JP6419106B2 - Vulcanized rubber composition and method for producing the same - Google Patents

Description

  The present invention relates to a vulcanized rubber composition and a method for producing the same.

  In recent years, silica has been actively blended into vulcanized rubber compositions for tires and the like. In a vulcanized rubber composition in which silica is blended, a silane coupling agent is generally blended for the purpose of improving the dispersion of silica in the rubber component. When producing a rubber composition (unvulcanized rubber composition) containing such silica and a silane coupling agent, the silanol group on the silica surface and the silane cup are kneaded, for example, at a high temperature of 140 ° C. or higher. React ring agent. Thereby, the reinforcement property of the vulcanized rubber composition by silica improves. Moreover, the dispersibility of the silica in a vulcanized rubber composition is improved, and a vulcanized rubber composition having low heat build-up can be obtained.

JP 2001-247718 A JP 2007-23155 A

  However, in the production of the vulcanized rubber composition as described above, the reaction of the silane coupling agent cannot be sufficiently completed at the time of kneading such as extrusion molding, and in order to obtain sufficient reinforcement, an excessive amount of A silane coupling agent may be blended. In addition, a silane coupling agent that could not be reacted during kneading (hereinafter referred to as unreacted silane coupling agent) reacts in the extrusion process to generate alcohol (such as ethanol), and in the extruded unvulcanized tread There is a problem of generating bubbles. Furthermore, if the unreacted silane coupling agent remains, in the step of producing the vulcanized rubber composition, the unvulcanized rubber composition is in close contact with a metal member such as a roll used for kneading, and the productivity is improved. There is also a problem that it falls.

  As a method for solving such a problem, for example, in Patent Documents 1 and 2, sodium salt or potassium salt is blended into a rubber composition to improve the reaction efficiency of the silane coupling agent during kneading in the extrusion process. Techniques for making them disclosed are disclosed.

  Under such circumstances, a main object of the present invention is to provide a vulcanized rubber composition having excellent mechanical strength and high productivity, and a method for producing the same.

  In order to solve the above-mentioned problems, the present inventors have made extensive studies. As a result, an unvulcanized rubber composition containing a rubber component, silica, and a silane coupling agent is kneaded and extruded, and after the extrusion process, a vulcanizing agent is added to the unvulcanized rubber composition. A vulcanizing agent kneading step for kneading, and a vulcanizing step for heating and vulcanizing the unvulcanized rubber composition after the vulcanizing agent kneading step. It has been found that the vulcanized rubber composition obtained by the degassing method has excellent mechanical strength and high productivity. The present invention has been completed by further studies based on these findings.

That is, this invention provides the invention of the aspect hung up below.
Item 1. An extrusion step of kneading and extruding an unvulcanized rubber composition containing a rubber component, silica, and a silane coupling agent;
After the extrusion step, a vulcanizing agent kneading step of adding and kneading a vulcanizing agent to the unvulcanized rubber composition;
After the vulcanizing agent kneading step, a vulcanization step of heating and vulcanizing the unvulcanized rubber composition;
With
A vulcanized rubber composition obtained by a method of degassing the unvulcanized rubber composition in the extrusion step.
Item 2. Item 2. The vulcanized rubber composition according to Item 1, further comprising a kneading step for further kneading the unvulcanized rubber composition between the extrusion step and the vulcanizing agent kneading step.
Item 3. Item 3. The vulcanized rubber composition according to Item 1 or 2, wherein the unvulcanized rubber composition is degassed in the vulcanizing agent kneading step.
Item 4. Item 4. The vulcanized rubber composition according to any one of Items 1 to 3, wherein in the extrusion step, degassing is performed immediately after the unvulcanized rubber has passed through a slit having a maximum width of 2 mm or less provided in a screw of an extruder. .
Item 5. Item 5. The vulcanized rubber composition according to any one of Items 1 to 4, wherein the heat history during the extrusion molding is 100 ° C or higher.
Item 6. Item 6. The vulcanized rubber composition according to any one of Items 1 to 5, comprising 60 parts by mass or more of the silica with respect to 100 parts by mass of the rubber component.
Item 7. An extrusion step of kneading and extruding an unvulcanized rubber composition containing a rubber component, silica, and a silane coupling agent;
After the extrusion step, a vulcanizing agent kneading step of adding and kneading a vulcanizing agent to the unvulcanized rubber composition;
After the vulcanizing agent kneading step, a vulcanization step of heating and vulcanizing the unvulcanized rubber composition;
With
A method for producing a vulcanized rubber composition, wherein the unvulcanized rubber composition is degassed in the extrusion step.

  ADVANTAGE OF THE INVENTION According to this invention, the vulcanized rubber composition provided with the outstanding mechanical strength and high productivity, and its manufacturing method can be provided.

  The vulcanized rubber composition of the present invention comprises an extruding step of kneading and extruding an unvulcanized rubber composition containing a rubber component, silica, and a silane coupling agent, and the unvulcanized rubber composition after the extruding step. A vulcanizing agent kneading step for adding a vulcanizing agent to the product and a vulcanizing step for heating and vulcanizing the unvulcanized rubber composition after the vulcanizing agent kneading step. The unvulcanized rubber composition is obtained by a method of degassing. Hereinafter, the vulcanized rubber composition of the present invention and the production method thereof will be described in detail.

  In the production of the vulcanized rubber composition of the present invention, an extrusion process is performed in which an unvulcanized rubber composition containing a rubber component, silica, and a silane coupling agent is kneaded and extruded.

  The rubber component used for the extrusion step is not particularly limited, and examples thereof include diene rubber, butyl rubber (IIR), and natural rubber (NR). Specific examples of the diene rubber include styrene butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IP), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile-butadiene rubber (NBR). Etc. Specific examples of the butyl rubber include halogenated butyl rubber (X-IIR) such as brominated butyl rubber (Br-IIR) and chlorinated butyl rubber (Cl-IIR), and butyl rubber (IIR). Specific examples of natural rubber include those common in the tire industry such as SIR20, RSS # 3, and TSR20. Further, as natural rubber, epoxidized natural rubber or the like may be used. A rubber component may be used individually by 1 type and may be used in combination of 2 or more type.

  Among these, from the viewpoint of enhancing the mechanical strength and productivity of the vulcanized rubber composition, it is preferable to use a diene rubber as the rubber component, and it is more preferable to use a styrene butadiene rubber.

  In the present invention, from the viewpoint of enhancing the mechanical strength and productivity of the vulcanized rubber composition, the composition of the rubber component is 60% by mass or more of styrene butadiene rubber, 20% by mass or more of butadiene rubber, and 20% by mass or less of natural rubber. It is particularly preferred that

  The silica used for extrusion molding is not particularly limited, and those generally used in the tire industry and the like can be used. Specific examples of silica include dry process silica (anhydrous silica), wet process silica (hydrous silica), and the like. Of these, wet-process silica is preferred because it has many silanol groups.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 40 m ² / g or more, more preferably 70 m ² / g or more, and further preferably 110 m ² / g or more. If it is less than 40 m ² / g, the fracture strength tends to decrease. The N ₂ SA of silica is preferably 220 m ² / g or less, more preferably 200 m ² / g or less. If it exceeds 220 m ² / g, silica is difficult to disperse and processability may be deteriorated. N ₂ SA of silica is a value measured by the BET method according to ASTM D3037-93.

  The compounding amount of silica is not particularly limited, but preferably 60 parts by mass or more with respect to 100 parts by mass of the rubber component from the viewpoint of increasing the mechanical strength and productivity of the vulcanized rubber composition. If the amount is less than 60 parts by mass, the reinforcing effect by silica may not be sufficiently obtained. Moreover, as content of this silica, Preferably it is 120 mass parts or less, More preferably, 100 mass parts or less is mentioned. When it exceeds 120 parts by mass, silica is difficult to disperse, and workability may be deteriorated. In general, as the amount of silica is increased, the amount of voids formed in the unvulcanized rubber composition and the amount of VOC such as alcohol generated by the reaction of the silane coupling agent are increased. In the composition, as will be described later, since deaeration is performed in the extrusion step, voids and VOC contained in the unvulcanized rubber composition are suitably removed. For this reason, the present invention is particularly effective in a vulcanized rubber composition having a high silica content.

  As the silane coupling agent to be used for extrusion molding, a silane coupling agent that has been conventionally used in combination with silica can be used. Specifically, bis- (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) tetrasulfide, bis (3-trimethoxysilylpropyl) ) Tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (4-trimethoxysilylbutyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (2-triethoxysilylethyl) trisulfide Sulfide, bis (4-triethoxysilylbutyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (2-trimethoxysilylethyl) trisulfide, bis (4-trimethoxysilylbutyl) trisulfide, Screw (3 Triethoxysilylpropyl) disulfide, bis (2-triethoxysilylethyl) disulfide, bis (4-triethoxysilylbutyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, bis (2-trimethoxysilylethyl) disulfide Bis (4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxy Silylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilylethyl-N, N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyl Sulfide systems such as trisulfide, 3-triethoxysilylpropylbenzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide; 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyl Mercapto series such as triethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane; Vinyl series such as vinyltriethoxysilane, vinyltrimethoxysilane; 3-aminopropyltriethoxysilane, 3-aminopropyl Amino acids such as trimethoxysilane, 3- (2-aminoethyl) aminopropyltriethoxysilane, and 3- (2-aminoethyl) aminopropyltrimethoxysilane Glycidoxy systems such as γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane; 3- Nitro group such as nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane; 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane And chloro-type. Bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) disulfide, 3-mercaptopropyltrimethoxysilane and the like are preferably used because of the addition effect of the silane coupling agent and cost. These silane coupling agents may be used alone or in combination of two or more.

  The amount of the silane coupling agent is not particularly limited, but from the viewpoint of increasing the mechanical strength and productivity of the vulcanized rubber composition, preferably 3 parts by mass or more, more preferably 100 parts by mass of silica. Is 5 parts by mass or more. When the content is less than 3 parts by mass, the coupling effect becomes insufficient, and the wear resistance tends to be lowered. Moreover, content of a silane coupling agent is 15 mass parts or less with respect to 100 mass parts of silica, Preferably it is 13 mass parts or less. When this content exceeds 15 mass parts, the obtained rubber composition may become hard too much.

  In the extrusion process, in addition to the rubber component, silica, and silane coupling agent, carbon black, a filler, and the like may be further blended.

  The carbon black is not particularly limited, and known carbon black blended in the vulcanized rubber composition can be used. Specific examples of carbon black include SAF, ISAF, HAF, FF, FEF, GPF and the like commonly used in the tire industry. Carbon black may be used alone or in combination of two or more.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 20 m ² / g or more, and more preferably 30 m ² / g or more. When N ₂ SA of carbon black is less than 20 m ² / g, there is a tendency that sufficient reinforcing properties cannot be obtained. Further, N ₂ SA of the carbon black is preferably 80 m ² / g or less, and more preferably 50 m ² / g or less. When N ₂ SA of carbon black exceeds 80 m ² / g, heat generation increases and low fuel consumption performance tends to decrease. The N ₂ SA of carbon black in the present invention is a value determined by the A method of JIS K6217.

  The dibutyl phthalate oil absorption (DBP) of carbon black is preferably 70 ml / 100 g or more, more preferably 90 ml / 100 g or more, from the viewpoint that sufficient reinforcing properties can be obtained. The DBP of carbon black is preferably 150 ml / 100 g or less, and more preferably 130 ml / 100 g or less, from the viewpoint of excellent fatigue resistance such as elongation at break. In addition, DBP of carbon black is a value calculated | required by the measuring method of JISK6217-4.

  The blending amount of carbon black is not particularly limited, but preferably 30 parts by mass or less with respect to 100 parts by mass of the rubber component from the viewpoint of improving the mechanical strength and productivity of the vulcanized rubber composition.

  It does not restrict | limit especially as a filler, Any of an organic type filler and an inorganic type filler may be included. Specific examples of the filler include zinc oxide, calcium carbonate, mica, aluminum hydroxide, magnesium hydroxide, magnesium oxide, clay, talc, titanium oxide, carbon fiber, cellulose fiber, carbon nanotube (multi-layer, single-layer), graphene Etc. Among these, it is preferable to contain zinc oxide from the viewpoint of effectively accelerating the vulcanization reaction of the unvulcanized rubber composition. In addition, it is preferable to mix | blend zinc oxide with an unvulcanized rubber composition with a vulcanizing agent etc. in the below-mentioned vulcanizing agent kneading | mixing process instead of an extrusion process.

  The blending amount of the filler in the vulcanized rubber composition of the present invention is not particularly limited. For example, from the viewpoint of accelerating the vulcanization of the vulcanized rubber composition using zinc oxide as a filler, the amount of zinc oxide is preferably about 1 to 6 parts by mass, more preferably 1.2 to 5 parts. About a mass part is mentioned.

  In the extrusion process, in addition to the above components, other additives conventionally used in the rubber industry, for example, other additives such as thermoplastic polyurethane, stearic acid, anti-aging agent, oil, wax and the like are appropriately mixed. be able to.

  In the present invention, in the extrusion process of kneading the unvulcanized rubber composition containing the rubber component, silica, silane coupling agent, carbo black, filler, other additives, and the like as necessary. The unvulcanized rubber composition is degassed. In the extrusion process, by degassing the unvulcanized rubber composition, bubbles and spaces existing in the unvulcanized rubber composition are efficiently removed, and the reaction efficiency by the silane coupling agent can be effectively increased. it can. Furthermore, by-products (VOC) such as alcohol generated by the reaction of the silane coupling agent can also be effectively removed by the degassing. Therefore, the mechanical strength such as wear resistance and fracture resistance of the vulcanized rubber composition can be effectively increased, and further, the above-described decrease in productivity caused by alcohol or the like is effectively suppressed. be able to. In addition, VOCs harmful to the human body and the environment can be effectively supplemented and removed in the production process of the vulcanized rubber composition.

  In the present invention, in the extrusion step, it is preferable to deaerate immediately after the unvulcanized rubber composition passes through a slit having a maximum width of 2 mm or less provided in the screw of the extruder. More specifically, when each component constituting the unvulcanized rubber is kneaded using a Banbury mixer, an extruder or the like, a slit having a maximum width of 2 mm or less provided on the screw of the extruder (usually a screw) It is preferable to perform deaeration through a deaeration hole provided immediately after the slit. In the vulcanized rubber composition of the present invention, when degassing is performed in such a specific extrusion process, it is generated by the reaction of the gas, voids, and further the silane coupling agent contained in the unvulcanized rubber composition. By-products (VOC) such as alcohol can be removed more effectively. Therefore, the mechanical strength of the obtained vulcanized rubber composition can be further increased, and furthermore, the adhesion to the processing roll can be more effectively suppressed, and thus the productivity can be further improved.

  The shape of each slit provided in the screw is not particularly limited. Each slit is preferably provided, for example, as a hole having a circular cross section in the screw. The number of slits is not particularly limited and may be set as appropriate.

  In the extrusion step, the kneading temperature until the unvulcanized rubber composition is degassed (if it has a slit, the temperature of the unvulcanized rubber composition before passing through the slit) is not particularly limited, but each component is From the viewpoint of homogeneous mixing, the temperature is preferably about 75 to 95 ° C.

  Moreover, in extrusion formation, it is preferable that it is 100 degreeC or more as a heat history at the time of extrusion molding, and it is preferable that discharge temperature is 100-130 degreeC. By reaching such a temperature at the time of discharge, each component is homogeneously dispersed, and because it is a region that sufficiently reaches fluidization of rubber, it is easy to be molded into an arbitrary shape. When the unvulcanized rubber composition reaches a high temperature, the aforementioned VOC contained in the unvulcanized rubber composition is vaporized and large voids are easily formed in the vulcanized rubber composition. For example, since deaeration is performed in the extrusion process, VOC contained in the unvulcanized rubber composition is effectively removed, the mechanical strength of the vulcanized rubber composition is improved, and the productivity is increased. Furthermore, from the viewpoint of increasing the mechanical strength and productivity of the vulcanized rubber composition, the kneading temperature immediately before degassing (particularly the temperature at which the unvulcanized rubber composition passes through the slit) during the above-described extrusion molding. ) Is preferably 140 ° C. or higher. Thereby, removal of VOC etc. by deaeration immediately after the unvulcanized rubber composition passes through the slit can be performed more efficiently while the reaction of the silane coupling agent proceeds efficiently.

  In the present invention, after the extrusion step, a vulcanizing agent kneading step is performed in which the vulcanizing agent is added to the unvulcanized rubber composition and kneaded. Examples of the vulcanizing agent include powdered sulfur.

  In the vulcanizing agent kneading step, it is preferable to add a vulcanization accelerator, zinc oxide and the like in addition to the vulcanizing agent. Examples of the vulcanization accelerator include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N, N′-dicyclohexyl-2- Examples include benzothiazolylsulfenamide (DZ), mercaptobenzothiazole (MBT), dibenzothiazolyl disulfide (MBTS), and diphenylguanidine (DPG). Among them, sulfenamide-based vulcanization accelerators such as TBBS, CBS, DZ, MBT, MBTS, etc. are excellent because of their excellent vulcanization characteristics and great effect of improving mechanical strength in the physical properties of rubber after vulcanization. The thiazole vulcanization accelerator is preferred.

  Kneading in the vulcanizing agent kneading step can be performed using a kneading machine such as a Banbury mixer. The kneading temperature in the vulcanizing agent kneading step is not particularly limited, but preferably about 60 ° C to 100 ° C. Moreover, as kneading | mixing time, about 2 minutes-10 minutes are mentioned.

  In the present invention, it is preferable to further deaerate the unvulcanized rubber composition in the vulcanizing agent kneading step. In addition to the above-described degassing in the extrusion process, VOC contained in the unvulcanized rubber composition can be further removed by performing degassing in the vulcanizing agent kneading process. Degassing in the vulcanizing agent kneading step can be performed by providing degassing holes in the kneader and sucking gas from the degassing holes.

  Further, in the present invention, a kneading step for further kneading the unvulcanized rubber composition may be provided between the extrusion step and the vulcanizing agent kneading step. By providing the kneading step, each component can be kneaded more uniformly, and the reaction of the silane coupling agent can be further advanced. The kneading can be performed using a Banbury mixer or the like. Although it does not restrict | limit especially as the kneading | mixing temperature in the said kneading | mixing process, Preferably about 140 to 175 degreeC is mentioned. Moreover, as kneading | mixing time, about 2 minutes-10 minutes are mentioned.

  In the present invention, after the vulcanizing agent kneading step, a vulcanizing step of heating and vulcanizing the unvulcanized rubber composition is performed. The vulcanization step can be performed by a known method, for example, by heating and pressurizing an unvulcanized rubber composition containing a vulcanizing agent, a vulcanization accelerator and the like at 138 to 191 ° C. Can do.

  The vulcanized rubber composition of the present invention can be suitably used as passenger car tires, truck / bus tires, motorcycle tires and the like.

  The vulcanized rubber composition of the present invention can be suitably produced by, for example, a production method including the aforementioned extrusion process, vulcanizing agent kneading process, vulcanization process, and kneading process provided as necessary. Each component, production conditions, etc. used for producing the vulcanized rubber composition are as described above.

Examples of the present invention will be described below. However, the present invention is not limited to the following examples. The details of the materials used in the examples are as follows.
Styrene butadiene rubber: SBR1502 manufactured by JSR Corporation
Butadiene rubber: BR150B manufactured by Ube Industries, Ltd.
Natural rubber: RSS # 3
Silica: 1165MP manufactured by Rhodia
Carbon black: Dia Black I (N220) manufactured by Mitsubishi Chemical Corporation
Silane coupling agent: Si363 made by Evonik Degussa
Aroma-based process oil: NC300SN manufactured by JX Nippon Oil & Energy Corporation
Anti-aging agent: Nocrack 6C manufactured by Ouchi Shinsei Chemical Co., Ltd.
Stearic acid: manufactured by NOF CORPORATION of Beads Stearic acid Tsubaki Zinc oxide: available from Mitsui Mining and Smelting Co., Ltd. of zinc oxide two tetraborate potassium tetrahydrate _{(K 2 B 4 O 7 ·} 4H 2 O): Yoneyama Chemicals 48 mesh under product manufactured by Kogyo Co., Ltd. (passed through a 48 mesh sieve) (average particle size 170 μm, melting point 815 ° C. (anhydride))
Powdered sulfur: Tsurumi Chemical Co., Ltd. vulcanization accelerator A: Noxeller NS-G manufactured by Ouchi Shinsei Chemical Co., Ltd.
Vulcanization accelerator B: Noxeller D manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

<Example 1>
Each component (components excluding powdered sulfur, vulcanization accelerators A and B, and zinc oxide) was kneaded with a 1.7 L Banbury mixer so as to achieve the blending ratio shown in Table 1. The kneading conditions are as follows. F. 58%, rotation speed 100 rpm, 160 ° C. Next, the unvulcanized rubber composition obtained by kneading was kneaded using an extrusion molding machine (manufactured by Nakata Engineering Co., Ltd., 60φ vent extruder) to perform extrusion molding. The screw of the extruder was provided with a slit having a maximum width of 2 mm, and the unvulcanized rubber composition was designed to pass through the slit. Further, immediately after the slit, a deaeration hole was provided, and gas was sucked from the deaeration hole to degas the unvulcanized rubber composition. The discharge temperature from the extruder is as shown in Table 1. Powdered sulfur, vulcanization accelerators A and B, and zinc oxide are added to the devulcanized rubber composition after degassing, kneaded for 3 minutes at 95 ° C. using a 1.7 L Banbury mixer, and a sheet having a thickness of 2 mm The vulcanizing agent kneading step was carried out by discharging from the die so as to form a shape. Next, the obtained sheet-like unvulcanized rubber composition was cut into a fixed size and subjected to a vulcanization step at 170 ° C. for 12 minutes to obtain a sheet-like vulcanized rubber composition.

<Example 2>
Table 1 shows the addition of a kneading step of kneading the unvulcanized rubber composition again with a 1.7 L Banbury mixer between the extrusion molding and the vulcanizing agent kneading step. A sheet-like vulcanized rubber composition was obtained in the same manner as in Example 1 except that the temperature was set as described. The kneading conditions in the kneading step are as follows. F. 58%, rotation speed 100 rpm, 160 ° C.

<Example 3>
In the vulcanizing agent kneading step, degassing holes are provided in the kneading part of the used kneader (1.7 L Banbury mixer), and gas is sucked from the degassing holes to degas the unvulcanized rubber composition. A sheet-like vulcanized rubber composition was obtained in the same manner as in Example 1 except that the discharge temperature from the extruder was set to the temperature shown in Table 1.

<Example 4>
A sheet-like vulcanized rubber composition was obtained in the same manner as in Example 3 except that the composition of each component was changed as shown in Table 1.

<Comparative Example 1>
A sheet-like vulcanized rubber composition was obtained in the same manner as in Example 1 except that deaeration was not performed in the extrusion.

<Comparative example 2>
A sheet-like vulcanized rubber composition was obtained in the same manner as in Example 2 except that degassing was not performed in extrusion molding and that potassium tetraborate was added to the unvulcanized rubber composition.

<Comparative Example 3>
A sheet-like vulcanized rubber composition was obtained in the same manner as in Comparative Example 1 except that the composition of each component was changed as shown in Table 1.

[Abrasion resistance evaluation]
Each unvulcanized rubber composition discharged in the vulcanizing agent kneading step of Examples and Comparative Examples is filled in a mold, and subjected to a vulcanization step at 170 ° C. for 12 minutes. A sample (a donut shape having a thickness of 13 mm, an outer diameter of 78 mm, and an inner diameter of 33 mm) was produced. About each obtained test sample, the volume loss amount was measured on the conditions of load 120N, speed | rate 20 km / h, and slip angle 5 degrees using the LAT tester (Laboratory Abbreviation and Skid Tester). Then, the wear resistance index of Comparative Example 1 was set to 100, and the wear resistance of each Example and Comparative Example was displayed as an index according to the following calculation formula. It shows that it is excellent in abrasion resistance, so that a numerical value is large. The results are shown in Table 1.
(Abrasion resistance index) = (Volume loss amount of Comparative Example 1) / (Volume loss amount of each Example and Comparative Example) × 100

[Evaluation of fracture resistance]
In accordance with JIS K 6251 “Vulcanized Rubber and Thermoplastic Rubber—How to Obtain Tensile Properties”, No. 3 dumbbell-shaped test pieces were prepared from the respective vulcanized rubber compositions obtained in Examples and Comparative Examples, and the room temperature ( The tensile test was carried out at 23 ° C., and the elongation at break EB (%) of each test piece was measured. Then, with the fracture characteristic index of Comparative Example 1 as the standard: 100, the fracture resistance of each Example and Comparative Example was displayed as an index according to the following calculation formula. The larger the value, the better the fracture resistance. The results are shown in Table 1.
(Fracture resistance index) = (Elongation at break (%) of each Example and Comparative Example) / (Elongation at break (%) of Comparative Example 1) × 100

[Roll processability]
About the unvulcanized rubber composition obtained in the vulcanizing agent kneading step of Examples and Comparative Examples, after roll milling for several minutes using two rolls, the unvulcanized rubber composition wound around the roll is knife-cut, The ease of work when removing the unvulcanized rubber composition from the roll was evaluated in the following five stages. The results are shown in Table 1.
1: The unvulcanized rubber composition did not adhere to the roll, the unvulcanized rubber composition peeled off very easily from the roll, and was particularly excellent in workability. 2: The unvulcanized rubber composition adhered slightly to the roll. However, it was easily peeled off from the roll and was excellent in workability. 3: The unvulcanized rubber composition was in close contact with the roll and slightly peeled off from the roll, and the workability was normal. 4: The unvulcanized rubber composition was Adhered slightly strongly to the roll, hardly peeled off from the roll, and the workability was poor 5: The unvulcanized rubber composition adhered strongly to the roll, and was particularly difficult to peel off from the roll, and the workability was very poor.

  As shown in Table 1, in Examples 1 to 4 in which the unvulcanized rubber composition was degassed in the extrusion process, the vulcanized rubber composition was excellent in wear resistance and fracture resistance, and was rolled. It was also excellent in performance. On the other hand, in Comparative Examples 1 to 3 in which the deaeration was not performed, the abrasion resistance and fracture resistance of the vulcanized rubber composition were inferior. In Comparative Example 2, since potassium tetraborate that promotes the reaction of the silane coupling agent was included, the roll processability was excellent. However, with respect to wear resistance and fracture resistance, Examples 1 to It was inferior to 4. Further, both Example 4 and Comparative Example 3 are compositions having a large amount of silica and silane coupling agent, but in Example 4 where deaeration was performed during extrusion molding, the abrasion resistance of the vulcanized rubber composition. In addition, it was excellent in fracture resistance and roll workability.

Claims (11)

An extrusion step of kneading and extruding an unvulcanized rubber composition containing a rubber component, silica, and a silane coupling agent;
After the extrusion step, a vulcanizing agent kneading step of adding and kneading a vulcanizing agent to the unvulcanized rubber composition;
After the vulcanizing agent kneading step, a vulcanization step of heating and vulcanizing the unvulcanized rubber composition;
With
A vulcanized rubber composition obtained by degassing the unvulcanized rubber composition in the extrusion step and degassing the unvulcanized rubber composition in the vulcanizing agent kneading step . An extrusion step of kneading and extruding an unvulcanized rubber composition containing a rubber component, silica, and a silane coupling agent;
  After the extrusion step, a vulcanizing agent kneading step of adding and kneading a vulcanizing agent to the unvulcanized rubber composition;
  After the vulcanizing agent kneading step, a vulcanization step of heating and vulcanizing the unvulcanized rubber composition;
With
  In the extrusion step, obtained by a method of degassing the unvulcanized rubber composition,
  In the extrusion step, a vulcanized rubber composition is deaerated immediately after the unvulcanized rubber passes through a slit having a maximum width of 2 mm or less provided in a screw of an extruder. An extrusion step of kneading and extruding an unvulcanized rubber composition containing a rubber component, silica, and a silane coupling agent;
  After the extrusion step, a vulcanizing agent kneading step of adding and kneading a vulcanizing agent to the unvulcanized rubber composition;
  After the vulcanizing agent kneading step, a vulcanization step of heating and vulcanizing the unvulcanized rubber composition;
With
  In the extrusion step, obtained by a method of degassing the unvulcanized rubber composition,
  A vulcanized rubber composition comprising 60 parts by mass or more of the silica with respect to 100 parts by mass of the rubber component. The vulcanized rubber composition according to any one of claims 1 to 3 , further comprising a kneading step for further kneading the unvulcanized rubber composition between the extrusion step and the vulcanizing agent kneading step. The vulcanized rubber composition according to any one of claims 2 to 4 , wherein the unvulcanized rubber composition is degassed in the vulcanizing agent kneading step. 6. The vulcanization according to claim 1 , wherein in the extrusion step, degassing is performed immediately after the unvulcanized rubber passes through a slit having a maximum width of 2 mm or less provided in a screw of an extruder. Rubber composition. The vulcanized rubber composition according to any one of claims 1 to 6 , wherein a heat history during the extrusion molding is 100 ° C or higher. The vulcanized rubber composition according to claim 1 , comprising 60 parts by mass or more of the silica with respect to 100 parts by mass of the rubber component. An extrusion step of kneading and extruding an unvulcanized rubber composition containing a rubber component, silica, and a silane coupling agent;
After the extrusion step, a vulcanizing agent kneading step of adding and kneading a vulcanizing agent to the unvulcanized rubber composition;
After the vulcanizing agent kneading step, a vulcanization step of heating and vulcanizing the unvulcanized rubber composition;
With
In the extrusion process, the production of the have line degassing of the unvulcanized rubber composition, and the at vulcanizing agent kneading step, degassing rows cormorants, vulcanized rubber composition of the unvulcanized rubber composition Method. An extrusion step of kneading and extruding an unvulcanized rubber composition containing a rubber component, silica, and a silane coupling agent;
  After the extrusion step, a vulcanizing agent kneading step of adding and kneading a vulcanizing agent to the unvulcanized rubber composition;
  After the vulcanizing agent kneading step, a vulcanization step of heating and vulcanizing the unvulcanized rubber composition;
With
  In the extrusion step, degassing the unvulcanized rubber composition,
  A method for producing a vulcanized rubber composition, wherein in the extrusion step, degassing is performed immediately after the unvulcanized rubber passes through a slit having a maximum width of 2 mm or less provided in a screw of an extruder. An extrusion step of kneading and extruding an unvulcanized rubber composition containing a rubber component, silica, and a silane coupling agent;
  After the extrusion step, a vulcanizing agent kneading step of adding and kneading a vulcanizing agent to the unvulcanized rubber composition;
  After the vulcanizing agent kneading step, a vulcanization step of heating and vulcanizing the unvulcanized rubber composition;
With
  In the extrusion step, degassing the unvulcanized rubber composition,
  A method for producing a vulcanized rubber composition, comprising 60 parts by mass or more of the silica with respect to 100 parts by mass of the rubber component.