lower end of the ram chamber 4b to the standby position, and water W is sprayed from the nozzle 13b and added to the silica compounded rubber material R.

  The predetermined amount of water W added to the silica-containing rubber material R is, for example, 0.5 parts by weight or more and 5.0 parts by weight or less with respect to the raw rubber G (100 parts by weight). After the predetermined amount of water W is added to the silica-blended rubber material R, the silica-blended rubber material R is kneaded as illustrated in FIG. 3 with the ram 8 being moved to the lower end of the ram chamber 4b.

  After completion of the uniform dispersion step, the unvulcanized rubber composition produced by kneading the silica-blended rubber material R is discharged from the open discharge door 10 to the outside of the closed kneader 2. In the next step, the released rubber composition is kneaded with a vulcanizing compound such as sulfur or a vulcanization accelerator in a predetermined ratio. The unvulcanized rubber composition produced through this process is molded into various shapes and vulcanized inside the mold.

  The rubber composition vulcanized through the vulcanization process becomes a part of various rubber products or rubber products. For example, a vulcanized rubber composition is used as a tread rubber, a shoulder rubber, or a side rubber in a tire manufacturing process.

  As described above, the silica-containing rubber material R with a predetermined amount of water W added thereto is kneaded while maintaining a predetermined temperature range, thereby promoting the chemical reaction (hydrolysis reaction) in the silica-containing rubber material R. Can be made. Along with this, shortening of the kneading time can be expected. Furthermore, specific rubber properties of the rubber composition obtained by vulcanization after kneading can be improved. Specifically, when a rubber composition obtained by vulcanization is used for a tread rubber of a tire, the rolling resistance and wet grip performance of the tire can be improved. The improvement of the rubber physical properties will be described later.

  If the predetermined amount of water W added to the silica-blended rubber material R is less than 0.5 parts by weight relative to the raw rubber G (100 parts by mass), the hydrolysis reaction of the silica-blended rubber material R can be sufficiently accelerated. Can not. On the other hand, if the amount exceeds 5.0 parts by weight, the rubber composition is porous (foamed and made porous) in the process after kneading the silica-containing rubber material R (rubber extrusion process, etc.), and the quality is increased. Increases the risk of decline.

  It is known that when an unvulcanized rubber composition to which water has been added is extruded, the rubber composition is likely to be porous. Therefore, conventionally, intentional addition of water during kneading of the rubber material has been avoided. However, in the kneading of the silica-blended rubber material R, it has been found that the hydrolysis reaction in the silica-blended rubber material R is promoted if an appropriate amount of water W is added. Furthermore, since it has been found that the specific rubber properties of the rubber composition obtained by vulcanization are improved, the present invention has been created based on the knowledge that it is rather beneficial.

  By maintaining the temperature T of the silica-blended rubber material R being kneaded at 130 ° C. or higher and 160 ° C. or lower, the chemical reaction in the silica-blended rubber material R being kneaded can be more easily promoted. In addition, when a rubber composition produced by applying the present invention is used as a tread rubber of a tire, the rolling resistance and wet grip performance of the tire can be further improved.

  The method of adding water W to the silica-blended rubber material R is not particularly limited, but when sprayed or dropped into the kneading chamber 4a, it becomes easy to uniformly mix with the silica-blended rubber material R. In connection with this, it becomes advantageous to suppress the dispersion | variation in the quality of the rubber composition obtained by vulcanization | cure. Alternatively, as illustrated in FIG. 4, when the ram 8 is raised from the lower end of the ram chamber 4 b and water W is supplied from the upper position of the silica compound rubber material R and added, the silica compound rubber material R is added. It becomes easy to mix uniformly.

  The temperature of the water W to be added can be equal to or higher than that of the silica compounding material R being kneaded, but can also be relatively low (for example, 10 ° C. or more and 50 ° C. or less). When relatively low-temperature water W of 10 ° C. or more and 50 ° C. or less is added, the temperature T of the silica-blended rubber material R is slightly lowered, so that the number of rotations of the rotor 3 is increased in order to maintain it within a predetermined temperature range ( Rotational speed is faster). This makes it possible to shorten the kneading time. Moreover, since the silica compounding material R is kneaded while being maintained in a predetermined temperature range, a certain rubber quality can be ensured for the rubber composition obtained by vulcanization.

  If the water storage part 13a of the water supply mechanism 13 is provided in the ram 8 as in this embodiment, the water W stored in the water storage part 13a can be used as a weight adjusting member of the ram 8. Accordingly, the total weight of the metal members constituting the ram 8 can be reduced.

  When kneading the tread rubber of a passenger car tire, two types of unvulcanized rubber compositions were produced by changing only whether or not water was added to the silica-containing rubber material. Then, each of the rubber composition to which water was added (Example) and the rubber composition to which water was not added (conventional example) was placed in a mold (15 cm × 15 cm × 0.2 cm). Press vulcanized at 160 ° C. for 20 minutes to produce a vulcanized rubber sheet. In addition, the addition amount of water in the Examples was 2 parts by weight with respect to 100 parts by mass of the raw rubber. In the examples and conventional examples, the silica-containing rubber material was kneaded in a temperature range of 130 ° C. or higher and 160 ° C. or lower.

[Tire rolling resistance]
For each vulcanized rubber sheet, a loss tangent tan δ at a temperature of 60 ° C. was measured using a viscoelastic spectrometer (manufactured by Toyo Seiki Seisakusho) under the conditions of an initial strain of 10%, an amplitude of ± 2%, and a frequency of 20 Hz. . Tan δ (60 ° C.) is used as an evaluation index of tire rolling resistance. As a result of comparing the measurement results of the vulcanized rubber sheet of the conventional example and the vulcanized rubber sheet of the example, it was confirmed that the rolling resistance was reduced by about 3% as compared with the conventional example.

[Wet grip performance]
For each vulcanized rubber sheet, a loss tangent tan δ at a temperature of 0 ° C. was measured using a viscoelastic spectrometer (manufactured by Toyo Seiki Seisakusho Co., Ltd.) under conditions of an initial strain of 10%, an amplitude of ± 2%, and a frequency of 20 Hz. . Tan δ (0 ° C.) is used as an evaluation index of the wet grip performance of the tire. As a result of comparing the measurement results of the vulcanized rubber sheet of the conventional example and the vulcanized rubber sheet of the example, it was confirmed that the wet grip performance of the example was improved by about 3.5% compared to the conventional example.

DESCRIPTION OF SYMBOLS 1 Kneading apparatus 2 Sealed kneading machine 3 Rotor 3a Rotating shaft 3b Blade 4a Kneading chamber 4b Ram chamber 5 Oil charging unit 6 Rubber charging unit 7 Hopper 8 Ram 9 Compounding agent charging unit 10 Discharge door 11 Temperature sensor 12 Control unit 12a Power meter 13 Water supply mechanism 13a Water reservoir 13b Nozzle 13c Channel G Raw material rubber N Non-vulcanized compounding agent R Silica compounding rubber material W Water

Claims (10)

In the kneading method of the rubber material in which the silica compounded rubber material composed of the raw rubber and the non-vulcanized compounding agent containing silica and the silane coupling agent is kneaded by the closed kneader,
A method for kneading a rubber material, characterized in that the silica-containing rubber material in a state where a predetermined amount of water is added is kneaded by the closed kneader while maintaining a predetermined temperature range set in advance.   The method for kneading a rubber material according to claim 1, wherein the predetermined temperature range is 130 ° C or higher and 160 ° C or lower.   The method for kneading a rubber material according to claim 1 or 2, wherein the water is added to the silica-blended rubber material by spraying or dripping the water into a kneading chamber of the closed kneader.   4. The water according to claim 1, wherein the water is added to the silica-containing rubber material in a state where the ram constituting the closed kneader is raised from the lower end of the ram chamber of the closed kneader. Rubber material kneading method.   The method for kneading a rubber material according to any one of claims 1 to 4, wherein the temperature of the water is 10 ° C to 50 ° C, which is lower than that of the silica-containing rubber material being kneaded. In a rubber material kneading apparatus equipped with a closed kneader for kneading a silica-blended rubber material comprising a raw rubber and a non-vulcanized compounding agent containing silica and a silane coupling agent,
A temperature sensor that detects the temperature of the silica-containing rubber material being kneaded by the closed kneader, a control unit that controls the rotation of the rotor of the closed kneader, and water in the kneading chamber of the closed kneader. A water supply mechanism for supplying,
By controlling the number of rotations of the rotor based on the detection data of the temperature sensor, the silica-containing rubber material in a state where a predetermined amount of water is added by the water supply mechanism is kept within a predetermined temperature range set in advance. A kneading apparatus for a silica-containing rubber material, characterized in that the kneading is performed while maintaining.   The rubber material kneading apparatus according to claim 6, wherein the predetermined temperature range is set to 130 ° C. or higher and 160 ° C. or lower.   The rubber material kneading apparatus according to claim 6 or 7, wherein the water supply mechanism includes a water storage section that stores the water and a nozzle that sprays or drops the water.   The water is supplied by the water supply mechanism in a state where the ram constituting the closed kneader is arranged above the lower end of the ram chamber connected to the upper side of the kneading chamber of the closed kneader. The rubber material kneading apparatus according to any one of claims 6 to 8, which is configured.   The rubber material kneading apparatus according to claim 6, wherein the temperature of the water is set to 10 ° C. or more and 50 ° C. or less, which is lower than the silica-containing rubber material being kneaded.

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