JP6645839B2 - Method for producing rubber composition, rubber composition and tire - Google Patents

Description

  The present invention relates to a method for producing a rubber composition, a rubber composition, and a tire.

Conventionally, studless tires with soft tread rubber have been used as tires for running safely on ice in addition to normal road surfaces, and by improving the tread rubber, tire performance on ice can be improved. Are known. However, a tire having a soft tread rubber generally has a problem of poor abrasion resistance on a normal road surface, and the performance on ice and the abrasion resistance have a trade-off relationship.
Further, as a technique for improving the performance on ice of a tire, for example, a technique for improving the performance on ice of a tire by blending organic fibers, glass fibers, and the like with a rubber composition used for a tread and scratching the icy road surface is known. Have been. However, organic fibers, glass fibers, and the like have no interaction with rubber and thus act as breaking nuclei, which is a factor that reduces the breaking resistance (wear resistance) of tread rubber.

  As a tire for solving such a problem, Japanese Patent Application Laid-Open No. 2008-303334 (Patent Document 1) discloses that a potassium titanate fiber is 0.5 to 20 parts by weight based on 100 parts by weight of a rubber component composed of natural rubber and butadiene rubber. And a rubber composition containing 5-200 parts by weight of carbon black having an iodine adsorption amount of 100-300 mg / g, and a rubber composition having a two-layer structure comprising a cap tread and a base tread. It has been reported that by using a tread cap tread, performance on ice (performance on ice and snow) is improved while suppressing a decrease in wear resistance.

JP 2008-303334 A

  However, as disclosed in Table 1 of Japanese Patent Application Laid-Open No. 2008-303334 (Patent Document 1), by using a rubber composition containing a specific amount of potassium titanate fiber in a cap tread, the performance on ice of a tire (on ice) Although the coefficient of friction is improved, the wear resistance is slightly reduced, and it is not possible to improve both the performance on ice and the wear resistance.

Then, an object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a rubber composition capable of improving both on-ice performance and abrasion resistance of a tire and a method for producing the same.
Another object of the present invention is to provide a tire having both excellent on-ice performance and wear resistance.

  The gist configuration of the present invention for solving the above problems is as follows.

The method for producing the rubber composition of the present invention comprises:
At least two diene-based polymers that form a plurality of polymer phases incompatible with each other, silica surface-treated with a sulfur-containing silane coupling agent, and carbon black,
At least two of the diene polymers have a blending amount of at least 20% by mass of the total amount of the diene polymers, and the blending amount is at least 20% by mass of the total amount of the diene polymers. The blending amount of the diene-based polymer (A) having the lowest glass transition temperature (Tg) in the coalesce is the diene-based polymer having the largest blending amount among the diene-based polymers other than the diene-based polymer (A). 85% by mass or more of the blending amount of the polymer,
A method for producing a rubber composition, wherein the compounding amount of the silica surface-treated with the sulfur-containing silane coupling agent is 25 parts by mass or more based on 100 parts by mass of the total of the diene-based polymer,
A diene polymer (B) which is incompatible with the diene polymer (A) having the lowest glass transition temperature (Tg) among the diene polymers, and the sulfur-containing silane coupling agent (A) preparing a master batch by mixing silica surface-treated with
(B) mixing, with the prepared masterbatch, the remainder of the diene-based polymer other than the diene-based polymer (B), and the carbon black;
It is characterized by including.
According to the method for producing a rubber composition of the present invention, it is possible to produce a rubber composition capable of improving both on-ice performance and wear resistance of a tire.

  In the present invention, the incompatibility of the polymer phase is determined by processing the target rubber composition into a sheet shape using a test roll, and using a 15 cm × 15 cm × 1 cm test mold at 150 ° C. for 30 minutes. Press vulcanization is performed to produce a vulcanized sheet, and the resulting vulcanized sheet is evaluated as an ultrathin section by a microtome using a scanning probe microscope and evaluated. The phases are incompatible with each other.

  Further, in the present invention, the glass transition temperature (Tg) of the diene-based polymer is determined by using a differential scanning calorimeter (DSC) in accordance with ASTM D3418-82, and an extrapolated onset temperature: Tf And

  In the method for producing a rubber composition according to the present invention, the diene-based polymer (A) having the lowest glass transition temperature (Tg) is the largest in the diene-based polymer in the amount of the diene-based polymer, or is the diene-based polymer. Among the diene polymers other than (A), it is preferable that the blending amount is equal to the diene polymer having the largest blending amount. In this case, the wear resistance of the tire can be further improved by applying the rubber composition to the tire.

In a preferred example of the method for producing a rubber composition of the present invention, the diene polymer (A) having the lowest glass transition temperature (Tg) has a butadiene skeleton. In this case, the rubber composition is softened, and when the rubber composition is used for the tread, the contact area of the tread is increased, and the performance on ice is further improved.
Here, the diene polymer (A) having the lowest glass transition temperature (Tg) is preferably a polybutadiene rubber. In this case, when the rubber composition is further softened, the ground contact area is further increased, and the performance on ice is further improved.

In another preferred embodiment of the method for producing a rubber composition according to the present invention, the glass transition temperature (Tg) of the diene-based polymer whose blending amount is 20% by mass or more of the total amount of the diene-based polymer is the most. The high diene polymer (C) has an isoprene skeleton. In this case, the reinforcing property of the rubber composition is increased, and the wear resistance is further improved.
Here, the diene polymer (C) having the highest glass transition temperature (Tg) is preferably a natural rubber. In this case, the reinforcing property of the rubber composition is further increased, and the wear resistance is further improved.

  In the method for producing a rubber composition of the present invention, the rubber composition preferably has a compounding amount of the carbon black of 25 parts by mass or more based on 100 parts by mass of the diene polymer in total. In this case, the wear resistance of the tire to which the rubber composition has been applied can be further improved.

  In a preferred example of the method for producing a rubber composition of the present invention, the rubber composition further contains a vulcanization accelerator, and in the step (a), at least one compound selected from the vulcanization accelerator is used. Mix to prepare the masterbatch. In this case, the performance on ice of the tire using the manufactured rubber composition is further improved.

In another preferred embodiment of the method for producing a rubber composition of the present invention, the diene polymer (A) having the lowest glass transition temperature (Tg) is modified with a compound containing at least one of a tin atom and a nitrogen atom. ing. In this case, the interaction between the diene polymer (A) having the lowest glass transition temperature (Tg) and carbon black is increased, and the wear resistance of the rubber composition is further improved.
Here, the diene polymer (A) having the lowest glass transition temperature (Tg) preferably contains both tin atoms and nitrogen atoms. In this case, the interaction between the diene polymer (A) having the lowest glass transition temperature (Tg) and carbon black is further increased, and the interaction between the diene polymer (A) having the lowest glass transition temperature (Tg) and The reinforcing property of the formed polymer phase is increased, and the wear resistance of the rubber composition is further improved.

Further, the diene polymer (A) having the lowest glass transition temperature (Tg) preferably has a modification ratio of 1.1 to 2.5 by a compound containing at least one of the tin atom and the nitrogen atom. . In this case, the interaction between the diene-based polymer (A) having the lowest glass transition temperature (Tg) and the carbon black is large, and the reinforcing property and the wear resistance are further improved.
Here, the modification rate of the diene polymer (A) refers to at least one of a tin atom (Sn) and a nitrogen atom (N) used for the modification reaction per 100 g of the rubber component of the diene polymer (A). Is the number of millimoles of the compound containing.

  In the method for producing a rubber composition of the present invention, the rubber composition preferably further contains a foaming agent. When a tire is manufactured by using a rubber composition containing a foaming agent for a tread rubber, when the raw tire is vulcanized, bubbles derived from the foaming agent are formed in the tread rubber, and a scratching effect and a drainage effect of the tread bubbles are generated. Thus, the on-ice performance of the tire can be further improved.

In the method of manufacturing the rubber composition of the present invention, the rubber composition preferably further comprises a C ₅ resin. In this case, the on-ice performance of the tire can be further improved.

  In the method for producing a rubber composition of the present invention, it is preferable that the rubber composition further contains a hydrophilic short fiber. In this case, the on-ice performance of the tire can be significantly improved.

  Further, a rubber composition of the present invention is characterized by being produced by the above-mentioned method for producing a rubber composition. According to the rubber composition of the present invention, when applied to a tire, both the on-ice performance and the wear resistance of the tire can be improved.

  Furthermore, a tire of the present invention is characterized by using the above rubber composition. Since the tire of the present invention uses the above rubber composition, it is excellent in both on-ice performance and abrasion resistance.

ADVANTAGE OF THE INVENTION According to this invention, the rubber composition which can improve both the on-ice performance and abrasion resistance of a tire, and its manufacturing method can be provided.
Further, according to the present invention, it is possible to provide a tire excellent in both on-ice performance and wear resistance.

<Method for producing rubber composition and rubber composition>
Hereinafter, the method for producing a rubber composition and the rubber composition of the present invention will be described in detail based on embodiments.
The method for producing a rubber composition of the present invention includes at least two kinds of diene polymers forming a plurality of mutually incompatible polymer phases, silica surface-treated with a sulfur-containing silane coupling agent, and carbon black. At least two of the diene-based polymers have a compounding amount of 20% by mass or more of the total amount of the diene-based polymers, and the compounding amount is 20% by mass or more of the total amount of the diene-based polymers. The blending amount of the diene polymer (A) having the lowest glass transition temperature (Tg) among certain diene polymers is determined by the blending amount among the diene polymers other than the diene polymer (A). Is 85% by mass or more of the compounding amount of the diene polymer which is the largest, and the compounding amount of the silica surface-treated with the sulfur-containing silane coupling agent is 25% based on 100 parts by mass of the total of the diene polymer. Over parts by mass That a method for producing a rubber composition,
A diene polymer (B) incompatible with the diene polymer (A) having the lowest glass transition temperature (Tg) of the diene polymer, and the sulfur-containing silane coupling agent. (A) preparing a masterbatch by mixing the surface-treated silica with
(B) mixing the carbon black with the remainder of the diene-based polymer other than the diene-based polymer (B) in the prepared masterbatch;
It is characterized by including.
Further, the rubber composition of the present invention is characterized by being produced by the above-mentioned method for producing a rubber composition of the present invention.

  The rubber composition produced by the method of the present invention contains at least two types of diene-based polymers, and a polymer blend comprising the two or more types of diene-based polymers forms a plurality of polymer phases that are incompatible with each other. I do. In the method for producing a rubber composition according to the present invention, in the step (a), the diene polymer (B) incompatible with the diene polymer (A) having the lowest glass transition temperature (Tg). And silica that has been surface-treated with the sulfur-containing silane coupling agent are mixed to prepare a master batch. As described above, in the method for producing a rubber composition of the present invention, the master batch is prepared by mixing the diene polymer (B) and the silica surface-treated with the sulfur-containing silane coupling agent. The silica surface-treated with the sulfur-containing silane coupling agent can be dispersed in the diene polymer (B) while being chemically bonded to the diene polymer (B). Here, the sulfur-containing silane coupling agent reacts with the surface of silica in the surface treatment and also reacts with the diene-based polymer (B). The coalesced (B) and the silica are chemically bonded, and the silica surface-treated with the sulfur-containing silane coupling agent is dispersed in the polymer phase containing the diene-based polymer (B). As described above, the polymer phase containing the diene-based polymer (B) has a high glass transition temperature (Tg) and is formed from the diene-based polymer (B) having a high reinforcing property, and thus has high wear resistance. In addition, since it contains silica surface-treated with a sulfur-containing silane coupling agent, it is soft while having microscopic irregularities. Therefore, when the rubber composition produced by the method of the present invention is used for a tread of a tire, the contact area of the tread is increased, and the performance of the tire on ice is improved.

  Further, in the method for producing a rubber composition according to the present invention, in the step (b), the masterbatch may include, in the diene-based polymer, a residue other than the diene-based polymer (B), and the carbon black; However, since silica that has been surface-treated with a sulfur-containing silane coupling agent is chemically bonded to the diene polymer (B) in the master batch, in the step (b), the carbon black is It is difficult to disperse in the diene polymer (B), and the remainder of the diene polymer [that is, the diene polymer (A) having the lowest glass transition temperature (Tg); Other diene-based polymer compatible with the polymer (A)]. The remainder of the diene-based polymer other than the diene-based polymer (B) contains the diene-based polymer (A) having the lowest glass transition temperature (Tg), so that it is soft and has high performance on ice. In addition, carbon black is mainly dispersed in the polymer phase consisting of the remainder other than the diene polymer (B). As described above, when the produced rubber composition is used in a tire, the wear resistance of the tire is reduced by the fact that the polymer phase composed of the remainder other than the diene polymer (B) contains carbon black having high reinforcing properties. improves.

For the above reasons, according to the method for producing a rubber composition of the present invention, by applying to a tire, it is possible to produce a rubber composition capable of improving both on-ice performance and wear resistance of the tire. Can be.
Further, by applying the rubber composition of the present invention produced by such a method to a tire, both the on-ice performance and the wear resistance of the tire can be improved.

As described above, in the process for producing a rubber composition of the present invention, in the step (a), the diene polymer (A) having the lowest glass transition temperature (Tg) among the diene polymers is used. A masterbatch is prepared by mixing a diene-based polymer (B) incompatible with the silica and the silica surface-treated with the sulfur-containing silane coupling agent, and the master batch is prepared in the step (b). In the masterbatch, the remainder of the diene-based polymer other than the diene-based polymer (B) and the carbon black are mixed. In step (a) and step (b), if desired, described below C ₅ resins, hydrophilic short fibers, plasticizers (process oil), stearic acid, zinc white (zinc oxide), anti-aging agents, may be blended other compounding agents such as wax.

In the case where the raw materials are mixed in a solid state in the steps (a) and (b), a mixing device such as a Banbury mixer, a roll, and an intensive mixer can be used. After the step (a), the obtained master batch may be once taken out of the mixing apparatus and then the step (b) may be carried out, or the step (b) may be carried out without taking out the master batch once. Preferably, after the step (a), the obtained master batch is temporarily removed from the mixing device.
When the obtained master batch is once taken out of the mixing device, the step (b) may be performed using the same mixing device as the step (a), or another mixing device different from the step (a) may be used. May be used.

In the step (a), the maximum temperature of the mixture (master batch) is preferably in the range of 120 to 190 ° C, more preferably in the range of 130 to 175 ° C, and still more preferably in the range of 140 to 170 ° C. When the maximum temperature of the mixture in the step (a) is 120 to 190 ° C., the dispersion of the silica in the diene polymer (B) proceeds favorably.
Further, the falling temperature of the mixture in step (a) (that is, the temperature at which the mixture is discharged from the mixing device) is preferably 145 ° C. or higher. If the falling temperature in the step (a) is 145 ° C. or higher, the dispersion of the silica surface-treated with the sulfur-containing silane coupling agent in the diene polymer (B) proceeds well, and the rubber composition produced The on-ice performance of the tire using the object is further improved.

  In the step (a), the mixing time (kneading time) of the mixture is preferably in the range of 10 to 180 seconds, more preferably in the range of 10 to 150 seconds, still more preferably in the range of 30 to 150, and more preferably in the range of 30 to 150. A range of 120 seconds is particularly preferred. When the mixing time is at least 10 seconds, the dispersion of the silica surface-treated with the sulfur-containing silane coupling agent in the diene polymer (B) can be sufficiently advanced, and the mixing time is 180 seconds. , It is difficult to enjoy further effects.

In the step (b), the maximum temperature of the mixture (the rubber composition or, in the case where a further mixing step is included after the step (b), a premix of the rubber composition) is 120 to 190 ° C. The range is preferable, the range of 130 to 175 ° C is more preferable, and the range of 140 to 170 ° C is even more preferable. When the maximum temperature of the mixture in the step (b) is 120 to 190 ° C., the dispersion of carbon black in the diene-based polymer other than the diene-based polymer (B) is good. move on.
Further, the falling temperature of the mixture in the step (b) is preferably 145 ° C. or higher. If the falling temperature in the step (b) is 145 ° C. or higher, the dispersion of carbon black in other diene polymers other than the diene polymer (B) out of the diene polymers proceeds well.

  In the step (b), the mixing time (kneading time) of the mixture is preferably in the range of 10 to 180 seconds, more preferably in the range of 10 to 150 seconds, still more preferably in the range of 30 to 150 seconds, and more preferably in the range of 30 to 150. A range of 120 seconds is particularly preferred. If the mixing time is 10 seconds or more, the dispersion of carbon black in the diene-based polymer other than the diene-based polymer (B) can be sufficiently advanced, and Even if the mixing time exceeds 180 seconds, it is difficult to enjoy a further effect.

  In the step (a), as described above, the solid-state diene polymer (B) and the silica surface-treated with the solid-state sulfur-containing silane coupling agent are mixed with a Banbury mixer, a roll, A master batch may be prepared by mixing using a mixing apparatus such as an intensive mixer, but a slurry of the latex of the diene polymer (B) and silica surface-treated with the sulfur-containing silane coupling agent is used. The solution may be mixed, further coagulated and dried to prepare a masterbatch (that is, a wet masterbatch).

  The slurry solution can be prepared, for example, by previously dispersing silica surface-treated with the sulfur-containing silane coupling agent in a dispersion medium such as water. Here, the preparation of the slurry solution can be performed by a known method, and for example, a mixing device such as a rotor-stator type high shear mixer, a high pressure homogenizer, an ultrasonic homogenizer, a colloid mill or the like can be used. Here, the high-shear mixer is a high-shear mixer including a rotor and a stator portion, in which a high-speed rotating rotor and a fixed stator are installed with a narrow clearance, and a high shear rate is generated by rotation of the rotor. In addition, high shear means that the shear rate is 2000 / s or more, preferably 4000 / s or more. Examples of the high shear mixer include a homomixer manufactured by Tokushu Kika Kogyo Co., Ltd., a colloid mill manufactured by PUC, Germany, a Cavitron manufactured by Cavitron, and a high shear mixer manufactured by Silverson, Inc.

  In the slurry solution, the concentration of silica surface-treated with the sulfur-containing silane coupling agent is preferably in a range of 1 to 15% by mass, and more preferably in a range of 2 to 10% by mass. If the concentration of the surface-treated silica is less than 1% by mass, the required volume of the slurry becomes too large, and if it exceeds 15% by mass, the viscosity of the slurry solution becomes too high, causing a problem in operation. In addition, as the slurry solution, an aqueous dispersion solution is preferable.

  On the other hand, as the latex of the diene polymer (B), natural rubber latex is preferable. As the natural rubber latex, field latex, ammonia-treated latex, centrifugal concentrated latex, deproteinized protein treated with a surfactant or an enzyme are preferable. Latex and the like.

  For mixing the slurry solution and the latex, for example, a method in which the slurry solution is dropped into a homomixer and the latex is dropped while stirring or the slurry solution is dropped while the latex is stirred. There is a way. Further, a method of mixing a slurry flow and a latex flow having a constant flow rate ratio under a condition of intense hydraulic stirring may be used.

  The coagulation method of the wet master batch prepared as described above is carried out using a coagulant of an acid such as formic acid or sulfuric acid or a salt such as sodium chloride in the same manner as usual. In the present invention, coagulation may be performed by mixing a latex and a slurry solution without adding a coagulant.

  In drying the wet master batch, a conventional dryer such as a vacuum dryer, an air dryer, a drum dryer, and a band dryer can be used.However, the dispersibility of the silica surface-treated with the sulfur-containing silane coupling agent may be reduced. For further improvement, it is preferable to perform drying while applying a mechanical shearing force. Further, the drying can be performed using a general kneader, but from the viewpoint of industrial productivity, it is preferable to use a continuous kneader. It is more preferable to use a shaft kneading extruder.

  The rubber composition produced by the method for producing a rubber composition of the present invention contains at least two kinds of diene polymers forming a plurality of mutually incompatible polymer phases. In the present invention, the diene-based polymer forming the polymer phase exhibits rubber elasticity at room temperature (25 ° C.). Examples of the diene polymer include natural rubber (NR) and synthetic diene rubber, and specific examples of the synthetic diene rubber include polybutadiene rubber (BR), synthetic polyisoprene rubber (IR), Styrene-butadiene copolymer rubber (SBR), styrene-isoprene copolymer rubber (SIR) and the like. Here, as the combination of the diene polymers forming a plurality of polymer phases that are incompatible with each other, a diene polymer having a butadiene skeleton / a diene polymer having an isoprene skeleton is preferable, and specific examples thereof include: Examples thereof include polybutadiene rubber (BR) / natural rubber (NR), polybutadiene rubber (BR) / synthetic polyisoprene rubber (IR), and polybutadiene rubber (BR) / natural rubber (NR) is preferable.

In the present invention, the diene polymer (A) having the lowest glass transition temperature (Tg) among the diene polymers having a blending amount of 20% by mass or more of the total amount of the diene polymer has a blending amount of Among the diene-based polymers other than the diene-based polymer (A), the blending amount is at least 85% by mass of the blending amount of the diene-based polymer which is the largest. A diene-based polymer having a compounding amount of less than 20% by mass of the total amount of the diene-based polymer has a small effect on the performance of the rubber composition. In the rubber composition of the present invention, the compounding amount of the diene polymer (A) is the largest among the diene polymers other than the diene polymer (A). When the amount is 85% by mass or more of the blending amount of the polymer, the effect of the polymer phase formed from the diene polymer (A) is sufficiently exerted, and the wear resistance is improved.
The diene polymer (A) having the lowest glass transition temperature (Tg) is preferably modified with a compound containing at least one of a tin atom (Sn) and a nitrogen atom (N). More preferably, the modification is performed at a modification ratio of 2.5 or more. As described above, the modification ratio is the number of millimoles of a compound containing at least one of a tin atom and a nitrogen atom used in the modification reaction per 100 g of the rubber component of the diene polymer (A).
Since the diene polymer (A) is modified with a compound containing at least one of a tin atom and a nitrogen atom, the interaction between the diene polymer (A) and carbon black is improved, and the diene polymer (A) is improved. The dispersibility of carbon black in the polymer phase containing the polymer (A) is improved, and the wear resistance of the rubber composition is improved.
Further, the diene polymer (A) is modified with a compound containing at least one of the tin atom and the nitrogen atom at a modification ratio of 1.1 or more, so that the diene polymer (A) and carbon black are modified. And the dispersibility of carbon black in the polymer phase containing the diene polymer (A) is further improved, and the abrasion resistance of the rubber composition is further improved.

  As the diene polymer (A) having the lowest glass transition temperature (Tg) [hereinafter sometimes abbreviated as “low Tg diene polymer (A)”], a conjugated diene compound as a monomer, or Obtained using a conjugated diene compound and an aromatic vinyl compound, a polymer or copolymer of the conjugated diene compound, or a copolymer of a conjugated diene compound and an aromatic vinyl compound, Further, those obtained by modifying the molecular terminals and / or main chains of these (co) polymers can also be used. Specific examples of known modified diene polymers having modified molecular terminals include WO 2003/046020, JP-T-2004-513987, JP-A-11-29603, and JP-A-2003-113202. And the modified diene polymer disclosed in JP-B-6-29338. Examples of the known modified diene polymer having a modified main chain include JP-A-2003-534426 and JP-A-2003-534426. The modified diene polymer disclosed in JP-A-2002-201310 can be exemplified.

  Concerning the monomers used for the synthesis of the low Tg diene polymer (A), conjugated diene compounds include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, and 2-phenyl- Examples thereof include 1,3-butadiene and 1,3-hexadiene, and examples of the aromatic vinyl compound include styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, -Cyclohexylstyrene, 2,4,6-trimethylstyrene and the like.

  The low-Tg diene-based polymer (A) having a modified molecular terminal is obtained, for example, by subjecting the above monomer to living polymerization using a polymerization initiator containing a tin atom and / or a nitrogen atom, and then changing the polymerization active terminal to tin. It can be produced by a method of modifying with a modifying agent containing atoms and / or nitrogen atoms. The living polymerization is preferably performed by anionic polymerization.

  In the case of producing a (co) polymer having an active terminal by anionic polymerization, a lithium amide compound is preferable as the polymerization initiator. Examples of the lithium amide compound include lithium hexamethylene imide, lithium pyrrolidide, lithium piperidide, lithium heptamethylene imide, lithium dodecamethylene imide, lithium dimethyl amide, lithium diethyl amide, lithium dipropyl amide, lithium dibutyl amide, and lithium dihexyl amide. , Lithium diheptylamide, lithium dioctylamide, lithimdi-2-ethylhexylamide, lithium didecylamide, lithium-N-methylpiperazide, lithium ethylpropylamide, lithium ethylbutylamide, lithium methylbutylamide, lithium ethylbenzylamide, lithium methyl Phenethylamide and the like.

（式中、Ｒ^１は、それぞれ独立して炭素数１〜１２の、アルキル基、シクロアルキル基又はアラルキル基である）で表される置換アミノ基又は下記式（II）：

（式中、Ｒ^２は、３〜１６のメチレン基を有する、アルキレン基、置換アルキレン基、オキシアルキレン基又はＮ−アルキルアミノ−アルキレン基を示す）で表される環状アミノ基である］で表されるリチウムアミド化合物を用いることで、式（I）で表される置換アミノ基及び式（II）で表される環状アミノ基からなる群から選択される少なくとも一種の窒素含有官能基が導入された低Ｔｇジエン系重合体（Ａ）が得られる。 Further, as the lithium amide compound, a compound represented by the following formula:

(Wherein R ¹ is each independently an alkyl group, a cycloalkyl group or an aralkyl group having 1 to 12 carbon atoms) or a substituted amino group represented by the following formula (II):

(Wherein, R ² is a cyclic amino group represented by an alkylene group, a substituted alkylene group, an oxyalkylene group or an N-alkylamino-alkylene group having 3 to 16 methylene groups). At least one nitrogen-containing functional group selected from the group consisting of a substituted amino group represented by the formula (I) and a cyclic amino group represented by the formula (II) is introduced by using the lithium amide compound represented by the formula (I). Thus, a low Tg diene polymer (A) is obtained.

In the above formula (I), R ¹ is an alkyl group, a cycloalkyl group or an aralkyl group having 1 to 12 carbon atoms, specifically, a methyl group, an ethyl group, a butyl group, an octyl group, a cyclohexyl group, Preferable examples include a 3-phenyl-1-propyl group and an isobutyl group. R ¹ may be the same or different.
In the above formula (II), R ² is an alkylene group, a substituted alkylene group, an oxyalkylene group or an N-alkylamino-alkylene group having 3 to 16 methylene groups. Here, the substituted alkylene group includes a mono- to octa-substituted alkylene group, and as the substituent, a chain or branched alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, a bicycloalkyl group, Aryl and aralkyl groups. Further, as R ² , specifically, a trimethylene group, a tetramethylene group, a hexamethylene group, an oxydiethylene group, an N-alkylazadiethylene group, a dodecamethylene group, a hexadecamethylene group, and the like are preferable.

The lithium amide compound may be prepared in advance from a secondary amine and a lithium compound and used for the polymerization reaction, or may be formed in a polymerization system.
Here, as the secondary amine, dimethylamine, diethylamine, dibutylamine, dioctylamine, dicyclohexylamine, diisobutylamine, etc., azacycloheptane (that is, hexamethyleneimine), 2- (2-ethylhexyl) pyrrolidine, -(2-propyl) pyrrolidine, 3,5-bis (2-ethylhexyl) piperidine, 4-phenylpiperidine, 7-decyl-1-azacyclotridecane, 3,3-dimethyl-1-azacyclotetradecane, 4- Dodecyl-1-azacyclooctane, 4- (2-phenylbutyl) -1-azacyclooctane, 3-ethyl-5-cyclohexyl-1-azacycloheptane, 4-hexyl-1-azacycloheptane, 9-isoamyl -1-azacycloheptadecane, 2-methyl-1-aza Cloheptadec-9-ene, 3-isobutyl-1-azacyclododecane, 2-methyl-7-tert-butyl-1-azacyclododecane, 5-nonyl-1-azacyclododecane, 8- (4′-methylphenyl ) -5-pentyl-3-azabicyclo [5.4.0] undecane, 1-butyl-6-azabicyclo [3.2.1] octane, 8-ethyl-3-azabicyclo [3.2.1] octane, 1-propyl-3-azabicyclo [3.2.2] nonane, 3- (tert-butyl) -7-azabicyclo [4.3.0] nonane, 1,5,5-trimethyl-3-azabicyclo [4. 4.0] decane and the like.
Examples of the lithium compound include ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-octyl lithium, n-decyl lithium, phenyl lithium, 2-naphthyl lithium, and 2-butyl- Hydrocarbyl lithium such as phenyllithium, 4-phenyl-butyllithium, cyclohexyllithium, cyclopentyllithium, or the reaction product of diisopropenylbenzene with butyllithium can be used.

  In modifying the active terminal of the (co) polymer having an active terminal with a modifier, a modifier containing at least one of a tin atom and a nitrogen atom can be used as the modifier.

The modifying agent containing a tin atom (that is, a tin-containing compound) includes the following formula (III):
R ³ _a SnX _b (III)
[Wherein, R ³ independently comprises an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and an aralkyl group having 7 to 20 carbon atoms. X is each independently chlorine or bromine; a is 0 to 3, b is 1 to 4, where a + b = 4. preferable. The low Tg diene polymer (A) modified with the tin-containing coupling agent of the formula (III) has at least one tin-carbon bond.
Here, specific examples of R ³ include a methyl group, an ethyl group, an n-butyl group, a neophyl group, a cyclohexyl group, an n-octyl group, and a 2-ethylhexyl group. As the coupling agent of formula (III), tin _{^{tetrachloride, R 3 SnCl 3, R 3}} 2 SnCl 2, R 3 3 SnCl , and the like are preferable, and tin tetrachloride is particularly preferred.

Further, examples of the modifying agent containing a nitrogen atom (that is, a nitrogen-containing compound) include a nitrogen-containing compound having a substituted or unsubstituted amino group, amide group, imino group, imidazole group, nitrile group, pyridyl group, or the like. More specifically, N, N′-dimethylimidazolidinone (ie, 1,3-dimethyl-2-imidazolidinone), N-methylpyrrolidone, 4-dimethylaminobenzylideneaniline, 4,4′-bis (N, N-dimethylamino) benzophenone, 4,4′-bis (N, N-diethylamino) benzophenone, 4- (N, N-dimethylamino) benzophenone, 4- (N, N-diethylamino) benzophenone, [4 -(N, N-dimethylamino) phenyl] methyl ethyl ketone, 4,4'-bis (1-hexamethyleneiminomethyl) benzopheno , 4,4'-bis (1-pyrrolidinomethyl) benzophenone, 4- (1-hexamethyleneiminomethyl) benzophenone, 4- (1-pyrrolidinomethyl) benzophenone, [4- (1-hexamethyleneimino) Phenyl] methylethylketone, 3- [N, N-methyl (trimethylsilyl) amino] propyldimethylethoxysilane, and the like.
Further, the modifying agent containing a nitrogen atom may further have a chlorosulfenyl group or a chlorosulfonyl group. Examples of the modifying agent having a chlorosulfenyl group or a chlorosulfonyl group in addition to the nitrogen atom include those described in 2,4-Dinitrobenzenesulfenyl chloride, 4-nitrobenzenesulfenyl chloride, 4-nitrobenzenesulfonyl chloride, 2-acetamidobenzenesulfonyl chloride, 1-aminonaphthyl-5-sulfonyl chloride disclosed in JP-A-11-29603. , Quinoline sulfonyl chloride, dimethyl sulfamoyl chloride, dimethyl sulfonyl chloride, 2,4-dinitrobenzene sulfonyl chloride and the like can be used.
Prior to the modification with the nitrogen atom-containing modifier, a 1,1-diphenylethylene compound having a polar group, which is disclosed in JP-A-2003-113202, is reacted with the (co) polymer having an active terminal. The 1,1-diphenylethylene compound may be, for example, 1- (4-N, N-dimethylaminophenyl) -1-phenylethylene.

On the other hand, the low-Tg diene-based polymer (A) having a modified main chain can be obtained by, for example, (1) a method in which a polar group-containing monomer is graft-polymerized to a (co) polymer of the above monomer, (2) It can be produced by a method of copolymerizing the above monomer and a polar group-containing monomer, or (3) a method of adding a polar group-containing compound to a (co) polymer of the above monomer. The copolymerization using the polar group-containing monomer may be performed by emulsion polymerization, living anion polymerization or living radical polymerization. The polymer may be a block polymer of a monomer selected from a conjugated diene compound and an aromatic vinyl compound and a polar group-containing monomer.
Further, the above (1) a method in which a polar group-containing monomer is graft-polymerized to a (co) polymer such as a conjugated diene compound or an aromatic vinyl compound; In the method of copolymerizing a polar group-containing monomer, the polar group-containing monomer to be used is preferably a polar group-containing vinyl monomer. In the method (3) of adding a polar group-containing compound to a (co) polymer such as a conjugated diene compound or an aromatic vinyl compound, the polar group-containing compound used is preferably a polar group-containing mercapto compound. In addition, specific examples of the polar group include amino groups, imino groups, nitrile groups, ammonium groups, imide groups, amide groups, hydrazo groups, azo groups, diazo groups, nitrogen-containing groups such as nitrogen-containing heterocyclic groups, Tin-containing groups and the like can be suitably mentioned.

  As the polar group-containing vinyl monomer, specifically, N, N-dimethylaminoethyl (meth) acrylate [here, “(meth) acrylate” refers to acrylate and / or methacrylate. same as below. ], N, N-diethylaminoethyl (meth) acrylate, N, N-dipropylaminoethyl (meth) acrylate, N, N-dioctylaminoethyl (meth) acrylate, N-methyl-N-ethylaminoethyl (meth) Acrylate, N, N-dimethylaminopropyl (meth) acrylamide [where "(meth) acrylamide" refers to acrylamide and / or methacrylamide. same as below. ], N, N-diethylaminopropyl (meth) acrylamide, N, N-dioctylaminopropyl (meth) acrylamide, 2-vinylpyridine, 4-vinylpyridine, allyltri-n-butyltin, allyltrimethyltin, allyltriphenyltin, Allyltri-n-octyltin, (meth) acryloxy-n-butyltin [where "(meth) acryloxy" refers to acryloxy and / or methacryloxy. same as below. ], (Meth) acryloxytrimethyltin, (meth) acryloxytriphenyltin, (meth) acryloxy-n-octyltin, vinyltri-n-butyltin, vinyltrimethyltin, vinyltriphenyltin, vinyltri-n-octyltin, etc. Is mentioned. These monomers may be used alone or in a combination of two or more.

  Specific examples of the polar group-containing mercapto compound include 2-mercaptoethylamine, N, N-dimethylaminoethanethiol, 2-mercaptopyridine, 4-mercaptopyridine, 2-mercaptoethyltri-n-butyltin, -Mercaptoethyltrimethyltin, 2-mercaptoethyltriphenyltin, 3-mercaptopropyltri-n-butyltin, 3-mercaptopropyltrimethyltin, 3-mercaptopropyltriphenyltin and the like. These compounds may be used alone or in a combination of two or more.

The low Tg diene polymer (A) preferably contains both a tin atom and a nitrogen atom. Here, the modified diene polymer containing both a tin atom and a nitrogen atom is, for example, using the above-mentioned lithium amide compound as a polymerization initiator, introducing a nitrogen-containing functional group at a polymerization initiation terminal, and as a modifier, Using the tin-containing coupling agent, a tin-containing functional group is introduced into a polymerization active terminal (polymerization termination terminal), or both a nitrogen-containing monomer and a tin-containing monomer are graft-polymerized, It can be obtained by adding both a nitrogen-containing compound and a tin-containing compound.
When the low Tg diene polymer (A) contains both a tin atom and a nitrogen atom, the interaction between the low Tg diene polymer (A) and carbon black is particularly large, and the low Tg diene polymer ( The dispersibility of carbon black in the polymer phase formed from A) is particularly good, the reinforcing effect on the polymer phase is further improved, and the abrasion resistance is particularly high.

  In the present invention, the diene polymer (A) having the lowest glass transition temperature (Tg) preferably has a butadiene skeleton. When the low Tg diene-based polymer (A) has a butadiene skeleton, the rubber composition becomes soft, and when the rubber composition is used for a tread, the contact area of the tread increases, and the performance on ice is further improved. Here, examples of the diene-based polymer having a butadiene skeleton include polybutadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), and the like. The low Tg diene polymer (A) is particularly preferably a polybutadiene rubber (BR) from the viewpoint of performance on ice.

The amount of the diene-based polymer (A) having the lowest glass transition temperature (Tg) is determined to be the largest among the diene-based polymers other than the diene-based polymer (A). The amount is not particularly limited as long as it is at least 85% by mass of the blending amount of the coalesce, but is preferably at least 50% by mass of the total amount of the diene-based polymer, more preferably at least 55% by mass of the total amount of the diene-based polymer, It is still more preferably 60% by mass or more of the total amount of the diene-based polymer, preferably 75% by mass or less of the total amount of the diene-based polymer, more preferably 70% by mass or less of the total amount of the diene-based polymer, particularly Preferably, it is 65% by mass or less of the total amount of the diene polymer. When the compounding amount of the diene polymer (A) having the lowest glass transition temperature (Tg) is within this range, the performance on ice and the abrasion resistance can be sufficiently improved.

  The diene polymer (A) having the lowest glass transition temperature (Tg) has the largest blending amount among the diene polymers or the diene polymer other than the diene polymer (A). It is preferable that the blending amount is equal to the diene polymer having the largest blending amount in the coalescing. In this case, the effect of the polymer phase formed from the low Tg diene-based polymer (A) increases, and the wear resistance of the tire can be further improved by applying the rubber composition to the tire.

  In the present invention, a diene-based polymer (B) incompatible with the diene-based polymer (A) having the lowest glass transition temperature (Tg) [hereinafter referred to as an “incompatible diene-based polymer (B)” May be abbreviated as above] is not particularly limited as long as it is incompatible with the aforementioned low Tg diene polymer (A). Such an incompatible diene polymer (B) has the highest glass transition temperature (Tg) among diene polymers having a blending amount of 20% by mass or more based on the total amount of the diene polymer (B). It is preferable to include C).

  In the present invention, the diene polymer (C) having the highest glass transition temperature (Tg) among the diene polymers having the blending amount of 20% by mass or more of the total amount of the diene polymer (hereinafter, referred to as “high May be abbreviated as “Tg diene polymer (C)”] preferably has an isoprene skeleton. When the high Tg diene polymer (C) has an isoprene skeleton, the reinforcing property of the rubber composition is increased, and the wear resistance is further improved. Here, examples of the diene polymer having an isoprene skeleton include natural rubber (NR), synthetic polyisoprene rubber (IR), and styrene-isoprene copolymer rubber (SIR). The high Tg diene polymer (C) is particularly preferably natural rubber (NR) from the viewpoint of abrasion resistance. Further, the proportion of the high Tg diene polymer (C) in the incompatible diene polymer (B) is preferably at least 60% by mass, more preferably at least 80% by mass. It is also preferred that the polymer (B) comprises only the high Tg diene polymer (C).

  The amount of the diene polymer (B) incompatible with the diene polymer (A) having the lowest glass transition temperature (Tg) is determined by the amount of the low Tg diene polymer (A). It is preferably smaller or equal to the blending amount of the low Tg diene polymer (A), more preferably 25% by mass or more of the total amount of the diene polymer, and still more preferably the total amount of the diene polymer. 30% by mass or more, particularly preferably 35% by mass or more of the total amount of the diene-based polymer, more preferably 45% by mass or less of the total amount of the diene-based polymer, and still more preferably the total amount of the diene-based polymer. 40% by mass or less. When the amount of the incompatible diene polymer (B) is within this range, the performance on ice and the abrasion resistance can be sufficiently improved.

  The rubber composition produced by the method of the present invention is different from the diene polymer (A) having the lowest glass transition temperature (Tg) and the diene polymer (A) having the lowest glass transition temperature (Tg). In addition to the diene-based polymer (B) and the diene-based polymer (C) having the highest glass transition temperature (Tg), it may further contain another diene-based polymer (D). Examples of the diene polymer (D) include other diene polymers compatible with the low Tg diene polymer (A).

  The rubber composition produced by the method of the present invention contains silica surface-treated with a sulfur-containing silane coupling agent [hereinafter sometimes abbreviated as “surface-treated silica”]. The surface-treated silica is relatively distributed to the polymer phase formed from the incompatible diene-based polymer (B) and softens the polymer phase while imparting micro unevenness to the polymer phase. Improve performance on ice.

  The surface-treated silica can be prepared, for example, by stirring silica in a mixer or blender, adding a solution containing a sulfur-containing silane coupling agent to the silica, and then drying the solution. Here, the solution containing the sulfur-containing silane coupling agent can be prepared, for example, by dissolving or dispersing the sulfur-containing silane coupling agent in a solvent such as water or alcohol. In addition, as an alcohol used as a solvent, methanol, ethanol, n-propanol, isopropanol, etc. are mentioned, and ethanol is preferable. In addition, depending on the type of the sulfur-containing silane coupling agent used, the solvent of the solution containing the sulfur-containing silane coupling agent is a mixed solvent of water and alcohol, particularly, a mixed solvent of water and ethanol. Is preferred. As a method for adding the solution, spraying is preferable.

  The silica used as a raw material of the surface-treated silica is not particularly limited, and examples thereof include wet silica (hydrous silicic acid), dry silica (silicic anhydride), calcium silicate, and aluminum silicate. And wet silica are preferred. These silicas may be used alone or in combination of two or more.

Further, as the sulfur-containing silane coupling agent as a raw material of the surface-treated silica, the following general formula (IV):
^{_{(R 41 O) 3-p}} (R 42) p Si-R 43 -S c -R 43 -Si (OR 41) 3-r (R 42) r ··· (IV)
The compound represented by is preferred.
In the formula (IV), when there are a plurality of R ^{41 s} , they may be the same or different, and each may be a straight-chain, cyclic or branched alkyl group having 1 to 8 carbon atoms, a straight-chain or branched alkyl group having 2 to 8 carbon atoms. A branched alkoxyalkyl group or a hydrogen atom, R ⁴² may be the same or different when there are a plurality of R ⁴² , and each is a linear, cyclic or branched alkyl group having 1 to 8 carbon atoms, and R ⁴³ is They may be the same or different and each is a linear or branched alkylene group having 1 to 8 carbon atoms. Further, c is 2 to 6 as an average value, and p and r may be the same or different, and each is 0 to 3 as an average value. However, p and r are not both 3.

  As the compound of the above formula (IV), specifically, bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (3-methyldimethoxysilylpropyl) tetrasulfide, Bis (2-triethoxysilylethyl) tetrasulfide, bis (3-triethoxysilylpropyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, bis (3-methyldimethoxysilylpropyl) disulfide, bis (2-tri Ethoxysilylethyl) disulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (3-methyldimethoxysilylpropyl) trisulfide, bis (2-triethoxysil) (Triethyl) trisulfide, bis (3-monoethoxydimethylsilylpropyl) tetrasulfide, bis (3-monoethoxydimethylsilylpropyl) trisulfide, bis (3-monoethoxydimethylsilylpropyl) disulfide, bis (3-monomethoxydimethyl) (Silylpropyl) tetrasulfide, bis (3-monomethoxydimethylsilylpropyl) trisulfide, bis (3-monomethoxydimethylsilylpropyl) disulfide, bis (2-monoethoxydimethylsilylethyl) tetrasulfide, bis (2-monoethoxy) Dimethylsilylethyl) trisulfide, bis (2-monoethoxydimethylsilylethyl) disulfide and the like.

Further, as the sulfur-containing silane coupling agent, the following general formula (V):
^{_{(R 51 O) 3-s}} (R 52) s Si-R 53 -S k -R 54 -S k -R 53 -Si (OR 51) 3-t (R 52) t ··· (V)
The compound represented by is also preferred.
In the formula (V), when there are a plurality of R ^{51 s} , they may be the same or different and each may be a straight-chain or cyclic or branched alkyl group having 1 to 8 carbon atoms, a straight-chain or branched alkyl group having 2 to 8 carbon atoms. alkoxyalkyl group or a hydrogen atom branch, R ⁵² is when there are a plurality may be the same or different, are each a linear, cyclic or branched alkyl group having 1 to 8 carbon atoms, R ⁵³ is They may be the same or different and each is a linear or branched alkylene group having 1 to 8 carbon atoms. ^{Further, R 54} is ^{formula: (- S-R 55 -S} -), (- R 56 -S m1 -R 57 -) and ^{_{(-R 58 -S m2 -R 59 -S}} m3 -R 60 -) Wherein R ^{55 to} R ⁶⁰ are each a divalent hydrocarbon group having 1 to 20 carbon atoms, a divalent aromatic group, or a divalent organic group containing a hetero element other than sulfur and oxygen. M1, m2, and m3 may be the same or different, and each has an average value of 1 or more and less than 4), and a plurality of k's may be the same or different, and each has an average value of 1 to 1. 6, and s and t are each 0 to 3 as an average value. However, s and t are not both 3.

As the compound of the above formula (V), specifically,
Average compositional _{formula: (CH 3 CH 2 O)} 3 Si- (CH 2) 3 -S 2 - (CH 2) 6 -S 2 - (CH 2) 3 -Si (OCH 2 CH 3) 3,
Average compositional _{formula: (CH 3 CH 2 O)} 3 Si- (CH 2) 3 -S 2 - (CH 2) 10 -S 2 - (CH 2) 3 -Si (OCH 2 CH 3) 3,
Average compositional _{formula: (CH 3 CH 2 O)} 3 Si- (CH 2) 3 -S 3 - (CH 2) 6 -S 3 - (CH 2) 3 -Si (OCH 2 CH 3) 3,
Average compositional _{formula: (CH 3 CH 2 O)} 3 Si- (CH 2) 3 -S 4 - (CH 2) 6 -S 4 - (CH 2) 3 -Si (OCH 2 CH 3) 3,
Average composition formula: (CH ₃ CH ₂ O) ₃ Si— (CH ₂ ) ₃ —S— (CH ₂ ) ₆ —S ₂ — (CH ₂ ) ₆ —S— (CH ₂ ) ₃ —Si (OCH ₂ CH ₃ ) ₃ ,
Average compositional _{formula: (CH 3 CH 2 O)} 3 Si- (CH 2) 3 -S- (CH 2) 6 -S 2.5 - (CH 2) 6 -S- (CH 2) 3 -Si (OCH 2 CH ₃ ) ₃ ,
Average composition formula: (CH ₃ CH ₂ O) ₃ Si— (CH ₂ ) ₃ —S— (CH ₂ ) ₆ —S ₃ — (CH ₂ ) ₆ —S— (CH ₂ ) ₃ —Si (OCH ₂ CH ₃ ) ₃ ,
Average compositional _{formula: (CH 3 CH 2 O)} 3 Si- (CH 2) 3 -S- (CH 2) 6 -S 4 - (CH 2) 6 -S- (CH 2) 3 -Si (OCH 2 CH ₃ ) ₃ ,
Average composition formula: (CH ₃ CH ₂ O) ₃ Si— (CH ₂ ) ₃ —S— (CH ₂ ) ₁₀ —S ₂ — (CH ₂ ) ₁₀ —S— (CH ₂ ) ₃ —Si (OCH ₂ CH ₃ ) ₃ ,
Average compositional _{formula: (CH 3 CH 2 O)} 3 Si- (CH 2) 3 -S 4 - (CH 2) 6 -S 4 - (CH 2) 6 -S 4 - (CH 2) 3 -Si (OCH ₂ CH ₃ ) ₃ ,
Average composition formula: (CH ₃ CH ₂ O) ₃ Si— (CH ₂ ) ₃ —S ₂ — (CH ₂ ) ₆ —S ₂ — (CH ₂ ) ₆ —S ₂ — (CH ₂ ) ₃ —Si (OCH ₂ CH ₃ ) ₃ ,
Average compositional _{formula: (CH 3 CH 2 O)} 3 Si- (CH 2) 3 -S- (CH 2) 6 -S 2 - (CH 2) 6 -S 2 - (CH 2) 6 -S- (CH ₂ ) ₃ -Si (OCH ₂ CH ₃ ) ₃
And the like.

  As the sulfur-containing silane coupling agent, a compound represented by the above general formula (IV) is particularly preferred. The above-mentioned sulfur-containing silane coupling agent may be used alone or in combination of two or more.

  In the surface-treated silica, the amount of the sulfur-containing silane coupling agent to be added is preferably in the range of 2 to 20 parts by mass, more preferably in the range of 4 to 15 parts by mass, per 100 parts by mass of the silica. When the addition amount of the sulfur-containing silane coupling agent is 2 parts by mass or more with respect to 100 parts by mass of silica, the dispersibility of the surface-treated silica in the incompatible diene polymer (B) is sufficiently improved. In addition, it is possible to sufficiently improve the performance on ice, and if the addition amount of the sulfur-containing silane coupling agent is 20 parts by mass or less based on 100 parts by mass of silica, it is possible to suppress an increase in the raw material cost of the rubber composition. .

  The silica surface-treated with the sulfur-containing silane coupling agent may be further subjected to a surface treatment with a fatty acid, an aminosilane coupling agent, and a sulfur-free organosilicon compound. By further surface-treating with these compounds, the dispersibility of the surface-treated silica in the incompatible diene-based polymer (B) can be improved.

Examples of the fatty acid include stearic acid, isostearic acid, oleic acid, palmitic acid, isopalmitic acid, myristic acid, isomyristic acid, lauric acid and the like.
The amount of the fatty acid used is preferably in the range of 1 to 20 parts by mass, and more preferably in the range of 2 to 10 parts by mass with respect to 100 parts by mass of the silica. When the amount of the fatty acid is in the range of 1 to 20 parts by mass, the dispersibility of the surface-treated silica in the incompatible diene polymer (B) can be sufficiently improved.

Examples of the aminosilane coupling agent include 3- (2-aminoethyl) aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-aminopropyl Examples include triethoxysilane, 2-aminoethyltrimethoxysilane, 2-aminoethyltriethoxysilane, and the like.
The amount of the aminosilane coupling agent to be used is preferably in the range of 0.5 to 10 parts by mass, more preferably 0.8 to 4 parts by mass, based on 100 parts by mass of the silica. When the amount of the aminosilane coupling agent is in the range of 0.5 to 10 parts by mass, the dispersibility of the surface-treated silica in the incompatible diene polymer (B) can be sufficiently improved.

As the sulfur-free organic silicon compound, specifically, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, diisopropyl Dimethoxysilane, isobutyltrimethoxysilane, diisobutyldimethoxysilane, n-propyltriethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, cyclohexylmethyldimethoxysilane, n-octyltrimethoxysilane, n-octyltriethoxy Examples include silane and n-decyltrimethoxysilane.
The amount of the sulfur-free organosilicon compound to be used is preferably in the range of 2 to 20 parts by mass, more preferably in the range of 3 to 12 parts by mass, based on 100 parts by mass of the silica. When the amount of the sulfur-free organic silicon compound used is in the range of 2 to 20 parts by mass, the dispersibility of the surface-treated silica in the incompatible diene polymer (B) can be sufficiently improved.

  The amount of the surface-treated silica is at least 25 parts by mass, preferably at least 27 parts by mass, more preferably at least 29 parts by mass, and preferably at least 29 parts by mass, based on 100 parts by mass of the diene polymer in total. It is 50 parts by mass or less, more preferably 40 parts by mass or less. By adjusting the blending amount of the surface-treated silica to 25 parts by mass or more based on 100 parts by mass of the total of the diene-based polymer, a non-phase with the diene-based polymer (A) having the lowest glass transition temperature (Tg) is obtained. While imparting microscopic irregularities to the polymer phase comprising the soluble diene polymer (B), the polymer phase can be softened to improve the performance on ice. Further, by setting the amount of the surface-treated silica to 50 parts by mass or less based on 100 parts by mass of the total of the diene-based polymer, the workability of the steps (a) and (b) can be improved.

The rubber composition produced by the method of the present invention contains carbon black. The carbon black is relatively distributed to the polymer phase containing the low Tg diene polymer (A), and the polymer phase is reinforced by containing a large amount of carbon black having a high reinforcing property. The performance is improved.
The carbon black is not particularly limited, and examples thereof include GPF, FEF, HAF, ISAF, and SAF grade carbon black. These carbon blacks may be used alone or in combination of two or more.

  The compounding amount of the carbon black is preferably 25 parts by mass or more, more preferably 27 parts by mass or more, even more preferably 29 parts by mass or more, based on 100 parts by mass of the diene polymer in total. Further, it is preferably at most 50 parts by mass, more preferably at most 40 parts by mass. By setting the blending amount of carbon black to 25 parts by mass or more based on 100 parts by mass of the total of the diene polymer, the polymer phase containing the low Tg diene polymer (A) is reinforced, and the abrasion resistance is improved. It can be further improved. Further, by setting the blending amount of carbon black to 50 parts by mass or less based on 100 parts by mass of the total of the diene polymer, the workability in the step (b) can be improved.

  The rubber composition produced by the method of the present invention preferably further contains a vulcanization accelerator. In the step (a), at least one compound selected from the vulcanization accelerator is mixed, and A masterbatch may be prepared. In the step (a), the reaction of the surface-treated silica with the incompatible diene-based polymer (B) is activated by mixing and mixing the vulcanization accelerator, and the incompatible diene-based polymer is activated. The dispersion of the surface-treated silica in the polymer (B) proceeds well, and the on-ice performance of the tire using the produced rubber composition is further improved.

  The step (a) is a step of mixing the raw materials without blending the vulcanizing agent. Since the vulcanizing agent is not blended, even if the vulcanization accelerator is blended, the rubber composition can be prepared quickly. Does not cause vulcanization.

As the vulcanization accelerator, guanidines, sulfenamides, and thiazoles are preferable.
Examples of the guanidines include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolyl guanidine, 1-o-tolyl biguanide, di-o-tolyl guanidine salt of dicatechol borate, 1,3- Di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, 1,3-di-o-cumenyl-2-propionylguanidine and the like can be mentioned.
Examples of the sulfenamides include N-cyclohexyl-2-benzothiazolylsulfenamide (CBS, CZ), N, N-dicyclohexyl-2-benzothiazolylsulfenamide, N-tert-butyl-2-benzo. Thiazolyl sulfenamide (NS), N-oxydiethylene-2-benzothiazolylsulfenamide, N-methyl-2-benzothiazolylsulfenamide, N-ethyl-2-benzothiazolylsulfenamide, N -Propyl-2-benzothiazolylsulfenamide, N-butyl-2-benzothiazolylsulfenamide, N-pentyl-2-benzothiazolylsulfenamide, N-hexyl-2-benzothiazolylsulfenamide , N-octyl-2-benzothiazolylsulfenamide, N-2-e Lehexyl-2-benzothiazolylsulfenamide, N-decyl-2-benzothiazolylsulfenamide, N-dodecyl-2-benzothiazolylsulfenamide, N-stearyl-2-benzothiazolylsulfenamide, N, N-dimethyl-2-benzothiazolylsulfenamide, N, N-diethyl-2-benzothiazolylsulfenamide, N, N-dipropyl-2-benzothiazolylsulfenamide, N, N-dibutyl -2-benzothiazolylsulfenamide, N, N-dipentyl-2-benzothiazolylsulfenamide, N, N-dihexyl-2-benzothiazolylsulfenamide, N, N-dioctyl-2-benzothia Zolylsulfenamide, N, N-di-2-ethylhexylbenzothiazolylsulfena De, N, N-didodecyl-2-benzothiazolyl sulfenamide, N, N-distearyl-2-benzothiazolyl sulfenamide and the like.
Examples of the thiazoles include 2-mercaptobenzothiazole (M), di-2-benzothiazolyl disulfide (MBTS, DM), zinc salt of 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, -(N, N-diethylthiocarbamoylthio) benzothiazole, 2- (4'-morpholinodithio) benzothiazole, 4-methyl-2-mercaptobenzothiazole, di- (4-methyl-2-benzothiazolyl) disulfide, 5 -Chloro-2-mercaptobenzothiazole, 2-mercaptobenzothiazole sodium, 2-mercapto-6-nitrobenzothiazole, 2-mercapto-naphtho [1,2-d] thiazole, 2-mercapto-5-methoxybenzothiazole, 6-amino-2-mer Hept benzothiazole and the like.

  In the method for producing a rubber composition of the present invention, among the above-mentioned vulcanization accelerators, 1,3-diphenylguanidine (DPG) is particularly preferred. By blending 1,3-diphenylguanidine as the vulcanization accelerator, the on-ice performance of a tire using the produced rubber composition is significantly improved.

  The amount of the vulcanization accelerator is preferably in the range of 2 to 100 parts by mass, more preferably in the range of 4 to 80 parts by mass, based on 100 parts by mass of the sulfur-containing silane coupling agent in the surface-treated silica. And the range of 4 to 50 parts by mass is even more preferred. If the compounding amount of the vulcanization accelerator is 2 parts by mass or more with respect to 100 parts by mass of the sulfur-containing silane coupling agent in the surface-treated silica, the activation of the surface-treated silica sufficiently occurs, and the vulcanization accelerator Is less than 100 parts by mass with respect to 100 parts by mass of the sulfur-containing silane coupling agent in the surface-treated silica, does not significantly affect the vulcanization rate of the rubber composition.

  In the present invention, the number of molecules (mole number) of the vulcanization accelerator ranges from 0.1 to 1.0 times the number of molecules (mole number) of the sulfur-containing silane coupling agent in the surface-treated silica. Is preferably 0.3 to 1.0 times, and more preferably 0.4 to 1.0 times. If the molecular number (mol number) of the vulcanization accelerator is 0.1 times or more the molecular number (mol number) of the sulfur-containing silane coupling agent in the surface-treated silica, the activation of the surface-treated silica is sufficient. If it is 1.0 times or less, there is no significant effect on the vulcanization rate of the rubber composition.

  Since the vulcanization accelerator is also used as a sulfur vulcanization accelerator, it is not necessary to mix all of it in the step (a), and in the step (b), an appropriate amount (part) may be added as desired. May be. When there is a mixing step between the step (a) and the step (b) or after the step (b), a part of the vulcanization accelerator may be blended in the mixing step.

Further, the rubber composition produced by the method of the present invention preferably further contains a foaming agent. When the rubber composition contains a foaming agent, when the rubber composition is vulcanized to produce a vulcanized rubber, bubbles derived from the foaming agent are formed in the vulcanized rubber. Therefore, when a tire is manufactured by using a rubber composition containing a foaming agent for a tread, the performance of the tire on ice can be further improved by a scratching effect and a drainage effect by bubbles of the tread.
Examples of the foaming agent include azodicarbonamide (ADCA), dinitrosopentamethylenetetramine (DNPT), dinitrosopentastyrenetetramine, a benzenesulfonylhydrazide derivative, p, p'-oxybisbenzenesulfonylhydrazide (OBSH), and ammonium bicarbonate. , Sodium bicarbonate, ammonium carbonate, nitrososulfonylazo compound, N, N'-dimethyl-N, N'-dinitrosophthalamide, toluenesulfonylhydrazide, p-toluenesulfonylsemicarbazide, p, p'-oxybisbenzenesulfonylsemicarbazide And the like. Among these blowing agents, dinitrosopentamethylenetetramine (DNPT) is preferred. These foaming agents may be used alone or in a combination of two or more.
The amount of the foaming agent is not particularly limited, but is preferably in the range of 0.1 to 30 parts by mass, and more preferably in the range of 1 to 20 parts by mass based on 100 parts by mass of the diene polymer. The range is more preferred.

It is preferable that urea, zinc stearate, zinc benzenesulfinate, zinc white, and the like are used in combination as the foaming aid with the foaming agent. These foaming assistants may be used alone or in a combination of two or more. By using a foaming aid together, the foaming reaction can be promoted, the degree of completion of the reaction can be increased, and unnecessary deterioration with time can be suppressed.
The amount of the foaming aid is not particularly limited, but is preferably in the range of 1 to 30 parts by mass with respect to 100 parts by mass of the diene polymer in total.

In addition, in the vulcanized rubber obtained after vulcanizing the rubber composition containing the foaming agent, the foaming rate is usually 1 to 50%, preferably 5 to 40%. When a foaming agent is blended, if the foaming rate is too large, the voids on the rubber surface also become large, and it may not be possible to secure a sufficient contact area, but if the foaming rate is within the above range, it effectively functions as a drainage ditch. Since the amount of air bubbles can be maintained at an appropriate level while ensuring the formation of air bubbles, the durability is not impaired. Here, the foaming rate of the vulcanized rubber means an average foaming rate Vs, specifically, a value calculated by the following formula (VI).
Vs = (ρ ₀ / ρ ₁ −1) × 100 (%) (VI)
In the formula (VI), ρ ₁ represents the density (g / cm ³ ) of the vulcanized rubber (foamed rubber), and ρ ₀ represents the density (g / cm ³ ) of the solid phase portion in the vulcanized rubber (foamed rubber). Show. The density of the vulcanized rubber and the density of the solid phase portion of the vulcanized rubber are calculated from the mass in ethanol and the mass in air. Further, the foaming ratio can be appropriately changed depending on the type and amount of the foaming agent and the foaming auxiliary.

Further, the rubber composition produced by the method of the present invention preferably further comprises a C ₅ resin. When a rubber composition containing a C ₅ resin used in the tire, it is possible to further improve the on-ice performance of the tire.
Examples of the C ₅ resin, and a petroleum chemical industry the C ₅ fraction obtained by thermal cracking of naphtha (co) polymer obtained by aliphatic petroleum resin. The aforementioned _{C 5} fraction, typically 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-2-butene, 3-methyl-1-olefin hydrocarbons butene, 2-methyl And diolefin hydrocarbons such as -1,3-butadiene, 1,2-pentadiene, 1,3-pentadiene, and 3-methyl-1,2-butadiene. As the above-mentioned C ₅ resins, it can be utilized commercially.
The amount of the C ₅ resin is not particularly limited, preferably in the range of 5 to 50 parts by weight per 100 parts by weight of the diene polymer, 10 to 20 parts by weight The range is more preferred. If the amount of C ₅ resin is 5 parts by mass or more, the performance on ice is sufficiently improved, and if more than 50 parts by mass, it is possible to sufficiently ensure wear resistance.

The rubber composition produced by the method of the present invention preferably further contains a hydrophilic short fiber. In particular, when the rubber composition contains hydrophilic short fibers and the above-mentioned foaming agent, gas generated from the foaming agent at the time of vulcanization penetrates into the inside of the hydrophilic short fibers, corresponding to the shape of the hydrophilic short fibers. Bubbles having a shape can be formed, and the walls of the bubbles are covered with a resin derived from a hydrophilic short fiber and are made hydrophilic. Therefore, when a tire is manufactured using a rubber composition containing a hydrophilic short fiber and a foaming agent for a tread, when the tire is used, the wall surfaces of the bubbles are exposed on the tread surface, thereby improving the affinity with water. However, the bubbles can actively take in water, the tire is provided with excellent drainage properties, and the on-ice performance of the tire can be significantly improved.
As the hydrophilic resin used as a raw material of the hydrophilic short fiber, ethylene-vinyl alcohol copolymer, vinyl alcohol homopolymer, poly (meth) acrylic acid or its ester, polyethylene glycol, carboxyvinyl copolymer, styrene- Maleic acid copolymer, polyvinylpyrrolidone, vinylpyrrolidone-vinyl acetate copolymer, mercaptoethanol, etc., among them, ethylene-vinyl alcohol copolymer, vinyl alcohol homopolymer, poly (meth) acrylic acid Preferably, an ethylene-vinyl alcohol copolymer is particularly preferred.

On the surface of the hydrophilic short fiber, a coating layer having a low melting point resin having an affinity for the diene polymer and preferably having a melting point lower than the vulcanization maximum temperature of the rubber composition is formed. It may be. By forming such a coating layer, the affinity between the coating layer and the diene-based polymer is good while effectively maintaining the affinity of the hydrophilic short fibers for water, and thus the short fiber diene-based polymer is used. Dispersibility is improved. In addition, the low-melting resin melts during vulcanization to form a fluid coating layer, which contributes to bonding between the diene polymer and the hydrophilic short fibers, and provides good drainage and durability. Can be easily realized. The thickness of the coating layer may vary depending on the amount of hydrophilic short fibers, the average diameter, and the like, but is usually 0.001 to 10 μm, and preferably 0.001 to 5 μm.
The melting point of the low melting point resin used for the coating layer is preferably lower than the maximum temperature of vulcanization of the rubber composition. The maximum temperature of vulcanization means the maximum temperature reached by the rubber composition during vulcanization of the rubber composition. For example, in the case of mold vulcanization, means the maximum temperature reached by the rubber composition after the rubber composition enters the mold and exits the mold and is cooled.The maximum vulcanization temperature is, for example, It can be measured by embedding a thermocouple in the rubber composition. The upper limit of the melting point of the low-melting resin is not particularly limited, but is preferably selected in consideration of the above points. Generally, the upper limit of the vulcanization temperature of the rubber composition is 10 ° C. or lower. It is more preferable that the temperature is 20 ° C. or lower. The industrial vulcanization temperature of the rubber composition is generally about 190 ° C. at the highest. For example, when the maximum vulcanization temperature is set at 190 ° C., Is usually selected in the range of less than 190 ° C., preferably 180 ° C. or less, more preferably 170 ° C. or less.
As the low melting point resin, a polyolefin resin is preferable, and examples thereof include polyethylene, polypropylene, polybutene, polystyrene, ethylene-propylene copolymer, ethylene-methacrylic acid copolymer, ethylene-ethyl acrylate copolymer, and ethylene- Examples include a propylene-diene terpolymer, an ethylene-vinyl acetate copolymer, and ionomer resins thereof.

The average length of the hydrophilic short fibers is preferably 0.1 to 50 mm, more preferably 1 to 7 mm, and the average diameter is preferably 1 μm to 2 mm, more preferably 5 μm to 0.5 mm. When the average length and the average diameter are within the above ranges, there is no possibility that the short fibers are entangled more than necessary, and good dispersibility can be secured.
The blending amount of the hydrophilic short fibers is preferably in the range of 0.1 to 100 parts by mass, more preferably in the range of 1 to 50 parts by mass, based on 100 parts by mass of the diene polymer in total. By keeping the amount of the hydrophilic short fibers within the above range, a good balance between performance on ice and abrasion resistance can be achieved.

The rubber composition produced by the process of the present invention, the diene polymer, surface treated silica, carbon black, vulcanization accelerator, foaming agent, foaming aid, C ₅ resins, other hydrophilic short fiber Any compounding agents commonly used in the rubber industry, such as softeners (such as process oils), stearic acid, antioxidants, waxes, zinc oxide (zinc white), vulcanizing agents, etc., may harm the objects of the present invention. You may select and mix suitably within the range which does not do. Commercially available products can be suitably used as these compounding agents.

In the manufacturing method of the rubber composition of the present invention, the C ₅ resins, hydrophilic short fibers, plasticizers, stearic acid, antioxidant, wax, zinc oxide (zinc white) is a step (a) It is preferable to mix them.

In addition, the method for producing a rubber composition of the present invention preferably includes a mixing step (c) after the step (b), and the foaming agent, the foaming auxiliary, and the vulcanizing agent are mixed in the step (b). It is also preferable to mix them in the subsequent mixing step (c). In the step (c), a vulcanization accelerator is preferably blended together with the vulcanization agent, and the vulcanization accelerator is the same as the vulcanization accelerator used in the preparation of the master batch in the step (a) described above. The agent may be the same or different.
After the step (b), a step (c) of separately blending and mixing a foaming agent, a foaming aid, and a vulcanizing agent is performed, so that the foaming agent, Auxiliary agents, vulcanizing agents can be compounded and mixed, and at a temperature at which foaming and vulcanization are difficult to proceed, a foaming agent, a foaming auxiliary, and a vulcanizing agent are added and kneaded to obtain a rubber composition. Foaming and early vulcanization can be prevented. Step (c) may be performed immediately after step (b), or another mixing step may be performed between step (b) and step (c).
The maximum temperature of the mixture in the step (c) is preferably in the range of 60 to 140C, more preferably in the range of 80 to 120C, and still more preferably in the range of 100 to 120C. Further, the mixing time in step (c) is preferably in the range of 10 seconds to 20 minutes, more preferably in the range of 10 seconds to 10 minutes, and still more preferably in the range of 20 seconds to 5 minutes. When proceeding from step (b) to step (c), it is preferable to lower the temperature of the mixture by 10 ° C. or more from the temperature after completion of step (b) before proceeding to step (c).

As described above, the rubber composition produced through at least the step (a) and the step (b) can be further heated, extruded, vulcanized, or the like to be a vulcanized rubber.
The heating conditions are not particularly limited, and various conditions such as a heating temperature, a heating time, and a heating device can be appropriately selected depending on the purpose. As the warming device, for example, a roll machine usually used for warming a rubber composition can be used.
The conditions for the extrusion are not particularly limited, and various conditions such as an extrusion time, an extrusion speed, an extrusion apparatus, and an extrusion temperature can be appropriately selected depending on the purpose. As the extruder, for example, an extruder or the like usually used for extruding a rubber composition for a tire can be used. The extrusion temperature can be appropriately determined.
The vulcanization apparatus, system, conditions, etc. are not particularly limited and can be appropriately selected according to the purpose. As an apparatus for performing the vulcanization, for example, a molding vulcanizer using a mold usually used for vulcanizing a rubber composition for a tire may be mentioned.

<Tire>
The tire of the present invention is characterized by using the above rubber composition, and it is preferable that the aforementioned rubber composition is used for a tread. A tire using the rubber composition for a tread is excellent in both on-ice performance and abrasion resistance, and is useful as a winter tire such as a studless tire.
The tire of the present invention may be obtained by vulcanizing after molding using an unvulcanized rubber composition, or a semi-vulcanized rubber that has undergone a preliminary vulcanization step, depending on the type and member of the tire to be applied. After use and molding, the composition may be further subjected to main vulcanization. In addition, as a gas to be filled into the tire, an inert gas such as nitrogen, argon, helium, or the like can be used in addition to normal or air having a regulated oxygen partial pressure.

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

(Example 1)
<Preparation of surface-treated silica>
80 g of 3-mercaptopropyltriethoxysilane, 50 g of distilled water, and 50 g of ethanol were put in a beaker and stirred to prepare a sulfur-containing silane coupling agent treatment liquid. 1000 g of silica 1 (* 7, trade name “Nip Seal HQ”, manufactured by Tosoh Silica, CTAB specific surface area = 200 m ² / g) was dried in an oven at 120 ° C. for 2 hours, and was heated to 110 ° C. for 20 L in a Henschel mixer having a capacity of 20 L. Then, the dried silica 1 was added thereto, stirred, and the sulfur-containing silane coupling agent treatment liquid was sprayed. Stirring was continued for another 15 minutes and the treated silica was removed. The resulting treated silica was heat-treated in an oven at 120 ° C. for 2 hours to obtain surface-treated silica 1 ′.
From the mass of the obtained surface-treated silica 1 ′, it was found that 2.0 parts by mass of 3-mercaptopropyltriethoxysilane was adhered to 100 parts by mass of silica 1.

<Preparation of rubber composition>
Using a normal Banbury mixer, in the first mixing step, 30 parts by mass of the surface-treated silica 1 ′, 15 parts by mass of process oil (* 15), and 15 parts by mass of stearic acid were added to 35 parts by mass of natural rubber (* 1). A first mixture was prepared by mixing 1.5 parts by mass, 1.5 parts by mass of zinc white, and 3 parts by mass of the antioxidant IPPD (* 16).
The obtained first mixture was once taken out of the Banbury mixer, and then the first mixture was again put into the Banbury mixer. Further, 65 parts by mass of polybutadiene rubber (* 4) and 30 parts of carbon black (* 14) were added. The second mixing step was carried out by blending parts by mass to prepare a second mixture.
Further, the obtained second mixture was once taken out of the Banbury mixer, and then the second mixture was again put into the Banbury mixer. Further, 1.5 parts by mass of sulfur and the vulcanization accelerator MBTS (* 20) were added. 0.5 parts by mass, 1.5 parts by mass of the vulcanization accelerator CBS (* 21) and 4 parts by mass of the foaming agent (* 22) were blended, and a final mixing step was carried out to prepare a rubber composition.
The maximum temperature of the mixture in the first mixing step and the second mixing step is 170 ° C., the falling temperature of the mixture in the first mixing step and the second mixing step is 170 ° C., and the maximum temperature of the rubber composition in the final mixing step is 110 ° C. Here, the first mixing step corresponds to the step (a), and the second mixing step corresponds to the step (b).
Observation with a scanning probe microscope according to the method described in paragraph [0009] revealed that the obtained rubber composition had a phase-separated structure, and a plurality of mutually incompatible polymer phases were formed. Was.

(Example 2)
<Preparation of wet master batch>
The surface-treated silica 1 ′ was placed in water at a ratio of 6% by mass, and finely dispersed by a high shear mixer manufactured by Silverson Corporation to prepare a slurry solution.
Next, 3 kg of the above slurry solution and 3 kg of a natural rubber concentrated latex diluted to 7% by mass were mixed with stirring, coagulated by controlling the pH to 4.5 with formic acid, washed, and washed, followed by a twin screw extruder [ ) KTX30) manufactured by Kobe Steel Ltd.] to obtain wet master batch A.
In the wet master batch A, the amount of the surface-treated silica 1 ′ per 35 parts by mass of the natural rubber was 30 parts by mass.

<Preparation of rubber composition>
Using a conventional Banbury mixer, in the first mixing step, 65 parts by mass of the wet master batch A, 15 parts by mass of process oil (* 15), 1.5 parts by mass of stearic acid, and 1.5 parts by mass of zinc white And 3 parts by mass of an antioxidant IPPD (* 16) were mixed to prepare a first mixture.
The obtained first mixture is once taken out of the Banbury mixer, and then the first mixture is again put into the Banbury mixer. Further, 65 parts by mass of polybutadiene rubber (* 4) and 30 parts by mass of carbon black (* 14) , And the second mixing step was performed to prepare a second mixture.
Furthermore, the obtained second mixture was once taken out of the Banbury mixer, and then the second mixture was again charged into the Banbury mixer. Further, 1.5 parts by mass of sulfur and the vulcanization accelerator MBTS (* 20) 0 0.5 part by mass, 1.5 parts by mass of a vulcanization accelerator CBS (* 21), and 4 parts by mass of a foaming agent (* 22), and a final mixing step was carried out to prepare a rubber composition. .
The maximum temperature of the mixture in the first mixing step and the second mixing step, the falling temperature of the mixture in the first mixing step and the second mixing step, and the maximum temperature of the rubber composition in the final mixing step were the same as those in Example 1. . Here, the step of preparing the wet master batch corresponds to the step (a), the first mixing step corresponds to an intermediate step between the steps (a) and (b), and the second mixing step corresponds to the step (a). This corresponds to step (b).
Observation using a scanning probe microscope according to the method described in paragraph [0009] revealed that the obtained rubber composition had a phase-separated structure, and a plurality of mutually incompatible polymer phases were formed. Was.

(Comparative Example 1)
Using a conventional Banbury mixer, in the first mixing step, 30 parts by mass of the surface-treated silica 1 ′, 30 parts by mass of carbon black, and 35 parts by mass of natural rubber (* 1) and 65 parts by mass of polybutadiene rubber (* 4). (* 14) 30 parts by mass, process oil (* 15) 15 parts by mass, stearic acid 1.5 parts by mass, zinc white 1.5 parts by mass, antioxidant IPPD (* 16) 3 parts by mass By mixing, a first mixture was prepared.
The obtained first mixture is once taken out of the Banbury mixer, and then the first mixture is again put into the Banbury mixer. Further, 1.5 parts by mass of sulfur, and 0.1% of the vulcanization accelerator MBTS (* 20) are added. 5 parts by mass, 1.5 parts by mass of the vulcanization accelerator CBS (* 21) and 4 parts by mass of the foaming agent (* 22) were blended, and a final mixing step was performed to prepare a rubber composition.
Observation using a scanning probe microscope according to the method described in paragraph [0009] revealed that the obtained rubber composition had a phase-separated structure, and a plurality of mutually incompatible polymer phases were formed.

(Examples 3 to 18, Comparative Examples 2 to 10)
A first mixing step, a second mixing step, and a final mixing step in the same manner as in Example 1 except that the mixing recipe in the first mixing step and the mixing recipe in the second mixing step are changed as shown in Tables 1 and 2. Was performed in this order to produce a rubber composition.
Observation using a scanning probe microscope according to the method described in paragraph [0009] revealed that each of the rubber compositions had a phase-separated structure, and a plurality of mutually incompatible polymer phases were formed.

<Production of tire>
A test tire (tire size 195 / 65R15) was prepared by a conventional method using the rubber composition obtained as described above for a tread, and the foaming ratio of the tread was calculated according to the above formula (VI). Next, the tires were evaluated for abrasion resistance and performance on ice by the following methods. The results are shown in Tables 1 and 2.

(1) Abrasion resistance After running 10,000 km on a pavement road surface with an actual vehicle using the test tire, the remaining groove was measured, and the running distance required for the tread to be worn by 1 mm was relatively compared. The index is indicated with the tire of No. 100 as 100. The larger the index value, the better the wear resistance.

(2) Performance on Ice Four of the above test tires were mounted on a 1600 cc class domestic passenger car, and braking performance on ice at an ice temperature of -1 ° C was confirmed. The tire of Comparative Example 1 was used as a control, and the performance on ice was calculated as (index of braking in Comparative Example 1 / braking distance of other examples) × 100. The larger the index value, the better the performance on ice.

* 1 Natural rubber: Tg = -60 ° C
* 2 Modified natural rubber: Modified natural rubber synthesized by the following method, Tg = -60 ° C
* 3 Modified natural rubber: Modified natural rubber synthesized by the following method, Tg = -60 ° C
* 4 Polybutadiene rubber: cis-1,4-polybutadiene rubber, trade name “UBEPOL 150L”, manufactured by Ube Industries, Tg = −110 ° C.
* 5 Modified polybutadiene rubber 1: Modified polybutadiene rubber synthesized by the following method, Tg = −95 ° C.
* 6 Modified polybutadiene rubber 2: Modified polybutadiene rubber synthesized by the following method, Tg = -95 ° C
* 7 Silica 1: Trade name “Nip Seal HQ”, manufactured by Tosoh Silica, CTAB specific surface area = 200 m ² / g
* 8 Silica 2: trade name “Nipsil EQ”, manufactured by Tosoh Silica, CTAB specific surface area = 100 m ² / g
* 9 Silica 3: Trade name “Nipsil AQ”, manufactured by Tosoh Silica, CTAB specific surface area = 150 m ² / g
* 10 Surface-treated silica 1 ′: silica prepared by the above method and surface-treated with a sulfur-containing silane coupling agent * 11 Surface-treated silica 2 ′: raw material silica 1 (* 7) was converted to silica 2 (* 8) ) Silica surface-treated with a sulfur-containing silane coupling agent * 12 Surface-treated silica 3 ′ prepared in the same manner as surface-treated silica 1 ′ except that Silica surface-treated with a sulfur-containing silane coupling agent prepared in the same manner as surface-treated silica 1 ', except that (* 9) was replaced with * 1. Silane coupling agent: "Si69", Evonic, bis (3 - triethoxysilylpropyl) tetrasulfide * 14 carbon black: N134, manufactured by Asahi carbon ^{_{Co., N 2 SA = 146m 2 /}} g
* 15 Process oil: Naphthenic process oil, trade name "Diana Process Oil NS-24", manufactured by Idemitsu Kosan, pour point = -30 ° C
* 16 Antioxidant IPPD: N-isopropyl -N'- phenyl -p- phenylene diamine * 17 _{C 5} resin: trade name "Escorez 1102", Tonen manufactured * 18 hydrophilic short fiber: were prepared by the following method Hydrophilic short fiber * 19 Vulcanization accelerator 1: 1,3-diphenylguanidine (DPG)
* 20 Vulcanization accelerator 2: di-2-benzothiazolyl disulfide (MBTS)
* 21 Vulcanization accelerator 3: N-cyclohexyl-2-benzothiazolylsulfenamide (CBS)
* 22 Foaming agent: dinitrosopentamethylenetetramine (DNPT)

<Modified natural rubber>
The field latex was centrifuged at 7,500 rpm using a latex separator (manufactured by Saito Centrifugal Industry) to obtain a concentrated latex having a dry rubber concentration of 60%. 1000 g of the concentrated latex is put into a stainless steel reaction vessel equipped with a stirrer and a temperature control jacket, and 10 mL of water and 90 mg of an emulsifier “Emulgen 1108” (manufactured by Kao) are added to 1.7 g of 4-vinylpyridine in advance. The emulsified product was added together with 990 mL of water, and the mixture was stirred for 30 minutes while purging with nitrogen. Next, 1.2 g of tert-butyl hydroperoxide and 1.2 g of tetraethylenepentamine were added and reacted at 40 ° C. for 1 hour to obtain a modified natural rubber latex.
Next, formic acid was added to the modified natural rubber latex to adjust the pH to 4.7, and the modified natural rubber latex was coagulated. The solid thus obtained was treated five times with a craper, passed through a shredder, crumbed, and dried with a hot air drier at 110 ° C. for 210 minutes to obtain a modified natural rubber.
From the mass of the modified natural rubber thus obtained, it was confirmed that the conversion of the added 4-vinylpyridine was 100%. Further, the modified natural rubber was extracted with petroleum ether and further extracted with a 2: 1 mixed solvent of acetone and methanol to attempt to separate a homopolymer. However, when the extract was analyzed, no homopolymer was detected. It was confirmed that 100% of the added monomer was introduced into the natural rubber molecules.

<Modified natural rubber>
After adjusting the solid content concentration (DRC) of the natural rubber latex to 30% (w / v), the surfactant [Emal-E27C, Kao, sodium polyoxyethylene lauryl ether sulfate] was added to 1000 g of the natural rubber latex. ] And 50 g of a 40% aqueous NaOH solution were added thereto, and a saponification reaction was carried out at room temperature for 48 hours to obtain a saponified natural rubber latex.
Next, after adding water to this latex to dilute the solid content concentration (DRC) to 15% (w / v), formic acid was added while slowly stirring to adjust the pH to 4.0, thereby causing aggregation. . The agglomerated rubber was pulverized, immersed in a 1% aqueous sodium carbonate solution for 5 hours at room temperature, pulled up, washed repeatedly with 1000 ml of water, and then dried at 90 ° C. for 4 hours to obtain a modified natural rubber.

<Modified polybutadiene rubber 1>
283 g of cyclohexane, 100 g of 1,3-butadiene monomer, and 0.015 mmol of 2,2-ditetrahydrofurylpropane were injected into a dried and nitrogen-substituted pressure-resistant glass container having an internal volume of about 900 mL as a cyclohexane solution. After adding 50 mmol of n-butyllithium (n-BuLi), polymerization was carried out in a 50 ° C warm water bath equipped with a stirrer for 4.5 hours. The polymerization conversion was almost 100%.
Next, 0.50 mmol of 3- [N, N-methyl (trimethylsilyl) amino] propyldimethylethoxysilane was added to this polymerization system as a cyclohexane solution, and the mixture was stirred at 50 ° C. for 30 minutes. Thereafter, the reaction was stopped by further adding 0.5 mL of an isopropanol solution of 2,6-di-tert-butyl-p-cresol (BHT) (BHT concentration: 5% by mass), and further dried by a conventional method. Thus, modified polybutadiene rubber 1 was obtained.
The resulting modified polybutadiene rubber 1 had a modification rate of 0.5 and a glass transition temperature of -95 ° C.

<Modified polybutadiene rubber 2>
283 g of cyclohexane, 50 g of 1,3-butadiene, 0.0057 mmol of 2,2-ditetrahydrofurylpropane, and 0.513 mmol of hexamethyleneimine were poured as a cyclohexane solution into a dried, nitrogen-purged pressure-resistant glass container having an internal volume of about 900 mL. Then, 0.57 mmol of n-butyllithium (n-BuLi) was added thereto, and a polymerization reaction was performed for 4.5 hours in a 50 ° C warm water bath equipped with a stirrer. The polymerization conversion at this time was almost 100%.
Next, 0.100 mmol of tin tetrachloride was added as a cyclohexane solution to the polymerization reaction system, followed by stirring at 50 ° C. for 30 minutes. Thereafter, 0.5 mL of an isopropanol solution of 2,6-di-tert-butyl-p-cresol (BHT) (BHT concentration: 5% by mass) was added to the reaction system to stop the polymerization reaction, and further according to a conventional method. After drying, modified polybutadiene rubber 2 was obtained.
The resulting modified polybutadiene rubber 2 had a modification ratio of 1.2 and a glass transition temperature of -95 ° C.

<Hydrophilic short fiber>
According to Production Example 3 disclosed in JP-A-2012-219245, using two twin-screw extruders, 40 parts by mass of polyethylene (made by Nippon Polyethylene, Novatec HJ360 (MFR 5.5, melting point 132 ° C.)) and ethylene -40 parts by mass of a vinyl alcohol copolymer [manufactured by Kuraray, Eval F104B (MFR4.4, melting point: 183 ° C)], and simultaneously extruded from a die outlet, the fiber obtained according to a conventional method was reduced to a length of 2 mm. By cutting, a hydrophilic short fiber having a coating layer made of polyethylene was formed.

  From the results of the examples shown in Tables 1 and 2, it is understood that both the on-ice performance and the wear resistance of the tire can be improved by using the rubber composition manufactured according to the present invention.

  The rubber composition produced by the method for producing a rubber composition of the present invention can be used for a tire, particularly a tread rubber of a studless tire. Further, the tire of the present invention is useful as a studless tire.

Claims (13)

At least two kinds of diene polymers forming a plurality of polymer phases incompatible with each other, silica surface-treated with a sulfur-containing silane coupling agent, carbon black, and a vulcanization accelerator,
At least two of the diene polymers have a blending amount of at least 20% by mass of the total amount of the diene polymers, and the blending amount is at least 20% by mass of the total amount of the diene polymers. The blending amount of the diene-based polymer (A) having the lowest glass transition temperature (Tg) in the coalesce is the diene-based polymer having the largest blending amount among the diene-based polymers other than the diene-based polymer (A). 85% by mass or more of the blending amount of the polymer,
A method for producing a rubber composition, wherein the compounding amount of the silica surface-treated with the sulfur-containing silane coupling agent is 25 parts by mass or more based on 100 parts by mass of the total of the diene-based polymer,
A diene polymer (B) incompatible with the diene polymer (A) having the lowest glass transition temperature (Tg) of the diene polymer, and the sulfur-containing silane coupling agent. (A) preparing a masterbatch by mixing the surface-treated silica with
(B) mixing the carbon black with the remainder of the diene-based polymer other than the diene-based polymer (B) in the prepared masterbatch;
Including
A method for producing a rubber composition, wherein in the step (a), at least one compound selected from the vulcanization accelerators is mixed to prepare the master batch.   The diene-based polymer (A) having the lowest glass transition temperature (Tg) has the largest blending amount among the diene-based polymers, or the diene-based polymer other than the diene-based polymer (A) has The method for producing a rubber composition according to claim 1, wherein the compounding amount is equal to the diene polymer having the largest compounding amount.   The method for producing a rubber composition according to claim 1 or 2, wherein the diene polymer (A) having the lowest glass transition temperature (Tg) has a butadiene skeleton.   The method for producing a rubber composition according to claim 3, wherein the diene polymer (A) having the lowest glass transition temperature (Tg) is a polybutadiene rubber.   The diene polymer (C) having the highest glass transition temperature (Tg) among diene polymers having the compounding amount of 20% by mass or more of the total amount of the diene polymer has an isoprene skeleton. A method for producing the rubber composition according to any one of claims 1 to 4.   The method for producing a rubber composition according to claim 5, wherein the diene polymer (C) having the highest glass transition temperature (Tg) is a natural rubber.   The rubber composition according to any one of claims 1 to 6, wherein the compounding amount of the carbon black is 25 parts by mass or more based on a total of 100 parts by mass of the diene polymer. Production method.   The rubber according to any one of claims 1 to 7, wherein the diene polymer (A) having the lowest glass transition temperature (Tg) is modified with a compound containing at least one of a tin atom and a nitrogen atom. A method for producing the composition.   The method for producing a rubber composition according to claim 8, wherein the diene-based polymer (A) having the lowest glass transition temperature (Tg) contains both tin atoms and nitrogen atoms.   The diene-based polymer (A) having the lowest glass transition temperature (Tg) has a modification rate of a compound containing at least one of the tin atom and the nitrogen atom of 1.1 to 2.5. 10. A method for producing the rubber composition according to item 9.   The method for producing a rubber composition according to any one of claims 1 to 10, wherein the rubber composition further comprises a foaming agent. Method for producing a rubber composition, further comprising a C ₅ resin, a rubber composition according to any one of claims 1 to 11.   The method for producing a rubber composition according to any one of claims 1 to 12, wherein the rubber composition further includes a hydrophilic short fiber.