JP6701892B2 - Rubber composition for heavy duty tires - Google Patents

Description

  The present invention relates to a rubber composition for heavy-duty tires, which can provide a rubber crosslinked product having high tensile strength and tensile stress and excellent wear resistance, and can be suitably used for heavy-duty tire applications.

  Butadiene rubber and styrene-butadiene rubber are widely used as synthetic rubbers used as tire materials. Butadiene, which is a raw material for butadiene rubber and styrene-butadiene rubber, is produced as a by-product when ethylene is produced by cracking naphtha.In recent years, however, natural gas such as ethane has been used as a raw material for producing ethylene. Due to the expansion of the method for producing butadiene, it is expected that the production amount of butadiene will decrease. Therefore, various studies have been conducted on the use of synthetic rubber that does not use butadiene as a raw material as a substitute material for butadiene rubber or styrene-butadiene rubber.

  A cyclic olefin ring-opening polymer that can be obtained by ring-opening polymerization of a cyclic olefin such as cyclopentene is mentioned as a kind of synthetic rubber that has been studied as a substitute material for butadiene rubber and styrene-butadiene rubber. For example, in Patent Document 1, ring-opening polymerization of cyclopentene is carried out in the presence of a compound having a modifying group and an ethylenically unsaturated bond to introduce a modifying group at the terminal of a cyclopentene ring-opening polymer, and thus cyclopentene opening Techniques have been proposed for improving the affinity between the ring polymer and the inorganic particles.

  However, in the rubber cross-linked product obtained from the rubber composition containing the cyclopentene ring-opening polymer specifically disclosed in Patent Document 1, the tensile strength and the tensile stress, and further the abrasion resistance are not sufficient. In some cases, it is not always suitable for use in applications where characteristics are particularly required, such as heavy-duty tire applications.

International Publication No. 2011/087072

  An object of the present invention is to provide a rubber composition for heavy-duty tires, which has a high tensile strength and a high tensile stress and can give a rubber cross-linked product having excellent wear resistance.

As a result of earnest studies to achieve the above-mentioned object, the present inventors have found that the terminal modified group-containing cyclic olefin ring-opening polymer has silica and a nitrogen adsorption specific surface area of 90 to 150 m ² /g measured by the BET method. It was found that the above object can be achieved by a rubber composition in which the above-mentioned carbon black is blended and the blending amount of carbon black is within a specific range, and the present invention has been completed.

That is, according to the present invention, a heavy-duty tire containing a terminal-modified group-containing cyclic olefin ring-opening polymer, silica, and carbon black having a nitrogen adsorption specific surface area of 90 to 150 m ² /g measured by the BET method. A rubber composition for heavy-duty tires, wherein the content ratio of the carbon black is 20 to 60 parts by weight relative to 100 parts by weight of the rubber component contained in the rubber composition for heavy-duty tires. Provided.

In the above-mentioned rubber composition for heavy duty tires, the cyclic olefin ring-opening polymer containing a terminal modifying group is preferably a polymer having an oxysilyl group introduced at the end of the polymer chain.
The above rubber composition for heavy duty tires preferably further contains natural rubber as the rubber component, and the content ratio of the natural rubber in the rubber component is more preferably 30 to 80% by weight.

  Further, according to the present invention, a rubber cross-linked product obtained by cross-linking the above rubber composition for heavy-duty tires, and a heavy-duty tire including the rubber cross-linked product are provided.

  According to the present invention, a rubber composition for heavy-duty tires having high tensile strength and tensile stress and capable of giving a rubber cross-linked product having excellent wear resistance, and such a rubber composition for heavy-duty tires are used. It is possible to provide a rubber cross-linked product obtained by the above, which has high tensile strength and tensile stress and is excellent in wear resistance.

<Rubber composition for heavy duty tires>
The rubber composition for heavy-duty tires of the present invention contains a cyclic olefin ring-opening polymer containing a terminal modified group, silica, and carbon black having a nitrogen adsorption specific surface area of 90 to 150 m ² /g measured by the BET method. A rubber composition for heavy-duty tires, wherein the content ratio of the carbon black is 20 to 60 parts by weight with respect to 100 parts by weight of the rubber component contained in the rubber composition for heavy-duty tires. is there.

<Terminal modifying group-containing cyclic olefin ring-opening polymer>
The terminal modified group-containing cyclic olefin ring-opening polymer used in the present invention comprises, as a repeating unit constituting the main chain thereof, a repeating unit obtained by ring-opening polymerization of a cyclic olefin, and substantially It is preferably composed only of repeating units obtained by ring-opening polymerization, and contains a modifying group at the polymer chain end.

The cyclic olefin for forming the terminal modified group-containing cyclic olefin ring-opening polymer used in the present invention is not particularly limited, and examples thereof include monocyclic olefins, monocyclic dienes, monocyclic trienes and polycyclic cyclic olefins, and polycyclic olefins. Examples include cyclic cyclic dienes and polycyclic cyclic trienes. Examples of the monocyclic olefin include cyclopentene that may have a substituent and cyclooctene that may have a substituent, and cyclopentene is preferable. Examples of monocyclic dienes include 1,5-cyclooctadiene which may have a substituent. Examples of the monocyclic triene include 1,5,9-cyclododecatriene which may have a substituent. In addition, examples of the polycyclic cyclic olefin, the polycyclic cyclic diene, and the polycyclic cyclic triene include 2-norbornene, dicyclopentadiene, 1,4-methano-1,4,4a,9a-tetrahydro-9H-fluorene. , Tetracyclo[6.2.1.1 ^3,6 . Examples thereof include a norbornene compound which may have a substituent such as 0 ^2,7 ]dodec-4-ene. As the terminal modified group-containing cyclic olefin ring-opening polymer used in the present invention, those having a structural unit derived from a monocyclic olefin as a repeating unit constituting the main chain are preferable, The content ratio of the structural unit derived from the monocyclic olefin is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more with respect to all the repeating structural units. Further, among the structural units derived from monocyclic olefins, structural units derived from cyclopentene are preferable. By setting the content ratio of the structural unit derived from a monocyclic olefin in the above range, the glass transition temperature of the terminal-modified group-containing cyclic olefin ring-opening polymer used in the present invention can be set low, whereby the low temperature The rubber characteristics can be improved.

  The terminal modifying group-containing cyclic olefin ring-opening polymer used in the present invention has a modifying group at the polymer chain end, and such a modifying group is not particularly limited, but is an atom of Group 15 of the periodic table. It is preferably a modifying group containing an atom selected from the group consisting of an atom of Group 16 of the periodic table and a silicon atom. By containing a terminal modifying group, it is possible to increase the affinity for silica, thereby, it is possible to enhance the dispersibility of silica in the rubber composition, as a result, in the case of a rubber cross-linked product, The tensile strength, tensile stress and wear resistance can be improved.

  As the modifying group for forming the terminal modifying group, it is possible to increase the affinity for silica, and thereby, it is possible to further increase the tensile strength, tensile stress and abrasion resistance in the case of forming a rubber cross-linked product. From the viewpoint, a modifying group containing an atom selected from the group consisting of a nitrogen atom, an oxygen atom, a phosphorus atom, a sulfur atom, and a silicon atom is more preferable, and among these, a nitrogen atom, an oxygen atom, and a silicon atom are formed. Further preferred are modifying groups containing atoms selected from the group.

  Examples of the modifying group containing a nitrogen atom include an amino group, a pyridyl group, an imino group, an amide group, a nitro group, a urethane bonding group, or a hydrocarbon group containing these groups. Examples of the modifying group containing an oxygen atom include a hydroxyl group, a carboxylic acid group, an ether group, an ester group, a carbonyl group, an aldehyde group, an epoxy group, or a hydrocarbon group containing these groups. Examples of the modifying group containing a silicon atom include an alkylsilyl group, an oxysilyl group, and a hydrocarbon group containing these groups. Examples of the modifying group containing a phosphorus atom include a phosphoric acid group, a phosphino group, and a hydrocarbon group containing these groups. Examples of the modifying group containing a sulfur atom include a sulfonyl group, a thiol group, a thioether group, and a hydrocarbon group containing these groups. The modifying group may be a modifying group containing a plurality of the above groups. Among these, specific examples of the modifying group particularly suitable from the viewpoint that the tensile strength, tensile stress and abrasion resistance in the case of a rubber crosslinked product can be further increased include an amino group, a pyridyl group and an imino group. , An amide group, a hydroxyl group, a carboxylic acid group, an aldehyde group, an epoxy group, an oxysilyl group, or a hydrocarbon group containing these groups, and an oxysilyl group is particularly preferable from the viewpoint of affinity for silica.

（上記一般式（１）中、Ｒ^１およびＲ^２は、それぞれ、水素原子、またはヘテロ原子が介在していてもよい炭素数１〜２０の炭化水素基を表す。ａは１〜３の整数である。） The oxysilyl group is a group having a silicon-oxygen bond. Examples of the oxysilyl group include groups represented by the following general formula (1).

(In the general formula (1), R ¹ and R ² each represent a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which may have a heteroatom interposed therebetween. a is an integer of 1 to 3. It is.)

  In the above general formula (1), the hydrocarbon group having 1 to 20 carbon atoms which may have a hetero atom interposed therein is an alkyl group having 1 to 20 carbon atoms, an aryl group, an acyl group, an alkylsilyl group or an arylsilyl group. Groups are exemplified. Among these, an alkyl group having 1 to 20 carbon atoms is preferable, an alkyl group having 1 to 4 carbon atoms is more preferable, and a methyl group and an ethyl group are further preferable, from the viewpoint of high affinity with silica.

  In the above general formula (1), a is an integer of 1 to 3, but a is preferably 2 or 3, and from the viewpoint of productivity, a is more preferably 3.

  Examples of such an oxysilyl group include an alkoxysilyl group, an aryloxysilyl group, an acyloxysilyl group, an alkylsiloxysilyl group, an arylsiloxysilyl group, and a hydroxysilyl group. Among these, the alkoxysilyl group is more preferable because it has a high affinity with silica and can further enhance the effects of improving the tensile strength, tensile stress, and abrasion resistance of the obtained rubber cross-linked product.

  The alkoxysilyl group is a group in which one or more alkoxy groups are bonded to a silicon atom, and specific examples thereof include trimethoxysilyl group, (dimethoxy)(methyl)silyl group, (methoxy)(dimethyl)silyl. Group, triethoxysilyl group, (diethoxy)(methyl)silyl group, (ethoxy)(dimethyl)silyl group, (dimethoxy)(ethoxy)silyl group, (methoxy)(diethoxy)silyl group, tripropoxysilyl group, tributoxy Examples thereof include a silyl group.

  The aryloxysilyl group is a group in which one or more aryloxy groups are bonded to a silicon atom, and specific examples thereof include triphenoxysilyl group, (diphenoxy)(methyl)silyl group, (phenoxy)(dimethyl). Examples thereof include a silyl group, a (diphenoxy)(ethoxy)silyl group, and a (phenoxy)(diethoxy)silyl group. Note that, of these, the (diphenoxy)(ethoxy)silyl group and the (phenoxy)(diethoxy)silyl group have an alkoxy group in addition to the aryloxy group, and are therefore classified as an alkoxysilyl group.

  The acyloxysilyl group is a group in which one or more acyloxy groups are bonded to a silicon atom, and specific examples thereof include triacyloxysilyl group, (diacyloxy)(methyl)silyl group, (acyloxy)(dimethyl) Examples thereof include a silyl group.

  The alkylsiloxysilyl group is a group in which one or more alkylsiloxy groups are bonded to a silicon atom, and specific examples thereof include tris(trimethylsiloxy)silyl group, trimethylsiloxy(dimethyl)silyl group, triethylsiloxy( Examples thereof include a diethyl)silyl group and a tris(dimethylsiloxy)silyl group.

  The arylsiloxysilyl group is a group in which one or more arylsiloxy groups are bonded to a silicon atom, and specific examples thereof include tris(triphenylsiloxy)silyl group, triphenylsiloxy(dimethyl)silyl group and tris. (Diphenylsiloxy)silyl group and the like.

  The hydroxysilyl group is a group in which one or more hydroxy groups are bonded to a silicon atom, and specific examples include trihydroxysilyl group, (dihydroxy)(methyl)silyl group, (hydroxy)(dimethyl)silyl group. , (Dihydroxy)(ethoxy)silyl group, (hydroxy)(diethoxy)silyl group and the like. Note that, of these, the (dihydroxy)(ethoxy)silyl group and the (hydroxy)(diethoxy)silyl group have an alkoxy group in addition to the hydroxy group, and thus are classified as an alkoxysilyl group.

  The terminal modified group-containing cyclic olefin ring-opening polymer used in the present invention has both polymer chain terminals (both terminals) even if the modified group is introduced into only one polymer chain terminal (one terminal). A modified group may be introduced into the above, or these may be mixed. In addition, the terminal modified group-containing cyclic olefin ring-opening polymer may include an unmodified polymer chain in which a modifying group is not introduced.

In the polymer chain terminal of the terminal modified group-containing cyclic olefin ring-opening polymer used in the present invention, the introduction ratio of the modifying group is not particularly limited, but the number of cyclic olefin ring-opening polymer chain terminals in which the modifying group is introduced/cyclic The percentage value of the total number of chain ends of the olefin ring-opening polymer is preferably 10% or more, more preferably 20% or more, further preferably 30% or more, and particularly preferably 40% or more. The higher the introduction ratio of the modifying group is, the higher the affinity with silica is, and thereby, the tensile strength, tensile stress and abrasion resistance of the obtained rubber cross-linked product can be further enhanced. The method of measuring the introduction ratio of the modifying group to the polymer chain terminal is not particularly limited, but for example, the peak area ratio corresponding to the modifying group determined by ¹ H-NMR spectrum measurement and gel permeation chromatography. It can be determined from the number average molecular weight determined from the graph.

  The molecular weight of the terminal-modified group-containing cyclic olefin ring-opening polymer used in the present invention is not particularly limited, but is preferably a polystyrene-equivalent weight average molecular weight (Mw) value measured by gel permeation chromatography. It is 100,000 to 800,000, more preferably 150,000 to 750,000, and further preferably 200,000 to 700,000. The terminal modified group-containing cyclic olefin ring-opening polymer having such a molecular weight can more appropriately enhance the tensile strength of the obtained rubber cross-linked product.

  The ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the terminal modified group-containing cyclic olefin ring-opening polymer used in the present invention, measured by gel permeation chromatography, is Although not limited, it is usually 1.1 to 5.0, preferably 1.2 to 4.5, and more preferably 1.3 to 4.0. By having such Mw/Mn, the tensile strength of the obtained rubber cross-linked product can be increased more appropriately.

  In the double bond present in the repeating unit constituting the cyclic olefin ring-opening polymer containing a terminal-modified group used in the present invention, the cis/trans ratio is not particularly limited, but is usually in the range of 10/90 to 90/10. It is preferably in the range of 30/70 to 90/10 from the viewpoint of obtaining a rubber composition which is set by the above and can give a crosslinked rubber exhibiting excellent properties at low temperature.

  The glass transition temperature of the terminal-modified group-containing cyclic olefin ring-opening polymer used in the present invention is preferably −40° C. or lower, more preferably −60° C. or lower, and further preferably from the viewpoint of exhibiting good rubber elasticity. It is −90° C. or lower. On the other hand, the lower limit of the glass transition temperature (Tg) is not particularly limited, but preferably −120° C. or higher. The glass transition temperature of the cyclic olefin ring-opening polymer containing a terminal-modifying group can be adjusted by, for example, adjusting the cis/trans ratio in the double bond present in the repeating unit.

  The terminal modified group-containing cyclic olefin ring-opening polymer used in the present invention may have a melting point. When the terminal-modified group-containing cyclic olefin ring-opening polymer has a melting point, its temperature is preferably 0° C. or lower, and −10° C. or lower, from the viewpoint of improving the rubber properties at low temperatures. Is more preferable. The presence or absence of the melting point of the cyclic olefin ring-opening polymer containing a terminal-modifying group, and the temperature in the case of having the melting point, can be adjusted by adjusting the cis/trans ratio in the double bond existing in the repeating unit. it can.

  The method for producing the terminal modified group-containing cyclic olefin ring-opening polymer used in the present invention is not particularly limited, and for example, in the presence of a modified group-containing olefin compound which is a compound having an olefinic unsaturated bond group and a modified group, a cyclic The method of ring-opening-polymerizing an olefin is mentioned. By carrying out the ring-opening polymerization in the presence of the modifying group-containing olefin compound, the ring-opening polymerization of the cyclic olefin and the terminal modification with the modifying group-containing olefin compound can be carried out simultaneously, which is simple and preferable. For example, when it is desired to introduce an oxysilyl group at the polymer chain end of the cyclic olefin ring-opening polymer, an oxysilyl group-containing olefin compound may be used as the modifying group-containing olefin compound.

  Such an oxysilyl group-containing olefin compound is not particularly limited and may be appropriately selected depending on the type of the oxysilyl group introduced at the polymer chain terminal. For example, the following general formula (2) or (3) The compounds shown may be mentioned.

（上記一般式（２）中、Ｒ^３〜Ｒ^５は、それぞれ、水素原子、または炭素数１〜１０の炭化水素基であり、Ｒ^６、Ｒ^７は、それぞれ、水素原子、またはヘテロ原子が介在していてもよい炭素数１〜２０の炭化水素基である。また、Ｌ^１は、単結合またはオキシシリル基とオレフィン性炭素−炭素二重結合を形成している炭素原子とを結ぶ基であり、ｂは１〜３の整数である。）

(In the general formula (2), R ^{3 to} R ⁵ are each a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and R ⁶ and R ⁷ are each a hydrogen atom or a hetero atom. It is an optionally interposed hydrocarbon group having 1 to 20 carbon atoms, and L ¹ is a group connecting a single bond or an oxysilyl group and a carbon atom forming an olefinic carbon-carbon double bond. And b is an integer of 1 to 3.)

（上記一般式（３）中、Ｒ^１０、Ｒ^１１は、それぞれ、水素原子、または炭素数１〜１０の炭化水素基であり、Ｒ^８、Ｒ^９、Ｒ^１２、Ｒ^１３は、それぞれ、水素原子、またはヘテロ原子が介在していてもよい炭素数１〜２０の炭化水素基である。また、Ｌ^２、Ｌ^３は、それぞれ、単結合、またはオキシシリル基とオレフィン性炭素−炭素二重結合を形成している炭素原子とを結ぶ基であり、ｃ，ｄは１〜３の整数である。）

(In the general formula (3), R ¹⁰ and R ¹¹ are each a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and R ⁸ , R ⁹ , R ¹² , and R ¹³ are each hydrogen. An atom or a hydrocarbon group having 1 to 20 carbon atoms in which a hetero atom may be present, and L ² and L ³ are each a single bond, or an oxysilyl group and an olefinic carbon-carbon double bond. Which is a group connecting with the carbon atom forming c, and c and d are integers of 1 to 3.)

  In the general formulas (2) and (3), the hydrocarbon group having 1 to 20 carbon atoms in which a hetero atom may intervene is an alkyl group having 1 to 20 carbon atoms, an aryl group, an acyl group, or an alkylsilyl group. Group and an arylsilyl group are exemplified.

In the general formulas (2) and (3), R ^{3 to} R ⁵ , R ¹⁰ and R ¹¹ are preferably hydrogen atoms, and by making them hydrogen atoms, the oxysilyl group-containing olefin compound is metathesis-reactive. Can be more excellent.

Further, in the above general formulas (2) and (3), L ^{1 to} L ³ may be any group as long as they can bond an oxysilyl group and a carbon atom forming an olefinic carbon-carbon double bond. Although not limited, a hydrocarbon group, an ether group, or a tertiary amino group is preferable from the viewpoint that an oxysilyl group-containing olefin compound can be made more excellent in metathesis reactivity, and an aliphatic carbon atom having 1 to 20 carbon atoms is preferable. A hydrogen group and an aromatic hydrocarbon group having 6 to 20 carbon atoms are more preferable. Further, the oxysilyl group and the carbon atom forming the olefinic carbon-carbon double bond may be directly bonded to each other without passing through these groups.

  In addition, when the compound represented by the general formula (2) is used among the compounds represented by the general formulas (2) and (3), these compounds undergo a metathesis reaction to give a cyclic olefin ring-opening polymer. An oxysilyl group can be introduced at one end, and when the compound represented by the general formula (3) is used, these undergo a metathesis reaction to give an oxysilyl group at both ends of the cyclic olefin ring-opening polymer. Can be introduced.

  Preferred specific examples of the compound represented by the general formula (2) include vinyl(trimethoxy)silane, vinyl(triethoxy)silane, allyl(trimethoxy)silane, allyl(methoxy)(dimethyl)silane, allyl(triethoxy)silane and allyl. Alkoxy such as (ethoxy)(dimethyl)silane, styryl(trimethoxy)silane, styryl(triethoxy)silane, styrylethyl(triethoxy)silane, allyl(triethoxysilylmethyl)ether, allyl(triethoxysilylmethyl)(ethyl)amine Silane compounds; aryloxysilane compounds such as vinyl(triphenoxy)silane, allyl(triphenoxy)silane, allyl(phenoxy)(dimethyl)silane; vinyl(triacetoxy)silane, allyl(triacetoxy)silane, allyl(diacetoxy) Acyloxysilane compounds such as methylsilane and allyl(acetoxy)(dimethyl)silane; alkylsiloxysilane compounds such as allyltris(trimethylsiloxy)silane; arylsiloxysilane compounds such as allyltris(triphenylsiloxy)silane; 1-allylheptamethyltri Polysiloxane compounds such as siloxane, 1-allylnonamethyltetrasiloxane, 1-allylnonamethylcyclopentasiloxane, 1-allylundecamethylcyclohexasiloxane; and the like.

  Preferred specific examples of the compound represented by the general formula (3) include bis(trimethoxysilyl)ethylene, bis(triethoxysilyl)ethylene, 2-butene-1,4-di(trimethoxysilane), and 2-butene. Alkoxysilane compounds such as -1,4-di(triethoxysilane) and 1,4-di(trimethoxysilylmethoxy)-2-butene; aryl such as 2-butene-1,4-di(triphenoxysilane) Roxysilane compound; Acyloxysilane compound such as 2-butene-1,4-di(triacetoxysilane); Alkylsiloxysilane compound such as 2-butene-1,4-di[tris(trimethylsiloxy)silane]; 2 -Arylsiloxysilane compounds such as butene-1,4-di[tris(triphenylsiloxy)silane]; 2-butene-1,4-di(heptamethyltrisiloxane), 2-butene-1,4-di( Undecamethylcyclohexasiloxane) and the like; and the like.

  The amount of the modifying group-containing olefin compound to be used may be appropriately selected according to the molecular weight of the terminal modifying group-containing cyclic olefin ring-opening polymer to be produced, but is usually 1 in molar ratio with respect to the monomer used for the polymerization. /100 to 1/100,000, preferably 1/200 to 1/50,000, and more preferably 1/500 to 1/10,000. The modifying group-containing olefin compound acts as a molecular weight modifier in addition to the function of introducing the modifying group into the polymer chain terminal of the cyclic olefin ring-opening polymer. When the amount of the modifying group-containing olefin compound used is too small, the rate of introduction of the modifying group in the terminal modifying group-containing cyclic olefin ring-opening polymer becomes low, and when the amount is too large, the molecular weight of the terminal modifying group-containing cyclic olefin ring-opening polymer obtained. May be low.

  Further, as a ring-opening polymerization catalyst that can be used in the method of ring-opening polymerization of a cyclic olefin in the presence of a modifying group-containing olefin compound, for example, a ruthenium carbene complex can be mentioned.

  The ruthenium carbene complex is not particularly limited as long as it serves as a ring-opening polymerization catalyst for cyclic olefins. Specific examples of the preferably used ruthenium carbene complex include bis(tricyclohexylphosphine)benzylidene ruthenium dichloride, bis(triphenylphosphine)-3,3-diphenylpropenylidene ruthenium dichloride, bis(tricyclohexylphosphine) t-butylvinylidene. Ruthenium dichloride, bis(1,3-diisopropylimidazoline-2-ylidene) benzylidene ruthenium dichloride, bis(1,3-dicyclohexyl imidazoline-2-ylidene) benzylidene ruthenium dichloride, (1,3-dimesityl imidazoline-2-ylidene ) (Tricyclohexylphosphine) benzylidene ruthenium dichloride, (1,3-Dimesitylimidazolidin-2-ylidene) (tricyclohexylphosphine) benzylidene ruthenium dichloride, bis(tricyclohexylphosphine) ethoxymethylidene ruthenium dichloride, (1,3) -Dimesityl imidazolidine-2-ylidene) (tricyclohexylphosphine) ethoxymethylidene ruthenium dichloride and the like.

  The amount of the ruthenium carbene complex used is not particularly limited, but is usually 1:1,000 to 1:2,000,000 as a molar ratio of (metal ruthenium in the catalyst:monomer used for polymerization). , Preferably 1:2,000 to 1:1,500,000, more preferably 1:3,000 to 1:1,000,000. If the amount used is too small, the polymerization reaction may not proceed sufficiently. On the other hand, if the amount is too large, it becomes difficult to remove the catalyst residue from the obtained terminal modified group-containing cyclic olefin ring-opening polymer.

  The polymerization reaction may be carried out in the absence of a solvent, but it is preferably carried out in a solution from the viewpoint of controlling the polymerization reaction and the like. When polymerizing in a solution, the solvent used is inert in the polymerization reaction and is not particularly limited as long as it can dissolve the cyclic olefin used for the polymerization, the polymerization catalyst and the like, but a hydrocarbon solvent or a halogen solvent is used. It is preferable to use. Examples of the hydrocarbon solvent include aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; aliphatic hydrocarbons such as n-hexane, n-heptane, and n-octane; cyclohexane, cyclopentane, methylcyclohexane, and the like. Alicyclic hydrocarbon; and the like. Examples of the halogen-based solvent include alkyl halogen such as dichloromethane and chloroform; aromatic halogen such as chlorobenzene and dichlorobenzene.

  The polymerization temperature is not particularly limited, but is usually set in the range of -50 to 100°C. The polymerization reaction time is preferably 1 minute to 72 hours, more preferably 5 hours to 20 hours. After the polymerization conversion rate reaches a predetermined value, the polymerization reaction can be stopped by adding a known polymerization terminator to the polymerization system.

  Alternatively, as another ring-opening polymerization catalyst that can be used in the method of ring-opening polymerization of a cyclic olefin in the presence of a modifying group-containing olefin compound, a molybdenum compound or a tungsten compound can be mentioned. Specific examples of the molybdenum compound that can be used as the ring-opening polymerization catalyst include molybdenum pentachloride, molybdenum oxotetrachloride, molybdenum (phenylimide) tetrachloride, and the like. In addition, specific examples of the tungsten compound include tungsten hexachloride, tungsten oxotetrachloride, tungsten (phenylimide) tetrachloride, monocatecholate tungsten tetrachloride, bis(3,5-ditertiarybutyl)catecholate tungsten dichloride, and bis. (2-chloro etherate) tetrachloride, tungsten oxo tetraphenolate, etc. can be mentioned.

  When a molybdenum compound or a tungsten compound is used as a ring-opening polymerization catalyst, an organometallic compound may be used in combination as a co-catalyst. Examples of the organometallic compound that can be used as the cocatalyst include organometallic compounds having a metal atom of Group 1, 2, 12, 13 or 14 of the periodic table having a hydrocarbon group having 1 to 20 carbon atoms. Among them, organolithium compounds, organomagnesium compounds, organozinc compounds, organoaluminum compounds, organotin compounds are preferably used, organolithium compounds, organotin compounds, organoaluminum compounds are more preferably used, and organoaluminum compounds are particularly preferred. Used.

  Specific examples of the organolithium compound that can be used as a cocatalyst include n-butyllithium, methyllithium, phenyllithium, neopentyllithium, neophylllithium, and the like. Specific examples of the organomagnesium compound include butylethylmagnesium, butyloctylmagnesium, dihexylmagnesium, ethylmagnesium chloride, n-butylmagnesium chloride, allylmagnesium bromide, neopentylmagnesium chloride and neophyllmagnesium chloride. Specific examples of the organic zinc compound include dimethyl zinc, diethyl zinc, and diphenyl zinc. Specific examples of the organic tin compound include tetramethyltin, tetra(n-butyl)tin, and tetraphenyltin. Specific examples of the organic aluminum compound include trialkylaluminums such as trimethylaluminum, triethylaluminum and triisobutylaluminum; alkylaluminum halides such as diethylaluminum chloride, ethylaluminum sesquichloride and ethylaluminum dichloride; represented by the following general formula (4): And the like.

（上記一般式（４）中、Ｒ^１４およびＲ^１５は、炭素数１〜２０の炭化水素基を表し、ｘは、０＜ｘ＜３である。）

(In the general formula (4), R ¹⁴ and R ¹⁵ represent a hydrocarbon group having 1 to 20 carbon atoms, and x is 0<x<3.)

In the general formula (4), specific examples of the hydrocarbon group having 1 to 20 carbon atoms represented by R ¹⁴ and R ¹⁵ include a methyl group, an ethyl group, an isopropyl group, an n-propyl group, an isobutyl group, and n. -Alkyl group such as -butyl group, t-butyl group, n-hexyl group, cyclohexyl group, n-octyl group, n-decyl group; phenyl group, 4-methylphenyl group, 2,6-dimethylphenyl group, 2, An aryl group such as a 6-diisopropylphenyl group and a naphthyl group; and the like. In addition, the hydrocarbon groups having 1 to 20 carbon atoms represented by R ¹⁴ and R ¹⁵ may be the same or different, but may be the same in the repeating unit of the cyclic olefin ring-opening polymer. From the viewpoint of obtaining a terminal-modified group-containing cyclic olefin ring-opening polymer excellent in physical properties as a rubber material by increasing the proportion of cis structure in the existing double bond, at least the hydrocarbon group represented by R ¹⁴ Is preferably an alkyl group in which four or more carbon atoms are continuously bonded, and in particular, n-butyl group, 2-methyl-pentyl group, n-hexyl group, cyclohexyl group, n-octyl group, It is preferably any of n-decyl groups.

  Further, in the general formula (4), x is 0<x<3, but in the double bond present in the repeating unit of the terminal-modified group-containing cyclic olefin ring-opening polymer, the proportion of the cis structure is high. From the viewpoint of obtaining a terminal-modified group-containing cyclic olefin ring-opening polymer having excellent properties as a rubber material, x in the general formula (4) is an organoaluminum having a range of 0.5<x<1.5. It is preferred to use the compounds as cocatalysts.

  The polymerization reaction conditions when using a molybdenum compound or a tungsten compound as the ring-opening polymerization catalyst may be appropriately set within the range of the conditions described in the case of using the ruthenium carbene complex.

  If desired, an antioxidant such as a phenol-based stabilizer, a phosphorus-based stabilizer or a sulfur-based stabilizer may be added to the obtained terminal modified group-containing cyclic olefin ring-opening polymer. The amount of the antioxidant added may be appropriately determined depending on the type of the antioxidant. Further, the terminal modified group-containing cyclic olefin ring-opening polymer may be blended with an extender oil, if desired.

  Furthermore, when carrying out the polymerization reaction, a solvent is used, and when the polymerization reaction is carried out in the solvent, as a method for obtaining the terminal modified group-containing cyclic olefin ring-opening polymer from the polymer solution, a known method is used. The method is not particularly limited, and for example, a method of separating the solvent by steam stripping, separating the solid by filtration, and then drying the solid to obtain a solid rubber can be used.

  When a molybdenum compound or a tungsten compound is used as a ring-opening polymerization catalyst and an organometallic compound is used as a cocatalyst in combination with the ring-opening polymerization catalyst, an ester and/or an ether is further contained in addition to these components. May be.

  Specific examples of the esters and/or ethers include ethers such as diethyl ether, tetrahydrofuran, ethylene glycol diethyl ether, and 1,4-dioxane; ethyl acetate, butyl acetate, amyl acetate, octyl acetate, 2-chloroethyl acetate. Esters such as methyl acetyl acrylate, ε-caprolactone, dimethyl glutarate, σ-hesanolactone, and diacetoxyethane; and the like. Among these, 1,4-dioxane and ethyl acetate are preferable from the viewpoint that the addition effect can be further enhanced. These esters and/or ethers can be used alone or in combination of two or more kinds.

  In the rubber composition for heavy-duty tires of the present invention, the content ratio of the terminal modified group-containing cyclic olefin ring-opening polymer is the content ratio in all the rubber components contained in the rubber composition for heavy-duty tires of the present invention. It is preferably 20 to 70% by weight, more preferably 25 to 60% by weight, still more preferably 30 to 50% by weight. If the content ratio of the terminal modified group-containing cyclic olefin ring-opening polymer is too low, the tensile strength, tensile stress, and abrasion resistance of the obtained rubber cross-linked product may be decreased, while if it is too high, the In some cases, the tensile strength of the rubber cross-linked product may be reduced. The above content is determined based on the weight of the polymer constituting the rubber component, for example, the weight of the extender oil and the like is excluded.

<Silica>
The rubber composition for heavy-duty tires of the present invention contains silica in addition to the above-mentioned terminal modified group-containing cyclic olefin ring-opening polymer.

  Such silica is not particularly limited, but for example, dry method white carbon, wet method white carbon, colloidal silica, precipitated silica and the like can be used. Alternatively, a carbon-silica dual phase filler in which silica is supported on the surface of carbon black may be used. Among these, wet method white carbon containing hydrous silicic acid as a main component is preferable. These can be used alone or in combination of two or more.

Silica, nitrogen adsorption specific surface area measured by the BET method, is preferably 100 m ² / g or more, more preferably 100 to 250 m ² / g, more preferably from 110~170m ² / g. When the specific surface area is within this range, the obtained rubber cross-linked product can have excellent tensile strength. Further, the pH of silica is preferably less than 7, more preferably 5 to 6.9. The nitrogen adsorption specific surface area can be measured by the BET method according to ASTM D3037-81.

  The compounding amount of silica in the rubber composition for heavy-duty tires of the present invention is preferably 20 to 100 parts by weight, and more preferably 25 to 100 parts by weight, relative to 100 parts by weight of the rubber component in the rubber composition for tires. 80 parts by weight, more preferably 30 to 50 parts by weight. By setting the compounding amount of silica in the above range, it is possible to appropriately enhance the tensile strength, tensile stress, and abrasion resistance of the obtained rubber cross-linked product while making the dispersion of silica at the time of production favorable.

<Carbon black>
The rubber composition for heavy-duty tires of the present invention has a nitrogen adsorption specific surface area of 90 to 150 m ² /g measured by the BET method, in addition to the above-mentioned terminal modified group-containing cyclic olefin ring-opening polymer and silica. Contains carbon black.

  The content of such carbon black in the rubber composition for heavy duty tires of the present invention is 20 to 60 parts by weight with respect to 100 parts by weight of the rubber component contained in the rubber composition for heavy duty tires. , Preferably 25 to 55 parts by weight, more preferably 30 to 50 parts by weight. In the present invention, in addition to the above-mentioned terminal modified group-containing cyclic olefin ring-opening polymer, and silica, by containing the above-mentioned predetermined amount of carbon black having such a predetermined specific surface area, The rubber cross-linked product obtained by using the rubber composition for heavy-duty tires can have high tensile strength and tensile stress and excellent wear resistance. If the content of carbon black is too low or too high, the obtained rubber cross-linked product will be inferior in tensile strength, tensile stress, and abrasion resistance.

In the present invention, carbon black having a nitrogen adsorption specific surface area measured by the BET method of 90 to 150 m ² /g is used as the carbon black, but the nitrogen adsorption specific surface area measured by the BET method is 90. What is -140 m< ² >/g is preferable, and what is 90-130 m< ² >/g is more preferable. If the nitrogen adsorption specific surface area is less than 90 m ² /g, the effect of improving tensile strength, tensile stress, and wear resistance cannot be obtained, and the obtained rubber cross-linked product has excellent tensile strength, tensile stress, and wear resistance. It becomes inferior. On the other hand, when the nitrogen adsorption specific surface area is more than 150 m ² /g, the dispersibility in the terminal-modified group-containing cyclic olefin ring-opening polymer is poor, and the resulting rubber cross-linked product has tensile strength, tensile stress, and abrasion resistance. It becomes inferior in sex. The nitrogen adsorption specific surface area can be measured by the BET method according to JIS K-6217.

  The carbon black used in the present invention may have a nitrogen adsorption specific surface area in the above range, but the primary particle diameter thereof is preferably in the range of 1 to 100 nm, more preferably 5 to 70 nm, further preferably 15 nm. ~35 nm.

  The carbon black used in the present invention may be any carbon black having a nitrogen adsorption specific surface area within the above range, and examples thereof include furnace black, acetylene black, thermal black, channel black and graphite. Of these, furnace black is preferably used, and specific examples thereof include SAF, ISAF, ISAF-HS, ISAF-LS, IISAF-HS, HAF, HAF-HS, HAF-LS and the like. These may be used alone or in combination of two or more.

  Further, in the rubber composition for heavy duty tires of the present invention, the content of carbon black may be in the above range, the resulting rubber cross-linked product has a high balance of tensile strength, tensile stress, and wear resistance. However, it is preferable that the relationship with the content of silica be as follows from the viewpoint that these can be further increased. That is, the total content of carbon black and silica is preferably 40 to 160 parts by weight, and 50 to 135 parts by weight with respect to 100 parts by weight of the rubber component contained in the rubber composition for heavy duty tires. More preferably, and more preferably 60 to 100 parts by weight. Further, the content ratio of carbon black and silica in the rubber composition for heavy duty tires is preferably in the range of 30:70 to 70:30 in terms of the weight ratio of "carbon black:silica", and 35: The range of 65 to 65:35 is more preferable, and the range of 40:60 to 60:40 is further preferable.

<Natural rubber>
The rubber composition for heavy duty tires of the present invention preferably contains natural rubber as a rubber component in addition to the terminal modified group-containing cyclic olefin ring-opening polymer. By containing natural rubber, the tensile strength of the obtained rubber cross-linked product can be further increased.

  The content ratio of the natural rubber in the rubber composition for heavy-duty tires of the present invention is the content ratio in all the rubber components contained in the rubber composition for heavy-duty tires of the present invention, and preferably 30 to 80% by weight. %, more preferably 40 to 75% by weight, still more preferably 50 to 70% by weight. By blending the natural rubber in the above ratio, the tensile strength of the obtained rubber cross-linked product can be more appropriately increased.

  The rubber composition for heavy duty tires of the present invention has, as a rubber component, a terminal modified group-containing cyclic olefin ring-opening polymer and a natural rubber, in addition to a terminal modified group-containing cyclic olefin ring-opening polymer and natural rubber. You may contain rubbers other than. Examples of the rubber other than such a terminal modified group-containing cyclic olefin ring-opening polymer and natural rubber include polyisoprene rubber (IR), solution polymerization SBR (solution polymerization styrene butadiene rubber), emulsion polymerization SBR (emulsion polymerization styrene butadiene). Rubber), low cis BR (polybutadiene rubber), high cis BR, high trans BR (trans bond content of butadiene part 70 to 95%), styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, emulsion polymerized styrene- Acrylonitrile-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, polyisoprene-SBR block copolymer rubber, polystyrene-polybutadiene-polystyrene block copolymer, acrylic rubber, epichlorohydrin rubber, fluororubber, silicone rubber, ethylene-propylene Examples thereof include rubber and urethane rubber. These rubbers may be used alone or in combination of two or more.

  When compounding a rubber other than the terminal modified group-containing cyclic olefin ring-opening polymer and natural rubber, the content is the content ratio in all the rubber components contained in the heavy duty tire rubber composition of the present invention. It is preferably 50% by weight or less, more preferably 35% by weight or less, further preferably 20% by weight or less.

<Other ingredients>
Further, the heavy-duty tire rubber composition of the present invention, in addition to the above components, according to a conventional method, a crosslinking agent, a crosslinking accelerator, a crosslinking activator, a silane coupling agent, an antioxidant, an activator, a process oil, A compounding agent such as a plasticizer, wax, silica, and a filler other than carbon book can be mixed in required amounts.

  Examples of the cross-linking agent include sulfur, sulfur halides, organic peroxides, quinone dioximes, organic polyvalent amine compounds, and methylphenol group-containing alkylphenol resins. Among these, sulfur is preferably used. The amount of the cross-linking agent blended is preferably 0.1 to 15 parts by weight, more preferably 0.3 to 10 parts by weight, and even more preferably 0 with respect to 100 parts by weight of the rubber component in the heavy duty tire rubber composition. 0.5 to 5 parts by weight.

  Examples of the crosslinking accelerator include N-cyclohexyl-2-benzothiazolyl sulfenamide, Nt-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazolyl sulfenamide, Sulfenamide-based crosslinking accelerators such as N-oxyethylene-2-benzothiazolyl sulfenamide and N,N'-diisopropyl-2-benzothiazolyl sulfenamide; 1,3-diphenylguanidine, dioltotolylguanidine , Guanidine crosslinking accelerators such as orthotolylbiguanidine; thiourea crosslinking accelerators; thiazole crosslinking accelerators; thiuram crosslinking accelerators; dithiocarbamic acid crosslinking accelerators; xanthogenic acid crosslinking accelerators. Among these, those containing a sulfenamide crosslinking accelerator are particularly preferable. These crosslinking accelerators may be used alone or in combination of two or more. The amount of the crosslinking accelerator compounded is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 5 parts by weight, and particularly preferably 100 parts by weight of the rubber component in the heavy duty tire rubber composition. It is 1.0 to 4.0 parts by weight.

  Examples of the cross-linking activator include higher fatty acids such as stearic acid and zinc oxide. The compounding amount of the crosslinking activator is not particularly limited, but is preferably 0.05 to 10 parts by weight, more preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the rubber component in the rubber composition for heavy duty tires. Parts by weight.

  Examples of the silane coupling agent include vinyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and 3-octanoylthio-. 1-propyl-triethoxysilane, bis(3-(triethoxysilyl)propyl)disulfide, bis(3-(triethoxysilyl)propyl)tetrasulfide, γ-trimethoxysilylpropyldimethylthiocarbamyltetrasulfide, and γ -Trimethoxysilylpropyl benzothiazyl tetrasulfide and the like can be mentioned. Among these, those containing 4 or less sulfur in one molecule are preferable from the viewpoint of avoiding scorch during kneading. These silane coupling agents can be used alone or in combination of two or more kinds. The compounding amount of the silane coupling agent is preferably 0.1 to 30 parts by weight, and more preferably 1 to 15 parts by weight with respect to 100 parts by weight of silica.

  Examples of the process oil include paraffin-based, aromatic-based, naphthene-based petroleum-based softeners; plant-based softeners; fatty acids; and the like.

  In order to obtain the rubber composition for heavy-duty tires of the present invention, each component may be kneaded according to a conventional method. For example, a compounding agent excluding a crosslinking agent and a crosslinking accelerator and a rubber component are kneaded, and then kneaded. If desired, a cross-linking agent and a cross-linking accelerator may be mixed with the product to obtain the desired composition. The kneading temperature of the compounding agent excluding the crosslinking agent and the crosslinking accelerator and the rubber component is preferably 80 to 200°C, more preferably 120 to 180°C. The kneading time is preferably 30 seconds to 30 minutes. The kneaded product is mixed with the crosslinking agent and the crosslinking accelerator after cooling to 100° C. or lower, preferably 80° C. or lower.

<Rubber cross-linked product>
The rubber cross-linked product of the present invention is obtained by cross-linking the above-mentioned rubber composition for heavy-duty tires of the present invention.

  The cross-linking method for cross-linking the rubber composition for heavy-duty tires of the present invention is not particularly limited, and may be selected according to the shape, size, etc. of the cross-linked rubber. The rubber composition for heavy-duty tires may be filled in a mold and heated to crosslink simultaneously with molding, or the rubber composition for heavy-duty tires previously molded may be heated and crosslinked. .. The crosslinking temperature is preferably 120 to 200° C., more preferably 140 to 180° C., and the crosslinking time is usually about 1 to 120 minutes.

  Since the rubber cross-linked product of the present invention is obtained by using the above-described rubber composition for heavy-duty tires of the present invention, it has high tensile strength and tensile stress and excellent wear resistance. Therefore, the rubber cross-linked product of the present invention is suitably used for various tire applications, in particular, heavy-duty tire applications to be mounted on trucks, buses, construction vehicles (for example, dump trucks, craders, tractors, trailers) and the like. is there. Further, the rubber cross-linked product of the present invention can be used for various parts of the tire such as a tread part, a carcass part, a side wall part and a bead part in such a tire, but it is particularly preferably used as a tread part. You can

  Hereinafter, the present invention will be described based on more detailed examples, but the present invention is not limited to these examples. In the following, "part" is based on weight unless otherwise specified. Moreover, various tests and evaluations were performed according to the following methods.

[Molecular Weight of Cyclopentene Ring-Opening Polymer]
By gel permeation chromatography (GPC) using tetrahydrofuran as a solvent (GPC system HLC-8220 (manufactured by Tosoh Corporation)), using an H type column HZ-M (manufactured by Tosoh Corporation) at a column temperature of 40° C. The number average molecular weight (Mn), the weight average molecular weight (Mw), and the molecular weight distribution (Mw/Mn) of the united product were measured as polystyrene conversion values.

[Cis/trans ratio of cyclopentene ring-opening polymer]
^It was determined by ¹³ C-NMR spectrum measurement.

[Melting point (Tm) and glass transition temperature (Tg) of cyclopentene ring-opening polymer]
It measured using the differential scanning calorimeter (DSC) on the temperature rising conditions of 10 degree-C/min.

[Introduction rate of oxysilyl group in cyclopentene ring-opening polymer]
^The ratio of the peak integrated value derived from the oxysilyl group and the peak integrated value derived from the carbon-carbon double bond in the main chain of the cyclopentene ring-opening polymer was determined by ¹ H-NMR spectrum measurement, and the ratio of this peak integrated value was determined. And the introduction rate of oxysilyl groups based on the measured value of the number average molecular weight (Mn) by GPC (percentage of (the number of cyclopentene ring-opening polymer chain terminals having oxysilyl group introduced/the total number of cyclopentene ring-opening polymer chain terminals)) Was calculated.

[Tensile strength, 300% tensile stress]
A sheet-shaped test piece (rubber crosslinked material) is produced by press-crosslinking the rubber composition at 160° C. for 20 minutes, and the obtained test piece is subjected to a tensile tester (trade name “STROGRAPH” according to JIS K6251). AE", manufactured by Toyo Seiki Seisakusho, Ltd.) was used to measure the tensile stress at 300% elongation (300% tensile stress) and the tensile stress at break (tensile strength) at a test temperature of 23° C. and a tensile speed of 500 mm/min. .. This value was obtained as an index with the measured value of Comparative Example 1 being 100. The larger this index is, the better the mechanical properties of the tire, particularly the tire tread, are preferable.

[Abrasion resistance]
The rubber composition was press-crosslinked at 160° C. for 20 minutes to prepare a test piece (rubber crosslinked product), and the obtained test piece was subjected to an FPS abrasion tester (trade name “AB-2010”, manufactured by Ueshima Seisakusho). ) Was used under the conditions of a load of 1 kgf and a slip ratio of 3%. This property was determined as an index with the measured value of Comparative Example 1 as 100. The larger this index is, the more excellent the abrasion resistance is, so that it is preferable.

[Reference Example 1]
Preparation of diisobutylaluminum mono(n-hexoxide)/toluene solution (2.5% by weight) 88 parts of toluene and 25.4% by weight of triisobutylaluminum/n in a glass container containing a stir bar under a nitrogen atmosphere. 7.8 parts of hexane solution (manufactured by Tosoh Finechem Co., Ltd.) was added. Then, the container was cooled to −45° C., and 1.02 parts (equivalent amount relative to triisobutylaluminum) of n-hexanol was slowly added dropwise with vigorous stirring. Then, the mixture was left to stand at room temperature with stirring to prepare a diisobutylaluminum mono(n-hexoxide)/toluene solution (2.5% by weight).

[Synthesis Example 1]
87 parts of a 1.0 wt% WCl ₆ /toluene solution and 2.5 wt% of diisobutylaluminum mono(n-hexoxide)/toluene prepared in Reference Example 1 were placed in a glass container containing a stir bar under a nitrogen atmosphere. A catalyst solution was obtained by adding 43 parts of the solution and stirring for 15 minutes. Then, under a nitrogen atmosphere, 300 parts of cyclopentene and 1.24 parts of 1,4-bis(triethoxysilyl)-2-butene were added to a pressure resistant glass reaction vessel equipped with a stirrer, and the catalyst solution 130 prepared above was added thereto. Parts were added and a polymerization reaction was carried out at 25° C. for 4 hours. After the polymerization reaction for 4 hours, excess ethyl alcohol was added to the pressure-resistant glass reaction container to stop the polymerization, and then the solution in the pressure-resistant glass reaction container was treated with 2,6-di-t-butyl-p-cresol (BHT). ) Containing a large excess of ethyl alcohol. Then, the precipitated polymer was recovered, washed with ethyl alcohol, and then vacuum-dried at 40° C. for 3 days to give 78 parts of a polymer chain having a triethoxysilyl group at both ends and a cyclopentene ring-opening modified at both ends. A polymer (a1) was obtained.

  Then, with respect to the obtained both-end modified cyclopentene ring-opening polymer (a1), each of the molecular weight, cis/trans ratio, oxysilyl group introduction rate, melting point (Tm), and glass transition temperature (Tg) was measured according to the above methods. went. The results are shown in Table 1.

[Synthesis example 2]
87 parts of a 1.0 wt% WCl ₆ /toluene solution and 2.5 wt% of diisobutylaluminum mono(n-hexoxide)/toluene prepared in Reference Example 1 were placed in a glass container containing a stir bar under a nitrogen atmosphere. A catalyst solution was obtained by adding 43 parts of the solution and stirring for 15 minutes. Then, under a nitrogen atmosphere, 300 parts of cyclopentene and 0.96 part of 1,4-bis(trimethoxysilyl)-2-butene were added to a pressure-resistant glass reaction vessel equipped with a stirrer, and the catalyst solution 130 prepared above was added thereto. Parts were added and a polymerization reaction was carried out at 25° C. for 24 hours. After the polymerization reaction for 24 hours, excess ethyl alcohol was added to the pressure-resistant glass reaction vessel to stop the polymerization, and then the solution in the pressure-resistant glass reaction vessel was mixed with 2,6-di-t-butyl-p-cresol (BHT). ) Containing a large excess of ethyl alcohol. Then, the precipitated polymer was recovered, washed with ethyl alcohol, and dried in vacuum at 40° C. for 3 days to give 90 parts of a polymer chain having both ends modified with a trimethoxysilyl group-modified cyclopentene ring-opening. A polymer (a2) was obtained.

  Then, with respect to the obtained both-end modified cyclopentene ring-opening polymer (a2), each of the molecular weight, cis/trans ratio, oxysilyl group introduction rate, melting point (Tm), and glass transition temperature (Tg) was measured according to the above methods. went. The results are shown in Table 1.

[Synthesis Example 3]
87 parts of a 1.0 wt% WCl ₆ /toluene solution and 2.5 wt% of diisobutylaluminum mono(n-hexoxide)/toluene prepared in Reference Example 1 were placed in a glass container containing a stir bar under a nitrogen atmosphere. A catalyst solution was obtained by adding 43 parts of the solution and stirring for 15 minutes. Then, under a nitrogen atmosphere, 300 parts of cyclopentene and 0.42 part of vinyl(triethoxy)silane were added to a pressure resistant glass reaction vessel equipped with a stirrer, 130 parts of the catalyst solution prepared above was added thereto, and the mixture was stirred at 4°C at 25°C. The polymerization reaction was carried out for a time. After the polymerization reaction for 4 hours, excess ethyl alcohol was added to the pressure-resistant glass reaction container to stop the polymerization, and then the solution in the pressure-resistant glass reaction container was treated with 2,6-di-t-butyl-p-cresol (BHT). ) Containing a large excess of ethyl alcohol. Then, the precipitated polymer was recovered, washed with ethyl alcohol, and then vacuum-dried at 40° C. for 3 days, whereby 76 parts of the polymer chain had a triethoxysilyl group at one end and a cyclopentene ring-opening modified with one end. A polymer (a3) was obtained.

  Then, the obtained one-end modified cyclopentene ring-opening polymer (a3) was measured for molecular weight, cis/trans ratio, oxysilyl group introduction rate, melting point (Tm), and glass transition temperature (Tg) according to the methods described above. went. The results are shown in Table 1.

[Synthesis Example 4]
Under a nitrogen atmosphere, in a glass container containing a stirrer, 44 parts of a 1.0 wt% WCl ₆ /toluene solution, and 2.5 wt% of diisobutylaluminum mono(n-hexoxide)/toluene prepared in Reference Example 1. A catalyst solution was obtained by adding 22 parts of the solution and stirring for 15 minutes. Then, under a nitrogen atmosphere, 300 parts of cyclopentene and 1.86 parts of 1,4-bis(triethoxysilyl)-2-butene were added to a pressure resistant glass reaction vessel equipped with a stirrer, and the catalyst solution 66 prepared above was added thereto. Parts were added and a polymerization reaction was carried out at 0° C. for 4 hours. After the polymerization reaction for 4 hours, excess ethyl alcohol was added to the pressure-resistant glass reaction vessel to stop the polymerization, and then the solution in the pressure-resistant glass reaction vessel was mixed with 2,6-di-t-butyl-p-cresol (BHT). ) Containing a large excess of ethyl alcohol. Next, the precipitated polymer was recovered, washed with ethyl alcohol, and then vacuum dried at 40° C. for 3 days to open a cyclopentene ring-opened ring having 27 parts of polymer chains having triethoxysilyl groups at both ends. A polymer (a4) was obtained.

  Then, with respect to the obtained both-end modified cyclopentene ring-opening polymer (a4), each of the molecular weight, cis/trans ratio, oxysilyl group introduction rate, melting point (Tm), and glass transition temperature (Tg) was measured according to the above methods. went. The results are shown in Table 1.

[Synthesis example 5]
87 parts of a 1.0 wt% WCl ₆ /toluene solution and 2.5 wt% of diisobutylaluminum mono(n-hexoxide)/toluene prepared in Reference Example 1 were placed in a glass container containing a stir bar under a nitrogen atmosphere. A catalyst solution was obtained by adding 43 parts of the solution and stirring for 15 minutes. Then, under a nitrogen atmosphere, 300 parts of cyclopentene, 300 parts of toluene and 1.24 parts of 1,4-bis(triethoxysilyl)-2-butene were added to a pressure-resistant glass reaction vessel equipped with a stirrer, and prepared here above. 130 parts of the above catalyst solution was added, and a polymerization reaction was carried out at 25° C. for 4 hours. After the polymerization reaction for 4 hours, excess ethyl alcohol was added to the pressure-resistant glass reaction vessel to stop the polymerization, and then the solution in the pressure-resistant glass reaction vessel was mixed with 2,6-di-t-butyl-p-cresol (BHT). ) Containing a large excess of ethyl alcohol. Next, the precipitated polymer was recovered, washed with ethyl alcohol, and vacuum dried at 40° C. for 3 days to open a cyclopentene ring-opening group having a triethoxysilyl group at both ends of 63 parts of the polymer chain. A polymer (a5) was obtained.

  Then, with respect to the obtained both-end modified cyclopentene ring-opening polymer (a5), each of the molecular weight, cis/trans ratio, oxysilyl group introduction rate, melting point (Tm), and glass transition temperature (Tg) was measured according to the above methods. went. The results are shown in Table 1.

[Synthesis example 6]
87 parts of a 1.0 wt% WCl ₆ /toluene solution and 2.5 wt% of diisobutylaluminum mono(n-hexoxide)/toluene prepared in Reference Example 1 were placed in a glass container containing a stir bar under a nitrogen atmosphere. A catalyst solution was obtained by adding 43 parts of the solution and stirring for 15 minutes. Then, under a nitrogen atmosphere, 300 parts of cyclopentene, 300 parts of toluene and 0.12 part of 1-hexene were added to a pressure-resistant glass reaction vessel equipped with a stirrer, and 130 parts of the catalyst solution prepared above was added thereto at 25°C. The polymerization reaction was carried out for 4 hours. After the polymerization reaction for 4 hours, excess ethyl alcohol was added to the pressure-resistant glass reaction container to stop the polymerization, and then the solution in the pressure-resistant glass reaction container was treated with 2,6-di-t-butyl-p-cresol (BHT). ) Containing a large excess of ethyl alcohol. Next, the precipitated polymer was recovered, washed with ethyl alcohol, and vacuum dried at 40° C. for 3 days to obtain 81 parts of an unmodified cyclopentene ring-opening polymer (a6).

  Then, with respect to the obtained unmodified cyclopentene ring-opening polymer (a6), each of the molecular weight, the cis/trans ratio, the oxysilyl group introduction rate, the melting point (Tm), and the glass transition temperature (Tg) was measured according to the methods described above. went. The results are shown in Table 1.

[Example 1]
In a Brabender type mixer with a capacity of 250 ml, 50 parts of both-end modified cyclopentene ring-opening polymer (a1) obtained in Synthesis Example 1 and 50 parts of natural rubber were masticated for 30 seconds, and then silica (manufactured by Solvay Co., Product name “Zeosil 1115MP”, nitrogen adsorption specific surface area (BET method): 112 m ² /g, 40 parts, ISAF-HS carbon black (manufactured by Tokai Carbon Co., product name “Sheet 7HM”, nitrogen adsorption specific surface area (BET method): 126 m ² /g, primary particle size: 19 nm) 13.3 parts, process oil (JX Nikko Nisseki Energy Co., Ltd., trade name “Alomax T-DAE”) 25 parts, and silane coupling agent; bis-3- After adding 2.4 parts of triethoxysilylpropyl tetrasulfide (manufactured by Evonik, trade name “Si69”) and kneading for 1.5 minutes at 110° C. as a starting temperature, ISAF-HS carbon (manufactured by Tokai Carbon Co., Ltd., product Name "Cast 7HM) 26.7 parts, zinc oxide 3 parts, stearic acid 2 parts, and antioxidant: N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (Ouchi Shinko Kagaku) 2 parts by trade name "Nocrac 6C" manufactured by Kogyo Co., Ltd. was added, and the mixture was further kneaded for 2.5 minutes, and the kneaded product was discharged from the mixer. The temperature of the kneaded material at the end of kneading was 150°C. After cooling the kneaded product to room temperature, it was kneaded again in the Brabender type mixer with the starting temperature of 110° C. for 3 minutes, and then the kneaded product was discharged from the mixer. Then, with an open roll at 50° C., the obtained kneaded product, 1.4 parts of sulfur, a crosslinking accelerator: N-cyclohexylbenzothiazolyl-2-sulfenamide (trade name, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name) "Noxceller CZ-G") 1.2 parts and a cross-linking accelerator: 1,3-diphenylguanidine (Ouchi Shinko Kagaku Kogyo Co., Ltd., trade name "Noxceller D") 1.2 parts, and then a sheet is kneaded. A rubber composition in the form of a strip was obtained. The obtained rubber composition was evaluated for tensile strength, 300% tensile stress, and wear resistance according to the methods described above. The results are shown in Table 2.

[Example 2]
Other than using 50 parts of both-end modified cyclopentene ring-opening polymer (a1) obtained in Synthesis Example 1 instead of 50 parts of both-end modified cyclopentene ring-opening polymer (a1) obtained in Synthesis Example 1. A sheet-shaped rubber composition was obtained in the same manner as in Example 1. Then, the obtained rubber composition was evaluated for tensile strength, 300% tensile stress, and wear resistance according to the methods described above. The results are shown in Table 2.

[Example 3]
Except for using 50 parts of the one-end modified cyclopentene ring-opening polymer (a3) obtained in Synthesis Example 3 instead of 50 parts of the both-end modified cyclopentene ring-opening polymer (a1) obtained in Synthesis Example 1, A sheet-shaped rubber composition was obtained in the same manner as in Example 1. Then, the obtained rubber composition was evaluated for tensile strength, 300% tensile stress, and wear resistance according to the methods described above. The results are shown in Table 2.

[Example 4]
Except that 50 parts of both-end modified cyclopentene ring-opening polymer (a1) obtained in Synthesis Example 1 was used instead of 50 parts of both-end modified cyclopentene ring-opening polymer (a4) obtained in Synthesis Example 4, A sheet-shaped rubber composition was obtained in the same manner as in Example 1. Then, the obtained rubber composition was evaluated for tensile strength, 300% tensile stress, and wear resistance according to the methods described above. The results are shown in Table 2.

[Example 5]
Except for using 50 parts of both-end modified cyclopentene ring-opening polymer (a1) obtained in Synthesis Example 5 instead of 50 parts of both-end modified cyclopentene ring-opening polymer (a1) obtained in Synthesis Example 1, A sheet-shaped rubber composition was obtained in the same manner as in Example 1. Then, the obtained rubber composition was evaluated for tensile strength, 300% tensile stress, and wear resistance according to the methods described above. The results are shown in Table 2.

[Example 6]
Example 1 except that the compounding amount of the both-end modified cyclopentene ring-opening polymer (a1) obtained in Synthesis Example 1 was changed from 50 parts to 30 parts and the amount of natural rubber was changed from 50 parts to 70 parts. A sheet-shaped rubber composition was obtained by the same method. Then, the obtained rubber composition was evaluated for tensile strength, 300% tensile stress, and wear resistance according to the methods described above. The results are shown in Table 2.

[Example 7]
In place of 40 parts of ISAF-HS carbon black (manufactured by Tokai Carbon Co., Ltd., trade name "Cast 7HM"), HAF carbon black (manufactured by Tokai Carbon Co., Ltd., trade name "CEST KH", nitrogen adsorption specific surface area (BET method): 93 m ^A sheet-shaped rubber composition was obtained in the same manner as in Example 1 except that 40 parts of ² /g, primary particle diameter: 24 nm) was used. In Example 7, as in Example 1, 40 parts of HAF carbon black was mixed twice (13.3 parts and 26.7 parts). Then, the obtained rubber composition was evaluated for tensile strength, 300% tensile stress, and wear resistance according to the methods described above. The results are shown in Table 2.

[Comparative Example 1]
Instead of 50 parts of the both-end modified cyclopentene ring-opening polymer (a1) obtained in Synthesis Example 1, polybutadiene rubber (manufactured by Nippon Zeon Co., Ltd., trade name “Nipol BR1220”, cis content 97%, Mooney viscosity (ML _{1 +4} , 100° C.) 43, glass transition temperature (Tg)-110° C.) 50 parts were used in the same manner as in Example 1 to obtain a sheet-shaped rubber composition. Then, the obtained rubber composition was evaluated for tensile strength, 300% tensile stress, and wear resistance according to the methods described above. The results are shown in Table 2.

[Comparative Example 2]
Example except that 50 parts of the unmodified cyclopentene ring-opening polymer (a6) obtained in Synthesis Example 6 was used instead of 50 parts of both-end modified cyclopentene ring-opening polymer (a1) obtained in Synthesis Example 1 In the same manner as in Example 1, a sheet-shaped rubber composition was obtained. Then, the obtained rubber composition was evaluated for tensile strength, 300% tensile stress, and wear resistance according to the methods described above. The results are shown in Table 2.

[Comparative Example 3]
In place of 40 parts of ISAF-HS carbon black (manufactured by Tokai Carbon Co., Ltd., trade name "SEAST 7HM"), FEF carbon black (manufactured by Tokai Carbon Co., Ltd., trade name "SEAST SO", nitrogen adsorption specific surface area (BET method): 42 m ^A sheet-shaped rubber composition was obtained in the same manner as in Example 1 except that 40 parts of ² /g, primary particle diameter: 43 nm) was used. In Comparative Example 3 as well, as in Example 1, 40 parts of FEF carbon black was added twice (13.3 parts and 26.7 parts). Then, the obtained rubber composition was evaluated for tensile strength, 300% tensile stress, and wear resistance according to the methods described above. The results are shown in Table 2.

[Comparative Example 4]
A sheet-shaped rubber composition was prepared in the same manner as in Example 1 except that the amount of silica was changed from 40 parts to 70 parts and the amount of ISAF-HS carbon black was changed from 40 parts to 10 parts. Obtained. In Comparative Example 4 as well, as in Example 1, 10 parts of ISAF-HS carbon black was mixed twice (3.3 parts and 6.7 parts).

[Comparative Example 5]
A sheet-shaped rubber composition was prepared in the same manner as in Example 1 except that the amount of silica was changed from 40 parts to 10 parts and the amount of ISAF-HS carbon black was changed from 40 parts to 70 parts. Obtained. In Comparative Example 5 as well, as in Example 1, 70 parts of ISAF-HS carbon black was added twice (23.3 parts and 46.7 parts).

As is clear from the results shown in Tables 1 and 2, a rubber component 100 containing a terminal-modified group-containing cyclic olefin ring-opening polymer, silica, and carbon black having a nitrogen adsorption specific surface area of 90 to 150 m ² /g. The rubber composition of the present invention in which the content of carbon black was 20 to 60 parts with respect to 10 parts by weight gave a rubber cross-linked product having excellent tensile strength, tensile stress and abrasion resistance (Examples 1 to 7). ).

On the other hand, instead of the terminal modified group-containing cyclic olefin ring-opening polymer, when using a rubber composition prepared by blending a polybutadiene rubber, or a rubber composition prepared by blending an unmodified cyclic olefin ring-opening polymer. When used, the obtained rubber cross-linked product was inferior in tensile strength, tensile stress and abrasion resistance (Comparative Examples 1 and 2).
In addition, when the carbon black having a nitrogen adsorption specific surface area of less than 90 m ² /g is used as the carbon black, or when the blending amount of the carbon black is too small or too large, the obtained rubber cross-linked product has tensile strength, It was inferior in tensile stress and wear resistance (Comparative Examples 3 to 5).

Claims (5)

A rubber composition for heavy-duty tires, comprising an end-modified group-containing cyclic olefin ring-opening polymer, silica, and carbon black having a nitrogen adsorption specific surface area of 90 to 150 m ² /g measured by the BET method,
In the rubber component contained in the rubber composition for heavy duty tires, the content of the terminal modified group-containing cyclic olefin ring-opening polymer is 20% by weight or more,
Wherein for 100 parts by weight of the rubber component contained in the heavy duty tire rubber composition, the content of the carbon black, Ri 20-60 parts by der,
With respect to 100 parts by weight of the rubber component contained in the rubber composition for heavy duty tires, the total content ratio of the carbon black and the silica is 40 to 160 parts by weight,
The terminal modified group-containing cyclic olefin ring-opening polymer is a polymer polymer der Ru heavy duty tire rubber composition ends oxysilyl group is introduced in the chain. Wherein as the rubber component, heavy duty tire rubber composition according to claim 1, further comprising a natural rubber. The rubber composition for heavy-duty tires according to claim 2 , wherein the content ratio of the natural rubber in the rubber component is 30 to 80% by weight. Rubber cross-linked product obtained by crosslinking a heavy load tire rubber composition according to any one of claims 1-3. A heavy duty tire comprising the rubber cross-linked product according to claim 4 .