Rubber composition, crosslinked rubber, and tire

Abstract

Provided is a rubber composition comprising: a ring-opening polymer rubber including a structural unit derived from a cycloolefin and having a glass transition temperature (Tg) of 0°C or lower; and a petroleum resin including a structural unit derived from a polycyclic aliphatic cycloolefin and having a glass transition temperature (Tg) of 10°C or higher.

Description

Rubber composition, cross-linked rubber, and tire

[0001] The present invention relates to a ring-opening polymer rubber, a rubber composition, a cross-linked rubber product, and a tire.

[0002] An important characteristic required for tires is cut and chip resistance (block chipping resistance). For example, Patent Document 1 studies petroleum resins that can impart excellent cut and chipping resistance to isoprene-based rubber. Patent Document 1 also discloses Example 2-1 in which a specific petroleum resin (B-1) is added to natural rubber, and Example 2-2 in which a specific petroleum resin (B-2) is added to natural rubber.

[0003] International Publication No. 2022 / 255314

[0004] However, further improvement in chip-cut resistance is required, and a technique that can achieve chip-cut resistance superior to that of the technique of Patent Document 1 is desired.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a rubber composition that can give a cross-linked rubber product having excellent chip and cut resistance.

[0006] As a result of intensive research into achieving the above-mentioned object, the present inventors have found that the above-mentioned object can be achieved by a rubber composition obtained by blending a petroleum resin having structural units derived from a polycyclic aliphatic cyclic olefin with a ring-opening polymer rubber having structural units derived from a cyclic olefin, and have thereby completed the present invention.

[0007] That is, according to the present invention, the following rubber composition, cross-linked rubber, and tire are provided. [1] A rubber composition containing a ring-opening polymer rubber having structural units derived from a cyclic olefin and having a glass transition temperature (Tg) of 0°C or lower, and a petroleum resin having structural units derived from a polycyclic alicyclic olefin and having a glass transition temperature (Tg) of 10°C or higher. [2] The rubber composition according to [1], wherein the petroleum resin has structural units derived from dicyclopentadiene as the structural units derived from the polycyclic alicyclic olefin. [3] The rubber composition according to [2], wherein the petroleum resin contains 20% by weight or more of structural units derived from dicyclopentadiene. [4] The rubber composition according to any one of [1] to [3], wherein the ring-opening polymer rubber has structural units derived from cyclopentene as the structural units derived from the cyclic olefin. [5] The rubber composition according to [4], wherein the ring-opening polymer rubber contains 20% by weight or more of structural units derived from cyclopentene. [6] The rubber composition according to any one of [1] to [5], wherein the ring-opening polymer rubber has a structural unit derived from a norbornene compound as the structural unit derived from the cyclic olefin. [7] The rubber composition according to any one of [1] to [6], wherein the ring-opening polymer rubber contains 15% by weight or more of the structural unit derived from the norbornene compound. [8] The rubber composition according to any one of [1] to [7], wherein the petroleum resin is contained in an amount of 1 to 50 parts by weight per 100 parts by weight of the rubber component containing the ring-opening polymer rubber. [9] The rubber composition according to any one of [1] to [8], further containing a filler.

[10] The rubber composition according to any one of [1] to [9], further containing a crosslinking agent.

[11] A cross-linked rubber obtained by cross-linking the rubber composition according to any one of [1] to

[10] .

[12] A tire comprising the cross-linked rubber according to

[11] .

[0008] According to the present invention, it is possible to provide a rubber composition that can give a cross-linked rubber product having excellent chip and cut resistance.

[0009] The rubber composition of the present invention contains a ring-opening polymer rubber having structural units derived from a cyclic olefin and having a glass transition temperature (Tg) of 0°C or lower, and a petroleum resin having structural units derived from a polycyclic aliphatic cyclic olefin and having a glass transition temperature (Tg) of 10°C or higher. By containing such a combination of the ring-opening polymer rubber and the petroleum resin, the rubber composition of the present invention can provide a cross-linked rubber having excellent chip and cut resistance. First, the ring-opening polymer rubber and the petroleum resin that constitute the rubber composition of the present invention will be disclosed.

[0010] <Ring-opening polymer rubber> The ring-opening polymer rubber used in the present invention is a rubber having structural units derived from a cyclic olefin, which is obtained by ring-opening polymerization of a cyclic olefin, and has a glass transition temperature (Tg) of 0°C or lower.

[0011] Examples of the cyclic olefin for constituting the ring-opening polymer rubber used in the present invention include monocyclic cyclic olefins and polycyclic cyclic olefins such as norbornene compounds and polycyclic aromatic olefins (excluding norbornene compounds). The content of structural units derived from cyclic olefins in the ring-opening polymer rubber used in the present invention is preferably 80% by weight or more, more preferably 90% by weight or more, and even more preferably substantially 100% by weight, based on the total repeating structural units.

[0012] Examples of monocyclic olefins include cyclic monoolefins such as cyclopropene, cyclobutene, cyclopentene, methylcyclopentene, cyclohexene, methylcyclohexene, cycloheptene, and cyclooctene; cyclic diolefins such as cyclopentadiene, methylcyclopentadiene, cyclohexadiene, methylcyclohexadiene, cyclooctadiene, and methylcyclooctadiene; and cyclic triolefins such as cyclododecatriene. The monocyclic olefins may be used alone or in combination of two or more.

[0013] As the monocyclic olefin, cyclopentene, cyclohexene, cycloheptene, cyclooctene and cyclooctadiene are preferred, and from the viewpoint of more easily achieving the effects of the present invention, cyclopentene and cyclooctene are more preferred, and cyclopentene is even more preferred.

[0014] The content of the monocyclic cyclic olefin-derived structural units in the ring-opening polymer rubber used in the present invention is not particularly limited, but is preferably 20 to 100 wt %, more preferably 30 to 100 wt %, and even more preferably 40 to 100 wt %, based on all repeating structural units. When the content of the monocyclic cyclic olefin-derived structural units is within the above range, the resulting cross-linked rubber has sufficient wet grip performance while also exhibiting superior chip and cut resistance. Furthermore, when even superior wet grip performance is required, the content of the monocyclic cyclic olefin-derived structural units is preferably 85 wt % or less, more preferably 75 wt % or less, and even more preferably 65 wt % or less, based on all repeating structural units.

[0015] When the ring-opening polymer rubber used in the present invention contains structural units derived from cyclopentene, the content of the structural units derived from cyclopentene is not particularly limited, but is preferably 20% by weight or more, more preferably 30% by weight or more, and even more preferably 40% by weight or more, based on the total repeating structural units. Furthermore, when even better wet grip performance is required, the content of the structural units derived from cyclopentene is preferably 85% by weight or less, more preferably 75% by weight or less, and even more preferably 65% ​​by weight or less, based on the total repeating structural units.

[0016] The norbornene compound is a compound having a norbornene ring structure, and is preferably a norbornene compound represented by the following general formula (1):

[0017] In the formula, R １ ~R ４represents a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a substituent containing a halogen atom, a silicon atom, an oxygen atom, or a nitrogen atom; R ２ and R ３ may be bonded to each other to form a ring structure, and m is an integer of 0 to 2. In the above general formula (1), R １ ~R ４ may be the same or different.

[0018] In the above general formula (1), m is preferably 0 or 1, and more preferably 0, from the viewpoint that the effects of the present invention can be more easily obtained.

[0019] In the above general formula (1), from the viewpoint of more easily achieving the effects of the present invention, R １ ~R ４ is preferably a hydrogen atom, a chain hydrocarbon group having 1 to 20 carbon atoms, or a substituent containing a halogen atom, a silicon atom, an oxygen atom, or a nitrogen atom, and more preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or an alkenyl group having 1 to 3 carbon atoms.

[0020] R ２ and R ３ When R and R are bonded to each other to form a ring, specific examples of the ring structure include a cyclopentane ring, a cyclopentene ring, a cyclohexane ring, a cyclohexene ring, a benzene ring, etc., which may form a polycyclic structure and may further have a substituent. Among these, a cyclopentane ring, a cyclopentene ring, and a benzene ring are preferred, and a compound having a single cyclopentene ring or a polycyclic structure of a cyclopentane ring and a benzene ring is particularly preferred. ２ , R ３ Other than R １ , R ４ may be the same or different, and are preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. In this case, those represented by the general formula in which m is 0 are preferred.

[0021] Specific examples of the norbornene compound represented by the general formula (1) include the following compounds.

[0022] 2-norbornene, 5-methyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, 5-hexyl-2-norbornene, 5-decyl-2-norbornene, 5-cyclohexyl-2-norbornene, 5-cyclopentyl-2-norbornene, 5-ethylidene-2-norbornene, 5-vinyl-2-norbornene, 5-propenyl-2-norbornene, 5-cyclohexenyl-2-norbornene, 5-cyclopentenyl-2-norbornene, 5-phenyl-2-norbornene, tetracyclo[9.2.1.0 ２，１０ .0 ３，８ ]tetradeca-3,5,7,12-tetraene (also known as 1,4-methano-1,4,4a,9a-tetrahydro-9H-fluorene), tetracyclo[10.2.1.0 ２，１１ .0 ４，９ ]pentadeca-4,6,8,13-tetraene (also known as 1,4-methano-1,4,4a,9,9a,10-hexahydroanthracene), dicyclopentadiene, tricyclopentadiene, methyldicyclopentadiene, and dihydrodicyclopentadiene (tricyclo[5.2.1.0 ２，６ bicyclo[2.2.1]hept-2-enes, such as unsubstituted or hydrocarbon-substituted bicyclo[2.2.1]hept-2-enes;

[0023] Tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-methyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-ethyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-cyclohexyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-cyclopentyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-methylenetetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-ethylidenetetracyclo[6.2.1.1 ３，６ .0２，７ ] dodec-4-ene, 9-vinyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-propenyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-cyclohexenyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, 9-cyclopentenyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-ene, and 9-phenyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] tetracyclo[6.2.1.1] unsubstituted or having hydrocarbon substituents, such as dodec-4-ene; ３，６ .0 ２，７ ] dodec-4-enes;

[0024] bicyclo[2.2.1]hept-2-enes having an alkoxycarbonyl group, such as methyl 5-norbornene-2-carboxylate, ethyl 5-norbornene-2-carboxylate, methyl 2-methyl-5-norbornene-2-carboxylate, and ethyl 2-methyl-5-norbornene-2-carboxylate;

[0025] Tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-9-ene-4-carboxylate methyl, and 4-methyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] tetracyclo[6.2.1.1] having an alkoxycarbonyl group, such as methyl dodec-9-ene-4-carboxylate ３，６ .0 ２，７ ] dodec-4-enes;

[0026] bicyclo[2.2.1]hept-2-enes having a hydroxycarbonyl group or an acid anhydride group, such as 5-norbornene-2-carboxylic acid, 5-norbornene-2,3-dicarboxylic acid, and 5-norbornene-2,3-dicarboxylic acid anhydride;

[0027] Tetracyclo[6.2.1.1 ３，６ .0 ２，７] dodec-9-ene-4-carboxylic acid, tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-9-ene-4,5-dicarboxylic acid, and tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-9-ene-4,5-dicarboxylic acid anhydride, or other tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-enes;

[0028] bicyclo[2.2.1]hept-2-enes having a hydroxyl group, such as 5-hydroxy-2-norbornene, 5-hydroxymethyl-2-norbornene, 5,6-di(hydroxymethyl)-2-norbornene, 5,5-di(hydroxymethyl)-2-norbornene, 5-(2-hydroxyethoxycarbonyl)-2-norbornene, and 5-methyl-5-(2-hydroxyethoxycarbonyl)-2-norbornene;

[0029] Tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-9-ene-4-methanol, and tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-9-en-4-ol and other hydroxyl-containing tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-enes;

[0030] bicyclo[2.2.1]hept-2-enes having a hydrocarbonyl group such as 5-norbornene-2-carbaldehyde;

[0031] Tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-9-ene-4-carbaldehyde, and the like. ３，６ .0 ２，７ ] dodec-4-enes;

[0032] bicyclo[2.2.1]hept-2-enes having an alkoxycarbonyl group and a hydroxycarbonyl group, such as 3-methoxycarbonyl-5-norbornene-2-carboxylic acid;

[0033] bicyclo[2.2.1]hept-2-enes having a carbonyloxy group, such as 5-norbornen-2-yl acetate, 2-methyl-5-norbornen-2-yl acetate, 5-norbornen-2-yl acrylate, and 5-norbornen-2-yl methacrylate;

[0034] Acetic acid 9-tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-enyl acrylate, 9-tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-enyl, and 9-tetracyclo[6.2.1.1 methacrylate ３，６ .0 ２，７ ] tetracyclo[6.2.1.1] having a carbonyloxy group such as dodec-4-enyl ３，６ .0 ２，７ ] dodec-4-enes;

[0035] bicyclo[2.2.1]hept-2-enes having a functional group containing a nitrogen atom, such as 5-norbornene-2-carbonitrile, 5-norbornene-2-carboxamide, and 5-norbornene-2,3-dicarboxylic acid imide;

[0036] Tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-9-ene-4-carbonitrile, tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-9-ene-4-carboxamide, and tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-9-ene-4,5-dicarboxylic acid imide and other tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-4-enes;

[0037] Bicyclo[2.2.1]hept-2-enes having a halogen atom, such as 5-chloro-2-norbornene; 9-chlorotetracyclo[6.2.1.1 ３，６ .0 ２，７ ] tetracyclo[6.2.1.1] dodec-4-ene having a halogen atom, ３，６ .0 ２，７ ] dodec-4-enes;

[0038] bicyclo[2.2.1]hept-2-enes having a functional group containing a silicon atom, such as 5-trimethoxysilyl-2-norbornene and 5-triethoxysilyl-2-norbornene;

[0039] 4-trimethoxysilyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] dodec-9-ene, 4-triethoxysilyltetracyclo[6.2.1.1 ３，６ .0 ２，７ ] tetracyclo[6.2.1.1] having a functional group containing a silicon atom, such as dodec-9-ene ３，６ .0 ２，７ ] dodec-4-enes;

[0040] As the norbornene compound represented by the above general formula (1), from the viewpoint that the obtained cross-linked rubber has sufficient wet grip performance and further excellent chip and cut resistance, bicyclo[2.2.1]hept-2-enes which are unsubstituted or have a hydrocarbon substituent, and tetracyclo[6.2.1.1]hept-2-enes which are unsubstituted or have a hydrocarbon substituent are preferred. ３，６ .0 ２，７ ] dodec-4-enes are preferred, 2-norbornene, dicyclopentadiene, and tetracyclo[6.2.1.1 ３，６ .0 ２，７ ] Dodec-4-ene is more preferred, and 2-norbornene and dicyclopentadiene are particularly preferred. The norbornene compounds may be used alone or in combination of two or more.

[0041] The content of the structural units derived from norbornene compounds in the ring-opening polymer rubber used in the present invention is not particularly limited, but is preferably 0 to 80% by weight, more preferably 0 to 70% by weight, and even more preferably 0 to 60% by weight, based on all repeating structural units. When the content of the structural units derived from norbornene compounds is within the above range, the resulting cross-linked rubber has sufficient wet grip performance and even better chip and cut resistance. Furthermore, when even better wet grip performance is required, the content of the structural units derived from norbornene compounds is preferably 15% by weight or more, more preferably 25% by weight or more, and even more preferably 35% by weight or more.

[0042] Examples of polycyclic aromatic olefins (excluding norbornene compounds) include phenylcyclooctene, 5-phenyl-1,5-cyclooctadiene, phenylcyclopentene, etc. One type of polycyclic aromatic olefin may be used alone, or two or more types may be used in combination.

[0043] The structural units derived from the cyclic olefin in the ring-opening polymer rubber used in the present invention may be either an aliphatic cyclic olefin or an aromatic olefin, but are preferably alicyclic cyclic olefins. The content of the structural units derived from the aliphatic cyclic olefin in the ring-opening polymer rubber used in the present invention is not particularly limited, but is preferably 60 to 100% by weight, more preferably 80 to 100% by weight, and even more preferably substantially 100% by weight, based on the total repeating structural units.

[0044] The glass transition temperature (Tg) of the ring-opening polymer rubber used in the present invention is 0°C or lower. The glass transition temperature (Tg) of the ring-opening polymer rubber is not particularly limited as long as it is 0°C or lower, but is preferably -100 to -10°C, more preferably -90 to -20°C, and even more preferably -80 to -30°C. When the glass transition temperature (Tg) of the ring-opening polymer rubber used in the present invention is within the above range, the rubber composition will have excellent processability and rubber properties, and the resulting cross-linked rubber will have even better chip and cut resistance while maintaining sufficient wet grip performance. The glass transition temperature (Tg) of the ring-opening polymer rubber can be controlled, for example, by adjusting the molecular weight and polymer composition.

[0045] The weight average molecular weight (Mw) of the ring-opening polymer rubber used in the present invention is preferably 10,000 to 1,000,000, more preferably 50,000 to 800,0000, and even more preferably 100,000 to 600,000, as a polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography. When the weight average molecular weight (Mw) is within the above range, the rubber composition has excellent processability and rubber properties, and the resulting cross-linked rubber has even better chip and cut resistance while maintaining sufficient wet grip performance.

[0046] The cis / trans ratio of the ring-opening polymer rubber used in the present invention is preferably 90 / 10 to 5 / 95, more preferably 70 / 30 to 10 / 90, and even more preferably 50 / 50 to 15 / 85. The cis / trans ratio is the ratio of the cis structure to the trans structure of the double bond present in the repeating units constituting the ring-opening polymer rubber (cis / trans ratio).

[0047] The Mooney viscosity (ML1+4, 100°C) of the ring-opening polymer rubber used in the present invention is preferably 20 to 150, more preferably 30 to 130, and even more preferably 40 to 110. When the Mooney viscosity is within the above range, the rubber composition has excellent processability and rubber properties.

[0048] The ring-opening polymer rubber used in the present invention may have a modifying group at the polymer chain end. The modifying group to be introduced at the polymer chain end is not particularly limited, but is preferably a modifying group containing an atom selected from the group consisting of an atom of Group 15 of the periodic table, an atom of Group 16 of the periodic table, and a silicon atom.

[0049] As the modifying group for forming the terminal modified group, from the viewpoint of being able to increase affinity for fillers such as silica, 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 preferred, and among these, a modifying group containing an atom selected from the group consisting of a nitrogen atom, an oxygen atom, and a silicon atom is even more preferred.

[0050] Examples of modifying groups containing a nitrogen atom include an amino group, a pyridyl group, an imino group, an amide group, a nitro group, a urethane-bonded group, or a hydrocarbon group containing any of these groups. Examples of modifying groups 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 any of these groups. Examples of modifying groups containing a silicon atom include an alkylsilyl group, an oxysilyl group, or a hydrocarbon group containing any of these groups. Examples of modifying groups containing a phosphorus atom include a phosphate group, a phosphino group, or a hydrocarbon group containing any of these groups. Examples of modifying groups containing a sulfur atom include a sulfonyl group, a thiol group, a thioether group, or a hydrocarbon group containing any of these groups. Furthermore, the modifying group may contain multiple of the above groups. Note that an oxysilyl group refers to a group having a silicon-oxygen bond.

[0051] Specific examples of the oxysilyl group include an alkoxysilyl group, an aryloxysilyl group, an acyloxy group, an alkylsiloxysilyl group, and an arylsiloxysilyl group. Further examples include a hydroxysilyl group obtained by hydrolyzing an alkoxysilyl group, an aryloxysilyl group, or an acyloxy group.

[0052] An alkoxysilyl group is a group in which one or more alkoxy groups are bonded to a silicon atom, and specific examples thereof include a trimethoxysilyl group, a (dimethoxy)(methyl)silyl group, a (methoxy)(dimethyl)silyl group, a (methoxy)(dichloro)silyl group, a triethoxysilyl group, a (diethoxy)(methyl)silyl group, an (ethoxy)(dimethyl)silyl group, a (dimethoxy)(ethoxy)silyl group, a (methoxy)(diethoxy)silyl group, a tripropoxysilyl group, and a tris(trimethylsiloxy)silyl group.

[0053] The ratio of modified groups introduced into the polymer chain ends of the ring-opening polymer rubber used in the present invention is not particularly limited, but may be 10% or more as a percentage of the number of modified group-introduced ring-opening polymer rubber chain ends / total number of ring-opening polymer rubber chain ends.

[0054] <Method for Producing Ring-Opened Polymer Rubber> The method for producing the ring-opened polymer rubber of the present invention is not particularly limited, but for example, a method of polymerizing a cyclic olefin in the presence of a ring-opening polymerization catalyst can be mentioned.

[0055] The ring-opening polymerization catalyst may be any catalyst capable of ring-opening polymerization of cyclic olefins, and among these, ruthenium carbene complexes and so-called Ziegler-Natta catalysts are preferred. One type of ring-opening polymerization catalyst may be used alone, or two or more types may be used in combination.

[0056] Specific examples of ruthenium carbene complexes include bis(tricyclohexylphosphine)benzylideneruthenium dichloride, bis(triphenylphosphine)-3,3-diphenylpropenylideneruthenium dichloride, bis(tricyclohexylphosphine)t-butylvinylideneruthenium dichloride, dichloro-(3-phenyl-1H-inden-1-ylidene)bis(tricyclohexylphosphine)ruthenium, bis(1,3-diisopropylimidazolin-2-ylidene)benzylideneruthenium dichloride, and bis(1,3-dicyclohexyl

[0034] Examples of such compounds include (1,3-dimesitylimidazolin-2-ylidene)benzylideneruthenium dichloride, (1,3-dimesitylimidazolin-2-ylidene)(tricyclohexylphosphine)benzylideneruthenium dichloride, (1,3-dimesitylimidazolidin-2-ylidene)(tricyclohexylphosphine)benzylideneruthenium dichloride, (1,3-dimesitylimidazolidin-2-ylidene)(tricyclohexylphosphine)benzylideneruthenium dichloride, bis(tricyclohexylphosphine)ethoxymethylideneruthenium dichloride, and (1,3-dimesitylimidazolidin-2-ylidene)(tricyclohexylphosphine)ethoxymethylideneruthenium dichloride.

[0057] The Ziegler-Natta catalyst is a mixed catalyst of a Group 6 transition metal compound and an organoaluminum compound. Specific examples of the Group 6 transition metal compound include molybdenum compounds such as molybdenum pentachloride, molybdenum oxotetrachloride, molybdenum(phenylimido)tetrachloride, tridodecylammonium molybdate, methyltrioctylammonium molybdate, tridecylammonium molybdate, trioctylammonium molybdate, and tetraphenylammonium molybdate; and tungsten compounds such as tungsten hexachloride, tungsten oxotetrachloride, tungsten(phenylimido)tetrachloride, monocatecholatetungsten tetrachloride, bis(3,5-ditertiarybutyl)catecholatetungsten dichloride, bis(2-chloroetherate)tetrachloride, and tungsten oxotetraphenolate.

[0058] Specific examples of organoaluminum compounds contained in Ziegler-Natta catalysts include diethylaluminum ethoxide, diethylaluminum isopropoxide, diisobutylaluminum butoxide, diisobutylaluminum hexoxide, diethylaluminum (2-trichloroethoxide), diethylaluminum (2-tribromoethoxide), diethylaluminum (1,3-dichloro-2-propoxide), diethylaluminum (1,1,1,3,3,3-hexafluoro-2-propoxide), diethylaluminum (1,1,1-trichloro-2-methyl-2-propoxide), diethylaluminum (2,6-diisopropylphenoxide), ethylaluminum di(2-trichloroethoxide), ethylaluminum di(2-tribromoethoxide), ethylaluminum di(1,3-dichloro-2-propoxide), and ethylaluminum. di(1,1,1,3,3,3-hexafluoro-2-propoxide), ethylaluminum di(1,1,1-trichloro-2-methyl-2-propoxide), ethylaluminum bis(2,6-diisopropylphenoxide), ethyl(chloro)aluminum ethoxide, ethyl(chloro)aluminum isopropoxide, ethyl(chloro)aluminum butoxide, ethyl(chloro)aluminum(2-trichloroethoxide), ethyl(chloro)aluminum(2-tribromoethoxide), ethyl(bromo)aluminum(1,3-dichloro-2-propoxide), ethyl(chloro)aluminum(1,1,1,3,3,3-hexafluoro-2-propoxide), ethyl(chloro)aluminum(1,1,1-trichloro-2-methyl-2-propoxide), ethyl(chloro)aluminum(2,6-diisopropylphenoxide), and the like.

[0059] The amount of the ring-opening polymerization catalyst used is, in terms of the molar ratio of (ring-opening polymerization catalyst:monomer used in polymerization), usually in the range of 1:500 to 1:2,000,000, preferably 1:700 to 1:1,500,000, more preferably 1:1,000 to 1:1,000,000.

[0060] The polymerization reaction may be carried out in a solventless state or in a solution. When polymerizing in a solution, the solvent used is not particularly limited as long as it is inert to the polymerization reaction and can dissolve the cyclic olefin, polymerization catalyst, and the like used in the polymerization. However, it is preferable to use a hydrocarbon solvent or a halogenated solvent. Examples of hydrocarbon solvents include aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; aliphatic hydrocarbons such as hexane, n-heptane, and n-octane; and alicyclic hydrocarbons such as cyclohexane, cyclopentane, and methylcyclohexane. Examples of halogenated solvents include alkyl halogens such as dichloromethane and chloroform; and aromatic halogens such as chlorobenzene and dichlorobenzene. These solvents may be used alone or in combination of two or more.

[0061] When the cyclic olefin is subjected to ring-opening polymerization, an olefin compound or a diolefin compound may be added to the polymerization reaction system as a molecular weight modifier, if necessary, in order to adjust the molecular weight of the resulting ring-opening polymer rubber.

[0062] The olefin compound is not particularly limited as long as it is an organic compound having an ethylenically unsaturated bond, and examples thereof include α-olefins such as 1-butene, 1-pentene, 1-hexene, and 1-octene; styrenes such as styrene and vinyltoluene; halogen-containing vinyl compounds such as allyl chloride; vinyl ethers such as ethyl vinyl ether and i-butyl vinyl ether; amine-containing vinyl compounds such as allylamine, N,N-dimethylallylamine, and N,N-diethylallylamine; and disubstituted olefins such as 2-butene and 3-hexene.

[0063] The diolefin compounds include non-conjugated diolefins such as 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 1,6-heptadiene, 2-methyl-1,4-pentadiene, and 2,5-dimethyl-1,5-hexadiene.

[0064] The amount of the olefin compound and diolefin compound used as the molecular weight modifier may be appropriately selected depending on the molecular weight of the ring-opening polymer rubber to be produced, but is usually in the range of 1 / 100 to 1 / 100,000, preferably 1 / 200 to 1 / 50,000, and more preferably 1 / 500 to 1 / 10,000 in terms of molar ratio to the monomer used in polymerization.

[0065] Furthermore, when the ring-opening polymer rubber used in the present invention has a modifying group at the polymer chain end, it is preferable to use a modifying group-containing olefinically unsaturated hydrocarbon compound as the molecular weight modifier instead of the above-mentioned olefin compound or diolefin compound. By using such a modifying group-containing olefinically unsaturated hydrocarbon compound, the modifying group can be suitably introduced into the polymer chain end of the ring-opening polymer rubber obtained by polymerization.

[0066] The modifying group-containing olefinically unsaturated hydrocarbon compound is not particularly limited as long as it is a compound having a modifying group and one metathesis-reactive olefinic carbon-carbon double bond. For example, when it is desired to introduce an oxysilyl group into the polymer chain terminal of a ring-opening polymer rubber, an oxysilyl group-containing olefinically unsaturated hydrocarbon may be present in the polymerization reaction system.

[0067] Examples of such oxysilyl group-containing olefinically unsaturated hydrocarbons include those which introduce a modifying group only at one end (single end) of the polymer chain of the ring-opening polymer rubber, such as alkoxysilane compounds such as vinyl(trimethoxy)silane, vinyl(triethoxy)silane, allyl(trimethoxy)silane, allyl(methoxy)(dimethyl)silane, allyl(triethoxy)silane, allyl(ethoxy)(dimethyl)silane, styryl(trimethoxy)silane, styryl(triethoxy)silane, styrylethyl(triethoxy)silane, allyl(triethoxysilylmethyl)ether, and allyl(triethoxysilylmethyl)(ethyl)amine; aryloxysilane compounds such as vinyl(triacetoxy)silane, allyl(triacetoxy)silane, allyl(diacetoxy)methylsilane, and allyl(acetoxy)(dimethyl)silane; acyloxysilane compounds such as vinyl(triacetoxy)silane, allyl(triacetoxy)silane, allyl(diacetoxy)methylsilane, and allyl(acetoxy)(dimethyl)silane; alkylsiloxysilane compounds such as allyltris(trimethylsiloxy)silane; arylsiloxysilane compounds such as allyltris(triphenylsiloxy)silane; and polysiloxane compounds such as 1-allylheptamethyltrisiloxane, 1-allylnonamethyltetrasiloxane, 1-allylnonamethylcyclopentasiloxane, and 1-allylundecamethylcyclohexasiloxane.

[0068] Furthermore, examples of compounds for introducing modifying groups into both ends (both ends) of the polymer chain of the ring-opening polymer rubber include alkoxysilane compounds such as bis(trimethoxysilyl)ethylene, bis(triethoxysilyl)ethylene, 2-butene-1,4-di(trimethoxysilane), 2-butene-1,4-di(triethoxysilane), and 1,4-di(trimethoxysilylmethoxy)-2-butene; aryloxysilane compounds such as 2-butene-1,4-di(triphenoxysilane); Examples of the siloxysilane compound include 1,4-di(triacetoxysilane); alkylsiloxysilane compounds such as 2-butene-1,4-di[tris(trimethylsiloxy)silane]; arylsiloxysilane compounds such as 2-butene-1,4-di[tris(triphenylsiloxy)silane]; and polysiloxane compounds such as 2-butene-1,4-di(heptamethyltrisiloxane) and 2-butene-1,4-di(undecamethylcyclohexasiloxane).

[0069] The modifying group-containing olefinically unsaturated hydrocarbon compound, such as the oxysilyl group-containing olefinically unsaturated hydrocarbon compound, functions not only to introduce the modifying group into the polymer chain end of the ring-opening polymer rubber, but also as a molecular weight modifier. The amount of the modifying group-containing olefinically unsaturated hydrocarbon compound used may be appropriately selected depending on the molecular weight of the ring-opening polymer rubber to be produced, but is usually in the range of 1 / 100 to 1 / 100,000, preferably 1 / 200 to 1 / 50,000, and more preferably 1 / 500 to 1 / 10,000, in terms of molar ratio relative to the monomer used in polymerization.

[0070] The polymerization reaction temperature is not particularly limited, but is preferably −100° C. or higher, more preferably −50° C. or higher, even more preferably 0° C. or higher, and particularly preferably 20° C. or higher. The upper limit of the polymerization reaction temperature is not particularly limited, but is preferably less than 100° C., more preferably less than 90° C., even more preferably less than 80° C., and particularly preferably less than 70° C. The polymerization reaction time is also not particularly limited, but is preferably 1 minute to 72 hours, and more preferably 10 minutes to 20 hours.

[0071] If desired, an antioxidant such as a phenol-based stabilizer, a phosphorus-based stabilizer, or a sulfur-based stabilizer may be added to the ring-opening polymer rubber obtained by the polymerization reaction. The amount of the antioxidant to be added may be determined appropriately depending on the type of the antioxidant. Furthermore, if desired, an extender oil may be blended. When the ring-opening polymer rubber is obtained as a polymerization solution, known recovery methods may be employed to recover the ring-opening polymer rubber from the polymerization solution. For example, a method of separating the solvent by steam stripping or the like, filtering the solid, and then drying it to obtain a solid ring-opening polymer rubber, a method of directly devolatilizing the solvent or the like using a twin-screw heating dryer or the like to obtain a solid ring-opening polymer rubber, or a method of reprecipitation in a poor solvent, separating the solvent, filtering the solid, and then drying it to obtain a solid ring-opening polymer rubber may be employed.

[0072] <Petroleum Resin> The rubber composition of the present invention contains, in addition to the ring-opening polymer rubber described above, a petroleum resin having structural units derived from a polycyclic aliphatic cyclic olefin and having a glass transition temperature (Tg) of 10°C or higher.

[0073] The polycyclic aliphatic cyclic olefin for constituting the petroleum resin used in the present invention is preferably an aliphatic norbornene compound. Specific examples of the aliphatic norbornene compound include the aliphatic compounds among the norbornene compounds mentioned above as examples of the cyclic olefin for forming the ring-opening polymer rubber.

[0074] The polycyclic aliphatic cyclic olefins for constituting the petroleum resin used in the present invention include, among others, bicyclo[2.2.1]hept-2-enes which are unsubstituted or have a hydrocarbon substituent and tetracyclo[6.2.1.1]hept-2-enes which are unsubstituted or have a hydrocarbon substituent. ３，６ .0 ２，７ Among the dodec-4-enes, aliphatic compounds are more preferred, and dicyclopentadiene, tetracyclo[6.2.1.1 ３，６ .0 ２，７Dodec-4-ene, 2-norbornene, 5-ethylidene-2-norbornene, and tricyclopentadiene are particularly preferred, and dicyclopentadiene is most preferred. The polycyclic aliphatic cyclic olefins may be used alone or in combination of two or more.

[0075] The content of the structural units derived from polycyclic alicyclic olefins in the petroleum resin used in the present invention is not particularly limited, but is preferably 20 to 100 wt %, more preferably 30 to 99 wt %, even more preferably 32 to 97 wt %, and particularly preferably 35 to 95 wt %, based on the total repeating structural units. When the content of the structural units derived from polycyclic alicyclic olefins is within the above range, the resulting cross-linked rubber has excellent chip and cut resistance while providing sufficient wet grip performance. Furthermore, when even better chip and cut resistance is required, the content of the structural units derived from polycyclic alicyclic olefins is preferably 50 wt % or more, more preferably 60 wt % or more, and even more preferably 70 wt % or more.

[0076] When the petroleum resin used in the present invention has structural units derived from dicyclopentadiene, the content of the structural units derived from dicyclopentadiene is not particularly limited, but is preferably 20% by weight or more, more preferably 30 to 99% by weight, even more preferably 32 to 97% by weight, and particularly preferably 35 to 95% by weight, based on all repeating structural units. When the content of the structural units derived from dicyclopentadiene is within the above range, the resulting cross-linked rubber product has even better chip and cut resistance while still providing sufficient wet grip performance. Furthermore, when even better chip and cut resistance is required, the content of the structural units derived from dicyclopentadiene is preferably 50% by weight or more, more preferably 60% by weight or more, and even more preferably 70% by weight or more.

[0077] The petroleum resin used in the present invention may further contain a structural unit derived from an acyclic diolefin having 4 to 6 carbon atoms. Examples of the acyclic diolefin having 4 to 6 carbon atoms include 1,3-pentadiene, 1,3-butadiene, 1,2-butadiene, isoprene, 1,3-hexadiene, and 1,4-pentadiene. Of these, 1,3-pentadiene and isoprene are preferred. The acyclic diolefin having 4 to 6 carbon atoms may be used alone or in combination of two or more.

[0078] The content of structural units derived from acyclic diolefins having 4 to 6 carbon atoms in the petroleum resin used in the present invention is not particularly limited, but is preferably 0 to 40% by weight, more preferably 1 to 30% by weight, even more preferably 3 to 25% by weight, and particularly preferably 5 to 20% by weight, based on all repeating structural units. When the content of structural units derived from acyclic diolefins having 4 to 6 carbon atoms is within the above range, the resulting cross-linked rubber product has even better chip and cut resistance while still having sufficient wet grip performance.

[0079] The petroleum resin used in the present invention may further contain structural units derived from aromatic monoolefins having 8 to 10 carbon atoms. Examples of aromatic monoolefins having 8 to 10 carbon atoms include styrene and C9 fractions. The C9 fractions mainly contain styrene, α-methylstyrene, β-methylstyrene, vinyltoluene, and indene as aromatic monomers. The aromatic monoolefins having 8 to 10 carbon atoms may be used alone or in combination of two or more.

[0080] The content of structural units derived from aromatic monoolefins having 8 to 10 carbon atoms in the petroleum resin used in the present invention is not particularly limited, but is preferably 0 to 50% by weight based on all repeating structural units. Furthermore, when even better chip / cut resistance is required, the content of structural units derived from aromatic monoolefins having 8 to 10 carbon atoms is preferably 40% by weight or less, more preferably 30% by weight or less, even more preferably 20% by weight or less, and particularly preferably 10% by weight or less.

[0081] The petroleum resin used in the present invention may further contain other monomer units as long as the effects of the present invention can be obtained. Examples of other monomers (monomers other than polycyclic aliphatic cyclic olefins, acyclic diolefins having 4 to 6 carbon atoms, and aromatic monoolefins) for constituting the other monomer units include monocyclic alicyclic monoolefins having 4 to 6 carbon atoms, aromatic monoolefins, acyclic monoolefins having 4 to 8 carbon atoms, and monocyclic alicyclic diolefins. One type of other monomer may be used alone, or two or more types may be used in combination.

[0082] Examples of the monocyclic alicyclic monoolefin having 4 to 6 carbon atoms include cyclobutene, cyclopentene, cyclohexene, methylcyclobutene, and methylcyclopentene.

[0083] Examples of the acyclic monoolefins having 4 to 8 carbon atoms include 1-butene, 2-butene, isobutylene (2-methylpropene), 1-pentene, 2-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene, 1-hexene, 2-hexene, 2-methyl-1-pentene, 1-heptene, 2-heptene, 2-methyl-1-hexene, 1-octene, 2-octene, 2-methyl-1-heptene, and diisobutylene (2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-1-pentene).

[0084] Examples of the monocyclic alicyclic diolefin include cyclopentadiene and methylcyclopentadiene.

[0085] As other monomers, in addition to the above, monocyclic alicyclic monoolefins having 7 or more carbon atoms such as cycloheptene; acyclic monoolefins having other than 4 to 8 carbon atoms such as ethylene, propylene, and nonene; and the like can also be used.

[0086] The content of structural units derived from other monomers (monomers other than polycyclic aliphatic cyclic olefins, acyclic diolefins having 4 to 6 carbon atoms, and aromatic monoolefins) in the petroleum resin used in the present invention is not particularly limited, but is preferably 0 to 40% by weight, more preferably 0 to 20% by weight, even more preferably 0 to 10% by weight, and particularly preferably substantially 0% by weight, based on the total weight of all repeating structural units.

[0087] The glass transition temperature (Tg) of the petroleum resin used in the present invention is 10°C or higher. The glass transition temperature (Tg) of the petroleum resin is not particularly limited as long as it is 10°C or higher, but is preferably 20 to 100°C, more preferably 30 to 90°C, even more preferably 35 to 85°C, and particularly preferably 50 to 80°C. When the glass transition temperature (Tg) of the ring-opening polymer rubber used in the present invention is within the above range, the resulting cross-linked rubber has sufficient wet grip properties and even better chip and cut resistance. The glass transition temperature (Tg) of the petroleum resin can be controlled, for example, by adjusting the molecular weight and polymer composition.

[0088] The weight average molecular weight (Mw) of the petroleum resin used in the present invention is preferably 400 to 8,000, more preferably 600 to 5,000, even more preferably 700 to 3,000, and particularly preferably 750 to 1,700, as a polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography. When the weight average molecular weight (Mw) is within the above range, the rubber composition has excellent processability and rubber properties, and the resulting cross-linked rubber has even better chip and cut resistance while providing sufficient wet grip properties.

[0089] The softening point of the petroleum resin used in the present invention is preferably 70 to 160°C, more preferably 80 to 150°C, even more preferably 90 to 145°C, and particularly preferably 98 to 140°C. When the softening point is within the above range, the rubber composition has excellent processability and rubber properties, and the resulting cross-linked rubber has even better chip and cut resistance while maintaining sufficient wet grip performance. The softening point can be measured in accordance with JIS K 6863.

[0090] <Method for Producing Petroleum Resin> The method for producing the petroleum resin used in the present invention is not particularly limited, and examples thereof include a method of addition polymerization of a polymerizable component having a polycyclic aliphatic cyclic olefin, and, if necessary, an acyclic diolefin having 4 to 6 carbon atoms, an aromatic monoolefin, and other monomers.

[0091] A suitable method for producing petroleum resins is, for example, a thermal polymerization method in which a monomer component is heated to cause a thermal polymerization reaction.

[0092] The polymerization temperature when carrying out the thermal polymerization reaction is not particularly limited, but is preferably in the range of 150°C to 350°C, and more preferably in the range of 240°C to 300°C. When the polymerization temperature is in the above range, the polymerization activity is good and reactions other than the target polymerization reaction can be suppressed. The pressure when carrying out the polymerization reaction may be atmospheric pressure or under pressure. The polymerization reaction time can be selected appropriately, but is usually selected in the range of 10 minutes to 12 hours, preferably 30 minutes to 6 hours.

[0093] The polymerization system for the thermal polymerization reaction may contain a solvent. Examples of the solvent that can be used include aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; aliphatic hydrocarbons such as hexane, n-heptane, and n-octane; and alicyclic hydrocarbons such as cyclohexane, cyclopentane, and methylcyclohexane. These solvents may be used alone or in combination of two or more.

[0094] The polymerization reaction can be stopped by lowering the temperature when a desired polymerization conversion rate is obtained.

[0095] The petroleum resin used in the present invention can also be obtained by addition polymerization using a Friedel-Crafts type cationic polymerization catalyst. In this case, any known polymerization method can be used.

[0096] The method for producing the petroleum resin may include at least the polymerization step, but may also include other steps as necessary.

[0097] Other steps include, for example, a recovery step in which, after terminating the polymerization reaction in the polymerization step, unreacted monomers and solvent are removed, and low-molecular-weight oligomer components are further removed by steam distillation or the like, followed by cooling to obtain a solid petroleum resin.

[0098] <Rubber Composition> The rubber composition of the present invention contains the ring-opening polymer rubber and the petroleum resin.

[0099] In the rubber composition of the present invention, the content of the petroleum resin per 100 parts by weight of the rubber component containing the ring-opening polymer rubber is not particularly limited, but is preferably 1 to 50 parts by weight, more preferably 3 to 40 parts by weight, and even more preferably 5 to 30 parts by weight. When the content of the petroleum resin per 100 parts by weight of the rubber component is within the above range, the rubber composition has excellent processability and rubber properties, and the resulting cross-linked rubber has even better chip and cut resistance while maintaining sufficient wet grip performance. Furthermore, when even better chip and cut resistance and wet grip performance are required, the content of the petroleum resin per 100 parts by weight of the rubber component containing the ring-opening polymer rubber is preferably 10 parts by weight or more, more preferably 15 parts by weight or more, and even more preferably 18 parts by weight or more.

[0100] The rubber composition of the present invention may contain, in addition to the ring-opening polymer rubber and the petroleum resin, necessary amounts of compounding agents such as a filler, a crosslinking agent, a crosslinking accelerator, a crosslinking activator, an antioxidant, an activator, a process oil, a plasticizer, and a lubricant.

[0101] Examples of fillers include carbon black, silica, calcium carbonate, talc, clay, etc. These fillers may be used alone or in combination of two or more.

[0102] Examples of carbon black include furnace black, acetylene black, thermal black, channel black, graphite, etc. Among these, furnace black is preferred, and specific examples thereof include SAF, ISAF, ISAF-HS, ISAF-LS, IISAF-HS, HAF, HAF-HS, HAF-LS, FEF, etc. These carbon blacks can be used alone or in combination of two or more.

[0103] The nitrogen adsorption specific surface area of ​​carbon black (N ２ SA) is preferably 5 to 200 m ２ / g, more preferably 70 to 120m ２ The dibutyl phthalate (DBP) adsorption amount is preferably 5 to 300 ml / 100 g, more preferably 80 to 160 ml / 100 g.

[0104] The content of carbon black in the rubber composition of the present invention is preferably 1 to 150 parts by weight, more preferably 10 to 120 parts by weight, still more preferably 20 to 100 parts by weight, and particularly preferably 30 to 80 parts by weight, per 100 parts by weight of the rubber component containing the ring-opening polymer rubber in the rubber composition. When the content of carbon black is within the above range, the obtained cross-linked rubber product has even better chip and cut resistance while maintaining sufficient wet grip performance.

[0105] The silica is not particularly limited, but examples thereof include dry process white carbon, wet process white carbon, colloidal silica, and precipitated silica. A carbon-silica dual-phase filler in which silica is supported on the surface of carbon black may also be used. The content of silica in the rubber composition of the present invention is preferably 0 to 100 parts by weight, more preferably 0 to 50 parts by weight, and even more preferably 0 to 20 parts by weight, per 100 parts by weight of the rubber component containing the ring-opening polymer rubber in the rubber composition.

[0106] When silica is compounded in the rubber composition of the present invention, it is preferable to further compound a silane coupling agent for the purpose of further improving the affinity between the ring-opening polymer rubber and the silica. The compounding amount of the silane coupling agent is preferably 0.1 to 30 parts by weight, more preferably 1 to 15 parts by weight, per 100 parts by weight of silica.

[0107] Examples of crosslinking agents include sulfur such as powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur; sulfur halides such as sulfur monochloride and sulfur dichloride; organic peroxides such as dicumyl peroxide and ditertiary butyl peroxide; quinone dioximes such as p-quinone dioxime and p,p'-dibenzoylquinone dioxime; organic polyamine compounds such as triethylenetetramine, hexamethylenediamine carbamate, and 4,4'-methylenebis-o-chloroaniline; and alkylphenol resins having methylol groups. Among these, sulfur is preferred, and powdered sulfur is more preferred. These crosslinking agents may be used alone or in combination of two or more. The amount of crosslinking agent blended is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 5 parts by weight, per 100 parts by weight of the rubber component containing the ring-opening polymer rubber in the rubber composition.

[0108] Examples of the crosslinking accelerator include sulfenamide-based crosslinking accelerators such as N-cyclohexyl-2-benzothiazolylsulfenamide, N-(tert-butyl)-2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolylsulfenamide, and N,N'-diisopropyl-2-benzothiazolylsulfenamide; guanidine-based crosslinking accelerators such as 1,3-diphenylguanidine, 1,3-diorthotolylguanidine, and 1-orthotolylbiguanidine; and diethylthiourea. Examples of suitable crosslinking accelerators include thiourea-based crosslinking accelerators such as 2-mercaptobenzothiazole, dibenzothiazyl disulfide, and 2-mercaptobenzothiazole zinc salt; thiuram-based crosslinking accelerators such as tetramethylthiuram monosulfide and tetramethylthiuram disulfide; dithiocarbamic acid-based crosslinking accelerators such as sodium dimethyldithiocarbamate and zinc diethyldithiocarbamate; and xanthic acid-based crosslinking accelerators such as sodium isopropylxanthogenate, zinc isopropylxanthogenate, and zinc butylxanthogenate. Among these, those containing sulfenamide-based crosslinking accelerators are preferred. These crosslinking accelerators may be used alone or in combination of two or more. The amount of crosslinking accelerator blended is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 5 parts by weight, per 100 parts by weight of the rubber component containing the ring-opening polymer rubber in the rubber composition.

[0109] As the crosslinking activator, for example, a higher fatty acid such as stearic acid, zinc oxide, etc. The compounding amount of the crosslinking activator is appropriately selected, but the compounding amount of the higher fatty acid is preferably 0.05 to 15 parts by weight, more preferably 0.5 to 5 parts by weight, per 100 parts by weight of the rubber component containing the ring-opening polymer rubber in the rubber composition, and the compounding amount of the zinc oxide is preferably 0.05 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, per 100 parts by weight of the rubber component containing the ring-opening polymer rubber in the rubber composition.

[0110] The process oil may be a mineral oil or a synthetic oil. Typical mineral oils include aromatic oil, naphthenic oil, and paraffin oil. The amount of process oil added is preferably 1 to 30 parts by weight, more preferably 3 to 20 parts by weight, per 100 parts by weight of the rubber component containing the ring-opening polymer rubber in the rubber composition.

[0111] Other compounding agents include activators such as diethylene glycol, polyethylene glycol, and silicone oil; and waxes.

[0112] The rubber composition of the present invention may contain, as a rubber component, a rubber other than the above-mentioned ring-opening polymer rubber. Examples of rubbers other than the above-mentioned ring-opening polymer rubber include natural rubber (NR), polyisoprene rubber (IR), emulsion-polymerized SBR (styrene-butadiene copolymer rubber), solution-polymerized random SBR (bound styrene 5 to 50% by weight, 1,2-bond content in butadiene portion 10 to 80%), high trans SBR (trans bond content in butadiene portion 70 to 95%), low cis BR (polybutadiene rubber), high cis BR, high trans BR (trans bond content in butadiene portion 70 to 95%), ethylene-propylene-diene rubber, and the like. Examples of suitable rubbers include EPDM, styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, emulsion-polymerized styrene-acrylonitrile-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, high vinyl SBR-low vinyl SBR block copolymer rubber, polyisoprene-SBR block copolymer rubber, polystyrene-polybutadiene-polystyrene block copolymer, acrylic rubber, epichlorohydrin rubber, fluororubber, silicone rubber, ethylene-propylene rubber, and urethane rubber. These rubbers can be used either alone or in combination of two or more.

[0113] The content of the ring-opening polymer rubber used in the present invention in the rubber composition of the present invention is preferably 30 to 100 parts by weight, more preferably 40 to 100 parts by weight, and even more preferably 50 to 100 parts by weight, per 100 parts by weight of the total amount of the rubber components. On the other hand, the content of the rubber other than the ring-opening polymer rubber used in the present invention in the rubber composition of the present invention is preferably 0 to 70 parts by weight, more preferably 0 to 60 parts by weight, and even more preferably 0 to 50 parts by weight, per 100 parts by weight of the total amount of the rubber components.

[0114] The rubber composition of the present invention can be obtained by kneading the components according to a conventional method. For example, the compounding ingredients excluding the crosslinking agent and crosslinking accelerator are kneaded with a rubber component such as a ring-opening polymer rubber, and then the kneaded mixture is mixed with the crosslinking agent and crosslinking accelerator to obtain the rubber composition. The kneading temperature of the compounding ingredients excluding the crosslinking agent and crosslinking accelerator with the rubber component such as the ring-opening polymer rubber is preferably 20 to 200°C, more preferably 30 to 180°C, and the kneading time is preferably 30 seconds to 30 minutes. The mixing of the crosslinking agent and crosslinking accelerator is usually carried out after cooling to 100°C or less, preferably 80°C or less.

[0115] <Rubber Cross-Linked Product> The rubber cross-linked product of the present invention is obtained by cross-linking the above-described rubber composition of the present invention.

[0116] The cross-linked rubber product of the present invention can be produced by using the rubber composition of the present invention, for example, molding the rubber composition into a desired shape using a molding machine such as an extruder, injection molding machine, compressor, or roll, and then heating to cause a cross-linking reaction and fix the shape as a cross-linked rubber product. In this case, cross-linking may be carried out after molding in advance or simultaneously with molding. The molding temperature is usually 10 to 200°C, preferably 25 to 120°C. The cross-linking temperature is usually 100 to 200°C, preferably 130 to 190°C, and the cross-linking time is usually 1 minute to 24 hours, preferably 2 minutes to 12 hours, and particularly preferably 3 minutes to 6 hours.

[0117] Depending on the shape, size, etc. of the cross-linked rubber product, even if the surface is cross-linked, the inside may not be sufficiently cross-linked, so secondary cross-linking may be carried out by further heating.

[0118] The heating method may be appropriately selected from common methods used for crosslinking rubber, such as press heating, steam heating, oven heating, and hot air heating.

[0119] The cross-linked rubber product of the present invention obtained in this manner is obtained using the ring-opening polymer rubber of the present invention described above, and therefore has excellent chip and cut resistance and sufficient wet grip performance. Utilizing these properties, the cross-linked rubber product of the present invention can be used in a variety of applications, for example, as materials for various tire components such as cap treads, base treads, carcasses, sidewalls, and bead portions in tires; materials for hoses, belts, mats, anti-vibration rubbers, and various other industrial products; impact modifiers for resins; resin film cushioning agents; shoe soles; rubber shoes; golf balls; and toys. In particular, the cross-linked rubber product of the present invention can be suitably used as a tire material (for example, a material for heavy-duty tires).

[0120] The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. In the following, "parts" are by weight unless otherwise specified. Various tests and evaluations were carried out according to the following methods.

[0121] <Weight-average molecular weight (Mw)> The weight-average molecular weight (Mw) of the ring-opening polymer rubber and petroleum resin was measured as a polystyrene equivalent value by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent. The measurement device used was an HLC-8320GPC (manufactured by Tosoh Corporation). The measurement was carried out using a column consisting of four TSKgel Super Multipore HZ-H (manufactured by Tosoh Corporation) connected in series, under conditions of a flow rate of 0.35 ml / min, a sample injection amount of 10 μml, and a column temperature of 40°C.

[0122] <Monomer composition ratio> The monomer composition ratio of the ring-opening polymer rubber and the petroleum resin is １ It was determined by H-NMR spectrum measurement.

[0123] <Glass Transition Temperature (Tg)> The glass transition temperature (Tg) of the ring-opening polymer rubber and the petroleum resin was measured in accordance with JIS K7121 using a differential scanning calorimeter (DSC) at a temperature rise rate of 10°C / min at intervals of 0.13°C, and determined from the resulting DSC curve.

[0124] <Softening Point> The softening point of the petroleum resin was measured by the ring and ball method specified in JIS K2531.

[0125] <Chip-and-Cut Resistance> Chip-and-cut resistance was evaluated based on the tensile breaking energy. A tensile test was performed on a sheet-like cross-linked rubber product in accordance with JIS K6251, and the breaking energy was determined from the area of ​​the stress-strain curve up to break. For Examples 1 to 4 and Comparative Examples 1 to 5 (Table 3), an index was determined as an index of chip-and-cut resistance, with the breaking energy of Comparative Example 2 taken as 100. For Examples 4 to 7 and Comparative Examples 6 to 8 (Table 4), an index was determined as an index of chip-and-cut resistance, with the breaking energy of Comparative Example 8 taken as 100. It can be determined that the larger the index value, the higher the breaking energy and the better the chip-and-cut resistance.

[0126] <Wet Grip Property> For the sheet-like cross-linked rubber products, tan δ was measured at 0°C under conditions of a dynamic strain of 0.5% and 10 Hz using an ARES manufactured by Rheometrics Corporation. Then, for Examples 1 to 4 and Comparative Examples 1 to 5 (Table 3), an index was calculated as an index of chip and cut resistance, with the measured value for Comparative Example 2 set to 100. Furthermore, for Examples 4 to 7 and Comparative Examples 6 to 8 (Table 4), an index was calculated as an index of chip and cut resistance, with the measured value for Comparative Example 8 set to 100. The higher the wet grip property, the larger this index, and if this index is 90 or higher, it can be determined that the wet grip property is sufficient.

[0127] <Production Example 1 (Production of Ring-Opened Polymer Rubber 1)> Under a nitrogen atmosphere, 77 parts of cyclopentene (CPE), 23 parts of dicyclopentadiene (DCPD), 297 parts of cyclohexane, and 0.048 parts of 1-hexene were placed in a glass reaction vessel equipped with a stirrer. Next, 0.024 parts of dichloro-(3-phenyl-1H-inden-1-ylidene)bis(tricyclohexylphosphine)ruthenium(II) dissolved in 3 parts of toluene was added, and a polymerization reaction was carried out at 40°C for 2 hours. After the polymerization reaction, excess vinyl ethyl ether was added to terminate the polymerization.

[0128] The polymerization solution was poured into a large excess of methanol containing 2,6-di-t-butyl-p-cresol (BHT), and the precipitated polymer was recovered, washed with methanol, and then vacuum dried at 50°C for 3 days to obtain ring-opened polymer rubber 1. The monomer composition ratio, weight average molecular weight (Mw), glass transition temperature (Tg), and Mooney viscosity (ML(1+4) 100°C) of the obtained ring-opened polymer rubber 1 were measured. The results are shown in Table 1.

[0129] <Production Example 2 (Production of Ring-Opened Polymer Rubber 2)> Under a nitrogen atmosphere, 90 parts of cyclopentene (CPE), 10 parts of dicyclopentadiene (DCPD), 297 parts of cyclohexane, and 0.028 parts of 1-hexene were added to a glass reaction vessel equipped with a stirrer. Next, 0.026 parts of dichloro-(3-phenyl-1H-inden-1-ylidene)bis(tricyclohexylphosphine)ruthenium(II) dissolved in 3 parts of toluene was added, and the polymerization reaction was carried out at 40°C for 2 hours. After the polymerization reaction, the polymerization was terminated by adding excess vinyl ethyl ether. The polymerization solution was poured into a large excess of methanol containing 2,6-di-t-butyl-p-cresol (BHT), and the precipitated polymer was recovered, washed with methanol, and then vacuum-dried at 50°C for 3 days to obtain ring-opened polymer rubber 2. The monomer composition ratio, weight average molecular weight (Mw), glass transition temperature (Tg) and Mooney viscosity (ML(1+4) 100°C) of the obtained ring-opening polymer rubber 2 were measured. The results are shown in Table 1.

[0130] <Production Example 3 (Production of Ring-Opened Polymer Rubber 3)> Under a nitrogen atmosphere, 65 parts of cyclopentene (CPE), 35 parts of 2-norbornene, 297 parts of cyclohexane, and 0.066 parts of 1-hexene were added to a glass reaction vessel equipped with a stirrer. Next, 0.024 parts of dichloro-(3-phenyl-1H-inden-1-ylidene)bis(tricyclohexylphosphine)ruthenium(II) dissolved in 3 parts of toluene was added, and the polymerization reaction was carried out at 20°C for 2 hours. After the polymerization reaction, the polymerization was terminated by adding an excess of vinyl ethyl ether. The polymerization solution was poured into a large excess of methanol containing 2,6-di-t-butyl-p-cresol (BHT), and the precipitated polymer was recovered, washed with methanol, and then vacuum-dried at 50°C for 3 days to obtain ring-opened polymer rubber 3. The monomer composition ratio, weight average molecular weight (Mw), glass transition temperature (Tg) and Mooney viscosity (ML(1+4) 100°C) of the obtained ring-opening polymer rubber 3 were measured. The results are shown in Table 1.

[0131] Production Example 4 (Production of Ring-Opened Polymer Rubber 4) Under a nitrogen atmosphere, 100 parts of cyclopentene (CPE), 297 parts of cyclohexane, and 0.030 parts of 1-hexene were added to a glass reaction vessel equipped with a stirrer. Next, 0.027 parts of dichloro-(3-phenyl-1H-inden-1-ylidene)bis(tricyclohexylphosphine)ruthenium(II) dissolved in 3 parts of toluene was added, and the polymerization reaction was carried out at 20°C for 2 hours. After the polymerization reaction, the polymerization was terminated by adding excess vinyl ethyl ether. The polymerization solution was poured into a large excess of methanol containing 2,6-di-t-butyl-p-cresol (BHT), and the precipitated polymer was recovered, washed with methanol, and then vacuum-dried at 50°C for 3 days to obtain ring-opened polymer rubber 4. The monomer composition, weight-average molecular weight (Mw), glass transition temperature (Tg), and Mooney viscosity (ML(1+4) 100°C) of the obtained ring-opened polymer rubber 4 were measured. The results are shown in Table 1.

[0132]

[0133] Production Example 5 (Production of Petroleum Resin 1) A mixture of 86 parts of dicyclopentadiene, 14 parts of isoprene, and 25 parts of xylene was charged into a polymerization reactor under a nitrogen atmosphere, heated to 260°C, and then polymerized for 4 hours. The temperature was then returned to room temperature to terminate the polymerization reaction, yielding a polymer solution containing petroleum resin and unreacted monomers. The polymer solution was then transferred to a distillation kettle and heated at 240°C for 1 hour under a nitrogen atmosphere for stripping, thereby removing the hydrocarbon solvent and obtaining a solid petroleum resin. The resulting petroleum resin was then measured for monomer composition, weight average molecular weight (Mw), softening point, and glass transition temperature (Tg) according to the methods described above. The results are shown in Table 2.

[0134] <Production Examples 6 and 7 (Production of Petroleum Resins 2 and 3)> Petroleum Resins 2 and 3 were obtained in the same manner as in Production Example 5, except that the types and amounts of the monomers used were changed as shown in Table 2. The monomer composition ratio, weight average molecular weight (Mw), softening point, and glass transition temperature (Tg) of the obtained petroleum resins were measured according to the methods described above. The results are shown in Table 2.

[0135] Production Example 8 (Production of Petroleum Resin 4) Under a nitrogen atmosphere, 75 parts of cyclopentane were charged into a polymerization reactor, the temperature was raised to 65°C, and then 0.65 parts of aluminum chloride was added (mixture M1). Subsequently, a mixture a1 consisting of 50 parts of 1,3-pentadiene and 50 parts of olefins was continuously added to the polymerization reactor containing the mixture M1 through separate lines, and polymerization was carried out while maintaining the temperature (65°C) for 60 minutes. Thereafter, aqueous sodium hydroxide solution was added to the polymerization reactor to terminate the polymerization reaction. The precipitate formed upon termination of the polymerization was removed by filtration, yielding a polymer solution containing the petroleum resin and unreacted monomers. The polymer solution was then transferred to a distillation kettle and stripped by heating at 250°C for 1 hour under a nitrogen atmosphere. The hydrocarbon solvent was removed, yielding a solid petroleum resin. The resulting petroleum resin was then measured for its monomer composition, weight-average molecular weight (Mw), softening point, and glass transition temperature (Tg) according to the methods described above. The results are shown in Table 2.

[0136] <Production Examples 9 and 10 (Production of Petroleum Resins 5 and 6)> Petroleum resins 5 and 6 were obtained in the same manner as in Production Example 8, except that the types and amounts of the monomers used were changed as shown in Table 2. The obtained petroleum resins were measured in the same manner as in Production Example 5, and the results are shown in Table 2.

[0137] The "olefins" in Table 2 are mixtures of acyclic monoolefins and monocyclic olefins, mainly composed of cyclopentene and isobutylene. The "C9 fraction" in Table 2 are aromatic monoolefins having 8 to 10 carbon atoms, mainly composed of styrene, α-methylstyrene, β-methylstyrene, vinyltoluene, and indene.

[0138]

[0139] Comparative Example 1 100 parts of ring-opening polymer rubber 1 were masticated in a 250 ml Banbury mixer, to which 50 parts of carbon black (trade name "Seast 9H", manufactured by Tokai Carbon Co., Ltd.), 3 parts of zinc oxide (zinc oxide No. 1), 2 parts of stearic acid (trade name "SA-300", manufactured by ADEKA Corporation), and 2 parts of an antioxidant (N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine, trade name "Nocrac 6C", manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) were added, and the mixture was kneaded for 4 minutes starting at 80°C, and the rubber composition was discharged from the Banbury mixer. The temperature of the rubber composition at the end of kneading was 160°C. Next, the obtained rubber composition was kneaded with 1.75 parts of sulfur and 1 part of a crosslinking accelerator (N-cyclohexylbenzothiazole-2-sulfene, trade name "Noccela CZ-G (CZ)", manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) using an open roll at 50°C, and then a sheet-like rubber composition was taken out. The obtained rubber composition was press-crosslinked at 160°C for 13 minutes to produce a sheet-like crosslinked rubber product, and the chip / cut resistance and wet grip properties were evaluated according to the methods described above. The results are shown in Table 3.

[0140] Comparative Example 2 A rubber composition and a sheet-like cross-linked rubber product were obtained in the same manner as in Comparative Example 1, except that 20 parts of T-DAE oil (trade name "Aromax T-DAE", aromatic process oil, manufactured by Nippon Oil Corporation) were added at the same time as adding the carbon black, zinc oxide, stearic acid, and antioxidant, and then evaluated in the same manner as in Comparative Example 1. The results are shown in Table 3.

[0141] Example 1 A rubber composition and a sheet-like cross-linked rubber product were obtained in the same manner as in Comparative Example 1, except that 10 parts each of Petroleum Resin 1 and T-DAE oil were added at the same time as adding carbon black, zinc oxide, stearic acid, and the antioxidant, and then evaluated in the same manner as in Comparative Example 1. The results are shown in Table 3.

[0142] Examples 2 to 4, Comparative Examples 3 to 5 Rubber compositions and sheet-like cross-linked rubber products were obtained in the same manner as in Example 1, except that the type of petroleum resin was changed as shown in Table 3, and evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0143] Examples 5 to 7, Comparative Examples 6 to 8 Rubber compositions and sheet-shaped cross-linked rubber products were obtained in the same manner as in Example 1, except that the type of rubber was changed as shown in Table 4, and evaluated in the same manner as in Example 1. The "SBR" shown in Table 4 is "Nipol (registered trademark) 1502" manufactured by Zeon Corporation, the "natural rubber" shown in Table 4 is CV60 grade natural rubber, and the "polybutadiene rubber" shown in Table 4 is "Nipol (registered trademark) BR1220" manufactured by Zeon Corporation. The results are shown in Table 4, along with the results of Example 4. In Tables 3 and 4, the unit for the amount of each component in the formulation of the rubber composition is "parts."

[0144]

[0145]

[0146] As shown in Tables 3 and 4, the rubber compositions containing the ring-opening polymer rubber having structural units derived from a cyclic olefin and the petroleum resin having structural units derived from a polycyclic aliphatic cyclic olefin were capable of providing cross-linked rubber products having excellent chip and cut resistance (Examples 1 to 7).

[0147] On the other hand, when no petroleum resin was contained (Comparative Examples 1 and 2), or when other petroleum resins were contained in place of the petroleum resin having structural units derived from polycyclic aliphatic cyclic olefin (Comparative Examples 3 to 5), the obtained cross-linked rubber products were inferior in chip and cut resistance. Also, when other rubbers were contained in place of the ring-opening polymer rubber having structural units derived from cyclic olefin (Comparative Examples 6 to 8), the obtained cross-linked rubber products were also inferior in chip and cut resistance.

Claims

1. A rubber composition comprising: a ring-opening polymer rubber having a structural unit derived from a cyclic olefin and having a glass transition temperature (Tg) of 0°C or lower; and a petroleum resin having a structural unit derived from a polycyclic aliphatic cyclic olefin and having a glass transition temperature (Tg) of 10°C or higher.

2. The rubber composition according to claim 1, wherein the petroleum resin has a structural unit derived from dicyclopentadiene as the structural unit derived from the polycyclic aliphatic cyclic olefin.

3. The rubber composition according to claim 2, wherein the petroleum resin contains 20% by weight or more of structural units derived from dicyclopentadiene.

4. The rubber composition according to any one of claims 1 to 3, wherein the ring-opening polymer rubber has a structural unit derived from cyclopentene as the structural unit derived from the cyclic olefin.

5. The rubber composition according to claim 4, wherein the ring-opening polymer rubber contains 20% by weight or more of structural units derived from cyclopentene.

6. A rubber composition according to any one of claims 1 to 5, wherein the ring-opening polymer rubber has a structural unit derived from a norbornene compound as the structural unit derived from the cyclic olefin.

7. The rubber composition according to claim 6, wherein the ring-opening polymer rubber contains 15% by weight or more of structural units derived from the norbornene compound.

8. The rubber composition according to any one of claims 1 to 7, which contains 1 to 50 parts by weight of said petroleum resin per 100 parts by weight of the rubber component containing said ring-opening polymer rubber.

9. The rubber composition according to any one of claims 1 to 8, further comprising a filler.

10. The rubber composition according to any one of claims 1 to 9, further comprising a crosslinking agent.

11. A cross-linked rubber product obtained by cross-linking the rubber composition according to any one of claims 1 to 10.

12. A tire comprising the crosslinked rubber product according to claim 11.

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