WO2013027746A1 - ゴム組成物及び空気入りタイヤ - Google Patents
ゴム組成物及び空気入りタイヤ Download PDFInfo
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- WO2013027746A1 WO2013027746A1 PCT/JP2012/071120 JP2012071120W WO2013027746A1 WO 2013027746 A1 WO2013027746 A1 WO 2013027746A1 JP 2012071120 W JP2012071120 W JP 2012071120W WO 2013027746 A1 WO2013027746 A1 WO 2013027746A1
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
- C08L9/06—Copolymers with styrene
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
- B60C1/0016—Compositions of the tread
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08C—TREATMENT OR CHEMICAL MODIFICATION OF RUBBERS
- C08C19/00—Chemical modification of rubber
- C08C19/30—Addition of a reagent which reacts with a hetero atom or a group containing hetero atoms of the macromolecule
- C08C19/42—Addition of a reagent which reacts with a hetero atom or a group containing hetero atoms of the macromolecule reacting with metals or metal-containing groups
- C08C19/44—Addition of a reagent which reacts with a hetero atom or a group containing hetero atoms of the macromolecule reacting with metals or metal-containing groups of polymers containing metal atoms exclusively at one or both ends of the skeleton
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/34—Silicon-containing compounds
- C08K3/36—Silica
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L47/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds; Compositions of derivatives of such polymers
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/16—Nitrogen-containing compounds
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/54—Silicon-containing compounds
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/80—Technologies aiming to reduce greenhouse gasses emissions common to all road transportation technologies
- Y02T10/86—Optimisation of rolling resistance, e.g. weight reduction
Definitions
- the present invention relates to a rubber composition and a pneumatic tire produced using the rubber composition.
- the tire tread rubber is required to have low hysteresis loss for improving fuel efficiency and high wet skid resistance for improving wet grip performance.
- low hysteresis loss for improving fuel efficiency
- high wet skid resistance for improving wet grip performance.
- a typical technique for improving the rubber composition for tires is to improve the raw materials used, improving the structure of the raw rubber typified by styrene butadiene rubber and butadiene rubber, reinforcing fillers such as carbon black and silica, Improvements in the structure and composition of vulcanizing agents and plasticizers have been made.
- silica As a method for improving fuel economy and wet grip performance in a well-balanced manner, there is a method using silica as a filler.
- Silica has strong self-aggregation property and there is room for improvement in that it is difficult to disperse.
- Patent Document 1 a styrene butadiene rubber terminal-modified with a specific compound containing a nitrogen atom and a silicon atom and an aliphatic carboxylic acid zinc salt are blended, and a rubber composition excellent in fuel efficiency and wet grip performance is obtained.
- the present invention solves the above-described problems and can improve the fuel economy, wet grip performance, and dry grip performance in a well-balanced manner, and a pneumatic composition using the rubber composition for each tire member (particularly, tread).
- the object is to provide a tire.
- the present invention is obtained by copolymerizing 1,3-butadiene, styrene and a compound represented by the following formula (I), having an amino group at one end and nitrogen, oxygen and silicon at the other end.
- the present invention relates to a rubber composition comprising silica having an average length W 1 of ZZ between branched particles including branched particles Z of 30 to 400 nm, when three or more adjacent particles are branched particles Z. (Wherein R 1 represents a hydrocarbon group having 1 to 10 carbon atoms.)
- the present invention is also obtained by copolymerizing 1,3-butadiene, styrene and a compound represented by the following formula (I), having an amino group at one end and nitrogen, oxygen and silicon at the other end. Obtained by kneading a copolymer having a functional group containing at least one atom selected from the group consisting of a weight average molecular weight of 1.0 ⁇ 10 5 to 2.5 ⁇ 10 6 and silica sol.
- the present invention relates to a rubber composition. (Wherein R 1 represents a hydrocarbon group having 1 to 10 carbon atoms.)
- the functional group is preferably an alkoxysilyl group, and more preferably an alkoxysilyl group and an amino group.
- the amino group at one end is preferably an alkylamino group or a group represented by the following formula (II). (Wherein R 11 represents a divalent hydrocarbon group having 2 to 50 carbon atoms, and may have a nitrogen atom or an oxygen atom.)
- the group represented by the formula (II) is preferably a group represented by the following formula (III). (Wherein R 12 to R 19 are the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms, and may have a nitrogen atom or an oxygen atom.)
- the content of the compound represented by the formula (I) is preferably 0.05 to 35% by mass.
- the copolymer is prepared by copolymerizing 1,3-butadiene, styrene and a compound represented by the above formula (I) using a compound having a lithium atom and an amino group as a polymerization initiator, and then polymerizing the terminal with nitrogen, oxygen. And a material obtained by modification with a modifier having a functional group containing at least one atom selected from the group consisting of silicon and silicon.
- the modifying agent is preferably a compound represented by the following formula (IV), the following formula (V), or the following formula (VI).
- R 21 , R 22 and R 23 are the same or different and each represents an alkyl group, an alkoxy group, a silyloxy group, a carboxyl group, a mercapto group, or a derivative thereof.
- R 24 and R 25 are the same or different.
- And represents a hydrogen atom or an alkyl group, and n represents an integer.
- R 26 , R 27 and R 28 are the same or different and each represents an alkyl group, an alkoxy group, a silyloxy group, a carboxyl group, a mercapto group or a derivative thereof.
- R 29 represents a cyclic ether group. p and q represent integers.) (Wherein R 30 to R 33 are the same or different and each represents an alkyl group, an alkoxy group, a silyloxy group, a carboxyl group, a mercapto group, or a derivative thereof.)
- the polymerization initiator preferably has an alkylamino group or a group represented by the following formula (II). (Wherein R 11 represents a divalent hydrocarbon group having 2 to 50 carbon atoms, and may have a nitrogen atom or an oxygen atom.)
- the group represented by the formula (II) is preferably a group represented by the following formula (III). (Wherein R 12 to R 19 are the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms, and may have a nitrogen atom or an oxygen atom.)
- the polymerization initiator has an isoprene unit.
- the content of the copolymer is preferably 5% by mass or more.
- the silica is preferably contained in an amount of 5 to 150 parts by mass with respect to 100 parts by mass of the rubber component.
- the silica preferably has an average aspect ratio W 1 / D of 3 to 100 of the ZZ between the branched particles including the branched particles Z when the average primary particle size is D.
- the average primary particle diameter D of the silica is preferably 5 to 1000 nm.
- the rubber composition preferably contains 1 to 20 parts by mass of a silane coupling agent with respect to 100 parts by mass of silica.
- the rubber composition is preferably used as a rubber composition for tire treads.
- the present invention also relates to a pneumatic tire produced using the rubber composition.
- the present invention it is obtained by copolymerizing 1,3-butadiene, styrene and a compound represented by the above formula (I), has an amino group at one end, and nitrogen, oxygen and the other end.
- the rubber composition includes a rubber component containing a copolymer having a functional group containing at least one atom selected from the group consisting of silicon and having a weight average molecular weight within a specific range, and a specific silica. It is possible to improve the fuel economy, wet grip performance, and dry grip performance in a well-balanced manner, and to provide a pneumatic tire excellent in the above performance by using the rubber composition for each member (particularly, tread) of the tire. Can do.
- FIG. 2 is a schematic diagram of branched particles Z.
- FIG. Outline of average primary particle diameter D of silica, average length (W 1 ) of ZZ between branched particles including branched particles Z, and average length (W 2 ) of ZZ between branched particles not including branched particles Z It is a schematic diagram.
- the rubber composition of the present invention is obtained by copolymerizing 1,3-butadiene, styrene and a compound represented by the following formula (I), has an amino group at one end, nitrogen at the other end, A rubber component comprising a copolymer having a weight average molecular weight of 1.0 ⁇ 10 5 to 2.5 ⁇ 10 6 having a functional group containing at least one atom selected from the group consisting of oxygen and silicon;
- silica having an average length W 1 between the branched particles ZZ including the branched particle Z of 30 to 400 nm (structure silica (straight chain Silica)).
- R 1 represents a hydrocarbon group having 1 to 10 carbon atoms.
- the main chain of the copolymer is modified with the compound represented by the above formula (I), the interaction between the compound (particularly the oxygen atom contained in the compound) and the filler occurs, and the filler
- the dispersibility of the polymer is improved and the movement of the copolymer is restricted.
- hysteresis loss can be reduced, fuel efficiency can be improved, and good wet grip performance and dry grip performance can be obtained.
- the copolymer has an amino group at one end and the functional group at the other end, interaction with the filler occurs at both end portions of the copolymer, and the dispersibility of the filler is reduced. As it improves, the movement of the copolymer is constrained.
- the conventional rubber composition containing granular silica can improve wet grip performance, it has not been possible to achieve both improved fuel economy and improved dry grip performance.
- the occluder rubber rubber which is encapsulated in the silica aggregate and cannot be distorted
- the local stress concentration that is, the local Distortion is reduced.
- the structure silica is oriented in the tread circumferential direction of the tire when the tire is highly stretched (during high strain) such as during sudden braking or sharp turning.
- the rubber in the vicinity of the structure silica is abruptly distorted and the hysteresis loss is increased, thereby improving the dry grip performance.
- the improvement effect of each can synergistically be heightened by combined use of the said copolymer and the said structure silica.
- the rubber composition containing the structure silica of the present invention can be produced, for example, by kneading the copolymer and silica sol.
- R 1 represents a hydrocarbon group having 1 to 10 carbon atoms. If the carbon number exceeds 10, the cost tends to be high. In addition, there is a tendency that fuel economy, wet grip performance, and dry grip performance cannot be sufficiently improved.
- the carbon number is preferably 1 to 8, more preferably 1 to 6, and still more preferably 1 to 3 from the viewpoint that the resulting polymer has high fuel economy, wet grip performance, and high dry grip performance improvement effect. .
- Examples of the hydrocarbon group represented by R 1 include a monovalent aliphatic hydrocarbon group such as an alkyl group, and a monovalent aromatic hydrocarbon group such as an aryl group.
- R 1 is preferably an alkyl group, more preferably a methyl group or a tert-butyl group, from the viewpoint that the resulting polymer is highly effective in improving fuel economy, wet grip performance and dry grip performance.
- Examples of the compound represented by the formula (I) include p-methoxystyrene, p-ethoxystyrene, p- (n-propoxy) styrene, p- (tert-butoxy) styrene, m-methoxystyrene, and the like. . These may be used alone or in combination of two or more.
- the content of the compound represented by the above formula (I) in the copolymer is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and further preferably 0.3% by mass or more. Moreover, it is preferably 35% by mass or less, more preferably 20% by mass or less, further preferably 10% by mass or less, particularly preferably 5% by mass or less, and most preferably 2% by mass or less. If it is less than 0.05% by mass, it is difficult to obtain an effect of improving fuel economy, wet grip performance and dry grip performance, while if it exceeds 35% by mass, the cost tends to be high.
- the styrene content in the copolymer is preferably 2% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, particularly preferably 15% by mass or more, and preferably 50% by mass.
- it is more preferably 30% by mass or less, further preferably 25% by mass or less, and particularly preferably 22% by mass or less. If it is less than 2% by mass, wet grip performance and dry grip performance tend to be deteriorated, while if it exceeds 50% by mass, fuel efficiency tends to be deteriorated.
- the content of 1,3-butadiene in the copolymer is not particularly limited, and may be appropriately adjusted according to the content of other components, but is preferably 15% by mass or more, more preferably 20% by mass or more, More preferably, it is 60 mass% or more, Preferably it is 97 mass% or less, More preferably, it is 85 mass% or less, More preferably, it is 80 mass% or less. If it is less than 15% by mass, wet grip performance and dry grip performance tend to deteriorate, while if it exceeds 97% by mass, fuel economy tends to deteriorate.
- the contents of the compound represented by the formula (I), 1,3-butadiene and styrene in the copolymer can be measured by the method of Examples described later.
- the amino group (primary amino group, secondary amino group, tertiary amino group) at one end may be an acyclic amino group or a cyclic amino group.
- Examples of the acyclic amine constituting the acyclic amino group include 1,1-dimethylpropylamine, 1,2-dimethylpropylamine, 2,2-dimethylpropylamine, 2-ethylbutylamine, pentylamine, 2,2 -Monoalkylamines such as dimethylbutylamine, hexylamine, cyclohexylamine, octylamine, 2-ethylhexylamine, isodecylamine, dimethylamine, methylisobutylamine, methyl (t-butyl) amine, methylpentylamine, methylhexylamine Methyl (2-ethylhexyl) amine, methyloctylamine, methylnonylamine, methylisodecylamine, diethylamine, ethylpropylamine, ethylisopropylamine, ethylbutylamine, e
- the fuel economy, wet grip performance and dry grip performance are more synergistic.
- an alkylamino group (a group in which a hydrogen atom bonded to a nitrogen atom of a monoalkylamine or dialkylamine is eliminated) is preferred, and a dialkylamino group (bonded to a nitrogen atom of a dialkylamine) A group from which a hydrogen atom is eliminated) is more preferred.
- the alkyl group of the alkylamino group or dialkylamino group preferably has 1 to 10 carbon atoms, and more preferably 1 to 3 carbon atoms.
- Examples of the cyclic amine constituting the cyclic amino group include aziridine, 2-methylaziridine, 2-ethylaziridine, a compound having a pyrrolidine ring (pyrrolidine, 2-methylpyrrolidine, 2-ethylpyrrolidine, 2-pyrrolidone, succinimide).
- Piperidine 2-methylpiperidine, 3,5-dimethylpiperidine, 2-ethylpiperidine, 4-piperidinopiperidine, 2-methyl-4-pyrrolidinopiperidine, 1-methylpiperazine, 1-methyl-3-ethyl Piperazine morpholine, 2-methylmorpholine, 3,5-dimethylmorpholine, thiomorpholine, 3-pyrroline, 2,5-dimethyl-3-pyrroline, 2-phenyl-2-pyrroline, pyrazoline, 2-methylimidazole 2-ethyl-4-methylimidazole, 2 Phenyl imidazole, pyrazole, pyrazole carboxylic acid, alpha-pyridone, .gamma.-pyridone, aniline, 3-methylaniline, N- methyl aniline, N- isopropyl aniline.
- a cyclic amino group is formed by elimination of a hydrogen atom bonded to a nitrogen atom of these cyclic amines.
- the cyclic amino group is synergistic in terms of fuel efficiency, wet grip performance, and dry grip performance when combined with the structural unit based on the compound represented by the above formula (I) and the above functional group at the other end.
- the group represented by the following formula (II) is preferable because it can be improved. (Wherein R 11 represents a divalent hydrocarbon group having 2 to 50 carbon atoms, and may have a nitrogen atom or an oxygen atom.)
- R 11 represents a divalent hydrocarbon group having 2 to 50 carbon atoms (preferably 2 to 10, more preferably 3 to 5).
- the hydrocarbon group include alkylene groups having 2 to 10 carbon atoms, alkenylene groups having 2 to 10 carbon atoms, 2 to 10 alkynylene groups, and arylene groups having 6 to 10 carbon atoms. Of these, an alkylene group is preferable.
- R 12 to R 19 are the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms, and may have a nitrogen atom or an oxygen atom.
- Examples of the hydrocarbon group having 1 to 5 (preferably 1 to 3) carbon atoms of R 12 to R 19 include the same groups as the hydrocarbon group represented by R 1 . Of these, an alkyl group is preferable, and a methyl group and an ethyl group are more preferable.
- R 12 to R 19 are preferably hydrogen atoms, and more preferably all of R 12 to R 19 are hydrogen atoms.
- One terminal preferably has an isoprene unit (unit represented by the following formula (VII)) together with the amino group.
- an isoprene unit unit represented by the following formula (VII)
- the fuel economy, wet grip performance and dry grip performance can be improved more synergistically.
- it is more preferable to have an isoprene unit together with an alkylamino group more preferably an isoprene unit together with a dialkylamino group, and for example, a group represented by the formula (A) is preferable.
- s represents an integer of 1 to 100 (preferably 1 to 50, more preferably 1 to 10, more preferably 1 to 5).) (In the formula, s represents an integer of 1 to 100 (preferably 1 to 50, more preferably 1 to 10, more preferably 1 to 5).)
- examples of the functional group containing at least one atom selected from the group consisting of nitrogen, oxygen and silicon at the other end include an amino group, an amide group, an alkoxysilyl group, an isocyanate group, an imino group, and an imidazole.
- the functional group at the other end includes a structural unit based on the compound represented by the above formula (I) and, when combined with an amino group at one end, low fuel consumption, wet grip performance, dry grip performance Are more preferable to have both an alkoxysilyl group and an amino group.
- Examples of the amino group include the same groups as the amino group at one end described above. Of these, an alkylamino group is preferable, and a dialkylamino group is more preferable. Note that the alkyl group of the alkylamino group or dialkylamino group preferably has 1 to 10 carbon atoms, and more preferably 1 to 3 carbon atoms.
- alkoxysilyl group examples include a methoxysilyl group, an ethoxysilyl group, a propoxysilyl group, and a butoxysilyl group.
- the alkoxy group possessed by the alkoxysilyl group preferably has 1 to 10 carbon atoms, and more preferably 1 to 3 carbon atoms.
- the copolymer of the present invention for example, after copolymerizing 1,3-butadiene, styrene and the compound represented by the above formula (I) using a compound having a lithium atom and an amino group as a polymerization initiator, Can be produced by modifying with a modifier having a functional group containing at least one atom selected from the group consisting of nitrogen, oxygen and silicon. Specifically, it can be produced by the following production method.
- Polymerization method There is no particular limitation on the polymerization method when copolymerizing monomer components such as styrene, 1,3-butadiene and the compound represented by the above formula (I), and there are no limitations on solution polymerization method, gas phase polymerization method and bulk polymerization method. Any of them can be used, but the solution polymerization method is particularly preferable from the viewpoint of the stability of the compound represented by the formula (I). Moreover, any of a batch type and a continuous type may be sufficient as the superposition
- the monomer concentration in the solution is preferably 5% by mass or more, more preferably 10%. It is at least mass%.
- the monomer concentration in the solution is less than 5% by mass, the amount of the copolymer obtained is small and the cost tends to be high.
- the monomer concentration in the solution is preferably 50% by mass or less, more preferably 30% by mass or less. If the monomer concentration in the solution exceeds 50% by mass, the solution viscosity becomes too high, stirring becomes difficult, and polymerization tends to be difficult.
- the amino group possessed by the polymerization initiator compound having a lithium atom and an amino group
- the same groups as the acyclic amino group and the cyclic amino group described above Is preferred.
- the preferred embodiment is also the same.
- the compound having a lithium atom and an amino group can be obtained, for example, by reacting a lithium compound with a compound having an amino group (for example, a lithium amide compound).
- Hydrocarbyl lithium is used preferably.
- the hydrocarbyl lithium those having a hydrocarbyl group having 2 to 20 carbon atoms are preferable.
- n-butyllithium is particularly preferred.
- the amino group remains at the polymerization initiation terminal. Therefore, the acyclic amine constituting the above-mentioned acyclic amino group, the cyclic amine constituting the cyclic amino group (particularly, the pyrrolidine ring)
- the compound similar to the compound having () can be preferably used. Therefore, the compound having an amino group is preferably a compound having an alkylamino group (monoalkylamine or dialkylamine), and more preferably a compound having a dialkylamino group (dialkylamine).
- the preferable carbon number of the alkyl group which an alkylamino group and a dialkylamino group have is the same as that of the case of the above-mentioned acyclic amino group.
- the compound which has group represented by the said Formula (II) is preferable, and the compound which has group represented by the said Formula (III) is more preferable.
- the preferred embodiment of the group represented by the above formula (II) and the group represented by the above formula (III) is the same as in the case of the above-mentioned cyclic amino group.
- the conditions for reacting the lithium compound with the amino group-containing compound are not particularly limited.
- the lithium compound and the amino group-containing compound are dissolved in a hydrocarbon solvent, and the reaction temperature is 0 to 80 ° C.
- the reaction may be performed for up to 1 hour.
- the molar ratio of the lithium compound to be used and the compound having an amino group is not particularly limited, and may be, for example, 0.8 to 1.5.
- the hydrocarbon solvent used in the reaction is not particularly limited, but preferably has 3 to 8 carbon atoms.
- propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, propene examples include 1-butene, isobutene, trans-2-butene, cis-2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, and ethylbenzene. These may be used alone or in combination of two or more.
- the compound having a lithium atom and an amino group may be obtained by reacting a lithium compound with a compound having an amino group, or a commercially available product may be used.
- a lithium compound with a compound having an amino group it may be allowed to react in advance before adding the monomer component, and the lithium compound and the compound having an amino group are reacted in the presence of the monomer component. Also good. Even if the monomer component is present, the compound having an amino group is more reactive, so that the reaction between the lithium compound and the compound having an amino group proceeds preferentially.
- lithium amide compound examples include lithium hexamethylene imide, lithium pyrrolidide, lithium piperide, lithium heptamethylene imide, lithium dodecamethylene imide, lithium dimethyl amide, lithium diethyl amide, lithium dibutyl amide, lithium dipropyl amide, and lithium di Putylamide, lithium dihexylamide, lithium dioctylamide, lithium di-2-ethylhexylamide, lithium didecylamide, lithium-N-methylpiverazide, lithium ethylpropylamide, lithium ethylbutyramide, lithium ethylbenzylamide, lithium methylphenethylamide, below Examples include compounds represented by the formula. Of these, lithium pyrrolidide, lithium dimethylamide, and lithium diethylamide are preferable.
- the compound which has an isoprene unit (unit represented by following formula (VII)) with an amino group as a compound which has a lithium atom and an amino group can also be used conveniently.
- the fuel economy, wet grip performance and dry grip performance can be improved more synergistically.
- s represents an integer of 1 to 100 (preferably 1 to 50, more preferably 1 to 10, more preferably 1 to 5).
- the compound represented by a following formula is suitable.
- Method of anionic polymerization There is no restriction
- a hydrocarbon solvent such as an aliphatic, alicyclic or aromatic hydrocarbon compound
- the hydrocarbon solvent is preferably one having 3 to 8 carbon atoms.
- the randomizer is a microstructure control of a conjugated diene moiety in a copolymer (for example, an increase in 1,2-bonds in butadiene, etc.) and a control of a composition distribution of monomer units in the copolymer (for example, A compound having an action such as a butadiene unit in a butadiene-styrene copolymer or randomization of a styrene unit.
- the randomizer is not particularly limited, and any known compound generally used as a conventional randomizer can be used.
- the amount of randomizer used is preferably 0.01 molar equivalents or more, more preferably 0.05 molar equivalents or more per mole of the polymerization initiator. If the amount of randomizer used is less than 0.01 molar equivalent, the effect of addition tends to be small and it tends to be difficult to randomize.
- the amount of randomizer used is preferably 1000 molar equivalents or less, more preferably 500 molar equivalents or less per mole of the polymerization initiator. When the amount of the randomizer used exceeds 1000 molar equivalents, the monomer reaction rate changes greatly, and conversely, it tends to be difficult to randomize.
- a well-known method can be used. For example, after synthesizing a copolymer whose main chain is modified by anionic polymerization, the anion at the end of the copolymer reacts with the functional group of the modifying agent by bringing the copolymer into contact with the modifying agent. The terminal end of the copolymer is modified.
- the amount of the modifying agent to react is usually 0.01 to 10 parts by mass with respect to 100 parts by mass of the copolymer.
- modifiers examples include 3-glycidoxypropyltrimethoxysilane, (3-triethoxysilylpropyl) tetrasulfide, 1- (4-N, N dimethylaminophenyl) -1-phenylethylene, 1,1- Dimethoxytrimethylamine, 1,2-bis (trichlorosilyl) ethane, 1,3,5-tris (3-triethoxysilylpropyl) isocyanurate, 1,3,5-tris (3-trimethoxysilylpropyl) isocyanurate, 1,3-dimethyl-2-imidazolidinone, 1,3-propanediamine, 1,4-diaminobutane, 1- [3- (triethoxysilyl) propyl] -4,5-dihydroimidazole, 1-glycidyl- 4- (2-pyridyl) piperazine, 1-glycidyl-4-phenylpiperazine, 1-glycidyl
- an amino group having one terminal When combined with a structural unit based on the compound represented by the above formula (I), an amino group having one terminal, low fuel economy, wet grip performance, and dry grip performance can be improved synergistically,
- a compound represented by the following formula (IV), the following formula (V), or the following formula (VI) is preferable, and a compound represented by the following formula (IV) or the following formula (V) is more preferable.
- the compound represented by the following formula (IV) is more preferable.
- R 21 , R 22 and R 23 are the same or different and each represents an alkyl group, an alkoxy group, a silyloxy group, a carboxyl group (—COOH), a mercapto group (—SH) or a derivative thereof
- R 24 And R 25 are the same or different and each represents a hydrogen atom or an alkyl group, and n represents an integer.
- R 26 , R 27 and R 28 are the same or different and each represents an alkyl group, an alkoxy group, a silyloxy group, a carboxyl group (—COOH), a mercapto group (—SH) or a derivative thereof
- R 29 Represents a cyclic ether group, and p and q represent an integer.
- R 30 to R 33 are the same or different and each represents an alkyl group, an alkoxy group, a silyloxy group, a carboxyl group (—COOH), a mercapto group (—SH) or a
- examples of the alkyl group of R 21 , R 22 and R 23 include an alkyl group having 1 to 4 carbon atoms such as a methyl group (preferably having 1 to 3 carbon atoms). Is mentioned.
- examples of the alkoxy group of R 21 , R 22 and R 23 include an alkoxy group having 1 to 8 carbon atoms such as a methoxy group (preferably having 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms).
- the alkoxy group includes a cycloalkoxy group and an aryloxy group.
- Examples of the silyloxy group for R 21 , R 22 and R 23 include silyloxy groups substituted with an aliphatic group having 1 to 20 carbon atoms and an aromatic group (such as a trimethylsilyloxy group and a tribenzylsilyloxy group). .
- examples of the alkyl group of R 24 and R 25 include the same groups as the above alkyl groups (alkyl groups of R 21 , R 22 and R 23 ). .
- R 21 , R 22 and R 23 are preferably an alkoxy group, and R 24 and R 25 are preferably an alkyl group because of the great effect of improving fuel economy, wet grip performance and dry grip performance.
- n integer is preferably 0 to 5 for reasons of availability. Further, n is more preferably from 2 to 4, and most preferably 3. If n is 6 or more, the cost increases.
- the compound represented by the formula (IV) include 3- (N, N-dimethylamino) propyltriethoxysilane and 3- (N, N-dimethylamino) propyltrimethoxy exemplified as the modifier. Silane etc. are mentioned. Of these, 3- (N, N-dimethylamino) propyltrimethoxysilane is preferable.
- R 26 , R 27 and R 28 are the same as R 21 , R 22 and R 23 in the compound represented by the above formula (IV).
- R 26 , R 27, and R 28 an alkoxy group is preferable because the effect of improving fuel economy, wet grip performance, and dry grip performance is great.
- examples of the cyclic ether group of R 29 include a cyclic ether group having one ether bond such as an oxirane group and a cyclic ether group having two ether bonds such as a dioxolane group. And a cyclic ether group having three ether bonds such as a trioxane group.
- a cyclic ether group having one ether bond is preferable, and an oxirane group is more preferable from the viewpoint that the effect of improving fuel economy, wet grip performance, and dry grip performance is great.
- the number of carbon atoms of the cyclic ether group is preferably 2 to 7, more preferably 2 to 4.
- the cyclic ether group preferably has no unsaturated bond in the ring skeleton.
- p integer is preferably 0 to 5 for reasons of availability and reactivity. Further, p is more preferably from 2 to 4, and most preferably 3. If p is 6 or more, the cost increases.
- q integer is preferably 0 to 5 for reasons of availability and reactivity. Furthermore, q is more preferably 1 to 3, and most preferably 1. If q is 6 or more, the cost increases.
- the compound represented by the formula (V) include 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane exemplified as the modifying agent. Of these, 3-glycidoxypropyltrimethoxysilane is preferable.
- R 30 to R 33 are the same as R 21 , R 22 and R 23 in the compound represented by the above formula (IV).
- R 30 to R 33 an alkoxy group is preferable because it has a large effect of improving fuel economy, wet grip performance, and dry grip performance.
- the compound represented by the formula (VI) include tetraethoxysilane and tetramethoxysilane exemplified as the modifier. Of these, tetraethoxysilane is preferable.
- Suitable modifiers other than the compounds represented by the above formula (IV), (V), or (VI) include N- (3-triethoxysilylpropyl) -4,5-dihydroimidazole, silicon tetrachloride, and the like. It can also be mentioned.
- a known anti-aging agent or alcohol may be added as necessary to stop the polymerization reaction.
- the copolymer has a weight average molecular weight Mw of 1.0 ⁇ 10 5 to 2.5 ⁇ 10 6 .
- Mw weight average molecular weight
- the lower limit of Mw is preferably 2.0 ⁇ 10 5 or more, more preferably 3.0 ⁇ 10 5 or more, and the upper limit is preferably 1.5 ⁇ 10 6 or less, more preferably 1.0 ⁇ 10 6. It is as follows.
- Mw can be adjusted suitably by methods, such as changing the quantity of the polymerization initiator used at the time of superposition
- the content of the copolymer in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 40% by mass or more. If it is less than 5% by mass, there is a tendency that it is difficult to obtain an effect of improving fuel economy, wet grip performance, and dry grip performance. Further, the content of the copolymer is preferably 90% by mass or less, more preferably 80% by mass or less, and still more preferably 60% by mass or less. When it exceeds 90 mass%, it will become high cost and there exists a tendency for abrasion resistance to fall.
- the above copolymer may be used in combination with other rubber components.
- a diene rubber As another rubber component, it is preferable to use a diene rubber.
- the diene rubber natural rubber (NR) and diene synthetic rubber can be used.
- the diene synthetic rubber include isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), and acrylonitrile butadiene rubber. (NBR), chloroprene rubber (CR), butyl rubber (IIR) and the like.
- IR isoprene rubber
- BR butadiene rubber
- SBR styrene butadiene rubber
- IIR chloroprene rubber
- NR, BR, and SBR are preferable because of low fuel consumption, wet grip performance, and dry grip performance, and it is more preferable to use NR, BR, and SBR together with the copolymer.
- These rubber components may be used alone or in combination of
- the content of NR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less.
- low fuel consumption, wet grip performance, and dry grip performance can be obtained in a well-balanced manner.
- the content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 8% by mass or more, and preferably 30% by mass or less, more preferably 20% by mass or less.
- low fuel consumption, wet grip performance, and dry grip performance can be obtained in a well-balanced manner.
- the content of SBR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, still more preferably. It is 75 mass% or less, Most preferably, it is 50 mass% or less. Within the above range, low fuel consumption, wet grip performance, and dry grip performance can be obtained in a well-balanced manner.
- branched particles Z are particles adjacent to one particle.
- the branched particle Z is a particle Z among the particles in FIG. 1, which is a schematic explanatory view of a branched particle, and is adjacent to three or more other particles.
- structure silica what has a branched structure (for example, FIG. 2) and what does not have are mentioned, However, Since the structured silica which does not have a branched structure will aggregate immediately, it does not exist substantially.
- the average length (W 1 in FIG. 2) of the ZZ between the branched particles including the branched particles Z of the structure silica is 30 nm or more, preferably 40 nm or more. If it is less than 30 nm, there is a tendency that the dry grip performance cannot be sufficiently improved.
- W 1 is 400 nm or less, preferably 200 nm or less, more preferably 100 nm or less. When it exceeds 400 nm, hysteresis loss increases and fuel efficiency tends to deteriorate.
- the average primary particle diameter of structure silica (D, see FIG. 2 which is a schematic explanatory diagram of structure silica containing branched particles) is preferably 5 nm or more, more preferably 7 nm or more. If it is less than 5 nm, the hysteresis loss increases and the fuel efficiency tends to deteriorate. Further, D is preferably 1000 nm or less, more preferably 100 nm or less, and still more preferably 18 nm. If it exceeds 1000 nm, the dry grip performance may not be sufficiently improved.
- the average aspect ratio (W 1 / D) of ZZ between branched particles including the branched particles Z of structure silica is preferably 3 or more, more preferably 4 or more. If it is less than 3, the dry grip performance may not be sufficiently improved.
- W 1 / D is preferably 100 or less, more preferably 30 or less. When W 1 / D exceeds 100, the hysteresis loss increases and the fuel efficiency tends to deteriorate.
- silica D, W 1 and W 1 / D can be measured by observation with a transmission electron microscope of silica dispersed in a vulcanized rubber composition.
- W 1 / D when the particle is a true sphere, W 1 / D is 5.
- the content of the structure silica is 5 parts by mass or more, preferably 10 parts by mass or more, more preferably 30 parts by mass or more with respect to 100 parts by mass of the rubber component. If it is less than 5 mass parts, there exists a tendency for the effect which mix
- the content of the structure silica in the total 100% by mass of the structure silica and the carbon black is preferably 60% by mass or more, more preferably 85% by mass or more, further preferably 95% by mass or more, and the upper limit is not particularly limited. . If it is in the said range, low-fuel-consumption property, wet grip performance, and dry grip performance can be improved in a high-dimensional and well-balanced manner.
- silane coupling agent In the present invention, it is preferable to use a silane coupling agent together with the structure silica.
- the silane coupling agent is not particularly limited, and those conventionally used in the tire field can be used. For example, sulfide-based, mercapto-based, vinyl-based, amino-based, glycidoxy-based, nitro-based, chloro-based silane coupling Agents and the like.
- a sulfide system can be preferably used.
- bis (3-triethoxysilylpropyl) tetrasulfide and 3-trimethoxysilylpropylbenzothiazolyl tetrasulfide are preferable from the viewpoint of improving the reinforcing property of the rubber composition.
- These silane coupling agents may be used alone or in combination of two or more.
- the content of the silane coupling agent is preferably 1 part by mass or more, more preferably 2 parts by mass or more with respect to 100 parts by mass of the structure silica.
- the content of the silane coupling agent is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and still more preferably 10 parts by mass or less with respect to 100 parts by mass of the structure silica.
- the content of the silane coupling agent exceeds 20 parts by mass, the blending effect of the silane coupling agent as much as the content cannot be obtained, and the cost tends to be high.
- the rubber composition of the present invention can contain an anti-aging agent.
- an anti-aging agent amine-based, phenol-based, and imidazole-based compounds, carbamic acid metal salts, waxes, and the like can be appropriately selected and used.
- Softeners include petroleum-based softeners such as process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt and petroleum jelly, and fatty oil-based softeners such as soybean oil, palm oil, castor oil, linseed oil, rapeseed oil and coconut oil. Agents, waxes such as tall oil, sub, beeswax, carnauba wax and lanolin, and fatty acids such as linoleic acid, palmitic acid, stearic acid and lauric acid.
- the blending amount of the softening agent is preferably 100 parts by mass or less, more preferably 10 parts by mass or less with respect to 100 parts by mass of the rubber component. In this case, there is little risk of reducing wet grip performance.
- the rubber composition of the present invention can contain a vulcanizing agent.
- a vulcanizing agent an organic peroxide or a sulfur vulcanizing agent can be used.
- the organic peroxide include benzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, 2,5-dimethyl-2, 5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne 3 or 1,3-bis (t-butylperoxypropyl) benzene or the like can be used.
- sulfur type vulcanizing agent sulfur, morpholine disulfide, etc.
- the rubber composition of the present invention can contain a vulcanization accelerator.
- a vulcanization accelerator examples include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine, aldehyde-ammonia, imidazoline, and xanthate vulcanization accelerators. Is mentioned. These may be used alone or in combination of two or more.
- the rubber composition of the present invention can contain a vulcanization aid.
- a vulcanization aid stearic acid, zinc oxide (zinc white) or the like can be used.
- the rubber composition of the present invention can be produced by a conventionally known production method, and the production method is not limited. For example, it can be produced by kneading each of the above components using a kneading machine such as a Banbury mixer or a kneading roll under ordinary methods and conditions.
- a kneading machine such as a Banbury mixer or a kneading roll under ordinary methods and conditions.
- the silica sol with a rubber component containing the above-mentioned copolymer with a rubber kneading apparatus from the viewpoint that the rubber composition of the present invention on which structure silica is formed can be easily produced.
- a final kneading step in which the kneaded product obtained by the base kneading step, the vulcanizing agent, and the vulcanization accelerator are kneaded at 30 to 70 ° C. (preferably 40 to 60 ° C.) for 3 to 10 minutes;
- a vulcanization step of vulcanizing the unvulcanized rubber composition obtained by the finish kneading step at 150 to 190 ° C. (preferably 160 to 180 ° C.) for 5 to 30 minutes is more preferable.
- the preferable compounding amount (silica conversion) of silica sol is the same as that of the above-mentioned structure silica.
- the kneading step (such as the base kneading step) for forming the structure silica, if each component is kneaded in toluene, which is a good solvent for rubber, the W 1 of the structure silica tends to become excessively long. It is preferable to knead without using.
- silica sol refers to a colloidal solution in which silica is dispersed in a solvent.
- the silica sol is not particularly limited, but a colloidal solution in which elongated silica is dispersed in a solvent is preferable because a structure silica can be suitably formed, and a colloidal solution in which elongated silica is dispersed in an organic solvent (organo Silica sol) is more preferable.
- the elongated silica means a silica (secondary particle) having a chain shape in which a plurality of primary particles such as a spherical shape and a granular shape are connected. It may be linear or branched.
- the solvent for dispersing silica is not particularly limited, but alcohols such as methanol and isopropanol are preferable, and isopropanol is more preferable.
- the average particle diameter of primary particles constituting silica (secondary particles) contained in the silica sol is preferably 1 to 100 nm, more preferably 5 to 80 nm.
- the average particle size of the primary particles was determined by visually measuring the particle size (average diameter) of 50 primary particles in a photograph taken with a transmission electron microscope JEM2100FX manufactured by JEOL. .
- the average diameter of the primary particles is an average value of thicknesses (diameters) measured at arbitrary 50 locations of the silica (secondary particles) in the electron micrograph.
- the silica (secondary particles) has a bead shape with a constriction, it can be obtained as an average value of the diameters of 50 bead beads in an electron micrograph.
- the average particle diameter of silica (secondary particles) contained in the silica sol is preferably 20 to 300 nm, more preferably 30 to 150 nm.
- the average particle diameter of silica (secondary particles) can be measured by a dynamic light scattering method, and specifically, can be measured by the following method.
- the average particle diameter of silica (secondary particles) was measured with a laser particle analysis system ELS-8000 (cumulant analysis) manufactured by Otsuka Electronics Co., Ltd.
- the measurement conditions are a temperature of 25 ° C., an angle between incident light and a detector of 90 °, and an integration count of 100.
- the refractive index of water (1.333) is input as the refractive index of the dispersion solvent.
- the measurement concentration was usually about 5 ⁇ 10 ⁇ 3 mass%.
- the silica (secondary particles) is, for example, a method described in claim 2 of International Publication No. 00/15552 pamphlet and the disclosure part of the specification related thereto, Japanese Patent No. 2803134, Japanese Patent No. 2926915. It can be produced according to the method described in claim 2 of the publication and the disclosure part of the specification related thereto.
- the rubber composition of the present invention thus obtained, a pneumatic tire having improved fuel economy, wet grip performance, and dry grip performance in a well-balanced manner can be obtained.
- the rubber composition can be used for each member of a tire, and in particular, can be suitably used for a tread, a sidewall, and the like.
- the pneumatic tire of the present invention is produced by a usual method using the rubber composition. That is, by extruding a rubber composition containing the above components in accordance with the shape of a tread or the like at an unvulcanized stage, and molding it with a tire molding machine by a normal method along with other tire members, Form an unvulcanized tire.
- the unvulcanized tire is heated and pressurized in a vulcanizer to obtain a pneumatic tire.
- A-1 Dimethylamine modification agent manufactured by Kanto Chemical Co., Ltd.
- A-2 Pyrrolidine modification agent manufactured by Kanto Chemical Co., Ltd.
- B-1 tetraethoxysilane modifier manufactured by Kanto Chemical Co., Ltd.
- B-2 3 manufactured by Amax Co., Ltd.
- -Glycidoxypropyltrimethoxysilane modifier B-3 3- (N, N-dimethylamino) propyltrimethoxysilane 2,6-tert-butyl-p-cresol manufactured by Amax Co., Ltd .: Ouchi Shinsei Chemical NOCRACK 200 manufactured by Kogyo Co., Ltd.
- the weight average molecular weight Mw of the copolymer is gel permeation chromatograph (GPC) (GPC-8000 series, manufactured by Tosoh Corp., detector: differential refractometer, column: TSKGEL SUPERMALTPORE HZ-M, manufactured by Tosoh Corp.) It calculated
- GPC gel permeation chromatograph
- copolymer (1) was obtained by reprecipitation purification.
- the weight average molecular weight of the obtained copolymer (1) is 500,000
- the content of the compound represented by the above formula (I) is 1.1% by mass
- the styrene content is 1.1% by mass
- the component content was 19% by mass.
- NR RSS # 3 BR: Ubepol BR150B manufactured by Ube Industries, Ltd.
- SBR SL574 manufactured by JSR Corporation Copolymers (1) to (15): Synthetic silica A by the above method: Organosilica sol IPA-ST-UP manufactured by Nissan Chemical Industries, Ltd.
- silica sol elongated isopropanol-dispersed silica sol (measured by dynamic light scattering method) (Average particle size of silica (secondary particles): 40 to 100 nm), silica content: 15% by mass) (The amounts shown in Tables 2 and 3 indicate the amount of silica in the organosilica sol.)
- Silica B Ultrasil VN3 manufactured by Evonik Degussa (granular silica, N 2 SA: 175 m 2 / g)
- Stearic acid Zinc stearate manufactured by NOF Corporation: Zinc Hana No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd.
- Sulfur Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd. (1): Emerging Ouchi Noxeller CZ (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Chemical Industry Co., Ltd.
- the obtained unvulcanized rubber composition was molded into a tread shape and bonded together with other tire members on a tire molding machine to form an unvulcanized tire, and then vulcanized at 170 ° C. for 12 minutes, A test tire (size: 195 / 65R15) was produced.
- the performance of the obtained vulcanized rubber composition and test tire was evaluated by the following test method.
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Abstract
Description
通常、主鎖に官能基を有する重合体(主鎖変性重合体)の末端に、更に官能基を付加した場合(主鎖末端変性重合体とした場合)であっても、上記性能が向上するとは一概には言えない。これは、官能基の種類によりフィラーとの親和性が異なるためであり、性能を好適に向上させるためには官能基の組合せが非常に重要である。本発明では、上記式(I)で表される化合物に基づく構成単位、一方の末端に有するアミノ基、他方の末端に有する上記官能基の組合せが非常に良好であるため、低燃費性、ウェットグリップ性能、ドライグリップ性能を相乗的に改善できるものと推測される。
<共重合体>
本明細書において「共重合体」は、ゴム成分に含まれる概念として記載する。
該炭化水素基としては、例えば、炭素数2~10のアルキレン基、炭素数2~10のアルケニレン基、2~10のアルキニレン基、炭素数6~10のアリーレン基などが挙げられる。なかでも、アルキレン基が好ましい。
本発明の共重合体は、例えば、リチウム原子とアミノ基を有する化合物を重合開始剤として、1,3-ブタジエン、スチレン及び上記式(I)で表される化合物を共重合した後、重合末端を窒素、酸素及びケイ素からなる群より選択される少なくとも1種の原子を含む官能基を有する変性剤により変性することにより製造でき、具体的には、以下の製造方法で製造できる。
スチレン、1,3-ブタジエンおよび上記式(I)で表される化合物などのモノマー成分を共重合する際の重合方法については特に制限はなく、溶液重合法、気相重合法、バルク重合法のいずれも用いることができるが、特に式(I)で表される化合物の安定性の観点から、溶液重合法が好ましい。また、重合形式は、回分式及び連続式のいずれであってもよい。
アニオン重合を行う場合、重合開始剤として、リチウム原子とアミノ基を有する化合物を使用することが好ましい。これにより、重合開始末端にアミノ基を有し、他方の末端が重合活性部位である共役ジエン系重合体(リビングポリマー)が得られる。
上記リチウム原子とアミノ基を有する化合物を重合開始剤として用い、アニオン重合によって共重合体を製造する方法としては、特に制限はなく、従来公知の方法を用いることができる。具体的には、反応に不活性な有機溶剤、例えば脂肪族、脂環族、芳香族炭化水素化合物などの炭化水素系溶剤中において、上記リチウム原子とアミノ基を有する化合物を重合開始剤とし、必要に応じてランダマイザーの存在下で、スチレン、1,3-ブタジエン及び式(I)で表される化合物などとをアニオン重合させればよい。なお、アニオン重合後に、必要に応じて、公知の老化防止剤や、重合反応を停止する目的でアルコールなどを加えてもよい。
上記炭化水素系溶剤としては、炭素数3~8のものが好ましく、例えばプロパン、n-ブタン、イソブタン、n-ペンタン、イソペンタン、n-ヘキサン、シクロヘキサン、プロペン、1-ブテン、イソブテン、トランス-2-ブテン、シス-2-ブテン、1-ペンテン、2-ペンテン、1-ヘキセン、2-ヘキセン、ベンゼン、トルエン、キシレン、エチルベンゼンなどを挙げることができる。これらは単独で用いてもよく、2種以上を混合して用いてもよい。
また、上記ランダマイザーとは、共重合体中の共役ジエン部分のミクロ構造制御(例えば、ブタジエンにおける1、2-結合の増加など)や、共重合体におけるモノマー単位の組成分布の制御(例えば、ブタジエン-スチレン共重合体におけるブタジエン単位、スチレン単位のランダム化など)などの作用を有する化合物のことである。このランダマイザーとしては、特に制限はなく、従来ランダマイザーとして一般に使用されている公知の化合物の中から任意のものを用いることができる。例えば、ジメトキシベンゼン、テトラヒドロフラン、ジメトキシエタン、ジエチレングリコールジブチルエーテル、ジエチレングリコールジメチルエーテル、ビステトラヒドロフリルプロパン、トリエチルアミン、ピリジン、N-メチルモルホリン、N,N,N’,N’-テトラメチルエチレンジアミン、1,2-ジピペリジノエタンなどのエーテル類及び第三級アミン類などを挙げることができる。また、カリウム-t-アミレート、カリウム-t-ブトキシドなどのカリウム塩類、ナトリウム-t-アミレートなどのナトリウム塩類も用いることができる。
上記変性剤としては、例えば3-グリシドキシプロピルトリメトキシシラン、(3-トリエトキシシリルプロピル)テトラスルフィド、1-(4-N,Nジメチルアミノフェニル)-1-フェニルエチレン、1,1-ジメトキシトリメチルアミン、1,2-ビス(トリクロロシリル)エタン、1,3,5-トリス(3-トリエトキシシリルプロピル)イソシアヌレート、1,3,5-トリス(3-トリメトキシシリルプロピル)イソシアヌレート、1,3-ジメチル-2-イミダゾリジノン、1,3-プロパンジアミン、1,4-ジアミノブタン、1-[3-(トリエトキシシリル)プロピル]-4,5-ジヒドロイミダゾール、1-グリシジル-4-(2-ピリジル)ピペラジン、1-グリシジル-4-フェニルピペラジン、1-グリシジル-4-メチルピベラジン、1-グリシジル-4-メチルホモピベラジン、1-グリシジルヘキサメチレンイミン、11-アミノウンデシルトリエトキシシラン、11-アミノウンデシルトリメトキシシラン、1-ベンジル-4-グリシジルピペラジン、2-(3,4-エポキシシクロヘキシル)エチルトリメトキシシラン、2-(4-モルフォリノジチオ)ベンゾチアゾール、2-(6-アミノエチル)-3-アミノプロピルトリメトキシシラン、2-(トリエトキシシリルエチル)ピリジン、2-(トリメトキシシリルエチル)ピリジン、2-(2-ピリジルエチル)チオプロピルトリメトキシシラン、2-(4-ピリジルエチル)チオプロビルトリメトキシシラン、2,2-ジエトキシ-1,6-ジアザ-2-シラシクロオクタン、2,2-ジメトキシ-1,6-ジアザ-2-シラシクロオクタン、2,3-シクロロ-1,4-ナフトキノン、2,4-ジニトロベンゼンスルホニルクロライド、2,4-トリレンジイソシアナート、2-(4-ピリジルエチル)トリエトキシシラン、2-(4-ピリジルエチル)トリメトキシシラン、2-シアノエチルトリエトキシシラン、2-トリブチルスタニル-1,3-ブタジエン、2-(トリメトキシシリルエチル)ピリジン、2-ビニルピリジン、2-(4-ピリジルエチル)トリエトキシシラン、2-(4-ピリジルエチル)トリメトキシシラン、2-ラウリルチオエチルフェニルケトン、3-(1-ヘキサメチレンイミノ)プロピル(トリエトキシ)シラン、3-(1,3-ジメチルブチリデン)アミノプロピルトリエトキシシラン、3-(1,3-ジメチルブチリデン)アミノプロピルトリメトキシシラン、3-(2-アミノエチルアミノプロピル)トリメトキシシラン、3-(m-アミノフェノキシ)プロピルトリメトキシシラン、3-(N,N-ジメチルアミノ)プロピルトリエトキシシラン、3-(N,N-ジメチルアミノ)プロピルトリメトキシシラン、3-(N-メチルアミノ)プロピルトリエトキシシラン、3-(N-メチルアミノ)プロピルトリメトキシシラン、3-(N-アリルアミノ)プロピルトリメトキシシラン、3,4-ジアミノ安息香酸、3-アミノプロピルジメチルエトキシシラン、3-アミノプロピルトリエトキシシラン、3-アミノプロピルトリメトキシシラン、3-アミノプロピルトリス(メトキシジエトキシ)シラン、3-アミノプロピルジイソプロピルエトキシシラン、3-イソシアネートプロピルトリエトキシシラン、3-グリシドキシプロピルトリエトキシシラン、3-グリシドキシプロピルトリメトキシシラン、3-グリシドキシプロピルメチルジメトキシシラン、3-ジエチルアミノプロピルトリメトキシシラン、3-ジエトキシ(メチル)シリルプロピル無水コハク酸、3-(N,N-ジエチルアミノプロピル)トリエトキシシラン、3-(N,N-ジエチルアミノプロピル)トリメトキシシラン、3-(N,N-ジメチルアミノプロピル)ジエトキシメチルシラン、3-(N,N-ジメチルアミノプロピル)トリエトキシシラン、3-(N,N-ジメチルアミノプロピル)トリメトキシシラン、3-トリエトキシシリルプロピル無水コハク酸、3-トリエトキシシリルプロピル無水酢酸、3-トリフェノキシシリルプロピル無水コハク酸、3-トリフェノキシシリルプロピル無水酢酸、3-トリメトキシシリルプロピルベンゾチアゾールテトラスルフィド、3-ヘキサメチレンイミノプロピルトリエトキシシラン、3-メルカプトプロピルトリメトキシシラン、(3-トリエトキシシリルプロピル)ジエチレントリアミン、(3-トリメトキシシリルプロピル)ジエチレントリアミン、4,4’-ビス(ジエチルアミノ)ベンゾフェノン、4,4’-ビス(ジメチルアミノ)ベンゾフェノン、4’-(イミダゾール-1-イル)-アセトフェノン、4-[3-(N,N-ジグリシジルアミノ)プロピル]モルホリン、4-グリシジル-2,2,6,6-テトラメチルピベリジニルオキシ、4-アミノブチルトリエトキシシラン、4-ビニルピリジン、4-モルホリノアセトフェノン、4-モルホリノベンゾフェノン、m-アミノフェニルトリメトキシシラン、N-(1,3-ジメチルブチリデン)-3-(トリエトキシシリル)-1-プロパンアミン、N-(1,3-ジメチルブチリデン)-3-(トリメトキシシリル)-1-プロパンアミン、N-(1-メチルエチリデン)-3-(トリエトキシシリル)-1-プロパンアミン、N-(2-アミノエチル)-3-アミノブロピルメチルジエトキシシラン、N-(2-アミノエチル)-3-アミノプロピルメチルジメトキシシラン、N-(2-アミノエチル)-3-アミノプロピルトリエトキシシラン、N-(2-アミノエチル)-3-アミノプロピルトリメトキシシラン、N-(2-アミノエチル)-11-アミノウンデシルトリエトキシシラン、N-(2-アミノエチル)-11-アミノウンデシルトリメトキシシラン、N-(2-アミノエチル)-3-アミノイソブチルメチルジエトキシシラン、N-(2-アミノエチル)-3-アミノイソブチルメチルジメトキシシラン、N-(3-ジエトキシメチルシリルプロピル)サクシンイミド、N-(3-トリエトキシシリルプロピル)-4,5-ジヒドロイミダゾール、N-(3-トリエトキシシリルプロピル)ピロール、N-(3-トリメトキシシリルプロピル)ピロール、N-3-[アミノ(ポリプロピレンオキシ)]アミノプロピルトリメトキシシラン、N-[5-(トリエトキシシリル)-2-アザ-1-オキソペンチル]カプロラクタム、N-[5-(トリメトキシシリル)-2-アザ-1-オキソペンチル]カプロラクタム、N-(6-アミノヘキシル)アミノメチルトリエトキシシラン、N-(6-アミノヘキシル)アミノメチルトリメトキシシラン、N-アリル-アザ-2,2-ジエトキシシラシクロペンタン、N-アリル-アザ-2,2-ジメトキシシラシクロペンタン、N-(シクロヘキシルチオ)フタルイミド、N-n-ブチル-アザ-2,2-ジエトキシシラシクロペンタン、N-n-ブチル-アザ-2,2-ジメトキシシラシクロペンタン、N,N,N’,N’-テトラエチルアミノベンゾフェノン、N,N,N’,N’-テトラメチルチオ尿素、N,N,N’,N’-テトラメチル尿素、N,N’-エチレン尿素、N,N’-ジエチルアミノベンゾフェノン、N,N’-ジエチルアミノベンゾフェノン、N,N’-ジエチルアミノベンゾフラン、N,N’-ジエチルカルバミン酸メチル、N,N’-ジエチル尿素、(N,N-ジエチル-3-アミノプロピル)トリエトキシシラン、(N,N-ジエチル-3-アミノプロピル)トリメトキシシラン、N,N-ジオクチル-N’-トリエトキシシリルプロピルウレア、N,N-ジオクチル-N’-トリメトキシシリルプロピルウレア、N,N-ジエチルカルバミン酸メチル、N,N-ジグリシジルシクロヘキシルアミン、N,N-ジメチル-o-トルイジン、N,N-ジメチルアミノスチレン、N,N-ジエチルアミノプロピルアクリルアミド、N,N-ジメチルアミノプロピルアクリルアミド、N-エチルアミノイソブチルトリエトキシシラン、N-エチルアミノイソブチルトリメトキシシラン、N-エチルアミノイソブチルメチルジエトキシシラン、N-オキシジエチレン-2-ベンゾチアゾールスルフェンアミド、N-シクロヘキシルアミノプロピルトリエトキシシラン、N-シクロヘキシルアミノプロピルトリメトキシシラン、N-メチルアミノプロピルメチルジメトキシシラン、N-メチルアミノプロピルメチルジエトキシシラン、N-ビニルベンジルアザシクロヘプタン、N-フェニルピロリドン、N-フェニルアミノプロピルトリエトキシシラン、N-フェニルアミノプロピルトリメトキシシラン、N-フェニルアミノメチルトリエトキシシラン、N-フェニルアミノメチルトリメトキシシラン、n-ブチルアミノプロピルトリエトキシシラン、n-ブチルアミノプロピルトリメトキシシラン、N-メチルアミノプロピルトリエトキシシラン、N-メチルアミノプロピルトリメトキシシラン、N-メチル-2-ピペリドン、N-メチル-2-ピロリドン、N-メチル-ε-カプロラクタム、N-メチルインドリノン、N-メチルピロリドン、p-(2-ジメチルアミノエチル)スチレン、p-アミノフェニルトリメトキシシラン、γ-グリシドキシプロピルトリメトキシシラン、γ-メタクリロキシプロピルトリメトキシシラン、(アミノエチルアミノ)-3-イソブチルジエトキシシラン、(アミノエチルアミノ)-3-イソブチルジメトキシシラン、(アミノエチルアミノメチル)フェネチルトリエトキシシラン、(アミノエチルアミノメチル)フェネチルトリメトキシシラン、アクリル酸、アジピン酸ジエチル、アセタミドプロピルトリメトキシシラン、アミノフェニルトリメトキシシラン、アミノベンゾフェノン、ウレイドプロピルトリエトキシシラン、ウレイドプロピルトリメトキシシラン、エチレンオキシド、オクタデシルジメチル(3-トリメトキシシリルプロピル)アンモニウムクロリド、グリシドキシプロピルトリエトキシシラン、グリシドキシプロピルトリメトキシシラン、グリセロールトリステアレート、クロロトリエトキシシラン、クロロプロピルトリエトキシシラン、クロロポリジメチルシロキサン、クロロメチルジフェノキシシラン、ジアリルジフェニルスズ、ジエチルアミノメチルトリエトキシシラン、ジエチルアミノメチルトリメトキシシラン、ジエチル(グリシジル)アミン、ジエチルジチオカルバミン酸2-ベンゾチアゾイルェステル、ジエトキシジクロロシラン、(シクロヘキシルアミノメチル)トリエトキシシラン、(シクロヘキシルアミノメチル)トリメトキシシラン、ジグリシジルポリシロキサン、ジクロロジフェノキシシラン、ジシクロヘキシルカルボジイミド、ジビニルベンゼン、ジフェニルカルボジイミド、ジフェニルシアナミド、ジフェニルメタンジイソシアネート、ジフェノキシメチルクロロシラン、ジブチルジクロロスズ、ジメチル(アセトキシ-メチルシロキサン)ポリジメチルシロキサン、ジメチルアミノメチルトリエトキシシラン、ジメチルアミノメチルトリメトキシシラン、ジメチル(メトキシ-メチルシロキサン)ポリジメチルシロキサン、ジメチルイミダゾリジノン、ジメチルエチレン尿素、ジメチルジクロロシラン、ジメチルスルホモイルクロライド、シルセスキオキサン、ソルビタントリオレイン酸エステル、ソルビタンモノラウリン酸エステル、チタンテトラキス(2-エチルヘキシオキシド)、テトラエトキシシラン、テトラグリシジル-1,3-ビスアミノメチルシクロヘキサン、テトラフェノキシシラン、テトラメチルチウラムジスルフィド、テトラメトキシシラン、トリエトキシビニルシラン、トリス(3-トリメトキシシリルプロピル)シアヌレート、トリフェニルホスフェート、トリフェノキシクロロシラン、トリフェノキシメチルケイ素、トリフェノキシメチルシラン、二酸化炭素、ビス(トリエトキシシリルプロピル)アミン、ビス(トリメトキシシリルプロピル)アミン、ビス[3-(トリエトキシシリル)プロピル]エチレンジアミン、ビス[3-(トリメトキシシリル)プロピル]エチレンジアミン、ビス[3-(トリエトキシシリル)プロピル]ウレア、ビス[(トリメトキシシリル)プロピル]ウレア、ビス(2-ヒドロキシメチル)-3-アミノプロピルトリエトキシシラン、ビス(2-ヒドロキシメチル)-3-アミ
ノプロピルトリメトキシシラン、ビス(2-エチルヘキサノエート)スズ、ビス(2-メチルブトキシ)メチルクロロシラン、ビス(3-トリエトキシシリルプロピル)テトラスルフィド、ビスジエチルアミノベンゾフェノン、ビスフェノールAジグリシジルエーテル、ビスフェノキシエタノールフルオレンジグリシジルエーテル、ビス(メチルジエトキシシリルプロピル)アミン、ビス(メチルジメトキシシリルプロピル)-N-メチルアミン、ヒドロキシメチルトリエトキシシラン、ビニルトリス(2-エチルヘキシルオキシ)シラン、ビニルベンジルジエチルアミン、ビニルベンジルジメチルアミン、ビニルベンジルトリブチルスズ、ビニルベンジルピペリジン、ビニルベンジルピロリジン、ピロリジン、フェニルイソシアナート、フェニルイソチオシアナート、(フェニルアミノメチル)メチルジメトキシシラン、(フェニルアミノメチル)メチルジエトキシシラン、フタル酸アミド、ヘキサメチレンジイソシアナート、ベンジリデンアニリン、ポリジフェニルメタンジイソシアネート、ポリジメチルシロキサン、メチル-4-ピリジルケトン、メチルカプロラクタム、メチルトリエトキシシラン、メチルトリフェノキシシラン、ラウリルチオプロピオン酸メチル、四塩化ケイ素などがあげられる。
なお、Mwは、重合時に使用する重合開始剤の量を変更するなどの方法により適宜調節することができ、後述の実施例の方法で測定できる。
本発明で使用するストラクチャーシリカ(直鎖シリカ)は、1つの粒子に対して隣接する粒子が3つ以上の粒子(以下、分岐粒子Zとする)を有し、分岐粒子Zとそれに隣接する粒子により分岐構造が形成される。分岐粒子Zとは、分岐粒子の概略説明図である図1における粒子のうちの粒子Zであり、3個以上の他の粒子と隣接している。なお、ストラクチャーシリカとしては、分岐構造を有するもの(例えば図2)と有しないものが挙げられるが、分岐構造を有しないストラクチャーシリカは、すぐに凝集してしまうため、実質的に存在しない。
本発明では、ストラクチャーシリカとともに、シランカップリング剤を使用することが好ましい。シランカップリング剤としては特に限定されず、従来からタイヤ分野において汎用されているものを使用でき、例えば、スルフィド系、メルカプト系、ビニル系、アミノ系、グリシドキシ系、ニトロ系、クロロ系シランカップリング剤などが挙げられる。なかでも、ビス(3-トリエトキシシリルプロピル)テトラスルフィド、ビス(2-トリエトキシシリルエチル)テトラスルフィド、ビス(3-トリエトキシシリルプロピル)ジスルフィド、ビス(2-トリエトキシシリルエチル)ジスルフィドなどのスルフィド系を好適に使用できる。なかでも、ゴム組成物の補強性改善効果などの点から、ビス(3-トリエトキシシリルプロピル)テトラスルフィド及び3-トリメトキシシリルプロピルベンゾチアゾリルテトラスルフィドが好ましい。これらのシランカップリング剤は単独で用いてもよく、2種以上を組み合わせて用いてもよい。
本発明のゴム組成物は、老化防止剤を含むことができる。老化防止剤としては、アミン系、フェノール系、イミダゾール系の各化合物や、カルバミン酸金属塩、ワックスなどを適宜選択して使用することが可能である。
軟化剤としては、プロセスオイル、潤滑油、パラフィン、流動パラフィン、石油アスファルト、ワセリンなどの石油系軟化剤、大豆油、パーム油、ヒマシ油、アマニ油、ナタネ油、ヤシ油などの脂肪油系軟化剤、トール油、サブ、蜜ロウ、カルナバロウ、ラノリンなどのワックス類、リノール酸、パルミチン酸、ステアリン酸、ラウリン酸などの脂肪酸、などが挙げられる。軟化剤の配合量は、ゴム成分100質量部に対して、好ましくは100質量部以下、より好ましくは10質量部以下である。この場合、ウェットグリップ性能を低下させる危険性が少ない。
本発明のゴム組成物は、加硫剤を含むことができる。加硫剤としては、有機過酸化物もしくは硫黄系加硫剤を使用できる。有機過酸化物としては、たとえば、ベンゾイルパーオキサイド、ジクミルパーオキサイド、ジ-t-ブチルパーオキサイド、t-ブチルクミルパーオキサイド、メチルエチルケトンパーオキサイド、クメンハイドロパーオキサイド、2,5-ジメチル-2,5-ジ(t-ブチルパーオキシ)ヘキサン、2,5-ジメチル-2,5-ジ(ベンゾイルパーオキシ)ヘキサン、2,5-ジメチル-2,5-ジ(t-ブチルパーオキシ)ヘキシン-3あるいは1,3-ビス(t-ブチルパーオキシプロピル)ベンゼンなどを使用することができる。また、硫黄系加硫剤としては、たとえば、硫黄、モルホリンジスルフィドなどを使用することができる。これらの中では硫黄が好ましい。
本発明のゴム組成物は、加硫促進剤を含むことができる。加硫促進剤としては、例えば、スルフェンアミド系、チアゾール系、チウラム系、チオウレア系、グアニジン系、ジチオカルバミン酸系、アルデヒド-アミン系、アルデヒド-アンモニア系、イミダゾリン系、キサンテート系加硫促進剤などが挙げられる。これらは単独で用いてもよいし、2種以上を併用してもよい。
本発明のゴム組成物は、加硫助剤を含むことができる。加硫助剤としては、ステアリン酸、酸化亜鉛(亜鉛華)などを使用することができる。
本発明のゴム組成物には、その他の補強剤、可塑剤、カップリング剤などのタイヤ用又は一般のゴム組成物用に配合される各種配合剤及び添加剤を配合することができる。また、これらの配合剤、添加剤の含有量も一般的な量とすることができる。
本発明のゴム組成物は、従来公知の製造方法により製造することができ、その製造方法が限定されるものではない。例えば、上記各成分をバンバリーミキサーや混練ロールなどの混練機を用いて、通常の方法及び条件で混練することによって製造することができる。
(I)上記共重合体を含むゴム成分と、シリカゾルと、必要に応じて、カーボンブラック、シランカップリング剤、酸化亜鉛、ステアリン酸、軟化剤、老化防止剤、ワックス等を80~180℃(好ましくは90~170℃)で3~10分間混練するベース練り工程と、
(II)ベース練り工程により得られた混練物と、加硫剤と、加硫促進剤とを30~70℃(好ましくは40~60℃)で3~10分間混練する仕上げ練り工程と、
(III)仕上げ練り工程により得られた未加硫ゴム組成物を150~190℃(好ましくは160~180℃)で5~30分間加硫する加硫工程とを含む製造方法がより好ましい。
一次粒子の平均粒子径は、日本電子製透過電子顕微鏡JEM2100FXで撮影した写真において、目視で50個の一次粒子の粒子径(平均直径)を測定し、それらを平均した値を平均粒子径とした。
シリカ(二次粒子)の平均粒子径は、大塚電子(株)製のレーザー粒子解析システムELS-8000(キュムラント解析)で測定した。測定条件は、温度25℃、入射光と検出器との角度90°、積算回数100回であり、分散溶媒の屈折率として水の屈折率(1.333)を入力する。測定濃度は、通常5×10-3質量%程度で行った。
本発明の空気入りタイヤは、上記ゴム組成物を用いて通常の方法で製造される。
すなわち、上記成分を配合したゴム組成物を、未加硫の段階でトレッドなどの形状にあわせて押出し加工し、他のタイヤ部材とともに、タイヤ成型機上にて通常の方法で成形することにより、未加硫タイヤを形成する。この未加硫タイヤを加硫機中で加熱加圧することにより空気入りタイヤを得る。
n-ヘキサン:関東化学(株)製
スチレン:関東化学(株)製
1,3-ブタジエン:東京化成工業(株)製
p-メトキシスチレン:関東化学(株)製(式(I)で表される化合物)
p-(tert-ブトキシ)スチレン:和光純薬工業(株)製(式(I)で表される化合物)
テトラメチルエチレンジアミン:関東化学(株)製
変性剤A-1:関東化学(株)製ジメチルアミン
変性剤A-2:関東化学(株)製ピロリジン
変性剤A-3:FMCリチウム社製のAI-200(下記式で表される化合物(s=2))
変性剤B-1:関東化学(株)製のテトラエトキシシラン
変性剤B-2:アヅマックス(株)製の3-グリシドキシプロピルトリメトキシシラン
変性剤B-3:アヅマックス(株)製の3-(N,N-ジメチルアミノ)プロピルトリメトキシシラン
2,6-tert-ブチル-p-クレゾール:大内新興化学工業(株)製のノクラック200
下記により得られた共重合体の分析は以下の方法で行った。
共重合体の重量平均分子量Mwは、ゲルパーミエーションクロマトグラフ(GPC)(東ソー(株)製GPC-8000シリーズ、検出器:示差屈折計、カラム:東ソー(株)製のTSKGEL SUPERMALTPORE HZ-M)による測定値を基に標準ポリスチレン換算により求めた。
共重合体の構造同定は、日本電子(株)製JNM-ECAシリーズの装置を用いて行った。測定結果から、共重合体中の1,3-ブタジエン、式(I)で表される化合物(p-メトキシスチレン、p-(tert-ブトキシ)スチレン)、及びスチレンの含有量を算出した。
(共重合体(1))
十分に窒素置換した耐熱容器にn-ヘキサン1500ml、スチレン100mmol、1,3-ブタジエン800mmol、p-メトキシスチレン5mmol、テトラメチルエチレンジアミン0.2mmol、変性剤A-1 0.12mmol、n-ブチルリチウム0.12mmolを加えて、0℃で48時間攪拌した。その後、変性剤B-1 0.15mmolを加えて0℃で15分間撹拌した。その後、アルコールを加えて反応を止め、反応溶液に2,6-tert-ブチル-p-クレゾール1gを添加後、再沈殿精製により共重合体(1)を得た。得られた共重合体(1)の重量平均分子量は500,000、上記式(I)で表される化合物の含有量(アルコキシスチレン成分含有率)は1.1質量%、スチレン含有量(スチレン成分含有率)は19質量%であった。
表1のレシピにて共重合体(1)と同様の方法で合成した。得られたポリマーの特性を表1に示す。
以下に、実施例及び比較例で用いた各種薬品について説明する。
NR:RSS#3
BR:宇部興産(株)製のウベポールBR150B
SBR:JSR(株)製のSL574
共重合体(1)~(15):上記方法で合成
シリカA:日産化学工業(株)製のオルガノシリカゾルIPA-ST-UP(細長い形状のイソプロパノール分散シリカゾル(動的光散乱法によって測定されたシリカ(二次粒子)の平均粒子径:40~100nm)、シリカ含有率:15質量%)(表2、3に記載の量は、オルガノシリカゾル中のシリカ量を示す。)
シリカB:エボニックデグッサ社製のウルトラシルVN3(粒状シリカ、N2SA:175m2/g)
シランカップリング剤:エボニックデグッサ社製のSi69(ビス(3-トリエトキシシリルプロピル)テトラスルフィド)
老化防止剤:大内新興化学工業(株)製のノクラック6C(N-1,3-ジメチルブチル-N’-フェニル-p-フェニレンジアミン)
ステアリン酸:日油(株)製のステアリン酸
酸化亜鉛:三井金属鉱業(株)製の亜鉛華1号
硫黄:鶴見化学工業(株)製の粉末硫黄
加硫促進剤(1):大内新興化学工業(株)製のノクセラーCZ(N-シクロヘキシル-2-ベンゾチアゾリルスルフェンアミド)
加硫促進剤(2):大内新興化学工業(株)製のノクセラーD(ジフェニルグアニジン)
また、得られた未加硫ゴム組成物をトレッドの形状に成形し、タイヤ成型機上で他のタイヤ部材とともに貼り合わせて未加硫タイヤを形成した後、170℃で12分間加硫し、試験用タイヤ(サイズ:195/65R15)を製造した。
得られた加硫ゴム組成物及び試験用タイヤについて以下に示す試験方法により性能を評価した。
(低燃費性)
(株)上島製作所製スペクトロメーターを用いて、動的歪振幅1%、周波数10Hz、温度50℃で、得られた加硫ゴム組成物のtanδを測定した。そして、下記計算式により測定結果を指数表示した。指数が大きいほど転がり抵抗が小さく、低燃費性に優れることを示す。
(低燃費性指数)=(比較例1のtanδ)/(各配合のtanδ)×100
(株)上島製作所製フラットベルト式摩擦試験機(FR5010型)を用いてウェットグリップ性能を評価した。上記加硫ゴム組成物からなる幅20mm、直径100mmの円筒形のゴム試験片をサンプルとして用い、速度20km/時間、荷重4kgf、路面温度20℃の条件で、路面に対するサンプルのスリップ率を0~70%まで変化させ、その際に検出される摩擦係数の最大値を読みとった。そして、下記計算式により測定結果を指数表示した。指数が大きいほどウェットグリップ性能に優れることを示す。
(ウェットグリップ性能(1)指数)=(各配合の摩擦係数の最大値)/(比較例1の摩擦係数の最大値)×100
水を撒いて湿潤路面としたテストコースにて、上記試験用タイヤを排気量2000ccの国産FR車に装着し、速度70km/hで制動し、タイヤに制動をかけてから停車するまでの走行距離(制動距離)を測定した。そして、下記計算式により測定結果を指数表示した。指数が大きいほどウェットグリップ性能に優れることを示す。
(ウェットグリップ性能(2)指数)=(比較例1の制動距離)/(各配合の制動距離)×100
(株)上島製作所製フラットベルト式摩擦試験機(FR5010型)を用いてドライグリップ性能を評価した。上記加硫ゴム組成物からなる幅20mm、直径100mmの円筒形のゴム試験片をサンプルとして用い、速度20km/時間、荷重4kgf、外気温度30℃の条件下で、乾燥路面に対するサンプルのスリップ率を0~50%まで変化させ、その際に検出される摩擦係数の最大値を読みとった。そして、下記計算式により測定結果を指数表示した。指数が大きいほどドライグリップ性能に優れることを示す。
(ドライグリップ性能指数)=(各配合の摩擦係数の最大値)/(比較例1の摩擦係数の最大値)×100
上記試験用タイヤのトレッドからサンプルを切り出し、該サンプル中に分散したシリカを透過型電子顕微鏡で観察し、シリカの平均一次粒子径(D)、分岐粒子Zを含む分岐粒子間Z-Zの平均長(図2におけるW1)、分岐粒子Zを含まない分岐粒子間Z-Zの平均長(図2におけるW2)、分岐粒子Zを含む分岐粒子間Z-Zの平均アスペクト比(W1/D)、分岐粒子Zを含まない分岐粒子間Z-Zの平均アスペクト比(W2/D)を算出した。数値は、30箇所を測定した平均値とした。
Claims (20)
- 前記官能基がアルコキシシリル基である請求項1又は2記載のゴム組成物。
- 前記官能基がアルコキシシリル基及びアミノ基である請求項1又は2記載のゴム組成物。
- 前記一方の末端にアミノ基と共に、イソプレン単位を有する請求項1~6のいずれかに記載のゴム組成物。
- 前記共重合体中、前記式(I)で表される化合物の含有量が0.05~35質量%である請求項1~7のいずれかに記載のゴム組成物。
- 前記共重合体は、リチウム原子とアミノ基を有する化合物を重合開始剤として、1,3-ブタジエン、スチレン及び前記式(I)で表される化合物を共重合した後、重合末端を窒素、酸素及びケイ素からなる群より選択される少なくとも1種の原子を含む官能基を有する変性剤により変性して得られるものである請求項1~8のいずれかに記載のゴム組成物。
- 前記変性剤が下記式(IV)、下記式(V)、又は下記式(VI)で表される化合物である請求項9記載のゴム組成物。
- 前記重合開始剤がイソプレン単位を有する請求項9~12のいずれかに記載のゴム組成物。
- 前記ゴム成分100質量%中、前記共重合体の含有量が5質量%以上である請求項1~13のいずれかに記載のゴム組成物。
- 前記ゴム成分100質量部に対して、前記シリカを5~150質量部含む請求項1又は3~14のいずれかに記載のゴム組成物。
- 前記シリカが、平均一次粒子径をDとしたとき、分岐粒子Zを含む分岐粒子間Z-Zの平均アスペクト比W1/Dが3~100のものである請求項1又は3~15のいずれかに記載のゴム組成物。
- 前記シリカの平均一次粒子径Dが5~1000nmである請求項1又は3~16のいずれかに記載のゴム組成物。
- シリカ100質量部に対して、シランカップリング剤を1~20質量部含む請求項1又は3~17のいずれかに記載のゴム組成物。
- タイヤトレッド用ゴム組成物として用いられる請求項1~18のいずれかに記載のゴム組成物。
- 請求項1~19のいずれかに記載のゴム組成物を用いて作製した空気入りタイヤ。
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DE69311666T2 (de) * | 1992-10-19 | 1997-11-20 | Bridgestone Corp | Verfahren zur Herstellung eines Polymers mit einem Initiator auf Lithium basiertem in situ hergestelltem Initiator |
JP3625919B2 (ja) * | 1995-10-16 | 2005-03-02 | 株式会社ブリヂストン | 重合体の製造方法 |
WO2003087171A1 (fr) * | 2002-04-12 | 2003-10-23 | Bridgestone Corporation | Procede de production de polymere modifie, polymere ainsi obtenu et composition elastomere |
SG159479A1 (en) * | 2008-08-27 | 2010-03-30 | Sumitomo Chemical Co | Conjugated diene polymer, conjugated diene polymer composition, and method for producing conjugated diene polymer |
JP2011132298A (ja) * | 2009-12-22 | 2011-07-07 | Sumitomo Rubber Ind Ltd | 変性共重合体、それを用いたゴム組成物および空気入りタイヤ |
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2011
- 2011-08-23 JP JP2011181868A patent/JP2013043927A/ja active Pending
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2012
- 2012-08-22 CN CN201280040947.4A patent/CN103764746A/zh active Pending
- 2012-08-22 EP EP12825185.7A patent/EP2740759A4/en not_active Withdrawn
- 2012-08-22 BR BR112014004207A patent/BR112014004207A2/pt not_active IP Right Cessation
- 2012-08-22 WO PCT/JP2012/071120 patent/WO2013027746A1/ja active Application Filing
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JP2803134B2 (ja) | 1988-03-16 | 1998-09-24 | 日産化学工業株式会社 | 細長い形状のシリカゾル及びその製造法 |
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WO2000015552A1 (fr) | 1998-09-10 | 2000-03-23 | Nissan Chemical Industries, Ltd. | Solution colloidale de silice moniliforme, procede de production associe et support d'enregistrement de jets d'encre |
JP2006257260A (ja) * | 2005-03-17 | 2006-09-28 | Sumitomo Chemical Co Ltd | 変性ジエン系重合体ゴム及びその製造方法 |
JP2007154158A (ja) * | 2005-11-14 | 2007-06-21 | Sumitomo Rubber Ind Ltd | ゴム組成物およびそれをトレッドに用いた空気入りタイヤ |
JP2010111754A (ja) | 2008-11-05 | 2010-05-20 | Sumitomo Rubber Ind Ltd | ゴム組成物及び空気入りタイヤ |
JP2011063714A (ja) * | 2009-09-17 | 2011-03-31 | Sumitomo Rubber Ind Ltd | 共重合体ならびにそれを用いたゴム組成物および空気入りタイヤ |
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See also references of EP2740759A4 * |
Also Published As
Publication number | Publication date |
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BR112014004207A2 (pt) | 2017-03-07 |
EP2740759A4 (en) | 2015-04-29 |
CN103764746A (zh) | 2014-04-30 |
JP2013043927A (ja) | 2013-03-04 |
EP2740759A1 (en) | 2014-06-11 |
US20140206793A1 (en) | 2014-07-24 |
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