JP2017128646A - Method for producing rubber composition, rubber composition, and tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a rubber composition capable of improving both on-ice performance and abrasion resistance of a tire.SOLUTION: A method for producing a rubber composition containing 25 pts.mass or more of silica and 25 pts.mass or more of carbon black with respect to 100 pts.mass of the total of at least two diene-based polymers forming a plurality of polymer phases incompatible with each other includes the steps of: (a) mixing a diene-based polymer (A) having the lowest glass transition temperature in the diene-based polymers with a blended amount of 20 mass% or more with respect to the total amount of the diene-based polymer with a part or all of the carbon black to prepare a master batch; and (b) mixing the rest of the diene-based polymer and the silica with the master batch.SELECTED DRAWING: None

Description

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

Conventionally, studless tires with softened tread rubber have been used as tires for safe driving on ice in addition to normal road surfaces. By softening the tread rubber, the on-ice performance of the tire can be improved. Are known. However, in general, a tire including a soft tread rubber has a problem of poor wear resistance on a normal road surface, and the on-ice performance and the wear resistance of the tire are in a trade-off relationship.
In addition, as a technique for improving the on-ice performance of a tire, for example, a technique for improving the on-ice performance of a tire by blending organic fiber, glass fiber, or the like with a rubber composition used for a tread and scratching an icy road surface is known. It has been. However, since organic fibers, glass fibers, and the like have no interaction with rubber, they function as fracture nuclei and cause a decrease in the fracture resistance (abrasion resistance) of the tread rubber.

  As a tire for solving such a problem, Japanese Patent Application Laid-Open No. 2008-303334 (Patent Document 1) discloses potassium titanate fibers in an amount of 0.5 to 20% by weight with respect to 100 parts by weight of a rubber component made of natural rubber and butadiene rubber. And a rubber composition containing 5 to 200 parts by weight of carbon black having an iodine adsorption amount of 100 to 300 mg / g is proposed, and the rubber composition has a two-layer structure composed of a cap tread and a base tread. It has been reported that use on a tread cap tread improves on-ice performance (on-ice / snow performance) 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 for a cap tread, the performance on ice (on ice) Although the coefficient of friction is improved, the wear resistance is slightly lowered, and it is impossible to improve both the performance on ice and the wear resistance.

Therefore, an object of the present invention is to provide a rubber composition that can solve the above-described problems of the prior art and improve both the performance on ice and the wear resistance of a tire, and a method for producing the same.
Moreover, this invention makes it the further subject to provide the tire which is excellent in both on-ice performance and abrasion 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:
Including at least two diene polymers that form a plurality of incompatible polymer phases, silica, and carbon black,
At least two of the diene polymers have a blending amount of 20% by mass or more of the total amount of the diene polymer, and the blending amount is 20% by mass or more of the total amount of the diene polymer. The blending amount of the diene polymer (A) having the lowest glass transition temperature (Tg) among the blends is the diene having the largest blending amount among the diene polymers other than the diene polymer (A). 85 mass% or more of the blend amount of the polymer,
The compounding amount of the silica is 25 parts by mass or more with respect to a total of 100 parts by mass of the diene polymer,
The amount of the carbon black is 25 parts by mass or more with respect to a total of 100 parts by mass of the diene polymer,
A step (a) of preparing a master batch by mixing the diene polymer (A) having the lowest glass transition temperature (Tg) and a part or all of the carbon black;
A step (b) of mixing the prepared masterbatch with the silica other than the diene polymer (A) having the lowest glass transition temperature (Tg) in the diene polymer; It is characterized by including these.
According to such a 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 abrasion 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 using a test roll, and 150 ° C. × 30 minutes in a 15 cm × 15 cm × 1 cm test mold. When a vulcanized sheet is prepared by press vulcanization, and the obtained vulcanized sheet is evaluated by observing with a scanning probe microscope as an ultrathin section by a microtome, and a phase separation structure is confirmed, a polymer The phases are incompatible with each other.

  In the present invention, the glass transition temperature (Tg) of the diene polymer is extrapolated onset temperature measured using a differential scanning calorimeter (DSC) in accordance with ASTM D3418-82: Tf. And

  In the method for producing a rubber composition of the present invention, the diene polymer (A) having the lowest glass transition temperature (Tg) has the largest compounding amount among the diene polymers, or the diene 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 becomes soft, and when the rubber composition is used for a tread, the ground contact area of the tread increases 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, since the rubber composition is further softened, the 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 of the present invention, the glass transition temperature (Tg) is the highest among the diene polymers in which the blending amount is 20% by mass or more of the total amount of the diene polymers. A high diene polymer (B) 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 (B) having the highest glass transition temperature (Tg) is preferably natural rubber. In this case, the reinforcing property of the rubber composition is further increased, and the wear resistance 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 the carbon black is increased, and the wear resistance of the rubber composition is further improved.
Here, it is preferable that the diene polymer (A) having the lowest glass transition temperature (Tg) contains both a tin atom and a nitrogen atom. In this case, the interaction between the carbon black and the diene polymer (A) having the lowest glass transition temperature (Tg) is further increased, and the diene polymer (A) having the lowest glass transition temperature (Tg). The reinforcing property of the polymer phase to be formed 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 rate of 1.1 or more and 2.5 or less by the compound containing at least one of the tin atom and the nitrogen atom. . In this case, the interaction between the diene 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) is at least one of tin atom (Sn) and nitrogen atom (N) used in the modification reaction per 100 g of rubber content of the diene polymer (A). Is the number of millimoles of the compound containing

  In the manufacturing method of the rubber composition of this invention, it is preferable that the said rubber composition contains a foaming agent further. When a tire is produced using a rubber composition containing a foaming agent for the tread rubber, when the raw tire is vulcanized, bubbles derived from the foaming agent are formed in the tread rubber. 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.

  Moreover, in the manufacturing method of the rubber composition of this invention, it is preferable that the said rubber composition contains a hydrophilic short fiber further. In this case, the on-ice performance of the tire can be greatly improved.

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

  Furthermore, the 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 performance on ice and wear 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.
In addition, according to the present invention, it is possible to provide a tire that is excellent in both on-ice performance and wear resistance.

<Method for producing rubber composition and rubber composition>
Below, the manufacturing method of the rubber composition of this invention and a rubber composition are illustrated and demonstrated in detail based on the embodiment.
The method for producing a rubber composition of the present invention comprises at least two diene polymers that form a plurality of incompatible polymer phases, silica, and carbon black, and includes at least one of the diene polymers. Two types are glass transition temperature in the diene polymer whose compounding amount is 20 mass% or more of the total amount of the diene polymer, and whose compounding amount is 20 mass% or more of the total amount of the diene polymer. The blending amount of the diene polymer (A) having the lowest (Tg) is the blending amount of the diene polymer having the largest blending amount among the diene polymers other than the diene polymer (A). 85% by mass or more, the compounding amount of the silica is 25 parts by mass or more based on 100 parts by mass of the diene polymer, and the compounding amount of the carbon black is 100 in total of the diene polymer. 25 quality to mass parts Is part above, a method for producing a rubber composition,
A step (a) of preparing a master batch by mixing the diene polymer (A) having the lowest glass transition temperature (Tg) and a part or all of the carbon black;
A step (b) of mixing the prepared masterbatch with the remainder of the diene polymer other than the diene polymer (A) having the lowest glass transition temperature (Tg) and the silica; , Including.
The rubber composition of the present invention is characterized by being produced by the above-described 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 diene polymers, and a polymer blend composed of the two or more diene polymers forms a plurality of incompatible polymer phases. To do. In the method for producing a rubber composition of the present invention, in step (a), the diene polymer (A) having the lowest glass transition temperature (Tg) and a part or all of the carbon black are mixed. To prepare a masterbatch. Thus, in the method for producing a rubber composition of the present invention, a master batch is prepared by mixing the diene polymer (A) having the lowest glass transition temperature (Tg) and at least a part of carbon black. Thus, at least a part of the carbon black can be dispersed while being chemically bonded to the diene polymer (A) having the lowest glass transition temperature (Tg). Moreover, since the polymer phase formed from the diene polymer (A) having the lowest glass transition temperature (Tg) is soft, its performance on ice is high. In addition, when at least a part of carbon black is dispersed in the polymer phase and the polymer phase contains carbon black having high reinforcing properties, the rubber composition manufactured in the tire is used as a tire. Abrasion resistance is improved.

  Further, in the method for producing a rubber composition of the present invention, in the step (b), the master batch other than the diene polymer (A) having the lowest glass transition temperature (Tg) of the diene polymer. In the step (b), carbon black is chemically bonded to the diene polymer (A) having the lowest glass transition temperature (Tg) in the masterbatch. , Silica is difficult to disperse in the diene polymer (A) having the lowest glass transition temperature (Tg), and mainly the balance of the diene polymer [that is, the glass transition temperature (than the diene polymer (A) ( In other diene polymers having a high Tg). And silica will mainly disperse | distribute in the polymer phase which consists of remainder other than the diene polymer (A) with the lowest said glass transition temperature (Tg) among diene polymers. Thus, the polymer phase consisting of the remainder other than the diene polymer (A) having the lowest glass transition temperature (Tg) among the diene polymers has a high glass transition temperature (Tg) and a high reinforcing property. Since it is formed from a diene polymer, in addition to high wear resistance, it contains silica and is soft while having micro unevenness. 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 on-ice performance of the tire is improved.

For the above reasons, 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 the on-ice performance and the wear resistance of a tire when applied to a tire. Can do.
Moreover, the rubber composition of this invention manufactured by this method can improve both on-ice performance and abrasion resistance of a tire by applying to a tire.

As described above, in the method for producing a rubber composition of the present invention, in step (a), the diene polymer (A) having the lowest glass transition temperature (Tg) and a part or all of the carbon black. In step (b), the diene polymer (A) having the lowest glass transition temperature (Tg) in the diene polymer is added to the prepared master batch. ) And the silica are mixed, but in the preparation of the masterbatch of step (a), when only a part of carbon black is blended, the balance of carbon black is blended in step (b). Or you may mix | blend in another process.
In the method of manufacturing the rubber composition of the present invention, in steps (a) and (b), optionally, described below C ₅ resins, hydrophilic short fibers, a silane coupling agent, a softening agent (process oil Etc.), stearic acid, zinc white (zinc oxide), anti-aging agent, wax and other compounding agents may be blended.

In the step (a) and the step (b), a mixing device such as a Banbury mixer, a roll, or an intensive mixer can be used. In addition, after the step (a), the obtained master batch is once taken out from the mixing apparatus, and then the step (b) may be performed, or the step (b) may be performed without taking out the master batch once. Although it is good, after the step (a), it is preferable that the obtained master batch is once taken out from the mixing apparatus.
Moreover, when taking out the obtained masterbatch from a mixing apparatus once, a process (b) may be performed using the same mixing apparatus as a process (a), or another mixing apparatus different from a process (a) is 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. If the maximum temperature of the mixture in the step (a) is 120 ° C. or higher and 190 ° C. or lower, the energy of the kneading is saved and the carbon black to the diene polymer (A) having the lowest glass transition temperature (Tg) Dispersion proceeds well.

  In the step (a), the mixing time (kneading time) of the mixture is preferably in the range of 10 to 300 seconds, more preferably in the range of 10 to 210 seconds, still more preferably in the range of 30 to 180 seconds, 30 A range of ˜150 seconds is particularly preferred. If the mixing time is 10 seconds or more, the dispersion of carbon black into the diene polymer (A) having the lowest glass transition temperature (Tg) can be sufficiently advanced, and the mixing time is 300 seconds or less. If so, energy required for kneading can be saved.

  In the step (b), the maximum temperature of the mixture (rubber composition or a premix of the rubber composition in the case of including another mixing step after the step (b)) 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. If the maximum temperature of the mixture of step (b) is 120 ° C. or higher and 190 ° C. or lower, other diene type having a glass transition temperature (Tg) higher than that of the diene polymer (A) while saving energy required for kneading The silica is well dispersed in the polymer.

  In the step (b), the mixing time (kneading time) of the mixture is preferably in the range of 10 to 300 seconds, more preferably in the range of 10 to 210 seconds, still more preferably in the range of 30 to 180 seconds, 30 A range of ˜150 seconds is particularly preferred. If the mixing time is 10 seconds or more, the silica can be sufficiently dispersed in another diene polymer having a glass transition temperature (Tg) higher than that of the diene polymer (A). If the time is 300 seconds or less, the energy required for kneading can be saved.

  The rubber composition produced by the method for producing a rubber composition of the present invention contains at least two diene polymers that form a plurality of incompatible polymer phases. In the present invention, the diene 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. Specific examples of the synthetic diene rubber include polybutadiene rubber (BR), synthetic polyisoprene rubber (IR), Examples thereof include styrene-butadiene copolymer rubber (SBR) and styrene-isoprene copolymer rubber (SIR). Here, as a combination of diene polymers that form 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. Examples include polybutadiene rubber (BR) / natural rubber (NR), polybutadiene rubber (BR) / synthetic polyisoprene rubber (IR), and polybutadiene rubber (BR) / natural rubber (NR) is preferred.

In the present invention, the diene polymer (A) having the lowest glass transition temperature (Tg) among the diene polymers whose blending amount is 20% by mass or more of the total amount of the diene polymer has a blending amount. Among the diene polymers other than the diene polymer (A), the blending amount is 85% by mass or more of the blending amount of the diene polymer having the largest blending amount. A diene polymer having a blending amount of less than 20% by mass of the total amount of the diene polymer has a small effect on the performance of the rubber composition. And in the rubber composition of this invention, the compounding quantity of the said diene polymer (A) is diene type with the largest compounding quantity in said diene polymers other than this diene polymer (A). By being 85 mass% or more of the compounding quantity of a polymer, the influence of the polymer phase formed from this diene polymer (A) is fully exhibited, and abrasion resistance improves.
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 rate of 2.5 or less. The modification rate is, as described above, the number of millimoles of the compound containing at least one of a tin atom and a nitrogen atom used for the modification reaction per 100 g of rubber 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 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.
The diene polymer (A) is modified with a compound containing at least one of the tin atom and the nitrogen atom at a modification rate 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 wear resistance of the rubber composition is further improved.

  The diene polymer (A) having the lowest glass transition temperature (Tg) [hereinafter sometimes abbreviated as “low Tg diene polymer (A)]” includes a conjugated diene compound as a monomer, or A polymer or copolymer of the conjugated diene compound obtained by using a conjugated diene compound and an aromatic vinyl compound, or a copolymer of a conjugated diene compound and an aromatic vinyl compound, Moreover, what modified | denatured the molecular terminal and / or main chain of these (co) polymers can also be used. Specific examples of the known modified diene polymer having a modified molecular terminal include International Publication No. 2003/046020, Japanese Translation of PCT International Publication No. 2004-513987, Japanese Patent Application Laid-Open No. 11-29603, and Japanese Patent Application Laid-Open No. 2003-113202. And the modified diene polymer disclosed in JP-B-6-29338. Examples of known modified diene polymers in which the main chain is modified include JP-A-2003-534426 and JP-A-2003-534426. The modified diene polymer disclosed in 2002-201310 can be exemplified.

  Concerning the monomer 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, 2-phenyl- 1,3-butadiene, 1,3-hexadiene, etc. are exemplified, and examples of the aromatic vinyl compound include styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4 -Cyclohexylstyrene, 2,4,6-trimethylstyrene and the like.

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

  When producing a (co) polymer having an active end by anionic polymerization, the polymerization initiator is preferably a lithium amide compound. Examples of the lithium amide compound include lithium hexamethylene imide, lithium pyrrolidide, lithium piperidide, lithium heptamethylene imide, lithium dodecamethylene imide, lithium dimethylamide, lithium diethylamide, lithium dipropylamide, lithium dibutylamide, lithium dihexylamide. , Lithium diheptylamide, lithium dioctylamide, lythym-2-ethylhexylamide, lithium didecylamide, lithium-N-methylpiperazide, lithium ethylpropylamide, lithium ethylbutyramide, lithium methylbutyramide, lithium ethylbenzylamide, lithium methyl Examples thereof include phenethylamide.

（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。 Moreover, as said lithium amide compound, Formula: Li-AM [In formula, AM is following formula (I):

(Wherein R ¹ is 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. By using the lithium amide compound, at least one nitrogen-containing functional group selected from the group consisting of a substituted amino group represented by formula (I) and a cyclic amino group represented by formula (II) is introduced. 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 3-phenyl-1-propyl group and isobutyl group. R ¹ may be the same or different from each other.
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 examples of the substituent include a chain or branched alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, a bicycloalkyl group, An aryl group and an aralkyl group are mentioned. R ² is specifically preferably a trimethylene group, a tetramethylene group, a hexamethylene group, an oxydiethylene group, an N-alkylazadiethylene group, a dodecamethylene group, a hexadecamethylene group, or the like.

The lithium amide compound may be preliminarily prepared from a secondary amine and a lithium compound and used for the polymerization reaction, but may be generated in a polymerization system.
Here, as the secondary amine, in addition to dimethylamine, diethylamine, dibutylamine, dioctylamine, dicyclohexylamine, diisobutylamine and the like, azacycloheptane (ie, hexamethyleneimine), 2- (2-ethylhexyl) pyrrolidine, 3 -(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 Chloheptade-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] cyclic amines such as decane.
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, 2-butyl- Hydrocarbyl lithium such as phenyl lithium, 4-phenyl-butyl lithium, cyclohexyl lithium, cyclopentyl lithium, a reaction product of diisopropenylbenzene and butyl lithium, and the like can be used.

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

As the modifier containing the tin atom (that is, the tin-containing compound), the following formula (III):
R ³ _a SnX _b (III)
[Wherein, R ³ each 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. Selected from the group; X is independently chlorine or bromine; a is 0 to 3, b is 1 to 4, provided that 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 neophyll 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.

Examples of the modifier containing nitrogen atoms (that is, nitrogen-containing compounds) include nitrogen-containing compounds having a substituted or unsubstituted amino group, amide group, imino group, imidazole group, nitrile group, pyridyl group, and 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] methyl ethyl ketone, 3- [N, N-methyl (trimethylsilyl) amino] propyldimethylethoxysilane, and the like.
The modifier containing a nitrogen atom may further have a chlorosulfenyl group or a chlorosulfonyl group. Examples of the modifier having a chlorosulfenyl group or a chlorosulfonyl group in addition to the nitrogen atom are disclosed in No. 11-29603, 2,4-dinitrobenzenesulfenyl chloride, 4-nitrobenzenesulfenyl chloride, 4-nitrobenzenesulfonyl chloride, 2-acetamidobenzenesulfonyl chloride, 1-aminonaphthyl-5-sulfonyl chloride Quinoline sulfonyl chloride, dimethyl sulfamoyl chloride, dimethyl sulfonyl chloride, 2,4-dinitrobenzene sulfonyl chloride, and the like can be used.
Prior to modification with the above-described modifier containing a nitrogen atom, the 1,1-diphenylethylene compound having a polar group disclosed in JP-A-2003-113202 is reacted with the (co) polymer having an active end. As the 1,1-diphenylethylene compound, specifically, 1- (4-N, N-dimethylaminophenyl) -1-phenylethylene or the like can be used.

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

  As the polar group-containing vinyl monomer, specifically, N, N-dimethylaminoethyl (meth) acrylate [where “(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 individually by 1 type, and may be used in combination of 2 or more type.

  Specific examples of the polar group-containing mercapto compound include 2-mercaptoethylamine, N, N-dimethylaminoethanethiol, 2-mercaptopyridine, 4-mercaptopyridine, 2-mercaptoethyltri-n-butyltin, 2 -Mercaptoethyltrimethyltin, 2-mercaptoethyltriphenyltin, 3-mercaptopropyltri-n-butyltin, 3-mercaptopropyltrimethyltin, 3-mercaptopropyltriphenyltin and the like. These compounds may be used individually by 1 type, and may be used in combination of 2 or more type.

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, for example, using the lithium amide compound as a polymerization initiator, introducing a nitrogen-containing functional group at the polymerization initiation terminal, as a modifier, Using the tin-containing coupling agent, introducing a tin-containing functional group at the polymerization active terminal (polymerization termination terminal), or graft-polymerizing both a nitrogen-containing monomer and a tin-containing monomer, 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 wear 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 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 polymer having a butadiene skeleton include polybutadiene rubber (BR) and styrene-butadiene copolymer rubber (SBR). The low Tg diene polymer (A) is particularly preferably a polybutadiene rubber (BR) from the viewpoint of performance on ice.

  The blending amount of the diene polymer (A) having the lowest glass transition temperature (Tg) described above is the diene polymer having the largest blending amount among the diene polymers other than the diene polymer (A). Although it is not particularly limited as long as it is 85% by mass or more of the blending amount of the coalescence, preferably 50% by mass or more of the total amount of the diene polymer, more preferably 55% by mass or more of the total amount of the diene polymer, More preferably, it is 60% by mass or more of the total amount of the diene polymer, preferably 75% by mass or less of the total amount of the diene polymer, more preferably 70% by mass or less of the total amount of the diene polymer, particularly Preferably, it is 65% by mass or less of the total amount of the diene polymer. If the blending amount of the diene polymer (A) having the lowest glass transition temperature (Tg) is within this range, the performance on ice and the wear resistance can be sufficiently improved.

  Further, 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 coalescence. In this case, the effect of the polymer phase formed from the low Tg diene polymer (A) is increased, and the wear resistance of the tire can be further improved by applying the rubber composition to the tire.

  In the present invention, the diene polymer (B) having the highest glass transition temperature (Tg) among the diene polymers whose blending amount is 20% by mass or more of the total amount of the diene polymer [hereinafter referred to as “high”. It may be abbreviated as “Tg diene polymer (B)”] preferably has an isoprene skeleton. When the high Tg diene polymer (B) has an isoprene skeleton, the reinforcing property of the rubber composition is increased and the wear resistance is further improved. 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 (B) is particularly preferably natural rubber (NR) from the viewpoint of wear resistance.

  The blending amount of the diene polymer (B) having the highest glass transition temperature (Tg) described above is less than the blending amount of the low Tg diene polymer (A) or the low Tg diene polymer (A). It is preferably equal to the blending amount of the diene polymer, more preferably 25% by mass or more of the total amount of the diene polymer, even more preferably 30% by mass or more of the total amount of the diene polymer, and particularly preferably of the diene polymer. It is 35% by mass or more of the total amount, more preferably 45% by mass or less of the total amount of the diene polymer, and still more preferably 40% by mass or less of the total amount of the diene polymer. If the blending amount of the diene polymer (B) having the highest glass transition temperature (Tg) is within this range, the performance on ice and the wear resistance can be sufficiently improved.

  The rubber composition produced by the method of the present invention includes the diene polymer (A) having the lowest glass transition temperature (Tg) and the diene polymer (B) having the highest glass transition temperature (Tg). Further, another diene polymer (C) may be included. A diene polymer (C) having such a glass transition temperature (Tg) between the low Tg diene polymer (A) and the high Tg diene polymer (B) [hereinafter referred to as “medium Tg diene polymer] “(C)” may be abbreviated as “low Tg diene polymer (A)” and “high Tg diene polymer (B)”. When A) is polybutadiene rubber (BR) and the high Tg diene polymer (B) is natural rubber (NR) or synthetic polyisoprene rubber (IR), the medium Tg diene polymer (C) is styrene. -Butadiene copolymer rubber (SBR), styrene-isoprene copolymer rubber (SIR), etc. are mentioned.

The rubber composition produced by the method of the present invention contains silica. The silica is relatively distributed in a polymer phase formed from another diene polymer having a glass transition temperature (Tg) higher than that of the low Tg diene polymer (A). While imparting irregularities, the polymer phase is softened to improve the performance on ice.
There is no restriction | limiting in particular as said silica, For example, wet silica (hydrous silicic acid), dry-type silica (anhydrous silicic acid), calcium silicate, aluminum silicate etc. are mentioned, Among these, wet silica is preferable. These silicas may be used individually by 1 type, and may use 2 or more types together.

  The compounding amount of the silica is 25 parts by mass or more, preferably 27 parts by mass or more, more preferably 29 parts by mass or more, and preferably 50 parts by mass with respect to a total of 100 parts by mass of the diene polymer. Part or less, more preferably 40 parts by weight or less. By making the compounding amount of silica 25 parts by mass or more with respect to 100 parts by mass of the total of the diene polymer, the diene polymer (A) having the lowest glass transition temperature (Tg) in the diene polymer. ) The polymer phase composed of the remainder other than () is imparted with micro unevenness, while the polymer phase is softened to improve the performance on ice. Moreover, the workability | operativity of a process (b) can be made favorable by the compounding quantity of a silica being 50 mass parts or less with respect to 100 mass parts of total of a diene polymer.

The rubber composition produced by the method of the present invention contains carbon black. The carbon black is relatively distributed in the polymer phase formed from the low Tg diene polymer (A), and the polymer phase is reinforced by containing a lot of carbon black having high reinforcing properties. Abrasion resistance 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 individually by 1 type, and may use 2 or more types together.

  The compounding amount of the carbon black is 25 parts by mass or more, preferably 27 parts by mass or more, more preferably 29 parts by mass or more, and preferably 50 parts by mass with respect to a total of 100 parts by mass of the diene polymer. It is 40 parts by mass or less, more preferably 40 parts by mass or less. The amount of carbon black is 25 parts by mass or more with respect to 100 parts by mass of the diene polymer, thereby reinforcing the polymer phase formed from the low-Tg diene polymer (A) and providing abrasion resistance. Can be improved. Moreover, workability | operativity of a process (a) and a process (b) can be made favorable by the compounding quantity of carbon black being 50 mass parts or less with respect to a total of 100 mass parts of a diene polymer.

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 produced using a rubber composition containing a foaming agent for the tread, the on-ice performance of the tire can be further improved by the scratching effect and drainage effect of the tread bubbles.
Examples of the foaming agent include azodicarbonamide (ADCA), dinitrosopentamethylenetetramine (DNPT), dinitrosopentastyrenetetramine, benzenesulfonyl hydrazide derivative, p, p'-oxybisbenzenesulfonylhydrazide (OBSH), ammonium bicarbonate. , Sodium bicarbonate, ammonium carbonate, nitrososulfonylazo compound, N, N′-dimethyl-N, N′-dinitrosophthalamide, toluenesulfonyl hydrazide, p-toluenesulfonyl semicarbazide, p, p′-oxybisbenzenesulfonyl semicarbazide Etc. Among these foaming agents, dinitrosopentamethylenetetramine (DNPT) is preferable. These foaming agents may be used individually by 1 type, and may use 2 or more types together.
Moreover, the compounding quantity of this foaming agent is not specifically limited, The range of 0.1-30 mass parts is preferable with respect to a total of 100 mass parts of the said diene polymer, 1-20 mass parts is preferable. A range is more preferred.

The foaming agent is preferably used in combination with urea, zinc stearate, zinc benzenesulfinate, zinc white or the like as a foaming aid. These foaming aids may be used alone or in combination of two or more. By using a foaming aid in combination, the foaming reaction can be promoted to increase the degree of completion of the reaction, and unnecessary deterioration can be suppressed over time.
Moreover, the compounding quantity of this foaming adjuvant is although it does not specifically limit, The range of 1-30 mass parts is preferable with respect to a total of 100 mass parts of the said diene polymer.

In addition, in the vulcanized rubber obtained after vulcanizing the rubber composition containing the said foaming agent, the foaming rate is 1-50% normally, Preferably it is 5-40%. When a foaming agent is blended, if the foaming rate is too large, the gap on the rubber surface will also increase and it may not be possible to secure a sufficient contact area, but if the foaming rate is within the above range, it will function effectively as a drainage groove. Since the amount of bubbles can be appropriately maintained while ensuring the formation of bubbles, the durability is not impaired. Here, the foaming rate of the vulcanized rubber means an average foaming rate Vs, and specifically means a value calculated by the following formula (IV).
Vs = (ρ ₀ / ρ ₁ −1) × 100 (%) (IV)
In formula (IV), 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 part 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 the air. Further, the foaming rate can be appropriately changed depending on the type and amount of the foaming agent and foaming aid.

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 Diolefin hydrocarbons such as -1,3-butadiene, 1,2-pentadiene, 1,3-pentadiene, 3-methyl-1,2-butadiene and the like are included. 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 A 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.

Moreover, it is preferable that the rubber composition manufactured by the method of the present invention further contains hydrophilic short fibers. In particular, when the rubber composition contains hydrophilic short fibers and the above-mentioned foaming agent, the gas generated from the foaming agent during vulcanization penetrates into the inside of the hydrophilic short fibers and corresponds to the shape of the hydrophilic short fibers. Bubbles having a shape can be formed, and the walls of the bubbles are made hydrophilic by being covered with a resin derived from hydrophilic short fibers. Therefore, when a tire is manufactured using a rubber composition containing hydrophilic short fibers and a foaming agent for the tread, the affinity for water is improved by exposing the wall surface of the bubbles to the tread surface when the tire is used. In addition, the bubbles can actively take in water, the tire is provided with excellent drainage, and the on-ice performance of the tire can be greatly improved.
Examples of the hydrophilic resin used as the raw material for the hydrophilic short fibers include ethylene-vinyl alcohol copolymer, vinyl alcohol homopolymer, poly (meth) acrylic acid or ester thereof, polyethylene glycol, carboxyvinyl copolymer, styrene- Examples include maleic acid copolymer, polyvinyl pyrrolidone, vinyl pyrrolidone-vinyl acetate copolymer, mercaptoethanol, etc. Among them, ethylene-vinyl alcohol copolymer, vinyl alcohol homopolymer, poly (meth) acrylic acid are used. Preferably, an ethylene-vinyl alcohol copolymer is particularly preferable.

A coating layer made of a low melting point resin having an affinity for the diene polymer and preferably having a melting point lower than the maximum vulcanization temperature of the rubber composition is formed on the surface of the hydrophilic short fiber. May be. By forming such a coating layer, the affinity between the hydrophilic short fibers and water is effectively maintained, and the affinity between the coating layer and the diene polymer is good, so that the short fiber diene polymer. Dispersibility in In addition, the low melting point resin melts during vulcanization and becomes a fluid coating layer that contributes to adhesion between the diene polymer and the hydrophilic short fibers, and has good drainage and durability. It is possible to easily realize a tire provided with In addition, although the thickness of this coating layer may be fluctuate | varied with the compounding quantity, average diameter, etc. of a hydrophilic short fiber, it is 0.001-10 micrometers normally, Preferably it is 0.001-5 micrometers.
The melting point of the low melting point resin used for the coating layer is preferably lower than the maximum temperature for vulcanization of the rubber composition. The maximum temperature for vulcanization means the maximum temperature that the rubber composition reaches when the rubber composition is vulcanized. For example, in the case of mold vulcanization, it means the maximum temperature that the rubber composition reaches from the time when the rubber composition enters the mold until the rubber composition exits the mold and cools. 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, it is 10 ° C. or more lower than the maximum vulcanization temperature of the rubber composition. Is preferable, and it is more preferably lower by 20 ° C. or more. The industrial vulcanization temperature of the rubber composition is generally about 190 ° C. at the maximum. For example, when the maximum vulcanization temperature is set to 190 ° C., the low melting point resin The melting point is usually selected within a range of less than 190 ° C, preferably 180 ° C or less, and more preferably 170 ° C or less.
The low melting point resin is preferably a polyolefin resin, and examples include polyethylene, polypropylene, polybutene, polystyrene, ethylene-propylene copolymer, ethylene-methacrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene- Examples thereof include propylene-diene terpolymers, ethylene-vinyl acetate copolymers, and ionomer resins thereof.

The hydrophilic short fibers preferably have an average length of 0.1 to 50 mm, more preferably 1 to 7 mm, and an average diameter of 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 ensured.
The blending amount of the hydrophilic short fibers is preferably in the range of 0.1 to 100 parts by mass and more preferably in the range of 1 to 50 parts by mass with respect to 100 parts by mass in total of the diene polymer. By keeping the blending amount of the hydrophilic short fibers in the above range, a good balance between performance on ice and wear resistance can be achieved.

The rubber composition produced by the process of the present invention, the diene polymer, silica, carbon black, blowing agent, foaming aid, C ₅ resins, other hydrophilic short fiber, usually used in the rubber industry For example, silane coupling agents, softeners (process oils, etc.), stearic acid, anti-aging agents, waxes, zinc oxide (zinc white), vulcanization accelerators, vulcanizing agents, etc. You may mix and select suitably in the range which does not injure the objective. As these compounding agents, commercially available products can be suitably used.

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 | blend and it is preferable to mix | blend the said silane coupling agent at a process (b).

Further, the method for producing a rubber composition of the present invention preferably includes a mixing step (c) after step (b), and the foaming agent, foaming aid, vulcanization accelerator, and vulcanizing agent are: It is preferable to mix | blend by the mixing process (c) after a process (b).
After the step (b), by separately performing a step (c) of mixing and mixing a foaming agent, a foaming aid, a vulcanization accelerator, and a vulcanizing agent, at a temperature different from the step (b). , Foaming agents, foaming aids, vulcanization accelerators, vulcanizing agents can be blended and mixed, and at a temperature at which foaming and vulcanization are difficult to proceed, foaming agents, foaming aids, vulcanization accelerators, By adding a vulcanizing agent and kneading, foaming and early vulcanization of the rubber composition can be prevented. In addition, although a process (c) may be immediately after a process (b), you may implement another mixing process between a process (b) and a process (c).
The maximum temperature of the mixture in the step (c) is preferably in the range of 60 to 140 ° C, more preferably in the range of 80 to 120 ° C, and still more preferably in the range of 100 to 120 ° C. 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 further preferably in the range of 20 seconds to 5 minutes. When proceeding from step (b) to step (c), it is preferable to proceed to step (c) after lowering the temperature of the mixture by 10 ° C. or more from the temperature after completion of step (b).

As described above, the rubber composition produced through at least the step (a) and the step (b) can be further heated, extruded, vulcanized, etc. to obtain a vulcanized rubber.
The heating conditions are not particularly limited, and various conditions such as the heating temperature, the heating time, and the heating apparatus can be appropriately selected according to the purpose. Examples of the heating device include a roll machine ordinarily used for heating a rubber composition.
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 according to the purpose. As said extrusion apparatus, the extruder etc. which are normally used for extrusion of the rubber composition for tires are mentioned, for example. The extrusion temperature can be appropriately determined.
There is no restriction | limiting in particular about the apparatus, system, conditions, etc. which perform the said vulcanization | cure, According to the objective, it can select suitably. Examples of the vulcanizing apparatus include a molding vulcanizer using a mold usually used for vulcanizing a rubber composition for tires.

<Tire>
The tire of the present invention is characterized by using the above rubber composition, and the above rubber composition is preferably used for a tread. A tire using the rubber composition as a tread is excellent in both on-ice performance and wear resistance, and is useful as a winter tire such as a studless tire.
The tire of the present invention may be obtained by vulcanization after molding using an unvulcanized rubber composition according to the type and member of the tire to be applied, or semi-vulcanized rubber that has undergone a preliminary vulcanization process or the like. It may be obtained by further vulcanization after use. In addition, as gas with which a tire is filled, inert gas, such as nitrogen, argon, helium other than the air which adjusted normal or oxygen partial pressure, can be used.

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

<Preparation of rubber composition>
The rubber composition was manufactured by mixing in the order of the first mixing step, the second mixing step, and the final mixing step using an ordinary Banbury mixer with the formulation shown in Tables 1-2. In addition, after the end of the first mixing step, the mixture is once taken out from the Banbury mixer, and then the mixture is again charged into the Banbury mixer to perform the second mixing step. After the second mixing step, the mixture is removed. Once removed from the Banbury mixer, the mixture was again charged into the Banbury mixer to carry out the final mixing step. The maximum temperature of the mixture in the first mixing step and the second mixing step was 170 ° C., and the maximum temperature of the rubber composition in the final mixing step was 110 ° C. Here, the first mixing step corresponds to the step (a), and the second mixing step corresponds to the step (b).
In Comparative Example 1, after the first mixing step, the second mixing step was omitted and the final mixing step was performed.
Further, when observed with a scanning probe microscope according to the method described in paragraph [0009], the phase separation structure was confirmed in each rubber composition, and a plurality of incompatible polymer phases were formed.

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

(1) Abrasion resistance After traveling 10,000 km on a paved road surface with the actual vehicle using the test tire, the remaining groove was measured, and the travel distance required for the tread to wear by 1 mm was compared. The tires were indexed with 100 as the tire. It shows that abrasion resistance is so favorable that an index value is large.

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

* 1 Polybutadiene rubber: cis-1,4-polybutadiene rubber, trade name “UBEPOL 150L”, manufactured by Ube Industries, Tg = −110 ° C.
* 2 Modified polybutadiene rubber 1: Modified polybutadiene rubber synthesized by the following method, Tg = −95 ° C.
* 3 Modified polybutadiene rubber 2: Modified polybutadiene rubber synthesized by the following method, Tg = −95 ° C.
* 4 Natural rubber: Tg = -60 ° C
* 5 Modified natural rubber: Modified natural rubber synthesized by the following method, Tg = −60 ° C.
* 6 Modified natural rubber: Modified natural rubber synthesized by the following method, Tg = −60 ° C.
* 7 Carbon black: N134, Asahi Carbon, N ₂ SA = 146 m ² / g
* 8 Silica: Trade name “Nipsil AQ”, manufactured by Tosoh Silica, CTAB specific surface area = 150 m ² / g
* 9 Large particle size silica: Product name “Nipsil EQ”, manufactured by Tosoh Silica, CTAB specific surface area = 100 m ² / g
* 10 Fine particle silica: Product name “Nip Seal HQ”, manufactured by Tosoh Silica, CTAB specific surface area = 200 m ² / g
* 11 Silane coupling agent: "Si69", manufactured by Evonic * 12 Process oil: Naphthenic process oil, trade name "Diana Process Oil NS-24", manufactured by Idemitsu Kosan, pour point = -30 ° C
* 13 Antioxidant IPPD: N-isopropyl -N'- phenyl -p- phenylene diamine * 14 _{C 5} resin: trade name "Escorez 1102", Tonen manufactured * 15 hydrophilic short fiber: were prepared by the following method Hydrophilic short fiber * 16 Vulcanization accelerator 1: Di-2-benzothiazolyl disulfide (MBTS)
* 17 Vulcanization accelerator 2: N-cyclohexyl-2-benzothiazolylsulfenamide (CBS)
* 18 Foaming agent: Dinitrosopentamethylenetetramine (DNPT)

<Modified polybutadiene rubber 1>
Into a pressure-resistant glass container having an internal volume of about 900 mL that has been dried and purged with nitrogen, 283 g of cyclohexane, 100 g of 1,3-butadiene monomer, and 0.015 mmol of 2,2-ditetrahydrofurylpropane are injected as a cyclohexane solution. After adding 50 mmol of n-butyllithium (n-BuLi), polymerization was performed in a 50 ° C. warm water bath equipped with a stirrer for 4.5 hours. The polymerization conversion rate 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, 0.5 mL of an isopropanol solution (BHT concentration: 5% by mass) of 2,6-di-tert-butyl-p-cresol (BHT) was added to stop the reaction, and further dried according to a conventional method. A 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>
Into a pressure-resistant glass container with an internal volume of about 900 mL that has been dried and purged with nitrogen, 283 g of cyclohexane, 50 g of 1,3-butadiene, 0.0057 mmol of 2,2-ditetrahydrofurylpropane and 0.513 mmol of hexamethyleneimine are each injected as a cyclohexane solution. Then, 0.57 mmol of n-butyllithium (n-BuLi) was added thereto, and then a polymerization reaction was carried out for 4.5 hours in a 50 ° C. warm water bath equipped with a stirrer. The polymerization conversion rate at this time was almost 100%.
Next, 0.100 mmol of tin tetrachloride was added to the polymerization reaction system as a cyclohexane solution, and the mixture was stirred at 50 ° C. for 30 minutes. Thereafter, 0.5 mL of an isopropanol solution (BHT concentration: 5% by mass) of 2,6-di-tert-butyl-p-cresol (BHT) was added to the reaction system to stop the polymerization reaction, and further according to a conventional method. By drying, modified polybutadiene rubber 2 was obtained.
The resulting modified polybutadiene rubber 2 had a modification rate of 1.2 and a glass transition temperature of -95 ° C.

<Modified natural rubber>
The field latex was centrifuged at a rotational speed of 7500 rpm using a latex separator (manufactured by Saito Centrifugal Co., Ltd.) to obtain a concentrated latex having a dry rubber concentration of 60%. 1000 g of this 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 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 to coagulate the modified natural rubber latex. The solid material thus obtained was treated with a creper five times, passed through a shredder and crushed, and then dried at 110 ° C. for 210 minutes with a hot air dryer to obtain a modified natural rubber.
From the mass of the modified natural rubber thus obtained, it was confirmed that the conversion rate of the added 4-vinylpyridine was 100%. In addition, the modified natural rubber was extracted with petroleum ether and further extracted with a 2: 1 mixed solvent of acetone and methanol to try to separate the homopolymer. However, when the extract was analyzed, the homopolymer was not detected. It was confirmed that 100% of the added monomer was introduced into the natural rubber molecule.

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

<Hydrophilic short fiber>
In accordance with Production Example 3 disclosed in JP2012-219245A, two twin-screw extruders were used, and 40 parts by mass of polyethylene [manufactured by Nippon Polyethylene, Novatec HJ360 (MFR5.5, melting point 132 ° C.)] as a hopper, ethylene -40 parts by weight of vinyl alcohol copolymer [manufactured by Kuraray, Eval F104B (MFR4.4, melting point 183 ° C)] and extruded simultaneously from the die exit, and the fibers obtained in accordance with the usual method to a length of 2 mm The hydrophilic short fiber in which the coating layer which consists of polyethylene was formed was cut.

  From the results of 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 produced 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 tread rubber of a tire, particularly a studless tire. The tire of the present invention is useful as a studless tire.

Claims (14)

Including at least two diene polymers that form a plurality of incompatible polymer phases, silica, and carbon black,
At least two of the diene polymers have a blending amount of 20% by mass or more of the total amount of the diene polymer, and the blending amount is 20% by mass or more of the total amount of the diene polymer. The blending amount of the diene polymer (A) having the lowest glass transition temperature (Tg) among the blends is the diene having the largest blending amount among the diene polymers other than the diene polymer (A). 85 mass% or more of the blend amount of the polymer,
The compounding amount of the silica is 25 parts by mass or more with respect to a total of 100 parts by mass of the diene polymer,
The amount of the carbon black is 25 parts by mass or more with respect to a total of 100 parts by mass of the diene polymer,
A step (a) of preparing a master batch by mixing the diene polymer (A) having the lowest glass transition temperature (Tg) and a part or all of the carbon black;
A step (b) of mixing the prepared masterbatch with the remainder of the diene polymer other than the diene polymer (A) having the lowest glass transition temperature (Tg) and the silica; ,
A process for producing a rubber composition, comprising:   The diene polymer (A) having the lowest glass transition temperature (Tg) has the largest compounding amount among the diene polymers, or the diene polymer other than the diene polymer (A). The method for producing a rubber composition according to claim 1, wherein the blending amount is the same as that of the diene polymer having the largest blending 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 (B) having the highest glass transition temperature (Tg) among diene polymers whose blending amount is 20% by mass or more of the total amount of the diene polymer has an isoprene skeleton. The manufacturing method of the rubber composition as described in any one of 1-4.   The method for producing a rubber composition according to claim 5, wherein the diene polymer (B) having the highest glass transition temperature (Tg) is natural rubber.   The rubber according to any one of claims 1 to 6, 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 7, wherein the diene polymer (A) having the lowest glass transition temperature (Tg) contains both a tin atom and a nitrogen atom.   The diene polymer (A) having the lowest glass transition temperature (Tg) has a modification rate of 1.1 or more and 2.5 or less by a compound containing at least one of the tin atom and the nitrogen atom. The manufacturing method of the rubber composition of 8.   The manufacturing method of the rubber composition as described in any one of Claims 1-9 in which the said rubber composition contains a foaming agent further. Method for producing a rubber composition, further comprising a C ₅ resin, a rubber composition according to any one of claims 1 to 10.   The manufacturing method of the rubber composition as described in any one of Claims 1-11 in which the said rubber composition contains a hydrophilic short fiber further.   A rubber composition produced by the method for producing a rubber composition according to any one of claims 1 to 12.   A tire comprising the rubber composition according to claim 13.