JP2016190984A - Rubber composition for run-flat tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for run-flat tire capable of providing a rubber crosslinked article excellent in low heat generation property and rigidity when used as a rubber layer for reinforcing sidewall portion.SOLUTION: There is provided a rubber composition for run-flat tire containing a terminal modified group-containing cyclopentene ring-opened polymer with cis percentage of a structural unit derived from cyclopentene of 20 to 80% and silica, where the percentage content of the silica is 30 to 200 pts.wt. based on 100 pts.wt. of the rubber component contained in the rubber composition for run-flat tire. There is provided a rubber composition for run-flat tire where the terminal modified group-containing cyclopentene ring-opened polymer is a polymer with an oxysilyl group introduced to a terminal of a polymer chain.SELECTED DRAWING: None

Description

  INDUSTRIAL APPLICABILITY The present invention can provide a rubber cross-linked product excellent in low heat generation and rigidity (for example, rigidity when used as a sidewall reinforcing rubber layer), and can be used suitably for run-flat tire applications. The present invention relates to a rubber composition for a flat tire.

  Run-flat tires have been developed as automobile tires that can safely travel a certain distance even when the tires are punctured. Examples of such run-flat tires include a core type system and a side reinforcing type system. In the core type system, an annular core is attached to the rim bottom, and a tire punctured by the core is supported from the inside to prevent deformation of the tire.

  In addition, the side-reinforced system has a thick rubber layer for reinforcement with a high modulus of elasticity on the side wall, so that even when the tire is punctured, it maintains the rigidity of the tire and undergoes repeated bending deformation. By reducing rubber breakage, it is possible to travel long distances.

  On the other hand, in recent years, low heat build-up has been strongly demanded for automobile tires due to environmental problems and resource problems, and low heat build-up is also demanded for such run-flat tires.

  For such a situation, for example, in Patent Document 1, at least one functional group selected from the group consisting of an amino group, a hydroxyl group, an epoxy group, a carbonyl group, an alkoxysilyl group, a silanol group, and a specific siloxane group is used. Proposed rubber composition for run-flat tires, comprising 100 parts by weight of a rubber component containing a modified conjugated diene rubber having an essential component, 30 to 80 parts by weight of a reinforcing agent containing silica as an essential component, and a crosslinking agent Has been.

  According to the technique of this Patent Document 1, although a run flat tire with improved low heat generation can be provided with good rigidity, low heat generation is not yet sufficient, and therefore, further low heat generation is possible. Further improvement was desired.

JP 2010-126656 A

  The object of the present invention is made in view of such a situation, and provides a rubber cross-linked product excellent in low heat buildup and rigidity (for example, rigidity when used as a rubber layer for reinforcing a sidewall portion). An object of the present invention is to provide a rubber composition for a run-flat tire that can be manufactured and a rubber cross-linked product obtained using the rubber composition for a run-flat tire.

  As a result of diligent research to achieve the above object, the present inventors have formulated a specific amount of silica in a terminally modified group-containing cyclopentene ring-opening polymer in which the cis ratio of the structural unit derived from cyclopentene is in a specific range. It has been found that the above object can be achieved by the rubber composition as described above, and the present invention has been completed.

  That is, according to the present invention, there is provided a rubber composition for a run-flat tire comprising a terminally modified group-containing cyclopentene ring-opening polymer having a cis ratio of a cyclopentene-derived structural unit of 20 to 80%, and silica, A rubber composition for a run-flat tire is provided in which the silica content is 30 to 200 parts by weight with respect to 100 parts by weight of the rubber component contained in the rubber composition for a run-flat tire.

In the rubber composition for a run-flat tire of the present invention, the terminal modified group-containing cyclopentene ring-opening polymer is preferably a polymer in which an oxysilyl group is introduced at the end of a polymer chain.
In the rubber composition for a run-flat tire of the present invention, the nitrogen adsorption specific surface area measured by the BET method of the silica is preferably 300 m ² / g or less.

The present invention also provides a rubber cross-linked product obtained by cross-linking the rubber composition for a run-flat tire, and a run-flat tire including the rubber cross-linked product.
The rubber cross-linked product is preferably a rubber layer for reinforcing a sidewall portion of a run flat tire.

  According to the present invention, a rubber composition for a run-flat tire that can provide a rubber cross-linked product excellent in low heat buildup and rigidity (for example, rigidity when used as a rubber layer for reinforcing a sidewall portion), and the run Rubber bridge obtained by using a rubber composition for a flat tire, excellent in low heat buildup and rigidity, and suitable for use in a run flat tire, more specifically as a rubber layer for reinforcing a sidewall portion of a run flat tire Things are provided.

<Rubber composition for run-flat tire>
The rubber composition for a run-flat tire of the present invention is a rubber composition containing a terminally modified group-containing cyclopentene ring-opening polymer having a cis ratio of a cyclopentene-derived structural unit of 20 to 80%, and silica, It is a composition whose content rate of the said silica is the range of 30-200 weight part with respect to 100 weight part of rubber components contained in the said rubber composition.

<Terminal modified group-containing cyclopentene ring-opening polymer>
The terminally modified group-containing cyclopentene ring-opening polymer used in the present invention is a polymer containing a repeating unit formed by ring-opening polymerization of cyclopentene as a repeating unit constituting the main chain, and a structure derived from cyclopentene. It is a polymer having a cis ratio of 20 to 80% and having a modifying group at the end of the polymer chain.

  In the terminally modified group-containing cyclopentene ring-opening polymer, the repeating unit constituting the main chain may consist only of a repeating unit obtained by ring-opening polymerization of cyclopentene, but other single units copolymerizable with cyclopentene. It may contain a repeating unit derived from a monomer. The proportion of the structural unit derived from cyclopentene in the terminally modified group-containing cyclopentene ring-opening polymer used in the present invention is preferably 80 mol% or more, and preferably 90 mol% or more, based on all repeating units. More preferably, it is 95 mol% or more, and the terminally modified group-containing cyclopentene ring-opening polymer used in the present invention is particularly preferably a polymer composed only of a structural unit derived from cyclopentene. When the proportion of the structural unit derived from cyclopentene is within the above range, the glass transition temperature of the terminally modified group-containing cyclopentene ring-opening polymer used in the present invention can be set low, and as a result, the resulting rubber cross-linked product has low heat generation. The property can be improved. On the other hand, the proportion of repeating units derived from other monomers is preferably 20 mol% or less, more preferably 10% mol or less, and more preferably 5% mol or less with respect to all repeating units. More preferably. Examples of other monomers copolymerizable with cyclopentene include monocyclic olefins other than cyclopentene, monocyclic dienes, monocyclic trienes and polycyclic cyclic olefins, polycyclic cyclic dienes, and polycyclic cyclic trienes. . Examples of monocyclic olefins other than cyclopentene include cyclooctene. Examples of the monocyclic diene include 1,5-cyclooctadiene. Examples of the monocyclic triene include 1,5,9-cyclododecatriene. Moreover, a norbornene compound is illustrated as a polycyclic cyclic olefin.

In the terminally modified group-containing cyclopentene ring-opening polymer used in the present invention, the cis ratio of the structural unit derived from cyclopentene is 20 to 80%, preferably 30 to 80%, more preferably 40 to 80%. By making the cis ratio of the structural unit derived from cyclopentene within the above range and adding a specific amount of silica to this, the low exothermic property and rigidity of the resulting rubber cross-linked product can be appropriately improved while being highly balanced. it can. If the cis ratio is too low, the resulting rubber cross-linked product is inferior in low heat build-up, while if it is too high, the resulting rubber cross-linked product is inferior in rigidity. The "cis ratio of the structural unit derived from cyclopentene" is derived from cyclopentene having a cis-type carbon-carbon double bond among all the structural units derived from cyclopentene constituting the terminally modified group-containing cyclopentene ring-opening polymer. The percentage occupied by the structural units is expressed as a percentage and can be measured by ¹³ C-NMR spectrum measurement of the terminally modified group-containing cyclopentene ring-opening polymer.

  Although the molecular weight of the terminally modified group-containing cyclopentene ring-opening polymer used in the present invention is not particularly limited, the polystyrene-converted weight average molecular weight (Mw) measured by gel permeation chromatography is 100,000 to 1. It is preferably 1,000,000,000, more preferably 150,000 to 900,000, and even more preferably 200,000 to 800,000. When the terminally modified group-containing cyclopentene ring-opening polymer has such a molecular weight, a rubber cross-linked product having excellent mechanical properties can be provided.

  The ratio (Mw / Mn) of polystyrene-equivalent number average molecular weight (Mn) and weight average molecular weight (Mw), measured by gel permeation chromatography, of the terminally modified group-containing cyclopentene ring-opening polymer used in the present invention is Although not particularly limited, it is usually 1.1 to 5.0, preferably 1.2 to 4.5, more preferably 1.3 to 4.0. In addition, it becomes possible to give the rubber crosslinked material which has the outstanding mechanical property by having such Mw / Mn.

  The glass transition temperature of the terminally modified group-containing cyclopentene ring-opening polymer used in the present invention is preferably -120 to -90 ° C, more preferably-from the viewpoint of improving the low exothermic property of the resulting rubber cross-linked product. It is 120--95 degreeC, More preferably, it is -120--100 degreeC. The glass transition temperature of the terminally modified group-containing cyclopentene ring-opening polymer can be adjusted, for example, by adjusting the cis ratio of the structural unit derived from cyclopentene within the above-described range.

  The terminally modified group-containing cyclopentene ring-opening polymer used in the present invention may have a melting point. In the case where the terminally modified group-containing cyclopentene ring-opening polymer has a melting point, the temperature is preferably 0 ° C. or less, and −10 ° C. or less from the viewpoint of improving rubber properties at low temperatures. More preferably. The presence or absence of the melting point of the terminally modified group-containing cyclopentene ring-opening polymer, and the temperature in the case of having the melting point, can be adjusted by adjusting the cis ratio of the structural unit derived from cyclopentene within the above-mentioned range. .

  The terminally modified group-containing cyclopentene ring-opening polymer used in the present invention has a modified group at the end of the polymer chain, and such a modified 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 a group 16 atom of the periodic table and a silicon atom. By containing the terminal modification group, it is possible to increase the affinity for silica, thereby increasing the dispersibility of silica in the rubber composition, and as a result, in the case of a rubber cross-linked product, The resulting rubber cross-linked product can have a low exothermic property.

  As a modifying group for forming a terminal-modified group, it is possible to increase the affinity for silica, and thereby, in the case of a rubber cross-linked product, from the viewpoint that the low heat build-up can be improved, 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 group selected from the group consisting of a nitrogen atom, an oxygen atom, and a silicon atom is selected. More preferred are modifying groups containing atoms.

  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 linking 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, or a hydrocarbon group containing these groups. The modifying group may be a modifying group containing a plurality of the groups described above. Among these, specific examples of the particularly preferred modifying group from the viewpoint that the low heat build-up property can be further improved when a rubber cross-linked product is used are amino group, pyridyl group, imino group, amide group, 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 preferred from the viewpoint of affinity for silica. The oxysilyl group refers to a group having a silicon-oxygen bond.

  Specific examples of the oxysilyl group include an alkoxysilyl group, an aryloxysilyl group, an acyloxy group, an alkylsiloxysilyl group, and an arylsiloxysilyl group. Moreover, the hydroxy silyl group formed by hydrolyzing an alkoxy silyl group or an aryloxy silyl group and an acyloxy group can be mentioned. Among these, an alkoxysilyl group is preferable from the viewpoint of affinity for silica.

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

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

  An acyloxysilyl group is a group in which one or more acyloxy groups are bonded to a silicon atom. Specific examples thereof include triacyloxysilyl groups, (diasiloxy) (methyl) silyl groups, and (acyloxy) (dimethyl). A silyl group, (acyloxy) (dichloro) silyl group, etc. are mentioned.

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

  The arylsiloxysilyl group is a group in which one or more arylsiloxy groups are bonded to a silicon atom. Specific examples thereof include tris (triphenylsiloxy) silyl group, triphenylsiloxy (dimethyl) silyl group, tris And (diphenylsiloxy) silyl group.

  The hydroxysilyl group is a group in which one or more hydroxy groups are bonded to a silicon atom. Specific examples thereof include a trihydroxysilyl group, a (dihydroxy) (methyl) silyl group, and a (hydroxy) (dimethyl) silyl group. , (Hydroxy) (dichloro) silyl group, (dihydroxy) (ethoxy) silyl group, (hydroxy) (diethoxy) silyl group, and the like. Of these, the (dihydroxy) (ethoxy) silyl group and the (hydroxy) (diethoxy) silyl group also have an alkoxy group in addition to the hydroxy group, and therefore are classified as an alkoxysilyl group.

  The terminally modified group-containing cyclopentene ring-opening polymer used in the present invention has a modified group introduced only at one polymer chain end (one end), but at both polymer chain ends (both ends). A modified group may be introduced, or a mixture of these may be used.

The rate of introduction of the modifying group at the end of the polymer chain of the terminally modified group-containing cyclopentene ring-opening polymer used in the present invention is not particularly limited, but the number of cyclopentene ring-opening polymer chain ends having a modified group introduced / cyclopentene polymer The percentage value of the total number of chain ends is preferably 30% or more, more preferably 50% or more, and still more preferably 70% or more. The higher the introduction ratio of the modifying group, the higher the affinity with silica, thereby improving the low exothermic property of the resulting rubber cross-linked product. The method for measuring the introduction ratio of the modifying group to the end of the polymer chain is not particularly limited. 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 method for synthesizing the terminally modified group-containing cyclopentene ring-opening polymer used in the present invention is not particularly limited as long as the desired polymer can be obtained, but may be synthesized according to a conventional method. For example, the method described below Can be synthesized.

That is, the terminally modified group-containing cyclopentene ring-opening polymer used in the present invention is a polymer containing, for example, a periodic table group 6 transition metal compound (A) and an organoaluminum compound (B) represented by the following general formula (1). It can be obtained by ring-opening polymerization of cyclopentene in the presence of a catalyst and a modifying group-containing olefinically unsaturated hydrocarbon (C).
(R ¹ ) _3-x Al (OR ² ) _x (1)
(In the general formula (1), R ¹ and R ² represent a hydrocarbon group having 1 to 20 carbon atoms, and x is 0 <x <3.)

  The periodic table group 6 transition metal compound (A) is a compound having a periodic table (long period type periodic table, hereinafter the same) group 6 transition metal atom, specifically, a chromium atom, a molybdenum atom, or a tungsten atom. A compound having a molybdenum atom or a compound having a tungsten atom is preferable, and a compound having a tungsten atom is more preferable from the viewpoint of high solubility in a cyclic olefin. The group 6 transition metal compound (A) in the periodic table is not particularly limited as long as it is a compound having a group 6 transition metal atom in the periodic table. , Arylates, oxydides, and the like. Among these, halides are preferable from the viewpoint of high polymerization activity.

  Specific examples of such a periodic table Group 6 transition metal compound (A) include molybdenum compounds such as molybdenum pentachloride, molybdenum oxotetrachloride, and molybdenum (phenylimide) tetrachloride; tungsten hexachloride, tungsten oxotetrachloride, Tungsten compounds such as tungsten (phenylimido) tetrachloride, monocatecholate tungsten tetrachloride, bis (3,5-ditertiarybutyl) catecholate tungsten dichloride, bis (2-chloroetherate) tetrachloride, tungsten oxotetraphenolate And so on.

  The amount of the Group 6 transition metal compound (A) used in the periodic table is usually 1: 100 to 1: 200,000, preferably 1: in the molar ratio of “Group 6 transition metal atom in the polymerization catalyst: cyclopentene”. It is in the range of 200 to 1: 150,000, more preferably 1: 500 to 1: 100,000. When there is too little usage-amount of a periodic table group 6 transition metal compound (A), a polymerization reaction may not fully advance. On the other hand, if too much, removal of the catalyst residue from the terminally modified group-containing cyclopentene ring-opening polymer becomes difficult, and the low exothermic property of the resulting rubber cross-linked product may be lowered.

The organoaluminum compound (B) is a compound represented by the general formula (1). Specific examples of the hydrocarbon group having 1 to 20 carbon atoms represented by R ¹ and R ² in the general formula (1) include a methyl group, an ethyl group, an isopropyl group, an n-propyl group, an isobutyl group, and an n-butyl group. Group, alkyl group such as t-butyl group, n-hexyl group and cyclohexyl group; aryl group such as phenyl group, 4-methylphenyl group, 2,6-dimethylphenyl group, 2,6-diisopropylphenyl group and naphthyl group And so on. In the compound represented by the general formula (1), the groups represented by R ¹ and R ² may be the same or different, but in the present invention, the resulting terminal modified group is contained. from the viewpoint that it is possible to properly control the cis ratio of structural units derived from cyclopentene cyclopentene ring-opening polymer, of R ¹ and R ^2, at least R ² is bonded continuously carbon atoms 4 or more In particular, an n-butyl group, a 2-methyl-pentyl group, an n-hexyl group, a cyclohexyl group, an n-octyl group, or an n-decyl group is more preferable.

In the general formula (1), x is 0 <x <3. That is, in the general formula (1), the composition ratio of R ¹ and OR ² can take any value in the ranges of 0 <3-x <3 and 0 <x <3, respectively. X is 0.5 <x <from the viewpoint that the polymerization activity can be increased and the cis ratio of the structural unit derived from cyclopentene in the resulting terminally modified group-containing cyclopentene ring-opening polymer can be appropriately controlled. It is preferably 1.5.

The organoaluminum compound (B) represented by the general formula (1) can be synthesized, for example, by a reaction between a trialkylaluminum and an alcohol as shown in the following general formula (2).
_{^{(R 1) 3 Al + xR}} 2 OH → (R 1) 3-x Al (OR 2) x + (R 1) x H (2)

  Note that x in the general formula (1) can be arbitrarily controlled by defining the reaction ratio of the corresponding trialkylaluminum and alcohol as shown in the general formula (2).

  Although the usage-amount of an organoaluminum compound (B) changes also with kinds of the organoaluminum compound (B) to be used, with respect to the periodic table group 6 transition metal atom which comprises a periodic table group 6 transition metal compound (A). The ratio is preferably 0.1 to 100 times mol, more preferably 0.2 to 50 times mol, and still more preferably 0.5 to 20 times mol. If the amount of the organoaluminum compound (B) used is too small, the polymerization activity may be insufficient, and if it is too large, side reactions tend to occur during ring-opening polymerization.

  The modifying group-containing olefinically unsaturated hydrocarbon (C) is a compound having a modifying group and one olefinic carbon-carbon double bond having metathesis reactivity. By allowing such a modifying group-containing olefinically unsaturated hydrocarbon (C) to be present in the polymerization reaction system of the ring-opening polymerization reaction, a modifying group can be introduced into the polymer chain end of the cyclopentene ring-opening polymer. . For example, when it is desired to introduce an oxysilyl group at the end of the polymer chain of the cyclopentene ring-opening polymer, an oxysilyl group-containing olefinically unsaturated hydrocarbon may be present in the polymerization reaction system.

  Examples of such oxysilyl group-containing olefinically unsaturated hydrocarbons include vinyl (trimethoxy) silane, which introduces a modifying group only at one end (one end) of the polymer chain of the cyclopentene ring-opening polymer, Vinyl (triethoxy) silane, allyl (trimethoxy) silane, allyl (methoxy) (dimethyl) silane, allyl (triethoxy) silane, allyl (ethoxy) (dimethyl) silane, styryl (trimethoxy) silane, styryl (triethoxy) silane, 2- Alkoxysilane compounds such as styrylethyl (triethoxy) silane, allyl (triethoxysilylmethyl) ether, allyl (triethoxysilylmethyl) (ethyl) amine; vinyl (triphenoxy) silane, allyl (triphenoxy) silane, allyl (phenoxy) Aryloxysilane compounds such as (dimethyl) silane; acyloxysilane compounds such as vinyl (triacetoxy) silane, allyl (triacetoxy) silane, allyl (diacetoxy) methylsilane, allyl (acetoxy) (dimethyl) silane; allyltris (trimethylsiloxy) ) Alkylsiloxysilane compounds such as silane; arylsiloxysilane compounds such as allyltris (triphenylsiloxy) silane; 1-allylheptamethyltrisiloxane, 1-allylnonamethyltetrasiloxane, 1-allylnonamethylcyclopentasiloxane, 1- Polysiloxane compounds such as allylundecamethylcyclohexasiloxane; and the like. In addition, as modifiers introduced at both ends (both ends) of the polymer chain of the cyclopentene ring-opening polymer, 1,4-bis (trimethoxysilyl) -2-butene, 1,4-bis (tri Alkoxysilane compounds such as ethoxysilyl) -2-butene and 1,4-bis (trimethoxysilylmethoxy) -2-butene; aryloxysilane compounds such as 1,4-bis (triphenoxysilyl) -2-butene; Acyloxysilane compounds such as 1,4-bis (triacetoxysilyl) -2-butene; alkylsiloxysilane compounds such as 1,4-bis [tris (trimethylsiloxy) silyl] -2-butene; 1,4-bis [Arylsiloxysilane compounds such as [tris (triphenylsiloxy) silyl] -2-butene; 1,4-bis (heptamethyltrisiloxy) 2-butene, 1,4-bis polysiloxane compounds such as (undecapeptide methylcyclohexanol siloxy) -2-butene; and the like.

  The amount of the modified group-containing olefinically unsaturated hydrocarbon (C) such as oxysilyl group-containing olefinically unsaturated hydrocarbon may be appropriately selected according to the molecular weight of the terminally modified group-containing cyclopentene ring-opening polymer to be produced. The molar ratio of cyclopentene used in the polymerization is usually 1/100 to 1 / 100,000, preferably 1/200 to 1 / 50,000, more preferably 1/500 to 1 / 10,000. It is. The modified group-containing olefinically unsaturated hydrocarbon acts as a molecular weight modifier in addition to the effect of introducing the modified group into the polymer chain end of the cyclopentene ring-opening polymer. If the amount of the modified group-containing olefinically unsaturated hydrocarbon (C) is too small, the introduction rate of the modified group in the terminal-modified group-containing cyclopentene ring-opening polymer will be low. The molecular weight of the ring polymer may be lowered.

  In the case of using a polymerization catalyst containing the Group 6 transition metal compound (A) of the periodic table and the organoaluminum compound (B) represented by the general formula (1), the polymerization catalyst is from the viewpoint of improving the polymerization activity, In addition to these components, esters and / or ethers (D) may further be contained.

  Specific examples of esters and / or ethers (D) include ethers such as diethyl ether, tetrahydrofuran, ethylene glycol diethyl ether, 1,4-dioxane; ethyl acetate, butyl acetate, amyl acetate, octyl acetate, acetic acid 2 -Esters such as chloroethyl, methyl acetyl acrylate, ε-caprolactone, dimethyl glutarate, σ-heisanolactone, 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 (D) can be used alone or in combination of two or more. Moreover, the usage-amount can be adjusted suitably.

  Using a polymerization catalyst containing a Group 6 transition metal compound (A) and an organoaluminum compound (B) in the periodic table and, if necessary, esters and / or ethers (D), these polymerization catalyst and modified group-containing olefin Ring-opening polymerization of cyclopentene can be carried out by bringing the unsaturated unsaturated hydrocarbon (C) into contact with cyclopentene. The method for carrying out this ring-opening polymerization is not particularly limited. For example, in the presence of cyclopentene, organoaluminum compound (B) and esters and / or ethers (D) used as necessary, a periodic table is used. A method of performing ring-opening polymerization of cyclopentene by adding the Group 6 transition metal compound (A) can be mentioned. Alternatively, the Group 6 transition metal compound (A) of the periodic table and the esters or ethers (D) used as needed are mixed in advance, cyclopentene is added thereto, and then the organoaluminum compound (B) May be added to perform ring-opening polymerization of cyclopentene. Furthermore, a periodic table group 6 transition metal compound (A) and an organoaluminum compound (B), and if necessary, esters and / or ethers (D) are mixed in advance, and cyclopentene is added thereto. By doing so, ring-opening polymerization of cyclopentene may be performed. The modifying group-containing olefinically unsaturated hydrocarbon (C) may be previously mixed with cyclopentene, or may be mixed with cyclopentene when performing ring-opening polymerization. After carrying out the ring-opening polymerization of cyclopentene, a modified group-containing olefinically unsaturated hydrocarbon (C) may be added to the obtained ring-opening polymer to cause a metathesis reaction with the obtained ring-opening polymer. .

  The ring-opening polymerization reaction may be performed in the absence of a solvent or in a solution. As a solvent used when the ring-opening polymerization reaction is performed in a solution, cyclopentene used for the ring-opening polymerization, the polymerization catalyst described above, and a modified group-containing olefinically unsaturated hydrocarbon (C) are used. The solvent is not particularly limited as long as it is a soluble solvent, and examples thereof include hydrocarbon solvents and halogen solvents. Specific 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 And alicyclic hydrocarbons. Specific examples of the halogen-based solvent include alkyl halogens such as dichloromethane and chloroform; aromatic halogens such as chlorobenzene and dichlorobenzene.

  The polymerization reaction temperature is not particularly limited, but is preferably −100 ° C. or higher, more preferably −50 ° C. or higher, still 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, still 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, more preferably 10 minutes to 20 hours.

  An anti-aging agent such as a phenol-based stabilizer, a phosphorus-based stabilizer, or a sulfur-based stabilizer may be added to the terminally modified group-containing cyclopentene ring-opened polymer obtained by the polymerization reaction, if desired. What is necessary is just to determine suitably the addition amount of an anti-aging agent according to the kind etc. Furthermore, you may mix | blend extension oil if desired. When a terminally modified group-containing cyclopentene ring-opened polymer is obtained as the polymer solution, a known recovery method may be employed to recover the polymer from the polymer solution, for example, a solvent such as steam stripping. After separating the solid, the solid can be filtered off and dried to obtain a solid rubber.

  The content ratio of the terminally modified group-containing cyclopentene ring-opening polymer in the rubber composition for run-flat tire of the present invention is the content ratio in all rubber components contained in the rubber composition for run-flat tire of the present invention. The content is preferably 20 to 90% by weight, more preferably 30 to 80% by weight, and still more preferably 40 to 70% by weight. By setting the content ratio of the terminally modified group-containing cyclopentene ring-opening polymer in the above range, the low exothermic property and rigidity of the obtained rubber crosslinked product can be appropriately increased. In addition, the said content shall be calculated | required based on the weight of the polymer which comprises a rubber component, for example, shall exclude | exclude weights, such as extending oil.

  In addition, the rubber composition for run-flat tires of this invention may contain rubbers other than the terminal modified group containing cyclopentene ring-opening polymer as a rubber component. Examples of the rubber other than the terminally modified group-containing cyclopentene ring-opening polymer include natural rubber (NR), polyisoprene rubber (IR), solution polymerization SBR (solution polymerization styrene butadiene rubber), emulsion polymerization SBR (emulsion polymerization styrene butadiene rubber). ), Polybutadiene rubber (including various microstructures such as low cis BR, high cis BR, high trans BR (including a trans bond content of 70 to 95% in the butadiene portion)), styrene-isoprene copolymer rubber, butadiene-isoprene copolymer Polymerized 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 , Rikongomu, ethylene - propylene rubber, and urethane rubber. Of these, natural rubber, polyisoprene rubber, and polybutadiene rubber are preferably used. These rubbers can be used alone or in combination of two or more. In the case of blending rubber other than the terminally modified group-containing cyclopentene ring-opening polymer, the content thereof is a content ratio in all rubber components contained in the rubber composition for run-flat tires of the present invention, preferably 10 It is -80 weight%, More preferably, it is 20-70 weight%, More preferably, it is 30-60 weight%.

<Silica>
The rubber composition for run-flat tires of the present invention is obtained by blending silica with the above-described terminally modified group-containing cyclopentene ring-opening polymer.

  Such silica is not particularly limited, and for example, dry method white carbon, wet method white carbon, colloidal silica, precipitated silica and the like can be used. Among these, wet method white carbon mainly containing hydrous silicic acid is preferable. These may be used alone or in combination of two or more.

Further, the silica used in the present invention is preferably one nitrogen adsorption specific surface area measured is not more than 300 meters ² / g by BET method, more preferably those which are ^{50~200m 2 / g, 80~150m 2 /} g Is more preferred. When the specific surface area is within this range, the resulting rubber cross-linked product can be made more excellent in low heat build-up. Moreover, it is preferable that the pH of a silica is less than 7, More preferably, it is 5-6.9. The nitrogen adsorption specific surface area can be measured by the BET method in accordance with ASTM D3037-81.

  Further, the silica used in the present invention preferably has a primary particle diameter in the range of 1 to 100 nm, more preferably 5 to 50 nm, and still more preferably 10 to 30 nm.

  The compounding quantity of the silica in the rubber composition for run-flat tires of this invention is 30-200 weight part with respect to 100 weight part of rubber components in the rubber composition for run-flat tire, Preferably it is 30-150. Part by weight, more preferably 40 to 120 parts by weight. If the amount of silica is too small, the low heat build-up of the resulting rubber cross-linked product will be deteriorated. On the other hand, if too large, silica will be difficult to disperse in the rubber component, and kneadability and extrusion processing will be difficult. Sexuality will deteriorate.

<Other ingredients>
In addition to the above components, the rubber composition for a run-flat tire of the present invention includes a crosslinking agent, a crosslinking accelerator, a crosslinking activator, a silane coupling agent, an anti-aging agent, an activator, a process oil, A necessary amount of compounding agents such as a plasticizer, a lubricant, a filler other than silica, a tackifier, and aluminum hydroxide can be blended.

  Examples of the crosslinking agent include sulfur, sulfur halides, organic peroxides, quinonedioximes, organic polyvalent amine compounds, and alkylphenol resins having a methylol group. Of these, sulfur is preferably used. The amount of the crosslinking agent is preferably 1 to 15 parts by weight, more preferably 2 to 12 parts by weight, and further preferably 3 to 10 parts by weight with respect to 100 parts by weight of the rubber component in the rubber composition for run-flat tires. It is. By making the compounding quantity of a crosslinking agent into the said range, the low exothermic property and rigidity of the rubber crosslinked material obtained can be improved more.

  Examples of the crosslinking accelerator include N-cyclohexyl-2-benzothiazolylsulfenamide, Nt-butyl-2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolylsulfenamide, Sulfenamide-based crosslinking accelerators such as N-oxyethylene-2-benzothiazolylsulfenamide and N, N′-diisopropyl-2-benzothiazolylsulfenamide; 1,3-diphenylguanidine, 1,3- Guanidine-based cross-linking accelerators such as diolthotolylguanidine and 1-ortho-tolylbiguanidine; thiourea-based cross-linking accelerators; thiazole-based cross-linking accelerators; thiuram-based cross-linking accelerators; dithiocarbamic acid-based cross-linking accelerators; And so on. Among these, those containing a sulfenamide-based crosslinking accelerator are particularly preferable. These crosslinking accelerators are used alone or in combination of two or more. The blending amount of the crosslinking accelerator is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 5 parts by weight, particularly preferably 100 parts by weight of the rubber component in the rubber composition for the run-flat tire. 1 to 4 parts by weight.

  Examples of the crosslinking activator include higher fatty acids such as stearic acid and zinc oxide. Although the compounding quantity of a crosslinking activator is not specifically limited, Preferably it is 0.05-10 weight part with respect to 100 weight part of rubber components in the rubber composition for run flat tires, More preferably, it is 0.5-5. Parts by weight.

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

  Examples of the process oil include paraffinic, aromatic, and naphthenic petroleum softeners; plant softeners; fatty acids.

  Examples of the filler other than silica include carbon black. Examples of carbon black 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, MAF, and FEF. Can be mentioned. These may be used alone or in combination of two or more.

  In order to obtain the rubber composition for a run-flat tire of the present invention, each component may be kneaded according to a conventional method, for example, after kneading a compounding agent excluding a crosslinking agent and a crosslinking accelerator, silica, and a rubber component. The kneaded product can be mixed with a crosslinking agent, a crosslinking accelerator and the like to obtain a desired composition. The kneading temperature of the compounding agent excluding the crosslinking agent and 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. Mixing of the kneaded material with the crosslinking agent, crosslinking accelerator, etc. is usually performed after cooling to 100 ° C. or lower, preferably 80 ° C. or lower. When obtaining the rubber composition for run-flat tires of the present invention, a compounding agent and silica are added to a solid rubber and kneaded (dry kneading method), or a compounding agent is added to a rubber solution. And silica may be added to solidify and dry (wet kneading method).

<Rubber cross-linked product>
The rubber cross-linked product of the present invention can be obtained by cross-linking the rubber composition for a run flat tire of the present invention described above.

  The crosslinking method for crosslinking the rubber composition for a run-flat tire of the present invention is not particularly limited, and may be selected according to the shape and size of the rubber crosslinked product. A rubber composition for a run-flat tire may be filled in a mold and heated to be crosslinked simultaneously with molding, or a rubber composition for a run-flat tire that has been molded in advance may be heated to be 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 using the rubber composition for a run-flat tire of the present invention described above, it is excellent in low heat buildup and rigidity. Therefore, taking advantage of such characteristics, it can be suitably used as a rubber layer for reinforcing a sidewall portion of a run flat tire, particularly a run flat tire.
The rubber layer for reinforcing the sidewall portion is disposed on the sidewall portion of the tire and used to increase the rigidity of the tire. Examples of the arrangement form of the reinforcing rubber layer include the following. That is, for example, a crescent-shaped reinforcing rubber layer that is disposed from the bead portion to the shoulder portion in contact with the inside of the tire carcass ply and gradually decreases in thickness in both end directions can be obtained. Alternatively, a reinforcing rubber layer disposed between the bead portion and the tread portion end between the carcass ply main body portion and the folded portion, or two layers of reinforcing rubber layers disposed between the plurality of carcass plies or the reinforcing plies. It can also be done.
In this case, the thickness of the reinforcing rubber layer is preferably 5 to 30 mm, more preferably 8 to 20 mm. If the thickness of the reinforcing rubber layer is less than 5 mm, the rigidity of the reinforcing rubber layer may be insufficient and the run-flat performance may be inferior. If it exceeds 30 mm, the reinforcing rubber layer may be thick and the tire weight may be too heavy. .

  Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples. In the following, “part” is based on weight unless otherwise specified. Various tests and evaluations were performed according to the following methods.

[Molecular weight of cyclopentene ring-opening polymer]
The weight average molecular weight (Mw) and number average molecular weight (Mn) of the cyclopentene ring-opening polymer were measured as polystyrene equivalent values by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent.

[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]
Using a differential scanning calorimeter (DSC), measurement was performed at a temperature increase of 10 ° C./min.

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

[Low exothermic evaluation]
The rubber composition as a sample was press-crosslinked at 160 ° C. for 20 minutes to produce a cross-linked test piece, and a viscoelasticity measuring device (trade name “ARES-G2”, manufactured by TA Instruments Co., Ltd.) was used. ) And tan δ at 60 ° C. was measured under conditions of a shear strain of 2.5% and a frequency of 10 Hz. This value was an index with the measured value of the reference sample (Comparative Example 1 described later) as 100. The larger this index, the better the low heat buildup.

[Side stiffness evaluation]
The rubber composition as a sample was press-crosslinked at 160 ° C. for 20 minutes to produce a cross-linked test piece. This test piece was subjected to a tensile tester (trade name “Strograph AE” Toyo Seiki in accordance with JIS K6251. The tensile stress at 300% elongation was measured at a test temperature of 23 ° C. and a tensile speed of 500 mm / min. This value was an index with the measured value of the reference sample (Comparative Example 1 described later) as 100. The larger the index, the better the side rigidity (that is, the rigidity when the rubber layer for reinforcing the sidewall portion of the run flat tire is used).

[Reference Example 1]
Preparation of diisobutylaluminum mono (n-hexoxide) / toluene solution (2.5% by weight) In a nitrogen atmosphere, 88 parts of toluene and 25.4% by weight of triisobutylaluminum / n were placed in a glass container containing a stirring bar. -7.8 parts of hexane solution (manufactured by Tosoh Finechem) was added. Subsequently, the container was cooled to −45 ° C., and 1.02 parts of n-hexanol (an equimolar amount with respect to triisobutylaluminum) was slowly added dropwise with vigorous stirring. Thereafter, the mixture was allowed to stand at room temperature while stirring to prepare a diisobutylaluminum mono (n-hexoxide) / toluene solution (2.5% by weight).

[Synthesis Example 1]
Under a nitrogen atmosphere, a glass container containing a stirrer was charged with 87 parts of a 1.0 wt% WCl ₆ / toluene solution and 2.5 wt% diisobutylaluminum mono (n-hexoxide) / toluene prepared in Reference Example 1. A catalyst solution was obtained by adding 43 parts of the solution and stirring for 15 minutes. In 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. The 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 dissolved in 2,6-di-t-butyl-p-cresol (BHT). ) Was poured into 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, thereby opening both ends-modified cyclopentene having triethoxysilyl groups at both ends of 78 parts of the polymer chain. A polymer (a1) was obtained.

  And about the obtained both terminal modified cyclopentene ring-opening polymer (a1), according to the said method, weight average molecular weight (Mw), cis / trans ratio, oxysilyl group introduction | transduction rate, melting | fusing point (Tm), and glass transition temperature (Tg) ) Was performed. The results are shown in Table 1.

[Synthesis Example 2]
Under a nitrogen atmosphere, a glass container containing a stirrer was charged with 87 parts of a 1.0 wt% WCl ₆ / toluene solution and 2.5 wt% diisobutylaluminum mono (n-hexoxide) / toluene prepared in Reference Example 1. A catalyst solution was obtained by adding 43 parts of the solution and stirring for 15 minutes. In a nitrogen atmosphere, 300 parts of cyclopentene and 0.96 parts 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. The 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 treated with 2,6-di-t-butyl-p-cresol (BHT). ) Was poured into 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, thereby opening both ends modified cyclopentene having a trimethoxysilyl group at both ends of 90 parts of the polymer chain. A polymer (a2) was obtained.

  And about the obtained both terminal modified cyclopentene ring-opening polymer (a2), according to the said method, weight average molecular weight (Mw), cis / trans ratio, oxysilyl group introduction | transduction rate, melting | fusing point (Tm), and glass transition temperature (Tg) ) Was performed. The results are shown in Table 1.

[Synthesis Example 3]
Under a nitrogen atmosphere, a glass container containing a stirrer was charged with 87 parts of a 1.0 wt% WCl ₆ / toluene solution and 2.5 wt% diisobutylaluminum mono (n-hexoxide) / toluene prepared in Reference Example 1. 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, and 130 parts of the catalyst solution prepared above was added thereto. A time polymerization reaction was carried out. 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 dissolved in 2,6-di-t-butyl-p-cresol (BHT). ) Was poured into a large excess of ethyl alcohol. Next, the precipitated polymer was collected, washed with ethyl alcohol, and vacuum-dried at 40 ° C. for 3 days to open one-end-modified cyclopentene having a triethoxysilyl group at one end of 76 parts of the polymer chain. A polymer (a3) was obtained.

  And about the obtained one terminal modified cyclopentene ring-opening polymer (a3), according to the said method, weight average molecular weight (Mw), cis / trans ratio, oxysilyl group introduction | transduction rate, melting | fusing point (Tm), and glass transition temperature (Tg) ) Was performed. The results are shown in Table 1.

[Synthesis Example 4]
Under a nitrogen atmosphere, in a glass container containing a stir bar, 44 parts of a 1.0 wt% WCl ₆ / toluene solution and 2.5 wt% 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. In 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. The 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 dissolved in 2,6-di-t-butyl-p-cresol (BHT). ) Was poured into a large excess of ethyl alcohol. Next, the precipitated polymer was collected, washed with ethyl alcohol, and vacuum-dried at 40 ° C. for 3 days to open both ends modified cyclopentene having a triethoxysilyl group at both ends of 27 parts of the polymer chain. A polymer (a4) was obtained.

  And about the obtained both terminal modified cyclopentene ring-opening polymer (a4), according to the said method, a weight average molecular weight (Mw), cis / trans ratio, an oxysilyl group introduction | transduction rate, melting | fusing point (Tm), and glass transition temperature (Tg) ) Was performed. The results are shown in Table 1.

[Synthesis Example 5]
Under a nitrogen atmosphere, a glass container containing a stirrer was charged with 87 parts of a 1.0 wt% WCl ₆ / toluene solution and 2.5 wt% diisobutylaluminum mono (n-hexoxide) / toluene prepared in Reference Example 1. A catalyst solution was obtained by adding 43 parts of the solution and stirring for 15 minutes. In 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. The 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 dissolved in 2,6-di-t-butyl-p-cresol (BHT). ) Was poured into 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, thereby opening both ends modified cyclopentene having triethoxysilyl groups at both ends of 63 parts of the polymer chain. A polymer (a5) was obtained.

  And about the obtained both terminal modified cyclopentene ring-opening polymer (a5), according to the said method, a weight average molecular weight (Mw), cis / trans ratio, an oxysilyl group introduction | transduction rate, melting | fusing point (Tm), and glass transition temperature (Tg) ) Was performed. The results are shown in Table 1.

[Synthesis Example 6]
Under a nitrogen atmosphere, in a glass container containing a stir bar, 44 parts of a 1.0 wt% WCl ₆ / toluene solution and 2.5 wt% 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. In a nitrogen atmosphere, 300 parts of cyclopentene and 2.52 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. The 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 dissolved in 2,6-di-t-butyl-p-cresol (BHT). ) Was poured into a large excess of ethyl alcohol. Next, the precipitated polymer is recovered, washed with ethyl alcohol, and vacuum-dried at 40 ° C. for 3 days to open both ends-modified cyclopentene having a triethoxysilyl group at both ends of 25 parts of the polymer chain. A polymer (a6) was obtained.

  And about the obtained both terminal modified cyclopentene ring-opening polymer (a6), according to the said method, a weight average molecular weight (Mw), cis / trans ratio, oxysilyl group introduction | transduction rate, melting | fusing point (Tm), and glass transition temperature (Tg) ) Was performed. The results are shown in Table 1.

[Synthesis Example 7]
Under a nitrogen atmosphere, add (1,3-dimesitylimidazolidine-2-ylidene) (tricyclohexylphosphine) benzylidene ruthenium dichloride 2.412 parts and toluene 127.58 parts to a glass container containing a stir bar. The catalyst solution was obtained by stirring for 15 minutes. Then, a polymerization reaction was carried out in the same manner as in Synthesis Example 1 except that 130 parts of the catalyst solution thus obtained was used instead of 130 parts of the catalyst solution used in Synthesis Example 1. A double-end modified cyclopentene ring-opening polymer (a7) having a triethoxysilyl group at both ends of the combined chain was obtained.

  And about the obtained both terminal modified cyclopentene ring-opening polymer (a7), according to the said method, a weight average molecular weight (Mw), cis / trans ratio, an oxysilyl group introduction | transduction rate, melting | fusing point (Tm), and glass transition temperature (Tg) ) Was performed. The results are shown in Table 1.

[Example 1]
In a Brabender type mixer with a capacity of 250 ml, 70 parts of the both-end-modified cyclopentene ring-opening polymer (a1) obtained in Synthesis Example 1 and 30 parts of natural rubber (SMR-CV60) were masticated for 30 seconds, Silica with a nitrogen adsorption specific surface area of 112 m ² / g (manufactured by Solvay, trade name “Zeosil1115MP”, nitrogen adsorption specific surface area (BET method): 112 m ² / g, primary particle diameter 25 nm), 33.3 parts, process oil (JX Nippon Mining) 5 parts manufactured by Nisseki Energy Co., Ltd., trade name “Aromax T-DAE”), and silane coupling agent: bis-3-triethoxysilylpropyl tetrasulfide (trade name “Si69” manufactured by Evonik) 2.5 part was added and after 1.5 minutes kneading a starting temperature of 110 ° C., the nitrogen adsorption specific surface area 112m ² / g of silica (sorbet 16.7 parts, trade name "Zeosil 1115MP"), 5 parts carbon black (trade name "Seast 7HM", trade name "Seast 7HM"), 3 parts zinc oxide, 2 parts stearic acid, and anti-aging agent: N-phenyl 2 parts of —N ′-(1,3-dimethylbutyl) -p-phenylenediamine (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name “NOCRACK 6C”) is added, kneaded for 2.5 minutes, and then kneaded from a mixer. The thing was discharged. The temperature of the kneaded product at the end of kneading was 150 ° C. After the kneaded product was cooled to room temperature, it was kneaded again in a Brabender type mixer at 110 ° C. for 3 minutes, and then the kneaded product was discharged from the mixer. Subsequently, with an open roll at 50 ° C., the obtained kneaded product, 4.5 parts of sulfur, a crosslinking accelerator: N-cyclohexyl-2-benzothiazolylsulfenamide (made by Ouchi Shinsei Chemical Co., Ltd., trade name “ 2 parts of Noxeller CZ-G ") and 2 parts of crosslinking accelerator: 1,3-diphenylguanidine (made by Ouchi Shinsei Chemical Co., Ltd., trade name" Noxeller D "), and then a sheet-like rubber composition Got. And about the obtained rubber composition, according to the said method, low exothermic property and side rigidity were evaluated. The results are shown in Table 2.

[Example 2]
Except for using 70 parts of both-ends modified cyclopentene ring-opening polymer (a2) obtained in Synthesis Example 2 instead of 70 parts of both-ends modified cyclopentene ring-opening polymer (a1) obtained in Synthesis Example 1, A sheet-like rubber composition was obtained in the same manner as in Example 1. And about the obtained rubber composition, according to the said method, low exothermic property and side rigidity were evaluated. The results are shown in Table 2.

Example 3
Except for using 70 parts of the one-end modified cyclopentene ring-opening polymer (a3) obtained in Synthesis Example 3 instead of 70 parts of the both-end-modified cyclopentene ring-opening polymer (a1) obtained in Synthesis Example 1, A sheet-like rubber composition was obtained in the same manner as in Example 1. And about the obtained rubber composition, according to the said method, low exothermic property and side rigidity were evaluated. The results are shown in Table 2.

Example 4
Instead of using 70 parts of both-ends modified cyclopentene ring-opening polymer (a1) obtained in Synthesis Example 1 except that 70 parts of both-ends modified cyclopentene ring-opening polymer (a4) obtained in Synthesis Example 4 was used, A sheet-like rubber composition was obtained in the same manner as in Example 1. And about the obtained rubber composition, according to the said method, low exothermic property and side rigidity were evaluated. The results are shown in Table 2.

Example 5
Instead of using 70 parts of both-ends modified cyclopentene ring-opening polymer (a1) obtained in Synthesis Example 1, except that 70 parts of both-ends modified cyclopentene ring-opening polymer (a5) obtained in Synthesis Example 5 was used, A sheet-like rubber composition was obtained in the same manner as in Example 1. And about the obtained rubber composition, according to the said method, low exothermic property and side rigidity were evaluated. The results are shown in Table 2.

Example 6
While changing the compounding quantity of the both terminal-modified cyclopentene ring-opening polymer (a1) obtained in Synthesis Example 1 from 70 parts to 40 parts, polybutadiene rubber (manufactured by Zeon Corporation, trade name “Nipol BR1220”, cis content) A sheet-like rubber composition in the same manner as in Example 1, except that 97%, Mooney viscosity (ML _{1 + 4} , 100 ° C.) 43, and glass transition temperature (Tg) −110 ° C. 30 parts were further added. Got. And about the obtained rubber composition, according to the said method, low exothermic property and side rigidity were evaluated. The results are shown in Table 2.

Example 7
Instead of 50 parts of silica with a nitrogen adsorption specific surface area of 112 m ² / g, silica with a nitrogen adsorption specific surface area of 163 m ² / g (product name “Zeosil 1165MP”, product of Solvay, nitrogen adsorption specific surface area (BET method): 163 m ² / g The primary particle diameter was 20 nm), and 50 parts was used, and the amount of silane coupling agent: bis-3-triethoxysilylpropyltetrasulfide was changed from 2.5 parts to 4 parts. Thus, a sheet-like rubber composition was obtained. Also in Example 7, when silica was added, divided addition was performed in the same manner as in Example 1, and the addition ratio (ratio of divided addition) was also the same as in Example 1. And about the obtained rubber composition, according to the said method, low exothermic property and side rigidity were evaluated. The results are shown in Table 2.

[Comparative Example 1]
Instead of 70 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 A} sheet-like rubber composition was obtained in the same manner as in Example 1 except that ₊₄ , 100 ° C) 43 and glass transition temperature (Tg)-110 ° C) 70 parts were used. And about the obtained rubber composition, according to the said method, low exothermic property and side rigidity were evaluated. The results are shown in Table 2.

[Comparative Example 2]
Instead of using 70 parts of both-ends modified cyclopentene ring-opening polymer (a1) obtained in Synthesis Example 1 except that 70 parts of both-ends modified cyclopentene ring-opening polymer (a6) obtained in Synthesis Example 6 was used, A sheet-like rubber composition was obtained in the same manner as in Example 1. And about the obtained rubber composition, according to the said method, low exothermic property and side rigidity were evaluated. The results are shown in Table 2.

[Comparative Example 3]
Instead of using 70 parts of both-ends modified cyclopentene ring-opening polymer (a1) obtained in Synthesis Example 1, except that 70 parts of both-ends modified cyclopentene ring-opening polymer (a7) obtained in Synthesis Example 7 was used, A sheet-like rubber composition was obtained in the same manner as in Example 1. And about the obtained rubber composition, according to the said method, low exothermic property and side rigidity were evaluated. The results are shown in Table 2.

[Comparative Example 4]
In a Brabender type mixer with a capacity of 250 ml, 70 parts of the both-end-modified cyclopentene ring-opening polymer (a1) obtained in Synthesis Example 1 and 30 parts of natural rubber (SMR-CV60) were masticated for 30 seconds, Silica having a nitrogen adsorption specific surface area of 112 m ² / g (manufactured by Solvay, trade name “Zeosil 1115MP”, nitrogen adsorption specific surface area (BET method): 112 m ² / g, primary particle diameter 25 nm), carbon black (manufactured by Tokai Carbon Co., Ltd.) , 13.3 parts of a trade name “Seast 7HM”), 5 parts of process oil (manufactured by JX Nippon Mining & Energy Corporation, trade name “Aromax T-DAE”), and silane coupling agent: bis-3-triethoxy Add 1 part of silylpropyl tetrasulfide (trade name “Si69”, manufactured by Evonik) and start at 110 ° C. After kneading for 1.5 minutes, 21.7 parts of carbon black (trade name “SEAST 7HM” manufactured by Tokai Carbon Co., Ltd.), 3 parts of zinc oxide, 2 parts of stearic acid, and anti-aging agent: N-phenyl-N′- 2 parts of (1,3-dimethylbutyl) -p-phenylenediamine (trade name “NOCRACK 6C”, manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.) is added and further kneaded for 2.5 minutes, and the kneaded product is discharged from the mixer. It was. The temperature of the kneaded product at the end of kneading was 150 ° C. After the kneaded product was cooled to room temperature, it was kneaded again in a Brabender type mixer at 110 ° C. for 3 minutes, and then the kneaded product was discharged from the mixer. Subsequently, with an open roll at 50 ° C., the obtained kneaded product, 4.5 parts of sulfur, a crosslinking accelerator: N-cyclohexyl-2-benzothiazolylsulfenamide (made by Ouchi Shinsei Chemical Co., Ltd., trade name “ Noxeller CZ-G ") and 2.5 parts of crosslinking accelerator: 1,3-diphenylguanidine (trade name" Noxeller D ", manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.) A composition was obtained. And about the obtained rubber composition, according to the said method, low exothermic property and side rigidity were evaluated. The results are shown in Table 2.

  As is apparent from the results shown in Tables 1 and 2, it contains a terminally modified group-containing cyclopentene ring-opening polymer in which the cis ratio of the structural unit derived from cyclopentene is 20 to 80%, and silica, and the content ratio of silica is determined. The rubber composition of 30 to 200 parts with respect to 100 parts of the rubber component contained in the rubber composition gives a rubber cross-linked product excellent in low heat generation and side rigidity, and is used as a run-flat tire application. It could be used suitably (Examples 1-7).

On the other hand, when a rubber composition comprising polybutadiene rubber is used instead of the terminally modified group-containing cyclopentene ring-opening polymer, the resulting rubber cross-linked product is inferior in low heat buildup and side rigidity. (Comparative Example 1).
Further, when a rubber composition formed by blending a cyclopentene ring-opening polymer containing a terminal modified group having a cis ratio of a structural unit derived from cyclopentene of more than 80% is used, the resulting rubber cross-linked product has a side rigidity. It was inferior (Comparative Example 2).
Furthermore, when a rubber composition obtained by blending a cyclopentene ring-opening polymer containing a terminal modified group having a cis ratio of a structural unit derived from cyclopentene of less than 20% is used, the resulting rubber cross-linked product has a low exothermic property. (Comparative Example 3).
Moreover, when the rubber composition which made the compounding quantity of silica into less than 30 parts with respect to 100 parts of rubber components contained in a rubber composition is used, the rubber cross-linked product obtained is inferior in low exothermic property. (Comparative Example 4).

Claims (6)

A rubber composition for a run-flat tire comprising a terminally modified group-containing cyclopentene ring-opening polymer having a cis ratio of a structural unit derived from cyclopentene of 20 to 80%, and silica,
The rubber composition for run-flat tires, wherein the silica content is 30 to 200 parts by weight with respect to 100 parts by weight of the rubber component contained in the rubber composition for run-flat tires.   The rubber composition for a run-flat tire according to claim 1, wherein the terminally modified group-containing cyclopentene ring-opening polymer is a polymer in which an oxysilyl group is introduced at the end of a polymer chain. The rubber composition for a run-flat tire according to claim 1 or 2, wherein the silica has a nitrogen adsorption specific surface area measured by a BET method of 300 m ² / g or less.   A crosslinked rubber product obtained by crosslinking the rubber composition for a run-flat tire according to any one of claims 1 to 3.   The rubber cross-linked product according to claim 4, which is a rubber layer for reinforcing a sidewall portion of a run flat tire.   A run-flat tire comprising the rubber cross-linked product according to claim 4 or 5.