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WO2025205189A1 - Composition de caoutchouc et composition de caoutchouc vulcanisé - Google Patents

Composition de caoutchouc et composition de caoutchouc vulcanisé

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Publication number
WO2025205189A1
WO2025205189A1 PCT/JP2025/010272 JP2025010272W WO2025205189A1 WO 2025205189 A1 WO2025205189 A1 WO 2025205189A1 JP 2025010272 W JP2025010272 W JP 2025010272W WO 2025205189 A1 WO2025205189 A1 WO 2025205189A1
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WO
WIPO (PCT)
Prior art keywords
conjugated diene
diene polymer
rubber composition
mass
modified conjugated
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/JP2025/010272
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English (en)
Japanese (ja)
Inventor
新一 関川
大祐 早田
忠大 杉本
優一 伊勢
崇吏 当房
未来 佐々木
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Asahi Kasei Corp
Asahi Chemical Industry Co Ltd
Original Assignee
Asahi Kasei Corp
Asahi Chemical Industry Co Ltd
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Filing date
Publication date
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Publication of WO2025205189A1 publication Critical patent/WO2025205189A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F36/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds
    • C08F36/02—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds
    • C08F36/04—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F8/00—Chemical modification by after-treatment
    • C08F8/30—Introducing nitrogen atoms or nitrogen-containing groups
    • 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
    • C08K3/01—Use of inorganic substances as compounding ingredients characterized by their specific function
    • C08K3/013—Fillers, pigments or reinforcing additives
    • 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
    • C08K3/02—Elements
    • C08K3/04—Carbon
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L15/00—Compositions of rubber derivatives
    • 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

Definitions

  • the present invention relates to a composition of a modified conjugated diene polymer, and more specifically to a rubber composition and a vulcanized rubber composition containing the modified conjugated diene polymer.
  • the performance requirements for heavy-load tires used on large vehicles such as trucks and buses include not only the high strength and wear resistance required to support conventional heavy loads, but also improved fuel efficiency with minimal energy loss.
  • the rubber material used in heavy-load tire treads requires a rubber composition with high tensile strength and excellent fuel economy.
  • modified conjugated diene polymers having hydroxyl groups at the ends of the polymer chains and compositions thereof as well as methods and compositions for producing conjugated diene polymers in which a hydrocarbyloxysilane compound is reacted with the ends of the polymer chains and then a specific compound such as a hydrocarbyloxysilane compound is further reacted (see, for example, Patent Documents 1 and 2).
  • rubber compositions containing carbon black are still preferred for heavy-load tires from the standpoint of durability and abrasion resistance. While there is a demand for rubber compositions containing carbon black as a filler that offer improved fuel economy, abrasion resistance, and tensile strength, there is a problem in that if the filler is not dispersed properly in the rubber composition, the fuel economy, abrasion resistance, and tensile strength are not fully realized.
  • Rubber composition ⁇ 2> The rubber composition according to ⁇ 1>, wherein the amount of 1,2 vinyl bonds in the conjugated diene units of the modified conjugated diene polymer is 10 mol % or more and 25 mol % or less.
  • the modified conjugated diene polymer has an aromatic vinyl bond content of 0% by mass or more and 10% by mass or less.
  • Tg glass transition temperature
  • the moiety derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group is a monomer unit derived from a compound represented by the following formula (3) or (4):
  • R 1 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms which may have a branched structure in part, or an aryl group having 6 to 20 carbon atoms
  • R 2 to R 3 each independently represent an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, which may have a branched structure in part;
  • the rubber composition of the present embodiment is a rubber composition containing 10 parts by mass or more and 150 parts by mass or less of carbon black relative to 100 parts by mass of a rubber component containing at least one type of conjugated diene-based polymer, and the content of a silica-based inorganic filler is 0% by mass or more and 30% by mass or less with respect to the total amount of the filler, and 10% by mass or more of the rubber component is a modified conjugated diene-based polymer, (1) A main chain branched structure having a branched structure in the main chain, (2) The main chain branch structure includes a structure derived from at least one type of conjugated diene monomer, or a structure derived from at least one type of conjugated diene monomer and a structure derived from an aromatic vinyl monomer, (3) At least one terminal has a terminal group having at least one carbonyl group and at least one substituted amino group in the molecule; (4) The Mooney viscosity measured at 100°C is 30
  • the rubber composition of the present embodiment includes a rubber component containing at least one conjugated diene polymer and carbon black.
  • the rubber composition of the present embodiment can also use a rubber-like polymer other than the modified conjugated diene polymer (hereinafter, sometimes simply referred to as a "rubber-like polymer") in combination as the rubber component.
  • Such rubbery polymers are not particularly limited, but examples include conjugated diene polymers such as conjugated diene polymers or hydrogenated products thereof, random copolymers of conjugated diene compounds and vinyl aromatic compounds or hydrogenated products thereof, and block copolymers of conjugated diene compounds and vinyl aromatic compounds or hydrogenated products thereof; non-diene polymers; and natural rubber.
  • conjugated diene polymers such as conjugated diene polymers or hydrogenated products thereof, random copolymers of conjugated diene compounds and vinyl aromatic compounds or hydrogenated products thereof, and block copolymers of conjugated diene compounds and vinyl aromatic compounds or hydrogenated products thereof; non-diene polymers; and natural rubber.
  • Specific conjugated diene polymers include, but are not limited to, styrene-based elastomers such as butadiene rubber or hydrogenated products thereof, isoprene rubber or hydrogenated products thereof, styrene-butadiene rubber or hydrogenated products thereof, styrene-butadiene block copolymer or hydrogenated products thereof, and styrene-isoprene block copolymer or hydrogenated products thereof, and acrylonitrile-butadiene rubber or hydrogenated products thereof.
  • styrene-based elastomers such as butadiene rubber or hydrogenated products thereof, isoprene rubber or hydrogenated products thereof, styrene-butadiene rubber or hydrogenated products thereof, styrene-butadiene block copolymer or hydrogenated products thereof, and styrene-isoprene block copolymer or hydrogenated products thereof, and acrylonitrile-butadiene rubber or hydrogen
  • Non-diene polymers include, but are not limited to, olefin elastomers such as ethylene-propylene rubber, ethylene-propylene-diene rubber, ethylene-butene-diene rubber, ethylene-butene rubber, ethylene-hexene rubber, and ethylene-octene rubber; butyl rubber, brominated butyl rubber, acrylic rubber, fluororubber, silicone rubber, chlorinated polyethylene rubber, epichlorohydrin rubber, ⁇ , ⁇ -unsaturated nitrile-acrylate-conjugated diene copolymer rubber, urethane rubber, and polysulfide rubber.
  • olefin elastomers such as ethylene-propylene rubber, ethylene-propylene-diene rubber, ethylene-butene-diene rubber, ethylene-butene rubber, ethylene-hexene rubber, and ethylene-octene rubber
  • butyl rubber brominated butyl rubber, acrylic rubber,
  • Natural rubber is not particularly limited, but examples include smoked sheet RSS3-5, SMR, and epoxidized natural rubber.
  • the various rubbery polymers mentioned above may also be modified rubbers to which polar functional groups such as hydroxyl groups or amino groups have been added.
  • polar functional groups such as hydroxyl groups or amino groups
  • butadiene rubber, isoprene rubber, styrene-butadiene rubber, natural rubber, and butyl rubber are preferably used.
  • the weight average molecular weight of the rubbery polymer is preferably 2,000 or more and 2,000,000 or less, and more preferably 5,000 or more and 1,500,000 or less.
  • low molecular weight rubbery polymers so-called liquid rubbers, can also be used as the rubbery polymer. These rubbery polymers may be used alone or in combination of two or more types.
  • the rubber component preferably contains 10 parts by mass or more and 100 parts by mass or less, more preferably 20 parts by mass or more and 90 parts by mass or less, and even more preferably 40 parts by mass or more and 80 parts by mass or less of the modified conjugated diene-based polymer described below, relative to the total amount (100 parts by mass) of the rubber component.
  • the content ratio of (modified conjugated diene polymer/rubber-like polymer) is within the above-mentioned range, the vulcanized rubber composition has excellent abrasion resistance and tensile strength, a balance between fuel economy and wet skid resistance, and excellent vibration-damping performance.
  • the carbon black contained in the rubber composition of the present embodiment is not particularly limited, and examples thereof include carbon blacks of various classes such as SRF, FEF, HAF, ISAF, SAF, etc. Among these, carbon black having a nitrogen adsorption specific surface area of 50 m 2 /g or more and a dibutyl phthalate (DBP) oil absorption of 80 mL/100 g or less is preferred.
  • SRF sulfur adsorption specific surface area
  • DBP dibutyl phthalate
  • the carbon black content is preferably 10 parts by mass or more and 150 parts by mass or less, more preferably 25 parts by mass or more and 125 parts by mass or less, and even more preferably 30 parts by mass or more and 100 parts by mass or less, per 100 parts by mass of the rubber component.
  • the carbon black content is preferably 10 parts by mass or more per 100 parts by mass of the rubber component from the viewpoint of achieving the performance required for industrial applications, such as hardness and vibration damping properties, and is preferably 150 parts by mass or less per 100 parts by mass of the rubber component from the viewpoint of dispersibility.
  • the rubber composition of the present embodiment may contain a filler other than carbon black.
  • Fillers other than carbon black are not particularly limited, but include, for example, silica-based inorganic fillers, metal oxides, and metal hydroxides. Among these, silica is preferred.
  • the fillers may be used alone or in combination of two or more.
  • the silica-based inorganic filler is not particularly limited and known fillers can be used, but solid particles containing SiO2 or Si3Al as a structural unit are preferred, and solid particles containing SiO2 or Si3Al as a main component of the structural unit are more preferred.
  • the main component refers to a component contained in the silica-based inorganic filler in an amount of 50 mass% or more, preferably 70 mass% or more, and more preferably 80 mass% or more.
  • silica-based inorganic fillers include, but are not limited to, inorganic fibrous substances such as silica, clay, talc, mica, diatomaceous earth, wollastonite, montmorillonite, zeolite, and glass fiber.
  • inorganic fibrous substances such as silica, clay, talc, mica, diatomaceous earth, wollastonite, montmorillonite, zeolite, and glass fiber.
  • Other examples include silica-based inorganic fillers with hydrophobic surfaces, and mixtures of silica-based inorganic fillers with non-silica-based inorganic fillers.
  • silica and glass fiber are preferred, with silica being more preferred, from the standpoint of strength and abrasion resistance.
  • Examples of silica include dry silica, wet silica, and synthetic silicate silica. Of these, wet silica is preferred.
  • the nitrogen adsorption specific surface area of the silica-based inorganic filler determined by the BET adsorption method is preferably 100 m 2 /g or more and 300 m 2 /g or less, more preferably 170 m 2 /g or more and 250 m 2 /g or less. If necessary, a silica-based inorganic filler having a relatively small specific surface area (for example, a specific surface area of 200 m 2 /g or less) can be used in combination with a silica-based inorganic filler having a relatively large specific surface area (for example, 200 m 2 /g or more).
  • the content of the silica-based inorganic filler in the rubber composition is 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less, based on the total amount of fillers.
  • the lower limit content thereof can be 15 mass% or more, 10 mass% or more, or 5 mass% or more, relative to the total amount of the filler.
  • the metal oxide refers to solid particles having a structural unit represented by the chemical formula MxOy (M represents a metal atom, and x and y each independently represent an integer of 1 to 6) as the main component.
  • M represents a metal atom, and x and y each independently represent an integer of 1 to 6) as the main component.
  • the metal oxide is not particularly limited, but examples thereof include alumina, titanium oxide, magnesium oxide, and zinc oxide.
  • the metal hydroxide is not particularly limited, but examples thereof include aluminum hydroxide, magnesium hydroxide, and zirconium hydroxide.
  • the rubber composition of the present embodiment contains a modified conjugated diene polymer that satisfies the following (1) to (7).
  • a main chain branched structure having a branched structure in the main chain (2)
  • the main chain branch structure includes a structure derived from at least one type of conjugated diene monomer, or a structure derived from at least one type of conjugated diene monomer and a structure derived from an aromatic vinyl monomer, (3) At least one terminal has a terminal group having at least one carbonyl group and at least one substituted amino group in the molecule;
  • the Mooney viscosity measured at 100°C is 30 to 120, (5)
  • the branching degree (Bn) measured by GPC-light scattering method with a viscosity detector is 1.1 or more and less than 4.0, (6)
  • the chromatogram measured by gel permeation chromatography (GPC) is unimodal, and the molecular weight distribution is 1.60 to 3.00; (7)
  • the hydrogenation rate is less than
  • the modified conjugated diene polymer in this embodiment can be synthesized by polymerizing at least one modified conjugated diene monomer or copolymerizing a conjugated diene monomer with an aromatic vinyl monomer while adding a branching agent, resulting in a conjugated diene polymer having a main chain branched structure.
  • the method for producing a modified conjugated diene polymer in this embodiment can include a polymerization and branching step of polymerizing a conjugated diene monomer using an organolithium compound as a polymerization initiator while adding a branching agent described later to obtain a conjugated diene polymer having a main chain branched structure, and a modification step of modifying the conjugated diene polymer with a modifying agent.
  • the polymerization and branching step in the method for producing a modified conjugated diene polymer is a step in which, for example, an organic monolithium compound is used as a polymerization initiator to polymerize at least one conjugated diene compound, and a branching agent is added to obtain a conjugated diene polymer having a branched structure in its main chain.
  • an organic monolithium compound is used as a polymerization initiator to polymerize at least one conjugated diene compound, and a branching agent is added to obtain a conjugated diene polymer having a branched structure in its main chain.
  • the polymerization reaction in the polymerization and branching step will be described as the “polymerization step”
  • the reaction with the branching agent will be described as the "branching step.”
  • polymerization process it is preferable to carry out polymerization through a propagation reaction using a living anionic polymerization reaction, which allows for the production of conjugated diene polymers with active terminals.
  • the subsequent branching process using a branching agent also allows for appropriate control of main chain branching, which tends to result in conjugated diene polymers with a high degree of modification.
  • the conjugated diene polymer may be a homopolymer obtained using a single conjugated diene compound as a monomer, or a polymer, i.e., a copolymer, obtained using different types of conjugated diene compounds as monomers.
  • conjugated diene monomer Specific examples of the conjugated diene monomer in this embodiment are not particularly limited, but include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 1,3-hexadiene, and 1,3-heptadiene. Among these, 1,3-butadiene and isoprene are preferred from the viewpoint of industrial availability. These may be used alone or in combination of two or more.
  • aromatic vinyl monomer examples include, but are not limited to, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o,p-dimethylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, ⁇ -methylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, and diphenylethylene.
  • styrene is preferred from the viewpoint of industrial availability. These may be used alone or in combination of two or more.
  • an organic monolithium compound As the polymerization initiator in this embodiment, at least an organic monolithium compound can be used.
  • the organic monolithium compound is not particularly limited, but examples thereof include low molecular weight compounds and solubilized oligomeric organic monolithium compounds.
  • examples of the organic monolithium compound include compounds having a carbon-lithium bond, a nitrogen-lithium bond, and a tin-lithium bond in terms of the bonding mode between the organic group and the lithium.
  • the amount of the organic monolithium compound used as the polymerization initiator is preferably determined depending on the target molecular weight of the conjugated diene polymer.
  • the amount of a monomer such as a conjugated diene compound used relative to the amount of a polymerization initiator used is related to the degree of polymerization, that is, tends to be related to the number average molecular weight and/or weight average molecular weight. Therefore, in order to increase the molecular weight, it is advisable to adjust the amount of polymerization initiator used in a direction to decrease it, and in order to decrease the molecular weight, it is advisable to adjust the amount of polymerization initiator used in a direction to increase it.
  • the organomonolithium compound is preferably an alkyllithium compound having a substituted amino group or a dialkylaminolithium compound, from the viewpoint that it can be used as one method for introducing nitrogen atoms into a conjugated diene polymer.
  • a conjugated diene polymer having a nitrogen atom consisting of an amino group at the polymerization initiation terminal is obtained.
  • the substituted amino group is an amino group that does not have an active hydrogen or has a structure in which the active hydrogen is protected.
  • Alkyllithium compounds having an amino group without active hydrogen include, but are not limited to, 3-dimethylaminopropyllithium, 3-diethylaminopropyllithium, 4-(methylpropylamino)butyllithium, and 4-hexamethyleneiminobutyllithium.
  • Alkyllithium compounds having an amino group with a structure in which an active hydrogen is protected include, but are not limited to, 3-bistrimethylsilylaminopropyllithium and 4-trimethylsilylmethylaminobutyllithium.
  • Dialkylaminolithiums include, but are not limited to, lithium dimethylamide, lithium diethylamide, lithium dipropylamide, lithium dibutylamide, lithium di-n-hexylamide, lithium diheptylamide, lithium diisopropylamide, lithium dioctylamide, lithium di-2-ethylhexylamide, lithium didecylamide, lithium ethylpropylamide, lithium ethylbutylamide, lithium ethylbenzylamide, lithium methylphenethylamide, lithium hexamethyleneimide, lithium pyrrolidide, lithium piperidide, lithium heptamethyleneimide, lithium morpholide, 1-lithioazacyclooctane, 6-lithio-1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, and 1-lithio-1,2,3,6-tetrahydropyridine.
  • organomagnesium compounds examples include dibutylmagnesium and ethylbutylmagnesium.
  • Other organometallic compounds include organoaluminum compounds.
  • a conjugated diene polymer with a high concentration of active ends tends to be obtained, which is preferable because it tends to produce a modified conjugated diene polymer with a high modification rate.
  • polar compound In the polymerization step, a polar compound may be added. This tends to be usable as a vinylating agent for controlling the amount of 1,2-vinyl bonds in the conjugated diene polymer. This also tends to be effective in accelerating the polymerization reaction.
  • polar compounds may be used alone or in combination of two or more.
  • the amount of the polar compound used is not particularly limited and can be selected depending on the purpose, but is preferably 0.01 moles or more and 100 moles or less per mole of the polymerization initiator.
  • the polymerization temperature in the polymerization step is preferably a temperature at which living anionic polymerization proceeds, and from the viewpoint of productivity, is more preferably 0°C or higher, and even more preferably 120°C or lower. By keeping the temperature in this range, it tends to be possible to ensure a sufficient amount of modifying agent reacting with the active terminals after the polymerization is completed. Even more preferably, it is 50°C or higher and 100°C or lower.
  • the rubber composition of this embodiment includes a modified conjugated diene polymer having (1) a main chain branched structure in which the main chain has a branched structure, and (2) the main chain branched structure is a structure derived from at least one conjugated diene monomer, or a structure derived from at least one conjugated diene monomer and an aromatic vinyl monomer.
  • the modified conjugated diene polymer can be obtained as a conjugated diene polymer having a main chain branched structure by polymerizing at least one conjugated diene monomer or copolymerizing a conjugated diene monomer and an aromatic vinyl monomer while adding a branching agent.
  • the amount of branching agent added in the branching step to form a branched structure is not particularly limited and can be selected depending on the purpose, etc., but is preferably 0.02 mol or more and 0.5 mol or less, more preferably 0.03 mol or more and 0.4 mol or less, and even more preferably 0.03 mol or more and 0.3 mol or less, per 1 mol of polymerization initiator.
  • the branching agent can be used in an appropriate amount to serve as the branching points of the branched structure of the conjugated diene portion of the conjugated diene polymer, depending on the desired number of branching points.
  • the desired raw materials may be further added, and the polymerization process may be continued after branching, or the above-described process may be repeated.
  • the modified conjugated diene polymer of this embodiment is not particularly limited and may be a polymer of a conjugated diene monomer and a branching agent, or a copolymer of a conjugated diene monomer, a branching agent, and other monomers.
  • the conjugated diene monomer is butadiene or isoprene and is polymerized with a branching agent containing a vinyl aromatic moiety (i.e., an aromatic vinyl monomer)
  • the resulting polymer chain is a polybutadiene or polyisoprene polymer containing a vinyl aromatic-derived structure in the branched portion.
  • the rubber composition of this embodiment is used for the tread of a highly loaded tire
  • a copolymer of a conjugated diene monomer and a branching agent is preferred as the modified conjugated diene polymer.
  • the carbonyl group and the substituted amino group may be adjacent or distant.
  • cyclic compounds are preferred, with N-substituted cyclic amides and N-substituted cyclic ureas being more preferred, and N-substituted cyclic ureas being particularly preferred.
  • Examples of compounds in which the carbonyl group and the substituted amino group are distant include N-substituted aminoketones and N-substituted aminoaldehydes, with N-substituted aminoketones being preferred.
  • the shrinkage factor (g') is an indicator of the ratio of the molecular size to that of a linear polymer of the same assumed absolute molecular weight. In other words, the greater the degree of branching of a polymer, the smaller the shrinkage factor (g') tends to be.
  • the shrinkage factor represents the rate of decrease in molecular size and does not accurately represent the branched structure of the polymer. Therefore, the degree of branching (Bn) of the conjugated diene polymer is calculated using the value of the shrinkage factor (g') at each absolute molecular weight of the conjugated diene polymer.
  • the calculated "degree of branching (Bn)" accurately represents the number of polymers that are directly or indirectly bonded to each other with respect to the longest main chain structure.
  • the calculated branching degree (Bn) is an index that expresses the branching structure of a conjugated diene polymer. For example, in the case of a typical four-branched star polymer (four polymer chains connected to the center), two polymer chain arms are connected to the longest highly branched main chain structure, and the branching degree (Bn) is evaluated as 2.
  • the conjugated diene polymer of this embodiment preferably has a degree of branching (Bn) of 1.1 or more and less than 4.0, which means that the conjugated diene polymer has a star polymer structure that is linear but has branches similar to a star polymer structure with less than 6 branches.
  • Bn degree of branching
  • branching refers to a structure formed by one polymer being directly or indirectly bonded to another polymer. Furthermore, “branching degree (Bn)” refers to the number of polymers that are directly or indirectly bonded to each other in the longest main chain structure.
  • the modified conjugated diene polymer of this embodiment exhibits good interaction with fillers while suppressing cold flow in the bale form, which is the product form of the conjugated diene copolymer, and tends to have excellent fuel economy and dynamic magnification when vulcanized.
  • the degree of branching (Bn) of the modified conjugated diene polymer in this embodiment is 1.1 or more and less than 4.0, preferably 1.2 or more and less than 3.9, more preferably 1.3 or more and less than 3.8, and even more preferably 1.4 or more and less than 3.7.
  • Conjugated diene polymers with a degree of branching (Bn) within this range tend to have excellent fuel economy and dynamic magnification when vulcanized.
  • the degree of branching of the modified conjugated diene polymer can be controlled to 1.1 or more and less than 4.0 by combining the amount of branching agent and the amount of terminal modifier added. Specifically, the degree of branching can be controlled by the number of functional groups of the branching agent, the amount of branching agent added, the timing of adding the branching agent, and the functionality and amount of the nitrogen-containing modifier added.
  • the modified conjugated diene polymer of this embodiment (6) has a unimodal chromatographic shape measured by gel permeation chromatography (GPC), and a molecular weight distribution of 1.60 to 3.00.
  • the modified conjugated diene polymer of this embodiment has a unimodal chromatographic shape measured by gel permeation chromatography (GPC).
  • GPC gel permeation chromatography
  • a unimodal chromatographic shape means that the chromatographic shape of gel permeation chromatography (GPC) measured by the method described in the Examples below has one peak derived from the polymer, and the peak shape has no valley.
  • the GPC chromatogram of the modified conjugated diene polymer can be controlled, for example, by using a continuous polymerization method as the polymerization mode and appropriately controlling the type and amount of branching agent added in the branching step and the type and amount of terminal modifier added in the modification step. More specifically, this can be achieved by the method described in the examples below.
  • the modified conjugated diene polymer in this embodiment has a molecular weight distribution (Mw/Mn) expressed as the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of 1.60 or more and 3.00 or less.
  • Mw/Mn molecular weight distribution
  • a conjugated diene polymer having a molecular weight distribution within this range tends to have excellent abrasion resistance and breaking strength when vulcanized with a composition containing a filler, etc.
  • the molecular weight distribution is more preferably 1.65 or more and 2.70 or less, and even more preferably 1.70 or more and 2.50 or less.
  • the number average molecular weight, weight average molecular weight, and molecular weight distribution of the modified conjugated diene polymer can be measured by the method described in the Examples below.
  • the number average molecular weight, weight average molecular weight, and molecular weight distribution of the conjugated diene polymer can be controlled within the above-mentioned ranges, for example, by controlling conditions such as temperature in the polymerization process or by adjusting the degree of branching in the branching process.
  • the modified conjugated diene polymer of the present embodiment has (7) a hydrogenation rate of less than 10 mol %.
  • the hydrogenation rate in the present embodiment refers to the hydrogenation rate relative to the double bonds in the structural units derived from the conjugated diene compound in the modified conjugated diene polymer.
  • a modified conjugated diene polymer having a hydrogenation rate within this range exhibits high phase separation when it is mixed with other rubber components such as natural rubber, and when it is mixed with a filler to form a composition, the effect of the terminal modified group is exerted, and the dispersibility of the filler tends to be excellent.
  • the hydrogenation rate is more preferably less than 5 mol %, even more preferably less than 3 mol %, and a non-hydrogenated form is even more preferred.
  • the hydrogenation rate can be controlled within the above range by appropriately controlling the amount of hydrogen added to the double bonds in the structural units derived from the conjugated diene compound, the amount of hydrogenation catalyst used in the hydrogenation reaction, hydrogen pressure, reaction temperature, reaction time, and other conditions. More specific details will be described in the Examples below.
  • the 1,2-vinyl bond content of the modified conjugated diene polymer in this embodiment is preferably 25 mol % or less, more preferably 23 mol % or less, even more preferably 22 mol % or less, and still more preferably 20 mol % or less.
  • the lower limit of the 1,2-vinyl bond content is not particularly limited, but is more preferably 7 mol % or more, even more preferably 10 mol % or more, and even more preferably 12 mol % or more.
  • examples of combinations of the upper and lower limits of the 1,2-vinyl bond content are preferably 10 mol % or more and 25 mol % or less, more preferably 10 mol % or more and 25 mol % or less, and even more preferably 12 mol % or more and 22 mol % or less.
  • the amount of 1,2 vinyl bonds can be controlled to fall within the specific range described above by adjusting the amount of polar substance added during the polymerization process. Increasing the amount of polar compound added not only increases the amount of 1,2 vinyl bonds, but also has the effect of accelerating the polymerization reaction. However, when a composition containing fillers or the like is formed, the breaking strength and abrasion resistance tend to deteriorate. Therefore, it is necessary to adjust the amount of polar substance added to control the amount of 1,2 vinyl bonds within a specific range. More specific details will be described in the Examples below.
  • the amount of aromatic vinyl bond can be controlled by adjusting the addition ratio of the conjugated diene monomer and aromatic vinyl compound in the polymerization process described above. More specific details will be described in the Examples below.
  • the amount of aromatic vinyl bonds in a conjugated diene polymer can be measured using an ultraviolet spectrophotometer by the method described in the Examples below.
  • the glass transition temperature of the conjugated diene polymer of the present embodiment is preferably within the range of ⁇ 110° C. to ⁇ 80° C.
  • the lower limit of the glass transition temperature of the conjugated diene polymer is more preferably ⁇ 105° C. or higher, even more preferably ⁇ 103° C. or higher, and still more preferably ⁇ 100° C. or higher.
  • the eluent used was tetrahydrofuran (THF) containing 5 mmol/L triethylamine.
  • THF tetrahydrofuran
  • Three Tosoh TSKgel SuperMultipore HZ-H columns were connected, with a Tosoh TSKguard column SuperMP(HZ)-H guard column connected in front of them.
  • 1,3-dimethylimidazolidinone (abbreviated as "A” in the table) was continuously added as a modifier to the polymer solution flowing out of the reactor outlet at a rate of 0.155 mmol/min, and the solution was mixed using a static mixer to carry out the modification reaction. It took 4.8 minutes for the modifier to be added to the polymer solution flowing out of the reactor outlet, and the temperature was 76°C, meaning that the difference between the temperature during the polymerization process and the temperature before the modifier was added was 2°C.
  • the structure of the modified conjugated diene polymer was identified by comparing the molecular weight measured by GPC with the branching degree measured by GPC with a viscometer for the polymer before the addition of the branching agent, the polymer before modification after the addition of the branching agent, and the polymer in each process after the addition of the modifier.
  • the structure of each sample below was identified in the same manner.
  • BS-2 dimethylmethoxy(4-vinylphenyl)silane
  • BS-3 1,1-bis(4-(methyldimethoxysilyl)phenyl)ethylene (compound represented by the above formula (4))
  • B N-methyl-2-pyrrolidone
  • 1,3-butadiene from which moisture had been removed in advance, was mixed at 30.8 g/min and n-hexane at 189.3 g/min.
  • n-butyllithium used to inactivate remaining impurities, was added at 0.072 mmol/min, and after mixing, the mixture was continuously supplied to the bottom of the reactor.
  • 2,2-bis(2-oxolanyl)propane as a polar substance at a rate of 0.027 mmol/min and n-butyllithium as a polymerization initiator at a rate of 0.205 mmol/min were supplied to the bottom of the first reactor, where they were being vigorously mixed using a stirrer, and the temperature inside the reactor was maintained at 78°C.
  • 1,3-butadiene from which moisture had been removed in advance, was mixed at 30.8 g/min and n-hexane at 189.3 g/min.
  • n-butyllithium used to inactivate remaining impurities, was added at 0.072 mmol/min, and after mixing, the mixture was continuously supplied to the bottom of the reactor.
  • 2,2-bis(2-oxolanyl)propane as a polar substance at a rate of 0.027 mmol/min and n-butyllithium as a polymerization initiator at a rate of 0.205 mmol/min were supplied to the bottom of the first reactor, where they were being vigorously mixed using a stirrer, and the temperature inside the reactor was maintained at 78°C.
  • the polymer solution was continuously withdrawn from the top of the first reactor and continuously fed to the bottom of the second reactor, where the reaction continued at 78°C, and then fed to a static mixer from the top of the second reactor.
  • a small amount of the conjugated diene polymer solution was withdrawn, and an antioxidant (BHT) was added so that the amount was 0.2 g per 100 g of polymer.
  • BHT antioxidant
  • the solvent was then removed, and the Mooney viscosity of the conjugated diene polymer was measured. The measurement results are shown in Table 2.
  • Comparative Synthesis Examples 2 and 3 Conjugated Diene Polymers (Samples 12 and 13)
  • the production conditions of Comparative Synthesis Example 1 were changed to those of Comparative Synthesis Examples 2 and 3 shown in Table 2, and when the polymerization reaction was sufficiently stabilized, a branching agent was added to carry out a polymerization reaction and a branching reaction to obtain a conjugated diene-based polymer having a branched structure. Thereafter, conjugated diene-based polymers (samples 12 and 13) were obtained in the same manner as in Comparative Example 1, except that no modifier was added, and various physical properties were measured. The measurement results are shown in Table 2.
  • the polymerization reactor was a tank-type pressure vessel equipped with a stirrer and a jacket for temperature control, which had an internal volume of 10 L and an internal height (L) to diameter (D) ratio (L/D) of 4.0.
  • 0.01 mmol of 2,2-bis(2-oxolanyl)propane was added as a polar substance to the reactor, and the internal temperature of the reactor was controlled to 45°C while continuing to stir.
  • Comparative Synthesis Example 9 Modified conjugated diene polymer (Sample 19)
  • the production conditions of Comparative Synthesis Example 9 shown in Table 2 were changed from those of Comparative Synthesis Example 1, and when the polymerization reaction was sufficiently stabilized, a branching agent was added, and a polymerization reaction and branching reaction were carried out to obtain a conjugated diene-based polymer having a branched structure. Thereafter, a modified conjugated diene-based polymer (Sample 19) was obtained in the same manner as in Comparative Synthesis Example 1, except that a modifier was added when the polymerization reaction and branching reaction were sufficiently stabilized, and various physical properties were measured. The measurement results are shown in Table 2.
  • "BS-3” shown as a branching agent in the table represents the following compound.
  • BS-3 1,1-bis(4-(methyldimethoxysilyl)phenyl)ethylene
  • 1,3-butadiene from which moisture had been removed in advance, was mixed at 30.8 g/min and n-hexane at 189.3 g/min.
  • n-butyllithium used to inactivate remaining impurities, was added at 0.072 mmol/min, and after mixing, the mixture was continuously supplied to the bottom of the reactor.
  • 2,2-bis(2-oxolanyl)propane as a polar substance at a rate of 0.027 mmol/min and n-butyllithium as a polymerization initiator at a rate of 0.205 mmol/min were supplied to the bottom of the first reactor, where they were being vigorously mixed using a stirrer, and the temperature inside the reactor was maintained at 78°C.
  • the polymer solution was continuously withdrawn from the top of the first reactor and continuously fed to the bottom of the second reactor, where the reaction continued at 78°C. It was then fed to a static mixer from the top of the second reactor.
  • trimethoxy(4-vinylphenyl)silane (abbreviated as "BS-1" in the table) was added as a branching agent from the bottom of the second reactor at a rate of 0.030 mmol/min while 1,3-butadiene polymerization was continuing. This carried out a polymerization and branching reaction to obtain a conjugated diene polymer with a branched structure.
  • 1,3-dimethylimidazolidinone (abbreviated as "A” in the table) was continuously added as a modifier to the polymer solution flowing out of the reactor outlet at a rate of 0.155 mmol/min, and the solution was mixed using a static mixer to carry out the modification reaction. It took 4.8 minutes for the modifier to be added to the polymer solution flowing out of the reactor outlet, and the temperature was 76°C, meaning that the difference between the temperature during the polymerization process and the temperature before the modifier was added was 2°C.
  • one tank-type pressure vessel of the same type as that used as the polymerization reactor was connected as a hydrogenation reactor, and the polymer solution after the modification reaction was continuously supplied to the bottom of the hydrogenation reactor.
  • the hydrogenation catalyst synthesized above was continuously added at a rate of 30 ppm/min in terms of titanium element and hydrogen at a rate of 1,536 ml/min (corresponding to a hydrogenation rate of 12 mol % relative to the double bonds derived from butadiene in the conjugated diene polymer) per 100 parts by mass of the conjugated diene polymer, thereby carrying out a continuous hydrogenation reaction.
  • the pressure in the hydrogenation reactor was 0.50 MPa, and the temperature inside the reactor was 75°C.
  • the compound obtained above was cooled to room temperature, and then an antioxidant was added and the compound was mixed again to improve the dispersion of the carbon black.
  • the temperature of the mixer was also controlled to adjust the discharge temperature of the compound to 155-160°C.
  • sulfur and vulcanization accelerator 1 were added and mixed using an open roll set at 70°C.
  • the mixture was then molded and vulcanized in a vulcanization press at 160°C for 30 minutes.
  • the rubber composition before vulcanization and the rubber composition after vulcanization were evaluated. Specifically, evaluation was performed using the following methods. The results are shown in Table 4.
  • the compound obtained above was cooled to room temperature, and then an antioxidant was added and the compound was mixed again to improve the dispersion of the silica.
  • the temperature of the mixer was also controlled to adjust the discharge temperature of the compound to 155-160°C.
  • sulfur and vulcanization accelerators 2 and 3 were added and mixed using an open roll set at 70°C.
  • the compound was then molded and vulcanized in a vulcanization press at 160°C for 20 minutes.
  • the rubber composition before vulcanization and the rubber composition after vulcanization were evaluated. Specifically, evaluation was performed using the following methods. The results are shown in Table 4.

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Abstract

La présente composition de caoutchouc contient entre 10 et 150 parties en masse de noir de carbone par rapport à 100 parties en masse de composants de caoutchouc comprenant au moins un polymère à base de diène conjugué, et contient une charge inorganique à base de silice en une quantité comprise entre 0 et 30 % en masse par rapport à la quantité totale de la charge. Dans les composants de caoutchouc, 10 % en masse ou plus de ceux-ci sont un polymère à base de diène conjugué modifié. Le polymère à base de diène conjugué modifié : (1) a une structure ramifiée de chaîne principale ayant une structure ramifiée dans la chaîne principale ; (2) comprend, dans la structure ramifiée de chaîne principale, une structure dérivée d'au moins un monomère à base de diène conjugué, ou une structure dérivée d'au moins un monomère à base de diène conjugué et une structure dérivée d'un monomère à base de vinyle aromatique ; (3) présente, au niveau d'au moins une terminaison, un groupe terminal ayant au moins un groupe carbonyle et au moins un groupe amino substitué par molécule ; (4) a une viscosité Mooney comprise entre 30 et120 telle que mesurée à 100°C ; (5) a un degré de ramification (Bn) supérieur ou égal à 1,1 mais inférieur à 4,0 tel que déterminé par un procédé de diffusion de lumière GPC fourni par un détecteur de viscosité ; (6) présente une forme de chromatographie ayant un pic unique tel que mesuré par chromatographie par perméation de gel (CPG) et a une distribution de poids moléculaire comprise entre 1,60 et 3,00 ; et (7) a un taux d'hydrogénation inférieur à 10 % en moles.
PCT/JP2025/010272 2024-03-28 2025-03-17 Composition de caoutchouc et composition de caoutchouc vulcanisé Pending WO2025205189A1 (fr)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2021152135A (ja) * 2019-12-12 2021-09-30 旭化成株式会社 分岐化共役ジエン系重合体の製造方法、ゴム組成物の製造方法、タイヤの製造方法、分岐化共役ジエン系重合体、及び分岐化共役ジエン系重合体組成物
JP2021167407A (ja) * 2020-04-08 2021-10-21 旭化成株式会社 共役ジエン系重合体及びその製造方法、並びにゴム組成物。

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2021152135A (ja) * 2019-12-12 2021-09-30 旭化成株式会社 分岐化共役ジエン系重合体の製造方法、ゴム組成物の製造方法、タイヤの製造方法、分岐化共役ジエン系重合体、及び分岐化共役ジエン系重合体組成物
JP2021167407A (ja) * 2020-04-08 2021-10-21 旭化成株式会社 共役ジエン系重合体及びその製造方法、並びにゴム組成物。

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